]>
Commit | Line | Data |
---|---|---|
80daa560 RZ |
1 | config ARCH |
2 | string | |
3 | option env="ARCH" | |
4 | ||
5 | config KERNELVERSION | |
6 | string | |
7 | option env="KERNELVERSION" | |
8 | ||
face4374 RZ |
9 | config DEFCONFIG_LIST |
10 | string | |
b2670eac | 11 | depends on !UML |
face4374 RZ |
12 | option defconfig_list |
13 | default "/lib/modules/$UNAME_RELEASE/.config" | |
14 | default "/etc/kernel-config" | |
15 | default "/boot/config-$UNAME_RELEASE" | |
73531905 | 16 | default "$ARCH_DEFCONFIG" |
face4374 RZ |
17 | default "arch/$ARCH/defconfig" |
18 | ||
b99b87f7 PO |
19 | config CONSTRUCTORS |
20 | bool | |
21 | depends on !UML | |
b99b87f7 | 22 | |
e360adbe PZ |
23 | config IRQ_WORK |
24 | bool | |
e360adbe | 25 | |
1dbdc6f1 DD |
26 | config BUILDTIME_EXTABLE_SORT |
27 | bool | |
28 | ||
c65eacbe AL |
29 | config THREAD_INFO_IN_TASK |
30 | bool | |
31 | help | |
32 | Select this to move thread_info off the stack into task_struct. To | |
33 | make this work, an arch will need to remove all thread_info fields | |
34 | except flags and fix any runtime bugs. | |
35 | ||
c6c314a6 AL |
36 | One subtle change that will be needed is to use try_get_task_stack() |
37 | and put_task_stack() in save_thread_stack_tsk() and get_wchan(). | |
38 | ||
ff0cfc66 | 39 | menu "General setup" |
1da177e4 | 40 | |
1da177e4 LT |
41 | config BROKEN |
42 | bool | |
1da177e4 LT |
43 | |
44 | config BROKEN_ON_SMP | |
45 | bool | |
46 | depends on BROKEN || !SMP | |
47 | default y | |
48 | ||
1da177e4 LT |
49 | config INIT_ENV_ARG_LIMIT |
50 | int | |
dd673bca AB |
51 | default 32 if !UML |
52 | default 128 if UML | |
1da177e4 | 53 | help |
34ad92c2 RD |
54 | Maximum of each of the number of arguments and environment |
55 | variables passed to init from the kernel command line. | |
1da177e4 | 56 | |
1da177e4 | 57 | |
84336466 RM |
58 | config CROSS_COMPILE |
59 | string "Cross-compiler tool prefix" | |
60 | help | |
61 | Same as running 'make CROSS_COMPILE=prefix-' but stored for | |
62 | default make runs in this kernel build directory. You don't | |
63 | need to set this unless you want the configured kernel build | |
64 | directory to select the cross-compiler automatically. | |
65 | ||
4bb16672 JS |
66 | config COMPILE_TEST |
67 | bool "Compile also drivers which will not load" | |
bc083a64 | 68 | depends on !UML |
4bb16672 JS |
69 | default n |
70 | help | |
71 | Some drivers can be compiled on a different platform than they are | |
72 | intended to be run on. Despite they cannot be loaded there (or even | |
73 | when they load they cannot be used due to missing HW support), | |
74 | developers still, opposing to distributors, might want to build such | |
75 | drivers to compile-test them. | |
76 | ||
77 | If you are a developer and want to build everything available, say Y | |
78 | here. If you are a user/distributor, say N here to exclude useless | |
79 | drivers to be distributed. | |
80 | ||
1da177e4 LT |
81 | config LOCALVERSION |
82 | string "Local version - append to kernel release" | |
83 | help | |
84 | Append an extra string to the end of your kernel version. | |
85 | This will show up when you type uname, for example. | |
86 | The string you set here will be appended after the contents of | |
87 | any files with a filename matching localversion* in your | |
88 | object and source tree, in that order. Your total string can | |
89 | be a maximum of 64 characters. | |
90 | ||
aaebf433 RA |
91 | config LOCALVERSION_AUTO |
92 | bool "Automatically append version information to the version string" | |
93 | default y | |
ac3339ba | 94 | depends on !COMPILE_TEST |
aaebf433 RA |
95 | help |
96 | This will try to automatically determine if the current tree is a | |
6e5a5420 RD |
97 | release tree by looking for git tags that belong to the current |
98 | top of tree revision. | |
aaebf433 RA |
99 | |
100 | A string of the format -gxxxxxxxx will be added to the localversion | |
6e5a5420 | 101 | if a git-based tree is found. The string generated by this will be |
aaebf433 | 102 | appended after any matching localversion* files, and after the value |
6e5a5420 | 103 | set in CONFIG_LOCALVERSION. |
aaebf433 | 104 | |
6e5a5420 RD |
105 | (The actual string used here is the first eight characters produced |
106 | by running the command: | |
107 | ||
108 | $ git rev-parse --verify HEAD | |
109 | ||
110 | which is done within the script "scripts/setlocalversion".) | |
aaebf433 | 111 | |
2e9f3bdd PA |
112 | config HAVE_KERNEL_GZIP |
113 | bool | |
114 | ||
115 | config HAVE_KERNEL_BZIP2 | |
116 | bool | |
117 | ||
118 | config HAVE_KERNEL_LZMA | |
119 | bool | |
120 | ||
3ebe1243 LC |
121 | config HAVE_KERNEL_XZ |
122 | bool | |
123 | ||
7dd65feb AT |
124 | config HAVE_KERNEL_LZO |
125 | bool | |
126 | ||
e76e1fdf KL |
127 | config HAVE_KERNEL_LZ4 |
128 | bool | |
129 | ||
30d65dbf | 130 | choice |
2e9f3bdd PA |
131 | prompt "Kernel compression mode" |
132 | default KERNEL_GZIP | |
2d3c6275 | 133 | depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 |
2e9f3bdd | 134 | help |
30d65dbf AK |
135 | The linux kernel is a kind of self-extracting executable. |
136 | Several compression algorithms are available, which differ | |
137 | in efficiency, compression and decompression speed. | |
138 | Compression speed is only relevant when building a kernel. | |
139 | Decompression speed is relevant at each boot. | |
140 | ||
141 | If you have any problems with bzip2 or lzma compressed | |
142 | kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older | |
143 | version of this functionality (bzip2 only), for 2.4, was | |
144 | supplied by Christian Ludwig) | |
145 | ||
146 | High compression options are mostly useful for users, who | |
147 | are low on disk space (embedded systems), but for whom ram | |
148 | size matters less. | |
149 | ||
150 | If in doubt, select 'gzip' | |
151 | ||
152 | config KERNEL_GZIP | |
2e9f3bdd PA |
153 | bool "Gzip" |
154 | depends on HAVE_KERNEL_GZIP | |
155 | help | |
7dd65feb AT |
156 | The old and tried gzip compression. It provides a good balance |
157 | between compression ratio and decompression speed. | |
30d65dbf AK |
158 | |
159 | config KERNEL_BZIP2 | |
160 | bool "Bzip2" | |
2e9f3bdd | 161 | depends on HAVE_KERNEL_BZIP2 |
30d65dbf AK |
162 | help |
163 | Its compression ratio and speed is intermediate. | |
0a4dd35c | 164 | Decompression speed is slowest among the choices. The kernel |
2e9f3bdd PA |
165 | size is about 10% smaller with bzip2, in comparison to gzip. |
166 | Bzip2 uses a large amount of memory. For modern kernels you | |
167 | will need at least 8MB RAM or more for booting. | |
30d65dbf AK |
168 | |
169 | config KERNEL_LZMA | |
2e9f3bdd PA |
170 | bool "LZMA" |
171 | depends on HAVE_KERNEL_LZMA | |
172 | help | |
0a4dd35c RD |
173 | This compression algorithm's ratio is best. Decompression speed |
174 | is between gzip and bzip2. Compression is slowest. | |
175 | The kernel size is about 33% smaller with LZMA in comparison to gzip. | |
30d65dbf | 176 | |
3ebe1243 LC |
177 | config KERNEL_XZ |
178 | bool "XZ" | |
179 | depends on HAVE_KERNEL_XZ | |
180 | help | |
181 | XZ uses the LZMA2 algorithm and instruction set specific | |
182 | BCJ filters which can improve compression ratio of executable | |
183 | code. The size of the kernel is about 30% smaller with XZ in | |
184 | comparison to gzip. On architectures for which there is a BCJ | |
185 | filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ | |
186 | will create a few percent smaller kernel than plain LZMA. | |
187 | ||
188 | The speed is about the same as with LZMA: The decompression | |
189 | speed of XZ is better than that of bzip2 but worse than gzip | |
190 | and LZO. Compression is slow. | |
191 | ||
7dd65feb AT |
192 | config KERNEL_LZO |
193 | bool "LZO" | |
194 | depends on HAVE_KERNEL_LZO | |
195 | help | |
0a4dd35c | 196 | Its compression ratio is the poorest among the choices. The kernel |
681b3049 | 197 | size is about 10% bigger than gzip; however its speed |
7dd65feb AT |
198 | (both compression and decompression) is the fastest. |
199 | ||
e76e1fdf KL |
200 | config KERNEL_LZ4 |
201 | bool "LZ4" | |
202 | depends on HAVE_KERNEL_LZ4 | |
203 | help | |
204 | LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding. | |
205 | A preliminary version of LZ4 de/compression tool is available at | |
206 | <https://code.google.com/p/lz4/>. | |
207 | ||
208 | Its compression ratio is worse than LZO. The size of the kernel | |
209 | is about 8% bigger than LZO. But the decompression speed is | |
210 | faster than LZO. | |
211 | ||
30d65dbf AK |
212 | endchoice |
213 | ||
bd5dc17b JT |
214 | config DEFAULT_HOSTNAME |
215 | string "Default hostname" | |
216 | default "(none)" | |
217 | help | |
218 | This option determines the default system hostname before userspace | |
219 | calls sethostname(2). The kernel traditionally uses "(none)" here, | |
220 | but you may wish to use a different default here to make a minimal | |
221 | system more usable with less configuration. | |
222 | ||
1da177e4 LT |
223 | config SWAP |
224 | bool "Support for paging of anonymous memory (swap)" | |
9361401e | 225 | depends on MMU && BLOCK |
1da177e4 LT |
226 | default y |
227 | help | |
228 | This option allows you to choose whether you want to have support | |
92c3504e | 229 | for so called swap devices or swap files in your kernel that are |
1da177e4 LT |
230 | used to provide more virtual memory than the actual RAM present |
231 | in your computer. If unsure say Y. | |
232 | ||
233 | config SYSVIPC | |
234 | bool "System V IPC" | |
1da177e4 LT |
235 | ---help--- |
236 | Inter Process Communication is a suite of library functions and | |
237 | system calls which let processes (running programs) synchronize and | |
238 | exchange information. It is generally considered to be a good thing, | |
239 | and some programs won't run unless you say Y here. In particular, if | |
240 | you want to run the DOS emulator dosemu under Linux (read the | |
241 | DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), | |
242 | you'll need to say Y here. | |
243 | ||
244 | You can find documentation about IPC with "info ipc" and also in | |
245 | section 6.4 of the Linux Programmer's Guide, available from | |
246 | <http://www.tldp.org/guides.html>. | |
247 | ||
a5494dcd EB |
248 | config SYSVIPC_SYSCTL |
249 | bool | |
250 | depends on SYSVIPC | |
251 | depends on SYSCTL | |
252 | default y | |
253 | ||
1da177e4 LT |
254 | config POSIX_MQUEUE |
255 | bool "POSIX Message Queues" | |
19c92399 | 256 | depends on NET |
1da177e4 LT |
257 | ---help--- |
258 | POSIX variant of message queues is a part of IPC. In POSIX message | |
259 | queues every message has a priority which decides about succession | |
260 | of receiving it by a process. If you want to compile and run | |
261 | programs written e.g. for Solaris with use of its POSIX message | |
b0e37650 | 262 | queues (functions mq_*) say Y here. |
1da177e4 LT |
263 | |
264 | POSIX message queues are visible as a filesystem called 'mqueue' | |
265 | and can be mounted somewhere if you want to do filesystem | |
266 | operations on message queues. | |
267 | ||
268 | If unsure, say Y. | |
269 | ||
bdc8e5f8 SH |
270 | config POSIX_MQUEUE_SYSCTL |
271 | bool | |
272 | depends on POSIX_MQUEUE | |
273 | depends on SYSCTL | |
274 | default y | |
275 | ||
226b4ccd KK |
276 | config CROSS_MEMORY_ATTACH |
277 | bool "Enable process_vm_readv/writev syscalls" | |
278 | depends on MMU | |
279 | default y | |
280 | help | |
281 | Enabling this option adds the system calls process_vm_readv and | |
282 | process_vm_writev which allow a process with the correct privileges | |
a2a368d9 | 283 | to directly read from or write to another process' address space. |
226b4ccd KK |
284 | See the man page for more details. |
285 | ||
69369a70 JT |
286 | config USELIB |
287 | bool "uselib syscall" | |
b2113a41 | 288 | def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION |
69369a70 JT |
289 | help |
290 | This option enables the uselib syscall, a system call used in the | |
291 | dynamic linker from libc5 and earlier. glibc does not use this | |
292 | system call. If you intend to run programs built on libc5 or | |
293 | earlier, you may need to enable this syscall. Current systems | |
294 | running glibc can safely disable this. | |
295 | ||
391dc69c FW |
296 | config AUDIT |
297 | bool "Auditing support" | |
298 | depends on NET | |
299 | help | |
300 | Enable auditing infrastructure that can be used with another | |
301 | kernel subsystem, such as SELinux (which requires this for | |
cb74ed27 PM |
302 | logging of avc messages output). System call auditing is included |
303 | on architectures which support it. | |
391dc69c | 304 | |
7a017721 AT |
305 | config HAVE_ARCH_AUDITSYSCALL |
306 | bool | |
307 | ||
391dc69c | 308 | config AUDITSYSCALL |
cb74ed27 | 309 | def_bool y |
7a017721 | 310 | depends on AUDIT && HAVE_ARCH_AUDITSYSCALL |
391dc69c FW |
311 | |
312 | config AUDIT_WATCH | |
313 | def_bool y | |
314 | depends on AUDITSYSCALL | |
315 | select FSNOTIFY | |
316 | ||
317 | config AUDIT_TREE | |
318 | def_bool y | |
319 | depends on AUDITSYSCALL | |
320 | select FSNOTIFY | |
321 | ||
391dc69c FW |
322 | source "kernel/irq/Kconfig" |
323 | source "kernel/time/Kconfig" | |
324 | ||
325 | menu "CPU/Task time and stats accounting" | |
326 | ||
abf917cd FW |
327 | config VIRT_CPU_ACCOUNTING |
328 | bool | |
329 | ||
fdf9c356 FW |
330 | choice |
331 | prompt "Cputime accounting" | |
332 | default TICK_CPU_ACCOUNTING if !PPC64 | |
02fc8d37 | 333 | default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 |
fdf9c356 FW |
334 | |
335 | # Kind of a stub config for the pure tick based cputime accounting | |
336 | config TICK_CPU_ACCOUNTING | |
337 | bool "Simple tick based cputime accounting" | |
c58b0df1 | 338 | depends on !S390 && !NO_HZ_FULL |
fdf9c356 FW |
339 | help |
340 | This is the basic tick based cputime accounting that maintains | |
341 | statistics about user, system and idle time spent on per jiffies | |
342 | granularity. | |
343 | ||
344 | If unsure, say Y. | |
345 | ||
abf917cd | 346 | config VIRT_CPU_ACCOUNTING_NATIVE |
b952741c | 347 | bool "Deterministic task and CPU time accounting" |
c58b0df1 | 348 | depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL |
abf917cd | 349 | select VIRT_CPU_ACCOUNTING |
b952741c FW |
350 | help |
351 | Select this option to enable more accurate task and CPU time | |
352 | accounting. This is done by reading a CPU counter on each | |
353 | kernel entry and exit and on transitions within the kernel | |
354 | between system, softirq and hardirq state, so there is a | |
355 | small performance impact. In the case of s390 or IBM POWER > 5, | |
356 | this also enables accounting of stolen time on logically-partitioned | |
357 | systems. | |
358 | ||
abf917cd FW |
359 | config VIRT_CPU_ACCOUNTING_GEN |
360 | bool "Full dynticks CPU time accounting" | |
ff3fb254 | 361 | depends on HAVE_CONTEXT_TRACKING |
554b0004 | 362 | depends on HAVE_VIRT_CPU_ACCOUNTING_GEN |
abf917cd FW |
363 | select VIRT_CPU_ACCOUNTING |
364 | select CONTEXT_TRACKING | |
365 | help | |
366 | Select this option to enable task and CPU time accounting on full | |
367 | dynticks systems. This accounting is implemented by watching every | |
368 | kernel-user boundaries using the context tracking subsystem. | |
369 | The accounting is thus performed at the expense of some significant | |
370 | overhead. | |
371 | ||
372 | For now this is only useful if you are working on the full | |
373 | dynticks subsystem development. | |
374 | ||
375 | If unsure, say N. | |
376 | ||
b58c3584 RR |
377 | endchoice |
378 | ||
fdf9c356 FW |
379 | config IRQ_TIME_ACCOUNTING |
380 | bool "Fine granularity task level IRQ time accounting" | |
b58c3584 | 381 | depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE |
fdf9c356 FW |
382 | help |
383 | Select this option to enable fine granularity task irq time | |
384 | accounting. This is done by reading a timestamp on each | |
385 | transitions between softirq and hardirq state, so there can be a | |
386 | small performance impact. | |
387 | ||
388 | If in doubt, say N here. | |
389 | ||
1da177e4 LT |
390 | config BSD_PROCESS_ACCT |
391 | bool "BSD Process Accounting" | |
2813893f | 392 | depends on MULTIUSER |
1da177e4 LT |
393 | help |
394 | If you say Y here, a user level program will be able to instruct the | |
395 | kernel (via a special system call) to write process accounting | |
396 | information to a file: whenever a process exits, information about | |
397 | that process will be appended to the file by the kernel. The | |
398 | information includes things such as creation time, owning user, | |
399 | command name, memory usage, controlling terminal etc. (the complete | |
400 | list is in the struct acct in <file:include/linux/acct.h>). It is | |
401 | up to the user level program to do useful things with this | |
402 | information. This is generally a good idea, so say Y. | |
403 | ||
404 | config BSD_PROCESS_ACCT_V3 | |
405 | bool "BSD Process Accounting version 3 file format" | |
406 | depends on BSD_PROCESS_ACCT | |
407 | default n | |
408 | help | |
409 | If you say Y here, the process accounting information is written | |
410 | in a new file format that also logs the process IDs of each | |
411 | process and it's parent. Note that this file format is incompatible | |
412 | with previous v0/v1/v2 file formats, so you will need updated tools | |
413 | for processing it. A preliminary version of these tools is available | |
37a4c940 | 414 | at <http://www.gnu.org/software/acct/>. |
1da177e4 | 415 | |
c757249a | 416 | config TASKSTATS |
19c92399 | 417 | bool "Export task/process statistics through netlink" |
c757249a | 418 | depends on NET |
2813893f | 419 | depends on MULTIUSER |
c757249a SN |
420 | default n |
421 | help | |
422 | Export selected statistics for tasks/processes through the | |
423 | generic netlink interface. Unlike BSD process accounting, the | |
424 | statistics are available during the lifetime of tasks/processes as | |
425 | responses to commands. Like BSD accounting, they are sent to user | |
426 | space on task exit. | |
427 | ||
428 | Say N if unsure. | |
429 | ||
ca74e92b | 430 | config TASK_DELAY_ACCT |
19c92399 | 431 | bool "Enable per-task delay accounting" |
6f44993f | 432 | depends on TASKSTATS |
f6db8347 | 433 | select SCHED_INFO |
ca74e92b SN |
434 | help |
435 | Collect information on time spent by a task waiting for system | |
436 | resources like cpu, synchronous block I/O completion and swapping | |
437 | in pages. Such statistics can help in setting a task's priorities | |
438 | relative to other tasks for cpu, io, rss limits etc. | |
439 | ||
440 | Say N if unsure. | |
441 | ||
18f705f4 | 442 | config TASK_XACCT |
19c92399 | 443 | bool "Enable extended accounting over taskstats" |
18f705f4 AD |
444 | depends on TASKSTATS |
445 | help | |
446 | Collect extended task accounting data and send the data | |
447 | to userland for processing over the taskstats interface. | |
448 | ||
449 | Say N if unsure. | |
450 | ||
451 | config TASK_IO_ACCOUNTING | |
19c92399 | 452 | bool "Enable per-task storage I/O accounting" |
18f705f4 AD |
453 | depends on TASK_XACCT |
454 | help | |
455 | Collect information on the number of bytes of storage I/O which this | |
456 | task has caused. | |
457 | ||
458 | Say N if unsure. | |
459 | ||
391dc69c | 460 | endmenu # "CPU/Task time and stats accounting" |
d9817ebe | 461 | |
5c4991e2 FW |
462 | config CPU_ISOLATION |
463 | bool "CPU isolation" | |
414a2dc1 | 464 | depends on SMP || COMPILE_TEST |
2c43838c | 465 | default y |
5c4991e2 FW |
466 | help |
467 | Make sure that CPUs running critical tasks are not disturbed by | |
468 | any source of "noise" such as unbound workqueues, timers, kthreads... | |
2c43838c FW |
469 | Unbound jobs get offloaded to housekeeping CPUs. This is driven by |
470 | the "isolcpus=" boot parameter. | |
471 | ||
472 | Say Y if unsure. | |
5c4991e2 | 473 | |
0af92d46 | 474 | source "kernel/rcu/Kconfig" |
c903ff83 | 475 | |
de5b56ba VG |
476 | config BUILD_BIN2C |
477 | bool | |
478 | default n | |
479 | ||
1da177e4 | 480 | config IKCONFIG |
f2443ab6 | 481 | tristate "Kernel .config support" |
de5b56ba | 482 | select BUILD_BIN2C |
1da177e4 LT |
483 | ---help--- |
484 | This option enables the complete Linux kernel ".config" file | |
485 | contents to be saved in the kernel. It provides documentation | |
486 | of which kernel options are used in a running kernel or in an | |
487 | on-disk kernel. This information can be extracted from the kernel | |
488 | image file with the script scripts/extract-ikconfig and used as | |
489 | input to rebuild the current kernel or to build another kernel. | |
490 | It can also be extracted from a running kernel by reading | |
491 | /proc/config.gz if enabled (below). | |
492 | ||
493 | config IKCONFIG_PROC | |
494 | bool "Enable access to .config through /proc/config.gz" | |
495 | depends on IKCONFIG && PROC_FS | |
496 | ---help--- | |
497 | This option enables access to the kernel configuration file | |
498 | through /proc/config.gz. | |
499 | ||
794543a2 AJS |
500 | config LOG_BUF_SHIFT |
501 | int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" | |
fb39f98d | 502 | range 12 25 |
f17a32e9 | 503 | default 17 |
361e9dfb | 504 | depends on PRINTK |
794543a2 | 505 | help |
23b2899f LR |
506 | Select the minimal kernel log buffer size as a power of 2. |
507 | The final size is affected by LOG_CPU_MAX_BUF_SHIFT config | |
508 | parameter, see below. Any higher size also might be forced | |
509 | by "log_buf_len" boot parameter. | |
510 | ||
f17a32e9 | 511 | Examples: |
23b2899f | 512 | 17 => 128 KB |
f17a32e9 | 513 | 16 => 64 KB |
23b2899f LR |
514 | 15 => 32 KB |
515 | 14 => 16 KB | |
794543a2 AJS |
516 | 13 => 8 KB |
517 | 12 => 4 KB | |
518 | ||
23b2899f LR |
519 | config LOG_CPU_MAX_BUF_SHIFT |
520 | int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" | |
2240a31d | 521 | depends on SMP |
23b2899f LR |
522 | range 0 21 |
523 | default 12 if !BASE_SMALL | |
524 | default 0 if BASE_SMALL | |
361e9dfb | 525 | depends on PRINTK |
23b2899f LR |
526 | help |
527 | This option allows to increase the default ring buffer size | |
528 | according to the number of CPUs. The value defines the contribution | |
529 | of each CPU as a power of 2. The used space is typically only few | |
530 | lines however it might be much more when problems are reported, | |
531 | e.g. backtraces. | |
532 | ||
533 | The increased size means that a new buffer has to be allocated and | |
534 | the original static one is unused. It makes sense only on systems | |
535 | with more CPUs. Therefore this value is used only when the sum of | |
536 | contributions is greater than the half of the default kernel ring | |
537 | buffer as defined by LOG_BUF_SHIFT. The default values are set | |
538 | so that more than 64 CPUs are needed to trigger the allocation. | |
539 | ||
540 | Also this option is ignored when "log_buf_len" kernel parameter is | |
541 | used as it forces an exact (power of two) size of the ring buffer. | |
542 | ||
543 | The number of possible CPUs is used for this computation ignoring | |
5e0d8d59 GU |
544 | hotplugging making the computation optimal for the worst case |
545 | scenario while allowing a simple algorithm to be used from bootup. | |
23b2899f LR |
546 | |
547 | Examples shift values and their meaning: | |
548 | 17 => 128 KB for each CPU | |
549 | 16 => 64 KB for each CPU | |
550 | 15 => 32 KB for each CPU | |
551 | 14 => 16 KB for each CPU | |
552 | 13 => 8 KB for each CPU | |
553 | 12 => 4 KB for each CPU | |
554 | ||
f92bac3b SS |
555 | config PRINTK_SAFE_LOG_BUF_SHIFT |
556 | int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" | |
427934b8 PM |
557 | range 10 21 |
558 | default 13 | |
f92bac3b | 559 | depends on PRINTK |
427934b8 | 560 | help |
f92bac3b SS |
561 | Select the size of an alternate printk per-CPU buffer where messages |
562 | printed from usafe contexts are temporary stored. One example would | |
563 | be NMI messages, another one - printk recursion. The messages are | |
564 | copied to the main log buffer in a safe context to avoid a deadlock. | |
565 | The value defines the size as a power of 2. | |
427934b8 | 566 | |
f92bac3b | 567 | Those messages are rare and limited. The largest one is when |
427934b8 PM |
568 | a backtrace is printed. It usually fits into 4KB. Select |
569 | 8KB if you want to be on the safe side. | |
570 | ||
571 | Examples: | |
572 | 17 => 128 KB for each CPU | |
573 | 16 => 64 KB for each CPU | |
574 | 15 => 32 KB for each CPU | |
575 | 14 => 16 KB for each CPU | |
576 | 13 => 8 KB for each CPU | |
577 | 12 => 4 KB for each CPU | |
578 | ||
a5574cf6 IM |
579 | # |
580 | # Architectures with an unreliable sched_clock() should select this: | |
581 | # | |
582 | config HAVE_UNSTABLE_SCHED_CLOCK | |
583 | bool | |
584 | ||
38ff87f7 SB |
585 | config GENERIC_SCHED_CLOCK |
586 | bool | |
587 | ||
be3a7284 AA |
588 | # |
589 | # For architectures that want to enable the support for NUMA-affine scheduler | |
590 | # balancing logic: | |
591 | # | |
592 | config ARCH_SUPPORTS_NUMA_BALANCING | |
593 | bool | |
594 | ||
72b252ae MG |
595 | # |
596 | # For architectures that prefer to flush all TLBs after a number of pages | |
597 | # are unmapped instead of sending one IPI per page to flush. The architecture | |
598 | # must provide guarantees on what happens if a clean TLB cache entry is | |
599 | # written after the unmap. Details are in mm/rmap.c near the check for | |
600 | # should_defer_flush. The architecture should also consider if the full flush | |
601 | # and the refill costs are offset by the savings of sending fewer IPIs. | |
602 | config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH | |
603 | bool | |
604 | ||
be5e610c PZ |
605 | # |
606 | # For architectures that know their GCC __int128 support is sound | |
607 | # | |
608 | config ARCH_SUPPORTS_INT128 | |
609 | bool | |
610 | ||
be3a7284 AA |
611 | # For architectures that (ab)use NUMA to represent different memory regions |
612 | # all cpu-local but of different latencies, such as SuperH. | |
613 | # | |
614 | config ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
615 | bool | |
616 | ||
be3a7284 AA |
617 | config NUMA_BALANCING |
618 | bool "Memory placement aware NUMA scheduler" | |
be3a7284 AA |
619 | depends on ARCH_SUPPORTS_NUMA_BALANCING |
620 | depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY | |
621 | depends on SMP && NUMA && MIGRATION | |
622 | help | |
623 | This option adds support for automatic NUMA aware memory/task placement. | |
624 | The mechanism is quite primitive and is based on migrating memory when | |
6d56a410 | 625 | it has references to the node the task is running on. |
be3a7284 AA |
626 | |
627 | This system will be inactive on UMA systems. | |
628 | ||
6f7c97e8 AK |
629 | config NUMA_BALANCING_DEFAULT_ENABLED |
630 | bool "Automatically enable NUMA aware memory/task placement" | |
631 | default y | |
632 | depends on NUMA_BALANCING | |
633 | help | |
634 | If set, automatic NUMA balancing will be enabled if running on a NUMA | |
635 | machine. | |
636 | ||
23964d2d | 637 | menuconfig CGROUPS |
6341e62b | 638 | bool "Control Group support" |
2bd59d48 | 639 | select KERNFS |
5cdc38f9 | 640 | help |
23964d2d | 641 | This option adds support for grouping sets of processes together, for |
5cdc38f9 KH |
642 | use with process control subsystems such as Cpusets, CFS, memory |
643 | controls or device isolation. | |
644 | See | |
5cdc38f9 | 645 | - Documentation/scheduler/sched-design-CFS.txt (CFS) |
9991a9c8 | 646 | - Documentation/cgroup-v1/ (features for grouping, isolation |
45ce80fb | 647 | and resource control) |
5cdc38f9 KH |
648 | |
649 | Say N if unsure. | |
650 | ||
23964d2d LZ |
651 | if CGROUPS |
652 | ||
3e32cb2e JW |
653 | config PAGE_COUNTER |
654 | bool | |
655 | ||
c255a458 | 656 | config MEMCG |
a0166ec4 | 657 | bool "Memory controller" |
3e32cb2e | 658 | select PAGE_COUNTER |
79bd9814 | 659 | select EVENTFD |
00f0b825 | 660 | help |
a0166ec4 | 661 | Provides control over the memory footprint of tasks in a cgroup. |
00f0b825 | 662 | |
c255a458 | 663 | config MEMCG_SWAP |
a0166ec4 | 664 | bool "Swap controller" |
c255a458 | 665 | depends on MEMCG && SWAP |
c077719b | 666 | help |
a0166ec4 JW |
667 | Provides control over the swap space consumed by tasks in a cgroup. |
668 | ||
c255a458 | 669 | config MEMCG_SWAP_ENABLED |
a0166ec4 | 670 | bool "Swap controller enabled by default" |
c255a458 | 671 | depends on MEMCG_SWAP |
a42c390c MH |
672 | default y |
673 | help | |
674 | Memory Resource Controller Swap Extension comes with its price in | |
675 | a bigger memory consumption. General purpose distribution kernels | |
43d547f9 | 676 | which want to enable the feature but keep it disabled by default |
07555ac1 | 677 | and let the user enable it by swapaccount=1 boot command line |
a42c390c MH |
678 | parameter should have this option unselected. |
679 | For those who want to have the feature enabled by default should | |
680 | select this option (if, for some reason, they need to disable it | |
00a66d29 | 681 | then swapaccount=0 does the trick). |
c077719b | 682 | |
6bf024e6 JW |
683 | config BLK_CGROUP |
684 | bool "IO controller" | |
685 | depends on BLOCK | |
2bc64a20 | 686 | default n |
6bf024e6 JW |
687 | ---help--- |
688 | Generic block IO controller cgroup interface. This is the common | |
689 | cgroup interface which should be used by various IO controlling | |
690 | policies. | |
2bc64a20 | 691 | |
6bf024e6 JW |
692 | Currently, CFQ IO scheduler uses it to recognize task groups and |
693 | control disk bandwidth allocation (proportional time slice allocation) | |
694 | to such task groups. It is also used by bio throttling logic in | |
695 | block layer to implement upper limit in IO rates on a device. | |
e5d1367f | 696 | |
6bf024e6 JW |
697 | This option only enables generic Block IO controller infrastructure. |
698 | One needs to also enable actual IO controlling logic/policy. For | |
699 | enabling proportional weight division of disk bandwidth in CFQ, set | |
700 | CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set | |
701 | CONFIG_BLK_DEV_THROTTLING=y. | |
702 | ||
9991a9c8 | 703 | See Documentation/cgroup-v1/blkio-controller.txt for more information. |
6bf024e6 JW |
704 | |
705 | config DEBUG_BLK_CGROUP | |
706 | bool "IO controller debugging" | |
707 | depends on BLK_CGROUP | |
708 | default n | |
709 | ---help--- | |
710 | Enable some debugging help. Currently it exports additional stat | |
711 | files in a cgroup which can be useful for debugging. | |
712 | ||
713 | config CGROUP_WRITEBACK | |
714 | bool | |
715 | depends on MEMCG && BLK_CGROUP | |
716 | default y | |
e5d1367f | 717 | |
7c941438 | 718 | menuconfig CGROUP_SCHED |
a0166ec4 | 719 | bool "CPU controller" |
7c941438 DG |
720 | default n |
721 | help | |
722 | This feature lets CPU scheduler recognize task groups and control CPU | |
723 | bandwidth allocation to such task groups. It uses cgroups to group | |
724 | tasks. | |
725 | ||
726 | if CGROUP_SCHED | |
727 | config FAIR_GROUP_SCHED | |
728 | bool "Group scheduling for SCHED_OTHER" | |
729 | depends on CGROUP_SCHED | |
730 | default CGROUP_SCHED | |
731 | ||
ab84d31e PT |
732 | config CFS_BANDWIDTH |
733 | bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" | |
ab84d31e PT |
734 | depends on FAIR_GROUP_SCHED |
735 | default n | |
736 | help | |
737 | This option allows users to define CPU bandwidth rates (limits) for | |
738 | tasks running within the fair group scheduler. Groups with no limit | |
739 | set are considered to be unconstrained and will run with no | |
740 | restriction. | |
741 | See tip/Documentation/scheduler/sched-bwc.txt for more information. | |
742 | ||
7c941438 DG |
743 | config RT_GROUP_SCHED |
744 | bool "Group scheduling for SCHED_RR/FIFO" | |
7c941438 DG |
745 | depends on CGROUP_SCHED |
746 | default n | |
747 | help | |
748 | This feature lets you explicitly allocate real CPU bandwidth | |
32bd7eb5 | 749 | to task groups. If enabled, it will also make it impossible to |
7c941438 DG |
750 | schedule realtime tasks for non-root users until you allocate |
751 | realtime bandwidth for them. | |
752 | See Documentation/scheduler/sched-rt-group.txt for more information. | |
753 | ||
754 | endif #CGROUP_SCHED | |
755 | ||
6bf024e6 JW |
756 | config CGROUP_PIDS |
757 | bool "PIDs controller" | |
758 | help | |
759 | Provides enforcement of process number limits in the scope of a | |
760 | cgroup. Any attempt to fork more processes than is allowed in the | |
761 | cgroup will fail. PIDs are fundamentally a global resource because it | |
762 | is fairly trivial to reach PID exhaustion before you reach even a | |
763 | conservative kmemcg limit. As a result, it is possible to grind a | |
764 | system to halt without being limited by other cgroup policies. The | |
6cc578df | 765 | PIDs controller is designed to stop this from happening. |
6bf024e6 JW |
766 | |
767 | It should be noted that organisational operations (such as attaching | |
6cc578df | 768 | to a cgroup hierarchy will *not* be blocked by the PIDs controller), |
6bf024e6 JW |
769 | since the PIDs limit only affects a process's ability to fork, not to |
770 | attach to a cgroup. | |
771 | ||
39d3e758 PP |
772 | config CGROUP_RDMA |
773 | bool "RDMA controller" | |
774 | help | |
775 | Provides enforcement of RDMA resources defined by IB stack. | |
776 | It is fairly easy for consumers to exhaust RDMA resources, which | |
777 | can result into resource unavailability to other consumers. | |
778 | RDMA controller is designed to stop this from happening. | |
779 | Attaching processes with active RDMA resources to the cgroup | |
780 | hierarchy is allowed even if can cross the hierarchy's limit. | |
781 | ||
6bf024e6 JW |
782 | config CGROUP_FREEZER |
783 | bool "Freezer controller" | |
784 | help | |
785 | Provides a way to freeze and unfreeze all tasks in a | |
786 | cgroup. | |
787 | ||
489c2a20 JW |
788 | This option affects the ORIGINAL cgroup interface. The cgroup2 memory |
789 | controller includes important in-kernel memory consumers per default. | |
790 | ||
791 | If you're using cgroup2, say N. | |
792 | ||
6bf024e6 JW |
793 | config CGROUP_HUGETLB |
794 | bool "HugeTLB controller" | |
795 | depends on HUGETLB_PAGE | |
796 | select PAGE_COUNTER | |
afc24d49 | 797 | default n |
6bf024e6 JW |
798 | help |
799 | Provides a cgroup controller for HugeTLB pages. | |
800 | When you enable this, you can put a per cgroup limit on HugeTLB usage. | |
801 | The limit is enforced during page fault. Since HugeTLB doesn't | |
802 | support page reclaim, enforcing the limit at page fault time implies | |
803 | that, the application will get SIGBUS signal if it tries to access | |
804 | HugeTLB pages beyond its limit. This requires the application to know | |
805 | beforehand how much HugeTLB pages it would require for its use. The | |
806 | control group is tracked in the third page lru pointer. This means | |
807 | that we cannot use the controller with huge page less than 3 pages. | |
afc24d49 | 808 | |
6bf024e6 JW |
809 | config CPUSETS |
810 | bool "Cpuset controller" | |
e1d4eeec | 811 | depends on SMP |
6bf024e6 JW |
812 | help |
813 | This option will let you create and manage CPUSETs which | |
814 | allow dynamically partitioning a system into sets of CPUs and | |
815 | Memory Nodes and assigning tasks to run only within those sets. | |
816 | This is primarily useful on large SMP or NUMA systems. | |
afc24d49 | 817 | |
6bf024e6 | 818 | Say N if unsure. |
afc24d49 | 819 | |
6bf024e6 JW |
820 | config PROC_PID_CPUSET |
821 | bool "Include legacy /proc/<pid>/cpuset file" | |
822 | depends on CPUSETS | |
823 | default y | |
afc24d49 | 824 | |
6bf024e6 JW |
825 | config CGROUP_DEVICE |
826 | bool "Device controller" | |
827 | help | |
828 | Provides a cgroup controller implementing whitelists for | |
829 | devices which a process in the cgroup can mknod or open. | |
830 | ||
831 | config CGROUP_CPUACCT | |
832 | bool "Simple CPU accounting controller" | |
833 | help | |
834 | Provides a simple controller for monitoring the | |
835 | total CPU consumed by the tasks in a cgroup. | |
836 | ||
837 | config CGROUP_PERF | |
838 | bool "Perf controller" | |
839 | depends on PERF_EVENTS | |
840 | help | |
841 | This option extends the perf per-cpu mode to restrict monitoring | |
842 | to threads which belong to the cgroup specified and run on the | |
843 | designated cpu. | |
844 | ||
845 | Say N if unsure. | |
846 | ||
30070984 DM |
847 | config CGROUP_BPF |
848 | bool "Support for eBPF programs attached to cgroups" | |
483c4933 AL |
849 | depends on BPF_SYSCALL |
850 | select SOCK_CGROUP_DATA | |
30070984 DM |
851 | help |
852 | Allow attaching eBPF programs to a cgroup using the bpf(2) | |
853 | syscall command BPF_PROG_ATTACH. | |
854 | ||
855 | In which context these programs are accessed depends on the type | |
856 | of attachment. For instance, programs that are attached using | |
857 | BPF_CGROUP_INET_INGRESS will be executed on the ingress path of | |
858 | inet sockets. | |
859 | ||
6bf024e6 | 860 | config CGROUP_DEBUG |
23b0be48 | 861 | bool "Debug controller" |
afc24d49 | 862 | default n |
23b0be48 | 863 | depends on DEBUG_KERNEL |
6bf024e6 JW |
864 | help |
865 | This option enables a simple controller that exports | |
23b0be48 WL |
866 | debugging information about the cgroups framework. This |
867 | controller is for control cgroup debugging only. Its | |
868 | interfaces are not stable. | |
afc24d49 | 869 | |
6bf024e6 | 870 | Say N. |
89e9b9e0 | 871 | |
73b35147 AB |
872 | config SOCK_CGROUP_DATA |
873 | bool | |
874 | default n | |
875 | ||
23964d2d | 876 | endif # CGROUPS |
c077719b | 877 | |
8dd2a82c | 878 | menuconfig NAMESPACES |
6a108a14 | 879 | bool "Namespaces support" if EXPERT |
2813893f | 880 | depends on MULTIUSER |
6a108a14 | 881 | default !EXPERT |
c5289a69 PE |
882 | help |
883 | Provides the way to make tasks work with different objects using | |
884 | the same id. For example same IPC id may refer to different objects | |
885 | or same user id or pid may refer to different tasks when used in | |
886 | different namespaces. | |
887 | ||
8dd2a82c DL |
888 | if NAMESPACES |
889 | ||
58bfdd6d PE |
890 | config UTS_NS |
891 | bool "UTS namespace" | |
17a6d441 | 892 | default y |
58bfdd6d PE |
893 | help |
894 | In this namespace tasks see different info provided with the | |
895 | uname() system call | |
896 | ||
ae5e1b22 PE |
897 | config IPC_NS |
898 | bool "IPC namespace" | |
8dd2a82c | 899 | depends on (SYSVIPC || POSIX_MQUEUE) |
17a6d441 | 900 | default y |
ae5e1b22 PE |
901 | help |
902 | In this namespace tasks work with IPC ids which correspond to | |
614b84cf | 903 | different IPC objects in different namespaces. |
ae5e1b22 | 904 | |
aee16ce7 | 905 | config USER_NS |
19c92399 | 906 | bool "User namespace" |
5673a94c | 907 | default n |
aee16ce7 PE |
908 | help |
909 | This allows containers, i.e. vservers, to use user namespaces | |
910 | to provide different user info for different servers. | |
e11f0ae3 EB |
911 | |
912 | When user namespaces are enabled in the kernel it is | |
d886f4e4 JW |
913 | recommended that the MEMCG option also be enabled and that |
914 | user-space use the memory control groups to limit the amount | |
915 | of memory a memory unprivileged users can use. | |
e11f0ae3 | 916 | |
aee16ce7 PE |
917 | If unsure, say N. |
918 | ||
74bd59bb | 919 | config PID_NS |
9bd38c2c | 920 | bool "PID Namespaces" |
17a6d441 | 921 | default y |
74bd59bb | 922 | help |
12d2b8f9 | 923 | Support process id namespaces. This allows having multiple |
692105b8 | 924 | processes with the same pid as long as they are in different |
74bd59bb PE |
925 | pid namespaces. This is a building block of containers. |
926 | ||
d6eb633f MH |
927 | config NET_NS |
928 | bool "Network namespace" | |
8dd2a82c | 929 | depends on NET |
17a6d441 | 930 | default y |
d6eb633f MH |
931 | help |
932 | Allow user space to create what appear to be multiple instances | |
933 | of the network stack. | |
934 | ||
8dd2a82c DL |
935 | endif # NAMESPACES |
936 | ||
5091faa4 MG |
937 | config SCHED_AUTOGROUP |
938 | bool "Automatic process group scheduling" | |
5091faa4 MG |
939 | select CGROUPS |
940 | select CGROUP_SCHED | |
941 | select FAIR_GROUP_SCHED | |
942 | help | |
943 | This option optimizes the scheduler for common desktop workloads by | |
944 | automatically creating and populating task groups. This separation | |
945 | of workloads isolates aggressive CPU burners (like build jobs) from | |
946 | desktop applications. Task group autogeneration is currently based | |
947 | upon task session. | |
948 | ||
7af37bec | 949 | config SYSFS_DEPRECATED |
5d6a4ea5 | 950 | bool "Enable deprecated sysfs features to support old userspace tools" |
7af37bec DL |
951 | depends on SYSFS |
952 | default n | |
953 | help | |
954 | This option adds code that switches the layout of the "block" class | |
955 | devices, to not show up in /sys/class/block/, but only in | |
956 | /sys/block/. | |
957 | ||
958 | This switch is only active when the sysfs.deprecated=1 boot option is | |
959 | passed or the SYSFS_DEPRECATED_V2 option is set. | |
960 | ||
961 | This option allows new kernels to run on old distributions and tools, | |
962 | which might get confused by /sys/class/block/. Since 2007/2008 all | |
963 | major distributions and tools handle this just fine. | |
964 | ||
965 | Recent distributions and userspace tools after 2009/2010 depend on | |
966 | the existence of /sys/class/block/, and will not work with this | |
967 | option enabled. | |
968 | ||
969 | Only if you are using a new kernel on an old distribution, you might | |
970 | need to say Y here. | |
971 | ||
972 | config SYSFS_DEPRECATED_V2 | |
5d6a4ea5 | 973 | bool "Enable deprecated sysfs features by default" |
7af37bec DL |
974 | default n |
975 | depends on SYSFS | |
976 | depends on SYSFS_DEPRECATED | |
977 | help | |
978 | Enable deprecated sysfs by default. | |
979 | ||
980 | See the CONFIG_SYSFS_DEPRECATED option for more details about this | |
981 | option. | |
982 | ||
983 | Only if you are using a new kernel on an old distribution, you might | |
984 | need to say Y here. Even then, odds are you would not need it | |
985 | enabled, you can always pass the boot option if absolutely necessary. | |
986 | ||
987 | config RELAY | |
988 | bool "Kernel->user space relay support (formerly relayfs)" | |
26b5679e | 989 | select IRQ_WORK |
7af37bec DL |
990 | help |
991 | This option enables support for relay interface support in | |
992 | certain file systems (such as debugfs). | |
993 | It is designed to provide an efficient mechanism for tools and | |
994 | facilities to relay large amounts of data from kernel space to | |
995 | user space. | |
996 | ||
997 | If unsure, say N. | |
998 | ||
f991633d DG |
999 | config BLK_DEV_INITRD |
1000 | bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" | |
f991633d DG |
1001 | help |
1002 | The initial RAM filesystem is a ramfs which is loaded by the | |
1003 | boot loader (loadlin or lilo) and that is mounted as root | |
1004 | before the normal boot procedure. It is typically used to | |
1005 | load modules needed to mount the "real" root file system, | |
8c27ceff | 1006 | etc. See <file:Documentation/admin-guide/initrd.rst> for details. |
f991633d DG |
1007 | |
1008 | If RAM disk support (BLK_DEV_RAM) is also included, this | |
1009 | also enables initial RAM disk (initrd) support and adds | |
1010 | 15 Kbytes (more on some other architectures) to the kernel size. | |
1011 | ||
1012 | If unsure say Y. | |
1013 | ||
c33df4ea JPS |
1014 | if BLK_DEV_INITRD |
1015 | ||
dbec4866 SR |
1016 | source "usr/Kconfig" |
1017 | ||
c33df4ea JPS |
1018 | endif |
1019 | ||
877417e6 AB |
1020 | choice |
1021 | prompt "Compiler optimization level" | |
2cc3ce24 | 1022 | default CC_OPTIMIZE_FOR_PERFORMANCE |
877417e6 AB |
1023 | |
1024 | config CC_OPTIMIZE_FOR_PERFORMANCE | |
1025 | bool "Optimize for performance" | |
1026 | help | |
1027 | This is the default optimization level for the kernel, building | |
1028 | with the "-O2" compiler flag for best performance and most | |
1029 | helpful compile-time warnings. | |
1030 | ||
c45b4f1f | 1031 | config CC_OPTIMIZE_FOR_SIZE |
96fffeb4 | 1032 | bool "Optimize for size" |
c45b4f1f | 1033 | help |
31a4af7f MY |
1034 | Enabling this option will pass "-Os" instead of "-O2" to |
1035 | your compiler resulting in a smaller kernel. | |
c45b4f1f | 1036 | |
3a55fb0d | 1037 | If unsure, say N. |
c45b4f1f | 1038 | |
877417e6 AB |
1039 | endchoice |
1040 | ||
0847062a RD |
1041 | config SYSCTL |
1042 | bool | |
1043 | ||
b943c460 RD |
1044 | config ANON_INODES |
1045 | bool | |
1046 | ||
657a5209 MF |
1047 | config HAVE_UID16 |
1048 | bool | |
1049 | ||
1050 | config SYSCTL_EXCEPTION_TRACE | |
1051 | bool | |
1052 | help | |
1053 | Enable support for /proc/sys/debug/exception-trace. | |
1054 | ||
1055 | config SYSCTL_ARCH_UNALIGN_NO_WARN | |
1056 | bool | |
1057 | help | |
1058 | Enable support for /proc/sys/kernel/ignore-unaligned-usertrap | |
1059 | Allows arch to define/use @no_unaligned_warning to possibly warn | |
1060 | about unaligned access emulation going on under the hood. | |
1061 | ||
1062 | config SYSCTL_ARCH_UNALIGN_ALLOW | |
1063 | bool | |
1064 | help | |
1065 | Enable support for /proc/sys/kernel/unaligned-trap | |
1066 | Allows arches to define/use @unaligned_enabled to runtime toggle | |
1067 | the unaligned access emulation. | |
1068 | see arch/parisc/kernel/unaligned.c for reference | |
1069 | ||
657a5209 MF |
1070 | config HAVE_PCSPKR_PLATFORM |
1071 | bool | |
1072 | ||
f89b7755 AS |
1073 | # interpreter that classic socket filters depend on |
1074 | config BPF | |
1075 | bool | |
1076 | ||
6a108a14 DR |
1077 | menuconfig EXPERT |
1078 | bool "Configure standard kernel features (expert users)" | |
f505c553 JT |
1079 | # Unhide debug options, to make the on-by-default options visible |
1080 | select DEBUG_KERNEL | |
1da177e4 LT |
1081 | help |
1082 | This option allows certain base kernel options and settings | |
1083 | to be disabled or tweaked. This is for specialized | |
1084 | environments which can tolerate a "non-standard" kernel. | |
1085 | Only use this if you really know what you are doing. | |
1086 | ||
ae81f9e3 | 1087 | config UID16 |
6a108a14 | 1088 | bool "Enable 16-bit UID system calls" if EXPERT |
2813893f | 1089 | depends on HAVE_UID16 && MULTIUSER |
ae81f9e3 CE |
1090 | default y |
1091 | help | |
1092 | This enables the legacy 16-bit UID syscall wrappers. | |
1093 | ||
2813893f IM |
1094 | config MULTIUSER |
1095 | bool "Multiple users, groups and capabilities support" if EXPERT | |
1096 | default y | |
1097 | help | |
1098 | This option enables support for non-root users, groups and | |
1099 | capabilities. | |
1100 | ||
1101 | If you say N here, all processes will run with UID 0, GID 0, and all | |
1102 | possible capabilities. Saying N here also compiles out support for | |
1103 | system calls related to UIDs, GIDs, and capabilities, such as setuid, | |
1104 | setgid, and capset. | |
1105 | ||
1106 | If unsure, say Y here. | |
1107 | ||
f6187769 FF |
1108 | config SGETMASK_SYSCALL |
1109 | bool "sgetmask/ssetmask syscalls support" if EXPERT | |
a687a533 | 1110 | def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH |
f6187769 FF |
1111 | ---help--- |
1112 | sys_sgetmask and sys_ssetmask are obsolete system calls | |
1113 | no longer supported in libc but still enabled by default in some | |
1114 | architectures. | |
1115 | ||
1116 | If unsure, leave the default option here. | |
1117 | ||
6af9f7bf FF |
1118 | config SYSFS_SYSCALL |
1119 | bool "Sysfs syscall support" if EXPERT | |
1120 | default y | |
1121 | ---help--- | |
1122 | sys_sysfs is an obsolete system call no longer supported in libc. | |
1123 | Note that disabling this option is more secure but might break | |
1124 | compatibility with some systems. | |
1125 | ||
1126 | If unsure say Y here. | |
1127 | ||
b89a8171 | 1128 | config SYSCTL_SYSCALL |
6a108a14 | 1129 | bool "Sysctl syscall support" if EXPERT |
26a7034b | 1130 | depends on PROC_SYSCTL |
c736de60 | 1131 | default n |
b89a8171 | 1132 | select SYSCTL |
ae81f9e3 | 1133 | ---help--- |
13bb7e37 EB |
1134 | sys_sysctl uses binary paths that have been found challenging |
1135 | to properly maintain and use. The interface in /proc/sys | |
1136 | using paths with ascii names is now the primary path to this | |
1137 | information. | |
b89a8171 | 1138 | |
13bb7e37 EB |
1139 | Almost nothing using the binary sysctl interface so if you are |
1140 | trying to save some space it is probably safe to disable this, | |
1141 | making your kernel marginally smaller. | |
b89a8171 | 1142 | |
c736de60 | 1143 | If unsure say N here. |
ae81f9e3 | 1144 | |
d1b069f5 RD |
1145 | config FHANDLE |
1146 | bool "open by fhandle syscalls" if EXPERT | |
1147 | select EXPORTFS | |
1148 | default y | |
1149 | help | |
1150 | If you say Y here, a user level program will be able to map | |
1151 | file names to handle and then later use the handle for | |
1152 | different file system operations. This is useful in implementing | |
1153 | userspace file servers, which now track files using handles instead | |
1154 | of names. The handle would remain the same even if file names | |
1155 | get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) | |
1156 | syscalls. | |
1157 | ||
baa73d9e NP |
1158 | config POSIX_TIMERS |
1159 | bool "Posix Clocks & timers" if EXPERT | |
1160 | default y | |
1161 | help | |
1162 | This includes native support for POSIX timers to the kernel. | |
1163 | Some embedded systems have no use for them and therefore they | |
1164 | can be configured out to reduce the size of the kernel image. | |
1165 | ||
1166 | When this option is disabled, the following syscalls won't be | |
1167 | available: timer_create, timer_gettime: timer_getoverrun, | |
1168 | timer_settime, timer_delete, clock_adjtime, getitimer, | |
1169 | setitimer, alarm. Furthermore, the clock_settime, clock_gettime, | |
1170 | clock_getres and clock_nanosleep syscalls will be limited to | |
1171 | CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only. | |
1172 | ||
1173 | If unsure say y. | |
1174 | ||
d59745ce MM |
1175 | config PRINTK |
1176 | default y | |
6a108a14 | 1177 | bool "Enable support for printk" if EXPERT |
74876a98 | 1178 | select IRQ_WORK |
d59745ce MM |
1179 | help |
1180 | This option enables normal printk support. Removing it | |
1181 | eliminates most of the message strings from the kernel image | |
1182 | and makes the kernel more or less silent. As this makes it | |
1183 | very difficult to diagnose system problems, saying N here is | |
1184 | strongly discouraged. | |
1185 | ||
42a0bb3f PM |
1186 | config PRINTK_NMI |
1187 | def_bool y | |
1188 | depends on PRINTK | |
1189 | depends on HAVE_NMI | |
1190 | ||
c8538a7a | 1191 | config BUG |
6a108a14 | 1192 | bool "BUG() support" if EXPERT |
c8538a7a MM |
1193 | default y |
1194 | help | |
1195 | Disabling this option eliminates support for BUG and WARN, reducing | |
1196 | the size of your kernel image and potentially quietly ignoring | |
1197 | numerous fatal conditions. You should only consider disabling this | |
1198 | option for embedded systems with no facilities for reporting errors. | |
1199 | Just say Y. | |
1200 | ||
708e9a79 | 1201 | config ELF_CORE |
046d662f | 1202 | depends on COREDUMP |
708e9a79 | 1203 | default y |
6a108a14 | 1204 | bool "Enable ELF core dumps" if EXPERT |
708e9a79 MM |
1205 | help |
1206 | Enable support for generating core dumps. Disabling saves about 4k. | |
1207 | ||
8761f1ab | 1208 | |
e5e1d3cb | 1209 | config PCSPKR_PLATFORM |
6a108a14 | 1210 | bool "Enable PC-Speaker support" if EXPERT |
8761f1ab | 1211 | depends on HAVE_PCSPKR_PLATFORM |
15f304b6 | 1212 | select I8253_LOCK |
e5e1d3cb SS |
1213 | default y |
1214 | help | |
1215 | This option allows to disable the internal PC-Speaker | |
1216 | support, saving some memory. | |
1217 | ||
1da177e4 LT |
1218 | config BASE_FULL |
1219 | default y | |
6a108a14 | 1220 | bool "Enable full-sized data structures for core" if EXPERT |
1da177e4 LT |
1221 | help |
1222 | Disabling this option reduces the size of miscellaneous core | |
1223 | kernel data structures. This saves memory on small machines, | |
1224 | but may reduce performance. | |
1225 | ||
1226 | config FUTEX | |
6a108a14 | 1227 | bool "Enable futex support" if EXPERT |
1da177e4 | 1228 | default y |
bc2eecd7 | 1229 | imply RT_MUTEXES |
1da177e4 LT |
1230 | help |
1231 | Disabling this option will cause the kernel to be built without | |
1232 | support for "fast userspace mutexes". The resulting kernel may not | |
1233 | run glibc-based applications correctly. | |
1234 | ||
bc2eecd7 NP |
1235 | config FUTEX_PI |
1236 | bool | |
1237 | depends on FUTEX && RT_MUTEXES | |
1238 | default y | |
1239 | ||
03b8c7b6 HC |
1240 | config HAVE_FUTEX_CMPXCHG |
1241 | bool | |
62b4d204 | 1242 | depends on FUTEX |
03b8c7b6 HC |
1243 | help |
1244 | Architectures should select this if futex_atomic_cmpxchg_inatomic() | |
1245 | is implemented and always working. This removes a couple of runtime | |
1246 | checks. | |
1247 | ||
1da177e4 | 1248 | config EPOLL |
6a108a14 | 1249 | bool "Enable eventpoll support" if EXPERT |
1da177e4 | 1250 | default y |
448e3cee | 1251 | select ANON_INODES |
1da177e4 LT |
1252 | help |
1253 | Disabling this option will cause the kernel to be built without | |
1254 | support for epoll family of system calls. | |
1255 | ||
fba2afaa | 1256 | config SIGNALFD |
6a108a14 | 1257 | bool "Enable signalfd() system call" if EXPERT |
448e3cee | 1258 | select ANON_INODES |
fba2afaa DL |
1259 | default y |
1260 | help | |
1261 | Enable the signalfd() system call that allows to receive signals | |
1262 | on a file descriptor. | |
1263 | ||
1264 | If unsure, say Y. | |
1265 | ||
b215e283 | 1266 | config TIMERFD |
6a108a14 | 1267 | bool "Enable timerfd() system call" if EXPERT |
448e3cee | 1268 | select ANON_INODES |
b215e283 DL |
1269 | default y |
1270 | help | |
1271 | Enable the timerfd() system call that allows to receive timer | |
1272 | events on a file descriptor. | |
1273 | ||
1274 | If unsure, say Y. | |
1275 | ||
e1ad7468 | 1276 | config EVENTFD |
6a108a14 | 1277 | bool "Enable eventfd() system call" if EXPERT |
448e3cee | 1278 | select ANON_INODES |
e1ad7468 DL |
1279 | default y |
1280 | help | |
1281 | Enable the eventfd() system call that allows to receive both | |
1282 | kernel notification (ie. KAIO) or userspace notifications. | |
1283 | ||
1284 | If unsure, say Y. | |
1285 | ||
1da177e4 | 1286 | config SHMEM |
6a108a14 | 1287 | bool "Use full shmem filesystem" if EXPERT |
1da177e4 LT |
1288 | default y |
1289 | depends on MMU | |
1290 | help | |
1291 | The shmem is an internal filesystem used to manage shared memory. | |
1292 | It is backed by swap and manages resource limits. It is also exported | |
1293 | to userspace as tmpfs if TMPFS is enabled. Disabling this | |
1294 | option replaces shmem and tmpfs with the much simpler ramfs code, | |
1295 | which may be appropriate on small systems without swap. | |
1296 | ||
ebf3f09c | 1297 | config AIO |
6a108a14 | 1298 | bool "Enable AIO support" if EXPERT |
ebf3f09c TP |
1299 | default y |
1300 | help | |
1301 | This option enables POSIX asynchronous I/O which may by used | |
657a5209 MF |
1302 | by some high performance threaded applications. Disabling |
1303 | this option saves about 7k. | |
1304 | ||
d3ac21ca JT |
1305 | config ADVISE_SYSCALLS |
1306 | bool "Enable madvise/fadvise syscalls" if EXPERT | |
1307 | default y | |
1308 | help | |
1309 | This option enables the madvise and fadvise syscalls, used by | |
1310 | applications to advise the kernel about their future memory or file | |
1311 | usage, improving performance. If building an embedded system where no | |
1312 | applications use these syscalls, you can disable this option to save | |
1313 | space. | |
1314 | ||
5b25b13a MD |
1315 | config MEMBARRIER |
1316 | bool "Enable membarrier() system call" if EXPERT | |
1317 | default y | |
1318 | help | |
1319 | Enable the membarrier() system call that allows issuing memory | |
1320 | barriers across all running threads, which can be used to distribute | |
1321 | the cost of user-space memory barriers asymmetrically by transforming | |
1322 | pairs of memory barriers into pairs consisting of membarrier() and a | |
1323 | compiler barrier. | |
1324 | ||
1325 | If unsure, say Y. | |
1326 | ||
d1b069f5 RD |
1327 | config CHECKPOINT_RESTORE |
1328 | bool "Checkpoint/restore support" if EXPERT | |
1329 | select PROC_CHILDREN | |
1330 | default n | |
1331 | help | |
1332 | Enables additional kernel features in a sake of checkpoint/restore. | |
1333 | In particular it adds auxiliary prctl codes to setup process text, | |
1334 | data and heap segment sizes, and a few additional /proc filesystem | |
1335 | entries. | |
1336 | ||
1337 | If unsure, say N here. | |
1338 | ||
1339 | config KALLSYMS | |
1340 | bool "Load all symbols for debugging/ksymoops" if EXPERT | |
1341 | default y | |
1342 | help | |
1343 | Say Y here to let the kernel print out symbolic crash information and | |
1344 | symbolic stack backtraces. This increases the size of the kernel | |
1345 | somewhat, as all symbols have to be loaded into the kernel image. | |
1346 | ||
1347 | config KALLSYMS_ALL | |
1348 | bool "Include all symbols in kallsyms" | |
1349 | depends on DEBUG_KERNEL && KALLSYMS | |
1350 | help | |
1351 | Normally kallsyms only contains the symbols of functions for nicer | |
1352 | OOPS messages and backtraces (i.e., symbols from the text and inittext | |
1353 | sections). This is sufficient for most cases. And only in very rare | |
1354 | cases (e.g., when a debugger is used) all symbols are required (e.g., | |
1355 | names of variables from the data sections, etc). | |
1356 | ||
1357 | This option makes sure that all symbols are loaded into the kernel | |
1358 | image (i.e., symbols from all sections) in cost of increased kernel | |
1359 | size (depending on the kernel configuration, it may be 300KiB or | |
1360 | something like this). | |
1361 | ||
1362 | Say N unless you really need all symbols. | |
1363 | ||
1364 | config KALLSYMS_ABSOLUTE_PERCPU | |
1365 | bool | |
1366 | depends on KALLSYMS | |
1367 | default X86_64 && SMP | |
1368 | ||
1369 | config KALLSYMS_BASE_RELATIVE | |
1370 | bool | |
1371 | depends on KALLSYMS | |
a687a533 | 1372 | default !IA64 |
d1b069f5 RD |
1373 | help |
1374 | Instead of emitting them as absolute values in the native word size, | |
1375 | emit the symbol references in the kallsyms table as 32-bit entries, | |
1376 | each containing a relative value in the range [base, base + U32_MAX] | |
1377 | or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either | |
1378 | an absolute value in the range [0, S32_MAX] or a relative value in the | |
1379 | range [base, base + S32_MAX], where base is the lowest relative symbol | |
1380 | address encountered in the image. | |
1381 | ||
1382 | On 64-bit builds, this reduces the size of the address table by 50%, | |
1383 | but more importantly, it results in entries whose values are build | |
1384 | time constants, and no relocation pass is required at runtime to fix | |
1385 | up the entries based on the runtime load address of the kernel. | |
1386 | ||
1387 | # end of the "standard kernel features (expert users)" menu | |
1388 | ||
1389 | # syscall, maps, verifier | |
1390 | config BPF_SYSCALL | |
1391 | bool "Enable bpf() system call" | |
1392 | select ANON_INODES | |
1393 | select BPF | |
1394 | default n | |
1395 | help | |
1396 | Enable the bpf() system call that allows to manipulate eBPF | |
1397 | programs and maps via file descriptors. | |
1398 | ||
290af866 AS |
1399 | config BPF_JIT_ALWAYS_ON |
1400 | bool "Permanently enable BPF JIT and remove BPF interpreter" | |
1401 | depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT | |
1402 | help | |
1403 | Enables BPF JIT and removes BPF interpreter to avoid | |
1404 | speculative execution of BPF instructions by the interpreter | |
1405 | ||
d1b069f5 RD |
1406 | config USERFAULTFD |
1407 | bool "Enable userfaultfd() system call" | |
1408 | select ANON_INODES | |
1409 | depends on MMU | |
1410 | help | |
1411 | Enable the userfaultfd() system call that allows to intercept and | |
1412 | handle page faults in userland. | |
1413 | ||
3ccfebed MD |
1414 | config ARCH_HAS_MEMBARRIER_CALLBACKS |
1415 | bool | |
1416 | ||
70216e18 MD |
1417 | config ARCH_HAS_MEMBARRIER_SYNC_CORE |
1418 | bool | |
1419 | ||
6befe5f6 RD |
1420 | config EMBEDDED |
1421 | bool "Embedded system" | |
5d2acfc7 | 1422 | option allnoconfig_y |
6befe5f6 RD |
1423 | select EXPERT |
1424 | help | |
1425 | This option should be enabled if compiling the kernel for | |
1426 | an embedded system so certain expert options are available | |
1427 | for configuration. | |
1428 | ||
cdd6c482 | 1429 | config HAVE_PERF_EVENTS |
0793a61d | 1430 | bool |
018df72d MF |
1431 | help |
1432 | See tools/perf/design.txt for details. | |
0793a61d | 1433 | |
906010b2 PZ |
1434 | config PERF_USE_VMALLOC |
1435 | bool | |
1436 | help | |
1437 | See tools/perf/design.txt for details | |
1438 | ||
ad90a3de | 1439 | config PC104 |
424529fb | 1440 | bool "PC/104 support" if EXPERT |
ad90a3de WBG |
1441 | help |
1442 | Expose PC/104 form factor device drivers and options available for | |
1443 | selection and configuration. Enable this option if your target | |
1444 | machine has a PC/104 bus. | |
1445 | ||
57c0c15b | 1446 | menu "Kernel Performance Events And Counters" |
0793a61d | 1447 | |
cdd6c482 | 1448 | config PERF_EVENTS |
57c0c15b | 1449 | bool "Kernel performance events and counters" |
392d65a9 | 1450 | default y if PROFILING |
cdd6c482 | 1451 | depends on HAVE_PERF_EVENTS |
4c59e467 | 1452 | select ANON_INODES |
e360adbe | 1453 | select IRQ_WORK |
83fe27ea | 1454 | select SRCU |
0793a61d | 1455 | help |
57c0c15b IM |
1456 | Enable kernel support for various performance events provided |
1457 | by software and hardware. | |
0793a61d | 1458 | |
dd77038d | 1459 | Software events are supported either built-in or via the |
57c0c15b | 1460 | use of generic tracepoints. |
0793a61d | 1461 | |
57c0c15b IM |
1462 | Most modern CPUs support performance events via performance |
1463 | counter registers. These registers count the number of certain | |
0793a61d TG |
1464 | types of hw events: such as instructions executed, cachemisses |
1465 | suffered, or branches mis-predicted - without slowing down the | |
1466 | kernel or applications. These registers can also trigger interrupts | |
1467 | when a threshold number of events have passed - and can thus be | |
1468 | used to profile the code that runs on that CPU. | |
1469 | ||
57c0c15b | 1470 | The Linux Performance Event subsystem provides an abstraction of |
dd77038d | 1471 | these software and hardware event capabilities, available via a |
57c0c15b | 1472 | system call and used by the "perf" utility in tools/perf/. It |
0793a61d TG |
1473 | provides per task and per CPU counters, and it provides event |
1474 | capabilities on top of those. | |
1475 | ||
1476 | Say Y if unsure. | |
1477 | ||
906010b2 PZ |
1478 | config DEBUG_PERF_USE_VMALLOC |
1479 | default n | |
1480 | bool "Debug: use vmalloc to back perf mmap() buffers" | |
cb307113 | 1481 | depends on PERF_EVENTS && DEBUG_KERNEL && !PPC |
906010b2 PZ |
1482 | select PERF_USE_VMALLOC |
1483 | help | |
1484 | Use vmalloc memory to back perf mmap() buffers. | |
1485 | ||
1486 | Mostly useful for debugging the vmalloc code on platforms | |
1487 | that don't require it. | |
1488 | ||
1489 | Say N if unsure. | |
1490 | ||
0793a61d TG |
1491 | endmenu |
1492 | ||
f8891e5e CL |
1493 | config VM_EVENT_COUNTERS |
1494 | default y | |
6a108a14 | 1495 | bool "Enable VM event counters for /proc/vmstat" if EXPERT |
f8891e5e | 1496 | help |
2aea4fb6 PJ |
1497 | VM event counters are needed for event counts to be shown. |
1498 | This option allows the disabling of the VM event counters | |
6a108a14 | 1499 | on EXPERT systems. /proc/vmstat will only show page counts |
2aea4fb6 | 1500 | if VM event counters are disabled. |
f8891e5e | 1501 | |
41ecc55b CL |
1502 | config SLUB_DEBUG |
1503 | default y | |
6a108a14 | 1504 | bool "Enable SLUB debugging support" if EXPERT |
f6acb635 | 1505 | depends on SLUB && SYSFS |
41ecc55b CL |
1506 | help |
1507 | SLUB has extensive debug support features. Disabling these can | |
1508 | result in significant savings in code size. This also disables | |
1509 | SLUB sysfs support. /sys/slab will not exist and there will be | |
1510 | no support for cache validation etc. | |
1511 | ||
1663f26d TH |
1512 | config SLUB_MEMCG_SYSFS_ON |
1513 | default n | |
1514 | bool "Enable memcg SLUB sysfs support by default" if EXPERT | |
1515 | depends on SLUB && SYSFS && MEMCG | |
1516 | help | |
1517 | SLUB creates a directory under /sys/kernel/slab for each | |
1518 | allocation cache to host info and debug files. If memory | |
1519 | cgroup is enabled, each cache can have per memory cgroup | |
1520 | caches. SLUB can create the same sysfs directories for these | |
1521 | caches under /sys/kernel/slab/CACHE/cgroup but it can lead | |
1522 | to a very high number of debug files being created. This is | |
1523 | controlled by slub_memcg_sysfs boot parameter and this | |
1524 | config option determines the parameter's default value. | |
1525 | ||
b943c460 RD |
1526 | config COMPAT_BRK |
1527 | bool "Disable heap randomization" | |
1528 | default y | |
1529 | help | |
1530 | Randomizing heap placement makes heap exploits harder, but it | |
1531 | also breaks ancient binaries (including anything libc5 based). | |
1532 | This option changes the bootup default to heap randomization | |
692105b8 | 1533 | disabled, and can be overridden at runtime by setting |
b943c460 RD |
1534 | /proc/sys/kernel/randomize_va_space to 2. |
1535 | ||
1536 | On non-ancient distros (post-2000 ones) N is usually a safe choice. | |
1537 | ||
81819f0f CL |
1538 | choice |
1539 | prompt "Choose SLAB allocator" | |
a0acd820 | 1540 | default SLUB |
81819f0f CL |
1541 | help |
1542 | This option allows to select a slab allocator. | |
1543 | ||
1544 | config SLAB | |
1545 | bool "SLAB" | |
04385fc5 | 1546 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1547 | help |
1548 | The regular slab allocator that is established and known to work | |
34013886 | 1549 | well in all environments. It organizes cache hot objects in |
02f56210 | 1550 | per cpu and per node queues. |
81819f0f CL |
1551 | |
1552 | config SLUB | |
81819f0f | 1553 | bool "SLUB (Unqueued Allocator)" |
ed18adc1 | 1554 | select HAVE_HARDENED_USERCOPY_ALLOCATOR |
81819f0f CL |
1555 | help |
1556 | SLUB is a slab allocator that minimizes cache line usage | |
1557 | instead of managing queues of cached objects (SLAB approach). | |
1558 | Per cpu caching is realized using slabs of objects instead | |
1559 | of queues of objects. SLUB can use memory efficiently | |
02f56210 SA |
1560 | and has enhanced diagnostics. SLUB is the default choice for |
1561 | a slab allocator. | |
81819f0f CL |
1562 | |
1563 | config SLOB | |
6a108a14 | 1564 | depends on EXPERT |
81819f0f CL |
1565 | bool "SLOB (Simple Allocator)" |
1566 | help | |
37291458 MM |
1567 | SLOB replaces the stock allocator with a drastically simpler |
1568 | allocator. SLOB is generally more space efficient but | |
1569 | does not perform as well on large systems. | |
81819f0f CL |
1570 | |
1571 | endchoice | |
1572 | ||
7660a6fd KC |
1573 | config SLAB_MERGE_DEFAULT |
1574 | bool "Allow slab caches to be merged" | |
1575 | default y | |
1576 | help | |
1577 | For reduced kernel memory fragmentation, slab caches can be | |
1578 | merged when they share the same size and other characteristics. | |
1579 | This carries a risk of kernel heap overflows being able to | |
1580 | overwrite objects from merged caches (and more easily control | |
1581 | cache layout), which makes such heap attacks easier to exploit | |
1582 | by attackers. By keeping caches unmerged, these kinds of exploits | |
1583 | can usually only damage objects in the same cache. To disable | |
1584 | merging at runtime, "slab_nomerge" can be passed on the kernel | |
1585 | command line. | |
1586 | ||
c7ce4f60 TG |
1587 | config SLAB_FREELIST_RANDOM |
1588 | default n | |
210e7a43 | 1589 | depends on SLAB || SLUB |
c7ce4f60 TG |
1590 | bool "SLAB freelist randomization" |
1591 | help | |
210e7a43 | 1592 | Randomizes the freelist order used on creating new pages. This |
c7ce4f60 TG |
1593 | security feature reduces the predictability of the kernel slab |
1594 | allocator against heap overflows. | |
1595 | ||
2482ddec KC |
1596 | config SLAB_FREELIST_HARDENED |
1597 | bool "Harden slab freelist metadata" | |
1598 | depends on SLUB | |
1599 | help | |
1600 | Many kernel heap attacks try to target slab cache metadata and | |
1601 | other infrastructure. This options makes minor performance | |
1602 | sacrifies to harden the kernel slab allocator against common | |
1603 | freelist exploit methods. | |
1604 | ||
345c905d JK |
1605 | config SLUB_CPU_PARTIAL |
1606 | default y | |
b39ffbf8 | 1607 | depends on SLUB && SMP |
345c905d JK |
1608 | bool "SLUB per cpu partial cache" |
1609 | help | |
1610 | Per cpu partial caches accellerate objects allocation and freeing | |
1611 | that is local to a processor at the price of more indeterminism | |
1612 | in the latency of the free. On overflow these caches will be cleared | |
1613 | which requires the taking of locks that may cause latency spikes. | |
1614 | Typically one would choose no for a realtime system. | |
1615 | ||
ea637639 JZ |
1616 | config MMAP_ALLOW_UNINITIALIZED |
1617 | bool "Allow mmapped anonymous memory to be uninitialized" | |
6a108a14 | 1618 | depends on EXPERT && !MMU |
ea637639 JZ |
1619 | default n |
1620 | help | |
1621 | Normally, and according to the Linux spec, anonymous memory obtained | |
1622 | from mmap() has it's contents cleared before it is passed to | |
1623 | userspace. Enabling this config option allows you to request that | |
1624 | mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus | |
1625 | providing a huge performance boost. If this option is not enabled, | |
1626 | then the flag will be ignored. | |
1627 | ||
1628 | This is taken advantage of by uClibc's malloc(), and also by | |
1629 | ELF-FDPIC binfmt's brk and stack allocator. | |
1630 | ||
1631 | Because of the obvious security issues, this option should only be | |
1632 | enabled on embedded devices where you control what is run in | |
1633 | userspace. Since that isn't generally a problem on no-MMU systems, | |
1634 | it is normally safe to say Y here. | |
1635 | ||
1636 | See Documentation/nommu-mmap.txt for more information. | |
1637 | ||
091f6e26 DH |
1638 | config SYSTEM_DATA_VERIFICATION |
1639 | def_bool n | |
1640 | select SYSTEM_TRUSTED_KEYRING | |
1641 | select KEYS | |
1642 | select CRYPTO | |
d43de6c7 | 1643 | select CRYPTO_RSA |
091f6e26 DH |
1644 | select ASYMMETRIC_KEY_TYPE |
1645 | select ASYMMETRIC_PUBLIC_KEY_SUBTYPE | |
091f6e26 DH |
1646 | select ASN1 |
1647 | select OID_REGISTRY | |
1648 | select X509_CERTIFICATE_PARSER | |
1649 | select PKCS7_MESSAGE_PARSER | |
82c04ff8 | 1650 | help |
091f6e26 DH |
1651 | Provide PKCS#7 message verification using the contents of the system |
1652 | trusted keyring to provide public keys. This then can be used for | |
1653 | module verification, kexec image verification and firmware blob | |
1654 | verification. | |
82c04ff8 | 1655 | |
125e5645 | 1656 | config PROFILING |
b309a294 | 1657 | bool "Profiling support" |
125e5645 MD |
1658 | help |
1659 | Say Y here to enable the extended profiling support mechanisms used | |
1660 | by profilers such as OProfile. | |
1661 | ||
5f87f112 IM |
1662 | # |
1663 | # Place an empty function call at each tracepoint site. Can be | |
1664 | # dynamically changed for a probe function. | |
1665 | # | |
97e1c18e | 1666 | config TRACEPOINTS |
5f87f112 | 1667 | bool |
97e1c18e | 1668 | |
fb32e03f MD |
1669 | source "arch/Kconfig" |
1670 | ||
1da177e4 LT |
1671 | endmenu # General setup |
1672 | ||
ee7e5516 DB |
1673 | config HAVE_GENERIC_DMA_COHERENT |
1674 | bool | |
1675 | default n | |
1676 | ||
ae81f9e3 | 1677 | config RT_MUTEXES |
6341e62b | 1678 | bool |
ae81f9e3 | 1679 | |
1da177e4 LT |
1680 | config BASE_SMALL |
1681 | int | |
1682 | default 0 if BASE_FULL | |
1683 | default 1 if !BASE_FULL | |
1684 | ||
66da5733 | 1685 | menuconfig MODULES |
1da177e4 | 1686 | bool "Enable loadable module support" |
11097a03 | 1687 | option modules |
1da177e4 LT |
1688 | help |
1689 | Kernel modules are small pieces of compiled code which can | |
1690 | be inserted in the running kernel, rather than being | |
1691 | permanently built into the kernel. You use the "modprobe" | |
1692 | tool to add (and sometimes remove) them. If you say Y here, | |
1693 | many parts of the kernel can be built as modules (by | |
1694 | answering M instead of Y where indicated): this is most | |
1695 | useful for infrequently used options which are not required | |
1696 | for booting. For more information, see the man pages for | |
1697 | modprobe, lsmod, modinfo, insmod and rmmod. | |
1698 | ||
1699 | If you say Y here, you will need to run "make | |
1700 | modules_install" to put the modules under /lib/modules/ | |
1701 | where modprobe can find them (you may need to be root to do | |
1702 | this). | |
1703 | ||
1704 | If unsure, say Y. | |
1705 | ||
0b0de144 RD |
1706 | if MODULES |
1707 | ||
826e4506 LT |
1708 | config MODULE_FORCE_LOAD |
1709 | bool "Forced module loading" | |
826e4506 LT |
1710 | default n |
1711 | help | |
91e37a79 RR |
1712 | Allow loading of modules without version information (ie. modprobe |
1713 | --force). Forced module loading sets the 'F' (forced) taint flag and | |
1714 | is usually a really bad idea. | |
826e4506 | 1715 | |
1da177e4 LT |
1716 | config MODULE_UNLOAD |
1717 | bool "Module unloading" | |
1da177e4 LT |
1718 | help |
1719 | Without this option you will not be able to unload any | |
1720 | modules (note that some modules may not be unloadable | |
f7f5b675 DV |
1721 | anyway), which makes your kernel smaller, faster |
1722 | and simpler. If unsure, say Y. | |
1da177e4 LT |
1723 | |
1724 | config MODULE_FORCE_UNLOAD | |
1725 | bool "Forced module unloading" | |
19c92399 | 1726 | depends on MODULE_UNLOAD |
1da177e4 LT |
1727 | help |
1728 | This option allows you to force a module to unload, even if the | |
1729 | kernel believes it is unsafe: the kernel will remove the module | |
1730 | without waiting for anyone to stop using it (using the -f option to | |
1731 | rmmod). This is mainly for kernel developers and desperate users. | |
1732 | If unsure, say N. | |
1733 | ||
1da177e4 | 1734 | config MODVERSIONS |
0d541643 | 1735 | bool "Module versioning support" |
1da177e4 LT |
1736 | help |
1737 | Usually, you have to use modules compiled with your kernel. | |
1738 | Saying Y here makes it sometimes possible to use modules | |
1739 | compiled for different kernels, by adding enough information | |
1740 | to the modules to (hopefully) spot any changes which would | |
1741 | make them incompatible with the kernel you are running. If | |
1742 | unsure, say N. | |
1743 | ||
56067812 AB |
1744 | config MODULE_REL_CRCS |
1745 | bool | |
1746 | depends on MODVERSIONS | |
1747 | ||
1da177e4 LT |
1748 | config MODULE_SRCVERSION_ALL |
1749 | bool "Source checksum for all modules" | |
1da177e4 LT |
1750 | help |
1751 | Modules which contain a MODULE_VERSION get an extra "srcversion" | |
1752 | field inserted into their modinfo section, which contains a | |
1753 | sum of the source files which made it. This helps maintainers | |
1754 | see exactly which source was used to build a module (since | |
1755 | others sometimes change the module source without updating | |
1756 | the version). With this option, such a "srcversion" field | |
1757 | will be created for all modules. If unsure, say N. | |
1758 | ||
106a4ee2 RR |
1759 | config MODULE_SIG |
1760 | bool "Module signature verification" | |
1761 | depends on MODULES | |
091f6e26 | 1762 | select SYSTEM_DATA_VERIFICATION |
106a4ee2 RR |
1763 | help |
1764 | Check modules for valid signatures upon load: the signature | |
1765 | is simply appended to the module. For more information see | |
cbdc8217 | 1766 | <file:Documentation/admin-guide/module-signing.rst>. |
106a4ee2 | 1767 | |
228c37ff DH |
1768 | Note that this option adds the OpenSSL development packages as a |
1769 | kernel build dependency so that the signing tool can use its crypto | |
1770 | library. | |
1771 | ||
ea0b6dcf DH |
1772 | !!!WARNING!!! If you enable this option, you MUST make sure that the |
1773 | module DOES NOT get stripped after being signed. This includes the | |
1774 | debuginfo strip done by some packagers (such as rpmbuild) and | |
1775 | inclusion into an initramfs that wants the module size reduced. | |
1776 | ||
106a4ee2 RR |
1777 | config MODULE_SIG_FORCE |
1778 | bool "Require modules to be validly signed" | |
1779 | depends on MODULE_SIG | |
1780 | help | |
1781 | Reject unsigned modules or signed modules for which we don't have a | |
1782 | key. Without this, such modules will simply taint the kernel. | |
ea0b6dcf | 1783 | |
d9d8d7ed MM |
1784 | config MODULE_SIG_ALL |
1785 | bool "Automatically sign all modules" | |
1786 | default y | |
1787 | depends on MODULE_SIG | |
1788 | help | |
1789 | Sign all modules during make modules_install. Without this option, | |
1790 | modules must be signed manually, using the scripts/sign-file tool. | |
1791 | ||
1792 | comment "Do not forget to sign required modules with scripts/sign-file" | |
1793 | depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL | |
1794 | ||
ea0b6dcf DH |
1795 | choice |
1796 | prompt "Which hash algorithm should modules be signed with?" | |
1797 | depends on MODULE_SIG | |
1798 | help | |
1799 | This determines which sort of hashing algorithm will be used during | |
1800 | signature generation. This algorithm _must_ be built into the kernel | |
1801 | directly so that signature verification can take place. It is not | |
1802 | possible to load a signed module containing the algorithm to check | |
1803 | the signature on that module. | |
1804 | ||
1805 | config MODULE_SIG_SHA1 | |
1806 | bool "Sign modules with SHA-1" | |
1807 | select CRYPTO_SHA1 | |
1808 | ||
1809 | config MODULE_SIG_SHA224 | |
1810 | bool "Sign modules with SHA-224" | |
1811 | select CRYPTO_SHA256 | |
1812 | ||
1813 | config MODULE_SIG_SHA256 | |
1814 | bool "Sign modules with SHA-256" | |
1815 | select CRYPTO_SHA256 | |
1816 | ||
1817 | config MODULE_SIG_SHA384 | |
1818 | bool "Sign modules with SHA-384" | |
1819 | select CRYPTO_SHA512 | |
1820 | ||
1821 | config MODULE_SIG_SHA512 | |
1822 | bool "Sign modules with SHA-512" | |
1823 | select CRYPTO_SHA512 | |
1824 | ||
1825 | endchoice | |
1826 | ||
22753674 MM |
1827 | config MODULE_SIG_HASH |
1828 | string | |
1829 | depends on MODULE_SIG | |
1830 | default "sha1" if MODULE_SIG_SHA1 | |
1831 | default "sha224" if MODULE_SIG_SHA224 | |
1832 | default "sha256" if MODULE_SIG_SHA256 | |
1833 | default "sha384" if MODULE_SIG_SHA384 | |
1834 | default "sha512" if MODULE_SIG_SHA512 | |
1835 | ||
beb50df3 BJ |
1836 | config MODULE_COMPRESS |
1837 | bool "Compress modules on installation" | |
1838 | depends on MODULES | |
1839 | help | |
beb50df3 | 1840 | |
b6c09b51 RR |
1841 | Compresses kernel modules when 'make modules_install' is run; gzip or |
1842 | xz depending on "Compression algorithm" below. | |
beb50df3 | 1843 | |
b6c09b51 | 1844 | module-init-tools MAY support gzip, and kmod MAY support gzip and xz. |
beb50df3 | 1845 | |
b6c09b51 RR |
1846 | Out-of-tree kernel modules installed using Kbuild will also be |
1847 | compressed upon installation. | |
beb50df3 | 1848 | |
b6c09b51 RR |
1849 | Note: for modules inside an initrd or initramfs, it's more efficient |
1850 | to compress the whole initrd or initramfs instead. | |
beb50df3 | 1851 | |
b6c09b51 RR |
1852 | Note: This is fully compatible with signed modules. |
1853 | ||
1854 | If in doubt, say N. | |
beb50df3 BJ |
1855 | |
1856 | choice | |
1857 | prompt "Compression algorithm" | |
1858 | depends on MODULE_COMPRESS | |
1859 | default MODULE_COMPRESS_GZIP | |
1860 | help | |
1861 | This determines which sort of compression will be used during | |
1862 | 'make modules_install'. | |
1863 | ||
1864 | GZIP (default) and XZ are supported. | |
1865 | ||
1866 | config MODULE_COMPRESS_GZIP | |
1867 | bool "GZIP" | |
1868 | ||
1869 | config MODULE_COMPRESS_XZ | |
1870 | bool "XZ" | |
1871 | ||
1872 | endchoice | |
1873 | ||
dbacb0ef NP |
1874 | config TRIM_UNUSED_KSYMS |
1875 | bool "Trim unused exported kernel symbols" | |
1876 | depends on MODULES && !UNUSED_SYMBOLS | |
1877 | help | |
1878 | The kernel and some modules make many symbols available for | |
1879 | other modules to use via EXPORT_SYMBOL() and variants. Depending | |
1880 | on the set of modules being selected in your kernel configuration, | |
1881 | many of those exported symbols might never be used. | |
1882 | ||
1883 | This option allows for unused exported symbols to be dropped from | |
1884 | the build. In turn, this provides the compiler more opportunities | |
1885 | (especially when using LTO) for optimizing the code and reducing | |
1886 | binary size. This might have some security advantages as well. | |
1887 | ||
f1cb637e | 1888 | If unsure, or if you need to build out-of-tree modules, say N. |
dbacb0ef | 1889 | |
0b0de144 RD |
1890 | endif # MODULES |
1891 | ||
6c9692e2 PZ |
1892 | config MODULES_TREE_LOOKUP |
1893 | def_bool y | |
1894 | depends on PERF_EVENTS || TRACING | |
1895 | ||
98a79d6a RR |
1896 | config INIT_ALL_POSSIBLE |
1897 | bool | |
1898 | help | |
5f054e31 RR |
1899 | Back when each arch used to define their own cpu_online_mask and |
1900 | cpu_possible_mask, some of them chose to initialize cpu_possible_mask | |
98a79d6a RR |
1901 | with all 1s, and others with all 0s. When they were centralised, |
1902 | it was better to provide this option than to break all the archs | |
692105b8 | 1903 | and have several arch maintainers pursuing me down dark alleys. |
98a79d6a | 1904 | |
3a65dfe8 | 1905 | source "block/Kconfig" |
e98c3202 AK |
1906 | |
1907 | config PREEMPT_NOTIFIERS | |
1908 | bool | |
e260be67 | 1909 | |
16295bec SK |
1910 | config PADATA |
1911 | depends on SMP | |
1912 | bool | |
1913 | ||
4520c6a4 DH |
1914 | config ASN1 |
1915 | tristate | |
1916 | help | |
1917 | Build a simple ASN.1 grammar compiler that produces a bytecode output | |
1918 | that can be interpreted by the ASN.1 stream decoder and used to | |
1919 | inform it as to what tags are to be expected in a stream and what | |
1920 | functions to call on what tags. | |
1921 | ||
6beb0009 | 1922 | source "kernel/Kconfig.locks" |
e61938a9 MD |
1923 | |
1924 | config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE | |
1925 | bool | |
1bd21c6c DB |
1926 | |
1927 | # It may be useful for an architecture to override the definitions of the | |
7303e30e DB |
1928 | # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h> |
1929 | # and the COMPAT_ variants in <linux/compat.h>, in particular to use a | |
1930 | # different calling convention for syscalls. They can also override the | |
1931 | # macros for not-implemented syscalls in kernel/sys_ni.c and | |
1932 | # kernel/time/posix-stubs.c. All these overrides need to be available in | |
1933 | # <asm/syscall_wrapper.h>. | |
1bd21c6c DB |
1934 | config ARCH_HAS_SYSCALL_WRAPPER |
1935 | def_bool n |