1 # SPDX-License-Identifier: GPL-2.0-only !! 1 config ARCH
2 config CC_VERSION_TEXT <<
3 string 2 string
4 default "$(CC_VERSION_TEXT)" !! 3 option env="ARCH"
5 help <<
6 This is used in unclear ways: <<
7 <<
8 - Re-run Kconfig when the compiler i <<
9 The 'default' property references <<
10 CC_VERSION_TEXT so it is recorded <<
11 When the compiler is updated, Kcon <<
12 <<
13 - Ensure full rebuild when the compi <<
14 include/linux/compiler-version.h c <<
15 line so fixdep adds include/config <<
16 auto-generated dependency. When th <<
17 will touch it and then every file <<
18 <<
19 config CC_IS_GCC <<
20 def_bool $(success,test "$(cc-name)" = <<
21 <<
22 config GCC_VERSION <<
23 int <<
24 default $(cc-version) if CC_IS_GCC <<
25 default 0 <<
26 <<
27 config CC_IS_CLANG <<
28 def_bool $(success,test "$(cc-name)" = <<
29 <<
30 config CLANG_VERSION <<
31 int <<
32 default $(cc-version) if CC_IS_CLANG <<
33 default 0 <<
34 <<
35 config AS_IS_GNU <<
36 def_bool $(success,test "$(as-name)" = <<
37 <<
38 config AS_IS_LLVM <<
39 def_bool $(success,test "$(as-name)" = <<
40 <<
41 config AS_VERSION <<
42 int <<
43 # Use clang version if this is the int <<
44 default CLANG_VERSION if AS_IS_LLVM <<
45 default $(as-version) <<
46 <<
47 config LD_IS_BFD <<
48 def_bool $(success,test "$(ld-name)" = <<
49 <<
50 config LD_VERSION <<
51 int <<
52 default $(ld-version) if LD_IS_BFD <<
53 default 0 <<
54 4
55 config LD_IS_LLD !! 5 config KERNELVERSION
56 def_bool $(success,test "$(ld-name)" = !! 6 string
57 !! 7 option env="KERNELVERSION"
58 config LLD_VERSION <<
59 int <<
60 default $(ld-version) if LD_IS_LLD <<
61 default 0 <<
62 <<
63 config RUSTC_VERSION <<
64 int <<
65 default $(rustc-version) <<
66 help <<
67 It does not depend on `RUST` since t <<
68 in a `depends on`. <<
69 <<
70 config RUST_IS_AVAILABLE <<
71 def_bool $(success,$(srctree)/scripts/ <<
72 help <<
73 This shows whether a suitable Rust t <<
74 <<
75 Please see Documentation/rust/quick- <<
76 to satisfy the build requirements of <<
77 <<
78 In particular, the Makefile target ' <<
79 why the Rust toolchain is not being <<
80 <<
81 config RUSTC_LLVM_VERSION <<
82 int <<
83 default $(rustc-llvm-version) <<
84 <<
85 config CC_CAN_LINK <<
86 bool <<
87 default $(success,$(srctree)/scripts/c <<
88 default $(success,$(srctree)/scripts/c <<
89 <<
90 config CC_CAN_LINK_STATIC <<
91 bool <<
92 default $(success,$(srctree)/scripts/c <<
93 default $(success,$(srctree)/scripts/c <<
94 <<
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5 <<
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id <<
97 config GCC_ASM_GOTO_OUTPUT_BROKEN <<
98 bool <<
99 depends on CC_IS_GCC <<
100 default y if GCC_VERSION < 110500 <<
101 default y if GCC_VERSION >= 120000 && <<
102 default y if GCC_VERSION >= 130000 && <<
103 <<
104 config CC_HAS_ASM_GOTO_OUTPUT <<
105 def_bool y <<
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN <<
107 depends on $(success,echo 'int foo(int <<
108 <<
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT <<
110 depends on CC_HAS_ASM_GOTO_OUTPUT <<
111 # Detect buggy gcc and clang, fixed in <<
112 def_bool $(success,echo 'int foo(int * <<
113 <<
114 config TOOLS_SUPPORT_RELR <<
115 def_bool $(success,env "CC=$(CC)" "LD= <<
116 <<
117 config CC_HAS_ASM_INLINE <<
118 def_bool $(success,echo 'void foo(void <<
119 <<
120 config CC_HAS_NO_PROFILE_FN_ATTR <<
121 def_bool $(success,echo '__attribute__ <<
122 8
123 config PAHOLE_VERSION !! 9 config DEFCONFIG_LIST
124 int !! 10 string
125 default $(shell,$(srctree)/scripts/pah !! 11 depends on !UML
>> 12 option defconfig_list
>> 13 default "/lib/modules/$UNAME_RELEASE/.config"
>> 14 default "/etc/kernel-config"
>> 15 default "/boot/config-$UNAME_RELEASE"
>> 16 default "$ARCH_DEFCONFIG"
>> 17 default "arch/$ARCH/defconfig"
126 18
127 config CONSTRUCTORS 19 config CONSTRUCTORS
128 bool 20 bool
>> 21 depends on !UML
129 22
130 config IRQ_WORK 23 config IRQ_WORK
131 def_bool y if SMP !! 24 bool
132 25
133 config BUILDTIME_TABLE_SORT !! 26 config BUILDTIME_EXTABLE_SORT
134 bool 27 bool
135 28
136 config THREAD_INFO_IN_TASK 29 config THREAD_INFO_IN_TASK
137 bool 30 bool
138 help 31 help
139 Select this to move thread_info off 32 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 33 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 34 except flags and fix any runtime bugs.
142 35
143 One subtle change that will be neede 36 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 37 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 38
146 menu "General setup" 39 menu "General setup"
147 40
148 config BROKEN 41 config BROKEN
149 bool 42 bool
150 43
151 config BROKEN_ON_SMP 44 config BROKEN_ON_SMP
152 bool 45 bool
153 depends on BROKEN || !SMP 46 depends on BROKEN || !SMP
154 default y 47 default y
155 48
156 config INIT_ENV_ARG_LIMIT 49 config INIT_ENV_ARG_LIMIT
157 int 50 int
158 default 32 if !UML 51 default 32 if !UML
159 default 128 if UML 52 default 128 if UML
160 help 53 help
161 Maximum of each of the number of arg 54 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 55 variables passed to init from the kernel command line.
163 56
>> 57
>> 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
164 config COMPILE_TEST 66 config COMPILE_TEST
165 bool "Compile also drivers which will 67 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM !! 68 depends on !UML
>> 69 default n
167 help 70 help
168 Some drivers can be compiled on a di 71 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 72 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 73 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 74 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 75 drivers to compile-test them.
173 76
174 If you are a developer and want to b 77 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 78 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 79 drivers to be distributed.
177 80
178 config WERROR <<
179 bool "Compile the kernel with warnings <<
180 default COMPILE_TEST <<
181 help <<
182 A kernel build should not cause any <<
183 enables the '-Werror' (for C) and '- <<
184 to enforce that rule by default. Cer <<
185 such as the linker may be upgraded t <<
186 well. <<
187 <<
188 However, if you have a new (or very <<
189 and unusual warnings, or you have so <<
190 you may need to disable this config <<
191 successfully build the kernel. <<
192 <<
193 If in doubt, say Y. <<
194 <<
195 config UAPI_HEADER_TEST <<
196 bool "Compile test UAPI headers" <<
197 depends on HEADERS_INSTALL && CC_CAN_L <<
198 help <<
199 Compile test headers exported to use <<
200 self-contained, i.e. compilable as s <<
201 <<
202 If you are a developer or tester and <<
203 headers are self-contained, say Y he <<
204 <<
205 config LOCALVERSION 81 config LOCALVERSION
206 string "Local version - append to kern 82 string "Local version - append to kernel release"
207 help 83 help
208 Append an extra string to the end of 84 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 85 This will show up when you type uname, for example.
210 The string you set here will be appe 86 The string you set here will be appended after the contents of
211 any files with a filename matching l 87 any files with a filename matching localversion* in your
212 object and source tree, in that orde 88 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 89 be a maximum of 64 characters.
214 90
215 config LOCALVERSION_AUTO 91 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 92 bool "Automatically append version information to the version string"
217 default y 93 default y
218 depends on !COMPILE_TEST 94 depends on !COMPILE_TEST
219 help 95 help
220 This will try to automatically deter 96 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 97 release tree by looking for git tags that belong to the current
222 top of tree revision. 98 top of tree revision.
223 99
224 A string of the format -gxxxxxxxx wi 100 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 101 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 102 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 103 set in CONFIG_LOCALVERSION.
228 104
229 (The actual string used here is the !! 105 (The actual string used here is the first eight characters produced
230 by running the command: 106 by running the command:
231 107
232 $ git rev-parse --verify HEAD 108 $ git rev-parse --verify HEAD
233 109
234 which is done within the script "scr 110 which is done within the script "scripts/setlocalversion".)
235 111
236 config BUILD_SALT <<
237 string "Build ID Salt" <<
238 default "" <<
239 help <<
240 The build ID is used to link binarie <<
241 this option will use the value in th <<
242 This is mostly useful for distributi <<
243 build is unique between builds. It's <<
244 <<
245 config HAVE_KERNEL_GZIP 112 config HAVE_KERNEL_GZIP
246 bool 113 bool
247 114
248 config HAVE_KERNEL_BZIP2 115 config HAVE_KERNEL_BZIP2
249 bool 116 bool
250 117
251 config HAVE_KERNEL_LZMA 118 config HAVE_KERNEL_LZMA
252 bool 119 bool
253 120
254 config HAVE_KERNEL_XZ 121 config HAVE_KERNEL_XZ
255 bool 122 bool
256 123
257 config HAVE_KERNEL_LZO 124 config HAVE_KERNEL_LZO
258 bool 125 bool
259 126
260 config HAVE_KERNEL_LZ4 127 config HAVE_KERNEL_LZ4
261 bool 128 bool
262 129
263 config HAVE_KERNEL_ZSTD <<
264 bool <<
265 <<
266 config HAVE_KERNEL_UNCOMPRESSED <<
267 bool <<
268 <<
269 choice 130 choice
270 prompt "Kernel compression mode" 131 prompt "Kernel compression mode"
271 default KERNEL_GZIP 132 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE !! 133 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
273 help 134 help
274 The linux kernel is a kind of self-e 135 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 136 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 137 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 138 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 139 Decompression speed is relevant at each boot.
279 140
280 If you have any problems with bzip2 141 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 142 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 143 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 144 supplied by Christian Ludwig)
284 145
285 High compression options are mostly 146 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 147 are low on disk space (embedded systems), but for whom ram
287 size matters less. 148 size matters less.
288 149
289 If in doubt, select 'gzip' 150 If in doubt, select 'gzip'
290 151
291 config KERNEL_GZIP 152 config KERNEL_GZIP
292 bool "Gzip" 153 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 154 depends on HAVE_KERNEL_GZIP
294 help 155 help
295 The old and tried gzip compression. 156 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 157 between compression ratio and decompression speed.
297 158
298 config KERNEL_BZIP2 159 config KERNEL_BZIP2
299 bool "Bzip2" 160 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 161 depends on HAVE_KERNEL_BZIP2
301 help 162 help
302 Its compression ratio and speed is i 163 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 164 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 165 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 166 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 167 will need at least 8MB RAM or more for booting.
307 168
308 config KERNEL_LZMA 169 config KERNEL_LZMA
309 bool "LZMA" 170 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 171 depends on HAVE_KERNEL_LZMA
311 help 172 help
312 This compression algorithm's ratio i 173 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 174 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 175 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 176
316 config KERNEL_XZ 177 config KERNEL_XZ
317 bool "XZ" 178 bool "XZ"
318 depends on HAVE_KERNEL_XZ 179 depends on HAVE_KERNEL_XZ
319 help 180 help
320 XZ uses the LZMA2 algorithm and inst 181 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 182 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 183 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 184 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 185 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 186 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 187
328 The speed is about the same as with 188 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 189 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 190 and LZO. Compression is slow.
331 191
332 config KERNEL_LZO 192 config KERNEL_LZO
333 bool "LZO" 193 bool "LZO"
334 depends on HAVE_KERNEL_LZO 194 depends on HAVE_KERNEL_LZO
335 help 195 help
336 Its compression ratio is the poorest 196 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 197 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 198 (both compression and decompression) is the fastest.
339 199
340 config KERNEL_LZ4 200 config KERNEL_LZ4
341 bool "LZ4" 201 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 202 depends on HAVE_KERNEL_LZ4
343 help 203 help
344 LZ4 is an LZ77-type compressor with 204 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 205 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 206 <https://code.google.com/p/lz4/>.
347 207
348 Its compression ratio is worse than 208 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 209 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 210 faster than LZO.
351 211
352 config KERNEL_ZSTD <<
353 bool "ZSTD" <<
354 depends on HAVE_KERNEL_ZSTD <<
355 help <<
356 ZSTD is a compression algorithm targ <<
357 with fast decompression speed. It wi <<
358 decompress around the same speed as <<
359 will need at least 192 KB RAM or mor <<
360 line tool is required for compressio <<
361 <<
362 config KERNEL_UNCOMPRESSED <<
363 bool "None" <<
364 depends on HAVE_KERNEL_UNCOMPRESSED <<
365 help <<
366 Produce uncompressed kernel image. T <<
367 you want. It is useful for debugging <<
368 environments, where decompressing an <<
369 slow. This option allows early boot <<
370 and jump right at uncompressed kerne <<
371 <<
372 endchoice 212 endchoice
373 213
374 config DEFAULT_INIT <<
375 string "Default init path" <<
376 default "" <<
377 help <<
378 This option determines the default i <<
379 option is passed on the kernel comma <<
380 not present, we will still then move <<
381 locations (e.g. /sbin/init, etc). If <<
382 the fallback list when init= is not <<
383 <<
384 config DEFAULT_HOSTNAME 214 config DEFAULT_HOSTNAME
385 string "Default hostname" 215 string "Default hostname"
386 default "(none)" 216 default "(none)"
387 help 217 help
388 This option determines the default s 218 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 219 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 220 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 221 system more usable with less configuration.
392 222
>> 223 config SWAP
>> 224 bool "Support for paging of anonymous memory (swap)"
>> 225 depends on MMU && BLOCK
>> 226 default y
>> 227 help
>> 228 This option allows you to choose whether you want to have support
>> 229 for so called swap devices or swap files in your kernel that are
>> 230 used to provide more virtual memory than the actual RAM present
>> 231 in your computer. If unsure say Y.
>> 232
393 config SYSVIPC 233 config SYSVIPC
394 bool "System V IPC" 234 bool "System V IPC"
395 help !! 235 ---help---
396 Inter Process Communication is a sui 236 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 237 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 238 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 239 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 240 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 241 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 242 you'll need to say Y here.
403 243
404 You can find documentation about IPC 244 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 245 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 246 <http://www.tldp.org/guides.html>.
407 247
408 config SYSVIPC_SYSCTL 248 config SYSVIPC_SYSCTL
409 bool 249 bool
410 depends on SYSVIPC 250 depends on SYSVIPC
411 depends on SYSCTL 251 depends on SYSCTL
412 default y 252 default y
413 253
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 254 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 255 bool "POSIX Message Queues"
420 depends on NET 256 depends on NET
421 help !! 257 ---help---
422 POSIX variant of message queues is a 258 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 259 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 260 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 261 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 262 queues (functions mq_*) say Y here.
427 263
428 POSIX message queues are visible as 264 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 265 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 266 operations on message queues.
431 267
432 If unsure, say Y. 268 If unsure, say Y.
433 269
434 config POSIX_MQUEUE_SYSCTL 270 config POSIX_MQUEUE_SYSCTL
435 bool 271 bool
436 depends on POSIX_MQUEUE 272 depends on POSIX_MQUEUE
437 depends on SYSCTL 273 depends on SYSCTL
438 default y 274 default y
439 275
440 config WATCH_QUEUE <<
441 bool "General notification queue" <<
442 default n <<
443 help <<
444 <<
445 This is a general notification queue <<
446 userspace by splicing them into pipe <<
447 with watches for key/keyring change <<
448 notifications. <<
449 <<
450 See Documentation/core-api/watch_que <<
451 <<
452 config CROSS_MEMORY_ATTACH 276 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 277 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 278 depends on MMU
455 default y 279 default y
456 help 280 help
457 Enabling this option adds the system 281 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 282 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 283 to directly read from or write to another process' address space.
460 See the man page for more details. 284 See the man page for more details.
461 285
>> 286 config FHANDLE
>> 287 bool "open by fhandle syscalls" if EXPERT
>> 288 select EXPORTFS
>> 289 default y
>> 290 help
>> 291 If you say Y here, a user level program will be able to map
>> 292 file names to handle and then later use the handle for
>> 293 different file system operations. This is useful in implementing
>> 294 userspace file servers, which now track files using handles instead
>> 295 of names. The handle would remain the same even if file names
>> 296 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
>> 297 syscalls.
>> 298
462 config USELIB 299 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 300 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 301 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 302 help
466 This option enables the uselib sysca 303 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 304 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 305 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 306 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 307 running glibc can safely disable this.
471 308
472 config AUDIT 309 config AUDIT
473 bool "Auditing support" 310 bool "Auditing support"
474 depends on NET 311 depends on NET
475 help 312 help
476 Enable auditing infrastructure that 313 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 314 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 315 logging of avc messages output). System call auditing is included
479 on architectures which support it. 316 on architectures which support it.
480 317
481 config HAVE_ARCH_AUDITSYSCALL 318 config HAVE_ARCH_AUDITSYSCALL
482 bool 319 bool
483 320
484 config AUDITSYSCALL 321 config AUDITSYSCALL
485 def_bool y 322 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 323 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
>> 324
>> 325 config AUDIT_WATCH
>> 326 def_bool y
>> 327 depends on AUDITSYSCALL
>> 328 select FSNOTIFY
>> 329
>> 330 config AUDIT_TREE
>> 331 def_bool y
>> 332 depends on AUDITSYSCALL
487 select FSNOTIFY 333 select FSNOTIFY
488 334
489 source "kernel/irq/Kconfig" 335 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 336 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" <<
492 source "kernel/Kconfig.preempt" <<
493 337
494 menu "CPU/Task time and stats accounting" 338 menu "CPU/Task time and stats accounting"
495 339
496 config VIRT_CPU_ACCOUNTING 340 config VIRT_CPU_ACCOUNTING
497 bool 341 bool
498 342
499 choice 343 choice
500 prompt "Cputime accounting" 344 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 345 default TICK_CPU_ACCOUNTING if !PPC64
>> 346 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 347
503 # Kind of a stub config for the pure tick base 348 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 349 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 350 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 351 depends on !S390 && !NO_HZ_FULL
507 help 352 help
508 This is the basic tick based cputime 353 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 354 statistics about user, system and idle time spent on per jiffies
510 granularity. 355 granularity.
511 356
512 If unsure, say Y. 357 If unsure, say Y.
513 358
514 config VIRT_CPU_ACCOUNTING_NATIVE 359 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 360 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 361 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 362 select VIRT_CPU_ACCOUNTING
518 help 363 help
519 Select this option to enable more ac 364 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 365 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 366 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 367 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 368 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 369 this also enables accounting of stolen time on logically-partitioned
525 systems. 370 systems.
526 371
527 config VIRT_CPU_ACCOUNTING_GEN 372 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 373 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 374 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 375 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS <<
532 select VIRT_CPU_ACCOUNTING 376 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 377 select CONTEXT_TRACKING
534 help 378 help
535 Select this option to enable task an 379 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 380 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 381 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 382 The accounting is thus performed at the expense of some significant
539 overhead. 383 overhead.
540 384
541 For now this is only useful if you a 385 For now this is only useful if you are working on the full
542 dynticks subsystem development. 386 dynticks subsystem development.
543 387
544 If unsure, say N. 388 If unsure, say N.
545 389
546 endchoice 390 endchoice
547 391
548 config IRQ_TIME_ACCOUNTING 392 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 393 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 394 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 395 help
552 Select this option to enable fine gr 396 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 397 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 398 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 399 small performance impact.
556 400
557 If in doubt, say N here. 401 If in doubt, say N here.
558 402
559 config HAVE_SCHED_AVG_IRQ <<
560 def_bool y <<
561 depends on IRQ_TIME_ACCOUNTING || PARA <<
562 depends on SMP <<
563 <<
564 config SCHED_HW_PRESSURE <<
565 bool <<
566 default y if ARM && ARM_CPU_TOPOLOGY <<
567 default y if ARM64 <<
568 depends on SMP <<
569 depends on CPU_FREQ_THERMAL <<
570 help <<
571 Select this option to enable HW pres <<
572 scheduler. HW pressure is the value <<
573 that reflects the reduction in CPU c <<
574 HW throttling. HW throttling occurs <<
575 a CPU is capped due to high operatin <<
576 <<
577 If selected, the scheduler will be a <<
578 i.e. put less load on throttled CPUs <<
579 <<
580 This requires the architecture to im <<
581 arch_update_hw_pressure() and arch_s <<
582 <<
583 config BSD_PROCESS_ACCT 403 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 404 bool "BSD Process Accounting"
585 depends on MULTIUSER 405 depends on MULTIUSER
586 help 406 help
587 If you say Y here, a user level prog 407 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 408 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 409 information to a file: whenever a process exits, information about
590 that process will be appended to the 410 that process will be appended to the file by the kernel. The
591 information includes things such as 411 information includes things such as creation time, owning user,
592 command name, memory usage, controll 412 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 413 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 414 up to the user level program to do useful things with this
595 information. This is generally a go 415 information. This is generally a good idea, so say Y.
596 416
597 config BSD_PROCESS_ACCT_V3 417 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 418 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 419 depends on BSD_PROCESS_ACCT
600 default n 420 default n
601 help 421 help
602 If you say Y here, the process accou 422 If you say Y here, the process accounting information is written
603 in a new file format that also logs 423 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th !! 424 process and it's parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 425 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 426 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 427 at <http://www.gnu.org/software/acct/>.
608 428
609 config TASKSTATS 429 config TASKSTATS
610 bool "Export task/process statistics t 430 bool "Export task/process statistics through netlink"
611 depends on NET 431 depends on NET
612 depends on MULTIUSER 432 depends on MULTIUSER
613 default n 433 default n
614 help 434 help
615 Export selected statistics for tasks 435 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 436 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 437 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 438 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 439 space on task exit.
620 440
621 Say N if unsure. 441 Say N if unsure.
622 442
623 config TASK_DELAY_ACCT 443 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 444 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 445 depends on TASKSTATS
626 select SCHED_INFO 446 select SCHED_INFO
627 help 447 help
628 Collect information on time spent by 448 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 449 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 450 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 451 relative to other tasks for cpu, io, rss limits etc.
632 452
633 Say N if unsure. 453 Say N if unsure.
634 454
635 config TASK_XACCT 455 config TASK_XACCT
636 bool "Enable extended accounting over 456 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 457 depends on TASKSTATS
638 help 458 help
639 Collect extended task accounting dat 459 Collect extended task accounting data and send the data
640 to userland for processing over the 460 to userland for processing over the taskstats interface.
641 461
642 Say N if unsure. 462 Say N if unsure.
643 463
644 config TASK_IO_ACCOUNTING 464 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 465 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 466 depends on TASK_XACCT
647 help 467 help
648 Collect information on the number of 468 Collect information on the number of bytes of storage I/O which this
649 task has caused. 469 task has caused.
650 470
651 Say N if unsure. 471 Say N if unsure.
652 472
653 config PSI !! 473 endmenu # "CPU/Task time and stats accounting"
654 bool "Pressure stall information track !! 474
655 select KERNFS !! 475 menu "RCU Subsystem"
>> 476
>> 477 config TREE_RCU
>> 478 bool
>> 479 default y if !PREEMPT && SMP
656 help 480 help
657 Collect metrics that indicate how ov !! 481 This option selects the RCU implementation that is
658 and IO capacity are in the system. !! 482 designed for very large SMP system with hundreds or
>> 483 thousands of CPUs. It also scales down nicely to
>> 484 smaller systems.
659 485
660 If you say Y here, the kernel will c !! 486 config PREEMPT_RCU
661 pressure statistics files cpu, memor !! 487 bool
662 the share of walltime in which some !! 488 default y if PREEMPT
663 delayed due to contention of the res !! 489 help
664 !! 490 This option selects the RCU implementation that is
665 In kernels with cgroup support, cgro !! 491 designed for very large SMP systems with hundreds or
666 have cpu.pressure, memory.pressure, !! 492 thousands of CPUs, but for which real-time response
667 which aggregate pressure stalls for !! 493 is also required. It also scales down nicely to
>> 494 smaller systems.
668 495
669 For more details see Documentation/a !! 496 Select this option if you are unsure.
670 497
671 Say N if unsure. !! 498 config TINY_RCU
>> 499 bool
>> 500 default y if !PREEMPT && !SMP
>> 501 help
>> 502 This option selects the RCU implementation that is
>> 503 designed for UP systems from which real-time response
>> 504 is not required. This option greatly reduces the
>> 505 memory footprint of RCU.
672 506
673 config PSI_DEFAULT_DISABLED !! 507 config RCU_EXPERT
674 bool "Require boot parameter to enable !! 508 bool "Make expert-level adjustments to RCU configuration"
675 default n 509 default n
676 depends on PSI <<
677 help 510 help
678 If set, pressure stall information t !! 511 This option needs to be enabled if you wish to make
679 per default but can be enabled throu !! 512 expert-level adjustments to RCU configuration. By default,
680 kernel commandline during boot. !! 513 no such adjustments can be made, which has the often-beneficial
681 !! 514 side-effect of preventing "make oldconfig" from asking you all
682 This feature adds some code to the t !! 515 sorts of detailed questions about how you would like numerous
683 paths of the scheduler. The overhead !! 516 obscure RCU options to be set up.
684 common scheduling-intense workloads <<
685 webservers, memcache), but it does s <<
686 scheduler stress tests, such as hack <<
687 517
688 If you are paranoid and not sure wha !! 518 Say Y if you need to make expert-level adjustments to RCU.
689 used for, say Y. <<
690 519
691 Say N if unsure. !! 520 Say N if you are unsure.
692 521
693 endmenu # "CPU/Task time and stats accounting" !! 522 config SRCU
>> 523 bool
>> 524 help
>> 525 This option selects the sleepable version of RCU. This version
>> 526 permits arbitrary sleeping or blocking within RCU read-side critical
>> 527 sections.
694 528
695 config CPU_ISOLATION !! 529 config TASKS_RCU
696 bool "CPU isolation" !! 530 bool
697 depends on SMP || COMPILE_TEST !! 531 default n
698 default y !! 532 select SRCU
>> 533 help
>> 534 This option enables a task-based RCU implementation that uses
>> 535 only voluntary context switch (not preemption!), idle, and
>> 536 user-mode execution as quiescent states.
>> 537
>> 538 config RCU_STALL_COMMON
>> 539 def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
>> 540 help
>> 541 This option enables RCU CPU stall code that is common between
>> 542 the TINY and TREE variants of RCU. The purpose is to allow
>> 543 the tiny variants to disable RCU CPU stall warnings, while
>> 544 making these warnings mandatory for the tree variants.
>> 545
>> 546 config CONTEXT_TRACKING
>> 547 bool
>> 548
>> 549 config CONTEXT_TRACKING_FORCE
>> 550 bool "Force context tracking"
>> 551 depends on CONTEXT_TRACKING
>> 552 default y if !NO_HZ_FULL
>> 553 help
>> 554 The major pre-requirement for full dynticks to work is to
>> 555 support the context tracking subsystem. But there are also
>> 556 other dependencies to provide in order to make the full
>> 557 dynticks working.
>> 558
>> 559 This option stands for testing when an arch implements the
>> 560 context tracking backend but doesn't yet fullfill all the
>> 561 requirements to make the full dynticks feature working.
>> 562 Without the full dynticks, there is no way to test the support
>> 563 for context tracking and the subsystems that rely on it: RCU
>> 564 userspace extended quiescent state and tickless cputime
>> 565 accounting. This option copes with the absence of the full
>> 566 dynticks subsystem by forcing the context tracking on all
>> 567 CPUs in the system.
>> 568
>> 569 Say Y only if you're working on the development of an
>> 570 architecture backend for the context tracking.
>> 571
>> 572 Say N otherwise, this option brings an overhead that you
>> 573 don't want in production.
>> 574
>> 575
>> 576 config RCU_FANOUT
>> 577 int "Tree-based hierarchical RCU fanout value"
>> 578 range 2 64 if 64BIT
>> 579 range 2 32 if !64BIT
>> 580 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
>> 581 default 64 if 64BIT
>> 582 default 32 if !64BIT
>> 583 help
>> 584 This option controls the fanout of hierarchical implementations
>> 585 of RCU, allowing RCU to work efficiently on machines with
>> 586 large numbers of CPUs. This value must be at least the fourth
>> 587 root of NR_CPUS, which allows NR_CPUS to be insanely large.
>> 588 The default value of RCU_FANOUT should be used for production
>> 589 systems, but if you are stress-testing the RCU implementation
>> 590 itself, small RCU_FANOUT values allow you to test large-system
>> 591 code paths on small(er) systems.
>> 592
>> 593 Select a specific number if testing RCU itself.
>> 594 Take the default if unsure.
>> 595
>> 596 config RCU_FANOUT_LEAF
>> 597 int "Tree-based hierarchical RCU leaf-level fanout value"
>> 598 range 2 64 if 64BIT
>> 599 range 2 32 if !64BIT
>> 600 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
>> 601 default 16
>> 602 help
>> 603 This option controls the leaf-level fanout of hierarchical
>> 604 implementations of RCU, and allows trading off cache misses
>> 605 against lock contention. Systems that synchronize their
>> 606 scheduling-clock interrupts for energy-efficiency reasons will
>> 607 want the default because the smaller leaf-level fanout keeps
>> 608 lock contention levels acceptably low. Very large systems
>> 609 (hundreds or thousands of CPUs) will instead want to set this
>> 610 value to the maximum value possible in order to reduce the
>> 611 number of cache misses incurred during RCU's grace-period
>> 612 initialization. These systems tend to run CPU-bound, and thus
>> 613 are not helped by synchronized interrupts, and thus tend to
>> 614 skew them, which reduces lock contention enough that large
>> 615 leaf-level fanouts work well.
>> 616
>> 617 Select a specific number if testing RCU itself.
>> 618
>> 619 Select the maximum permissible value for large systems.
>> 620
>> 621 Take the default if unsure.
>> 622
>> 623 config RCU_FAST_NO_HZ
>> 624 bool "Accelerate last non-dyntick-idle CPU's grace periods"
>> 625 depends on NO_HZ_COMMON && SMP && RCU_EXPERT
>> 626 default n
699 help 627 help
700 Make sure that CPUs running critical !! 628 This option permits CPUs to enter dynticks-idle state even if
701 any source of "noise" such as unboun !! 629 they have RCU callbacks queued, and prevents RCU from waking
702 Unbound jobs get offloaded to housek !! 630 these CPUs up more than roughly once every four jiffies (by
703 the "isolcpus=" boot parameter. !! 631 default, you can adjust this using the rcutree.rcu_idle_gp_delay
>> 632 parameter), thus improving energy efficiency. On the other
>> 633 hand, this option increases the duration of RCU grace periods,
>> 634 for example, slowing down synchronize_rcu().
>> 635
>> 636 Say Y if energy efficiency is critically important, and you
>> 637 don't care about increased grace-period durations.
>> 638
>> 639 Say N if you are unsure.
>> 640
>> 641 config TREE_RCU_TRACE
>> 642 def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
>> 643 select DEBUG_FS
>> 644 help
>> 645 This option provides tracing for the TREE_RCU and
>> 646 PREEMPT_RCU implementations, permitting Makefile to
>> 647 trivially select kernel/rcutree_trace.c.
>> 648
>> 649 config RCU_BOOST
>> 650 bool "Enable RCU priority boosting"
>> 651 depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
>> 652 default n
>> 653 help
>> 654 This option boosts the priority of preempted RCU readers that
>> 655 block the current preemptible RCU grace period for too long.
>> 656 This option also prevents heavy loads from blocking RCU
>> 657 callback invocation for all flavors of RCU.
>> 658
>> 659 Say Y here if you are working with real-time apps or heavy loads
>> 660 Say N here if you are unsure.
>> 661
>> 662 config RCU_KTHREAD_PRIO
>> 663 int "Real-time priority to use for RCU worker threads"
>> 664 range 1 99 if RCU_BOOST
>> 665 range 0 99 if !RCU_BOOST
>> 666 default 1 if RCU_BOOST
>> 667 default 0 if !RCU_BOOST
>> 668 depends on RCU_EXPERT
>> 669 help
>> 670 This option specifies the SCHED_FIFO priority value that will be
>> 671 assigned to the rcuc/n and rcub/n threads and is also the value
>> 672 used for RCU_BOOST (if enabled). If you are working with a
>> 673 real-time application that has one or more CPU-bound threads
>> 674 running at a real-time priority level, you should set
>> 675 RCU_KTHREAD_PRIO to a priority higher than the highest-priority
>> 676 real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO
>> 677 value of 1 is appropriate in the common case, which is real-time
>> 678 applications that do not have any CPU-bound threads.
>> 679
>> 680 Some real-time applications might not have a single real-time
>> 681 thread that saturates a given CPU, but instead might have
>> 682 multiple real-time threads that, taken together, fully utilize
>> 683 that CPU. In this case, you should set RCU_KTHREAD_PRIO to
>> 684 a priority higher than the lowest-priority thread that is
>> 685 conspiring to prevent the CPU from running any non-real-time
>> 686 tasks. For example, if one thread at priority 10 and another
>> 687 thread at priority 5 are between themselves fully consuming
>> 688 the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
>> 689 set to priority 6 or higher.
>> 690
>> 691 Specify the real-time priority, or take the default if unsure.
>> 692
>> 693 config RCU_BOOST_DELAY
>> 694 int "Milliseconds to delay boosting after RCU grace-period start"
>> 695 range 0 3000
>> 696 depends on RCU_BOOST
>> 697 default 500
>> 698 help
>> 699 This option specifies the time to wait after the beginning of
>> 700 a given grace period before priority-boosting preempted RCU
>> 701 readers blocking that grace period. Note that any RCU reader
>> 702 blocking an expedited RCU grace period is boosted immediately.
>> 703
>> 704 Accept the default if unsure.
>> 705
>> 706 config RCU_NOCB_CPU
>> 707 bool "Offload RCU callback processing from boot-selected CPUs"
>> 708 depends on TREE_RCU || PREEMPT_RCU
>> 709 depends on RCU_EXPERT || NO_HZ_FULL
>> 710 default n
>> 711 help
>> 712 Use this option to reduce OS jitter for aggressive HPC or
>> 713 real-time workloads. It can also be used to offload RCU
>> 714 callback invocation to energy-efficient CPUs in battery-powered
>> 715 asymmetric multiprocessors.
>> 716
>> 717 This option offloads callback invocation from the set of
>> 718 CPUs specified at boot time by the rcu_nocbs parameter.
>> 719 For each such CPU, a kthread ("rcuox/N") will be created to
>> 720 invoke callbacks, where the "N" is the CPU being offloaded,
>> 721 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
>> 722 "s" for RCU-sched. Nothing prevents this kthread from running
>> 723 on the specified CPUs, but (1) the kthreads may be preempted
>> 724 between each callback, and (2) affinity or cgroups can be used
>> 725 to force the kthreads to run on whatever set of CPUs is desired.
704 726
705 Say Y if unsure. !! 727 Say Y here if you want to help to debug reduced OS jitter.
>> 728 Say N here if you are unsure.
>> 729
>> 730 choice
>> 731 prompt "Build-forced no-CBs CPUs"
>> 732 default RCU_NOCB_CPU_NONE
>> 733 depends on RCU_NOCB_CPU
>> 734 help
>> 735 This option allows no-CBs CPUs (whose RCU callbacks are invoked
>> 736 from kthreads rather than from softirq context) to be specified
>> 737 at build time. Additional no-CBs CPUs may be specified by
>> 738 the rcu_nocbs= boot parameter.
>> 739
>> 740 config RCU_NOCB_CPU_NONE
>> 741 bool "No build_forced no-CBs CPUs"
>> 742 help
>> 743 This option does not force any of the CPUs to be no-CBs CPUs.
>> 744 Only CPUs designated by the rcu_nocbs= boot parameter will be
>> 745 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
>> 746 kthreads whose names begin with "rcuo". All other CPUs will
>> 747 invoke their own RCU callbacks in softirq context.
>> 748
>> 749 Select this option if you want to choose no-CBs CPUs at
>> 750 boot time, for example, to allow testing of different no-CBs
>> 751 configurations without having to rebuild the kernel each time.
>> 752
>> 753 config RCU_NOCB_CPU_ZERO
>> 754 bool "CPU 0 is a build_forced no-CBs CPU"
>> 755 help
>> 756 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
>> 757 callbacks are invoked by a per-CPU kthread whose name begins
>> 758 with "rcuo". Additional CPUs may be designated as no-CBs
>> 759 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
>> 760 All other CPUs will invoke their own RCU callbacks in softirq
>> 761 context.
>> 762
>> 763 Select this if CPU 0 needs to be a no-CBs CPU for real-time
>> 764 or energy-efficiency reasons, but the real reason it exists
>> 765 is to ensure that randconfig testing covers mixed systems.
>> 766
>> 767 config RCU_NOCB_CPU_ALL
>> 768 bool "All CPUs are build_forced no-CBs CPUs"
>> 769 help
>> 770 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
>> 771 boot parameter will be ignored. All CPUs' RCU callbacks will
>> 772 be executed in the context of per-CPU rcuo kthreads created for
>> 773 this purpose. Assuming that the kthreads whose names start with
>> 774 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
>> 775 on the remaining CPUs, but might decrease memory locality during
>> 776 RCU-callback invocation, thus potentially degrading throughput.
706 777
707 source "kernel/rcu/Kconfig" !! 778 Select this if all CPUs need to be no-CBs CPUs for real-time
>> 779 or energy-efficiency reasons.
>> 780
>> 781 endchoice
>> 782
>> 783 endmenu # "RCU Subsystem"
>> 784
>> 785 config BUILD_BIN2C
>> 786 bool
>> 787 default n
708 788
709 config IKCONFIG 789 config IKCONFIG
710 tristate "Kernel .config support" 790 tristate "Kernel .config support"
711 help !! 791 select BUILD_BIN2C
>> 792 ---help---
712 This option enables the complete Lin 793 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 794 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 795 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 796 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 797 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 798 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 799 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 800 /proc/config.gz if enabled (below).
720 801
721 config IKCONFIG_PROC 802 config IKCONFIG_PROC
722 bool "Enable access to .config through 803 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 804 depends on IKCONFIG && PROC_FS
724 help !! 805 ---help---
725 This option enables access to the ke 806 This option enables access to the kernel configuration file
726 through /proc/config.gz. 807 through /proc/config.gz.
727 808
728 config IKHEADERS <<
729 tristate "Enable kernel headers throug <<
730 depends on SYSFS <<
731 help <<
732 This option enables access to the in <<
733 the build process. These can be used <<
734 or similar programs. If you build t <<
735 kheaders.ko is built which can be lo <<
736 <<
737 config LOG_BUF_SHIFT 809 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 810 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 811 range 12 25
740 default 17 812 default 17
741 depends on PRINTK 813 depends on PRINTK
742 help 814 help
743 Select the minimal kernel log buffer 815 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 816 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 817 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 818 by "log_buf_len" boot parameter.
747 819
748 Examples: 820 Examples:
749 17 => 128 KB 821 17 => 128 KB
750 16 => 64 KB 822 16 => 64 KB
751 15 => 32 KB 823 15 => 32 KB
752 14 => 16 KB 824 14 => 16 KB
753 13 => 8 KB 825 13 => 8 KB
754 12 => 4 KB 826 12 => 4 KB
755 827
756 config LOG_CPU_MAX_BUF_SHIFT 828 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 829 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 830 depends on SMP
759 range 0 21 831 range 0 21
>> 832 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 833 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 834 depends on PRINTK
763 help 835 help
764 This option allows to increase the d 836 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 837 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 838 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 839 lines however it might be much more when problems are reported,
768 e.g. backtraces. 840 e.g. backtraces.
769 841
770 The increased size means that a new 842 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 843 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 844 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 845 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 846 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed !! 847 so that more than 64 CPUs are needed to trigger the allocation.
776 848
777 Also this option is ignored when "lo 849 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 850 used as it forces an exact (power of two) size of the ring buffer.
779 851
780 The number of possible CPUs is used 852 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 853 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 854 scenario while allowing a simple algorithm to be used from bootup.
783 855
784 Examples shift values and their mean 856 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 857 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 858 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 859 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 860 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 861 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 862 12 => 4 KB for each CPU
791 863
792 config PRINTK_INDEX !! 864 config PRINTK_SAFE_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 865 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 866 range 10 21
795 help !! 867 default 13
796 Add support for indexing of all prin !! 868 depends on PRINTK
797 at <debugfs>/printk/index/<module>. !! 869 help
798 !! 870 Select the size of an alternate printk per-CPU buffer where messages
799 This can be used as part of maintain !! 871 printed from usafe contexts are temporary stored. One example would
800 /dev/kmsg, as it permits auditing th !! 872 be NMI messages, another one - printk recursion. The messages are
801 kernel, allowing detection of cases !! 873 copied to the main log buffer in a safe context to avoid a deadlock.
802 changed or no longer present. !! 874 The value defines the size as a power of 2.
>> 875
>> 876 Those messages are rare and limited. The largest one is when
>> 877 a backtrace is printed. It usually fits into 4KB. Select
>> 878 8KB if you want to be on the safe side.
803 879
804 There is no additional runtime cost !! 880 Examples:
>> 881 17 => 128 KB for each CPU
>> 882 16 => 64 KB for each CPU
>> 883 15 => 32 KB for each CPU
>> 884 14 => 16 KB for each CPU
>> 885 13 => 8 KB for each CPU
>> 886 12 => 4 KB for each CPU
805 887
806 # 888 #
807 # Architectures with an unreliable sched_clock 889 # Architectures with an unreliable sched_clock() should select this:
808 # 890 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 891 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 892 bool
811 893
812 config GENERIC_SCHED_CLOCK 894 config GENERIC_SCHED_CLOCK
813 bool 895 bool
814 896
815 menu "Scheduler features" <<
816 <<
817 config UCLAMP_TASK <<
818 bool "Enable utilization clamping for <<
819 depends on CPU_FREQ_GOV_SCHEDUTIL <<
820 help <<
821 This feature enables the scheduler t <<
822 of each CPU based on RUNNABLE tasks <<
823 <<
824 With this option, the user can speci <<
825 utilization allowed for RUNNABLE tas <<
826 the maximum frequency a task should <<
827 defines the minimum frequency it sho <<
828 <<
829 Both min and max utilization clamp v <<
830 aiming at improving its frequency se <<
831 enforce or grant any specific bandwi <<
832 <<
833 If in doubt, say N. <<
834 <<
835 config UCLAMP_BUCKETS_COUNT <<
836 int "Number of supported utilization c <<
837 range 5 20 <<
838 default 5 <<
839 depends on UCLAMP_TASK <<
840 help <<
841 Defines the number of clamp buckets <<
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ <<
843 number of clamp buckets the finer th <<
844 the precision of clamping aggregatio <<
845 <<
846 For example, with the minimum config <<
847 clamp buckets tracking 20% utilizati <<
848 be refcounted in the [20..39]% bucke <<
849 effective value to 25%. <<
850 If a second 30% boosted task should <<
851 that task will be refcounted in the <<
852 it will boost the bucket clamp effec <<
853 The clamp effective value of a bucke <<
854 (20% in the example above) when ther <<
855 that bucket. <<
856 <<
857 An additional boost/capping margin c <<
858 example above the 25% task will be b <<
859 CPU. If that should be considered no <<
860 it's always possible to reduce the m <<
861 clamp buckets to trade off used memo <<
862 precision. <<
863 <<
864 If in doubt, use the default value. <<
865 <<
866 endmenu <<
867 <<
868 # 897 #
869 # For architectures that want to enable the su 898 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 899 # balancing logic:
871 # 900 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 901 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 902 bool
874 903
875 # 904 #
876 # For architectures that prefer to flush all T 905 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 906 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 907 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 908 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 909 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 910 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 911 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 912 bool
884 913
885 config CC_HAS_INT128 <<
886 def_bool !$(cc-option,$(m64-flag) -D__ <<
887 <<
888 config CC_IMPLICIT_FALLTHROUGH <<
889 string <<
890 default "-Wimplicit-fallthrough=5" if <<
891 default "-Wimplicit-fallthrough" if CC <<
892 <<
893 # Currently, disable gcc-10+ array-bounds glob <<
894 # It's still broken in gcc-13, so no upper bou <<
895 config GCC10_NO_ARRAY_BOUNDS <<
896 def_bool y <<
897 <<
898 config CC_NO_ARRAY_BOUNDS <<
899 bool <<
900 default y if CC_IS_GCC && GCC_VERSION <<
901 <<
902 # Currently, disable -Wstringop-overflow for G <<
903 config GCC_NO_STRINGOP_OVERFLOW <<
904 def_bool y <<
905 <<
906 config CC_NO_STRINGOP_OVERFLOW <<
907 bool <<
908 default y if CC_IS_GCC && GCC_NO_STRIN <<
909 <<
910 config CC_STRINGOP_OVERFLOW <<
911 bool <<
912 default y if CC_IS_GCC && !CC_NO_STRIN <<
913 <<
914 # 914 #
915 # For architectures that know their GCC __int1 915 # For architectures that know their GCC __int128 support is sound
916 # 916 #
917 config ARCH_SUPPORTS_INT128 917 config ARCH_SUPPORTS_INT128
918 bool 918 bool
919 919
920 # For architectures that (ab)use NUMA to repre 920 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 921 # all cpu-local but of different latencies, such as SuperH.
922 # 922 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 924 bool
925 925
926 config NUMA_BALANCING 926 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 927 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 928 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 929 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 930 depends on SMP && NUMA && MIGRATION
931 help 931 help
932 This option adds support for automat 932 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 933 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 934 it has references to the node the task is running on.
935 935
936 This system will be inactive on UMA 936 This system will be inactive on UMA systems.
937 937
938 config NUMA_BALANCING_DEFAULT_ENABLED 938 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 939 bool "Automatically enable NUMA aware memory/task placement"
940 default y 940 default y
941 depends on NUMA_BALANCING 941 depends on NUMA_BALANCING
942 help 942 help
943 If set, automatic NUMA balancing wil 943 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 944 machine.
945 945
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 946 menuconfig CGROUPS
950 bool "Control Group support" 947 bool "Control Group support"
951 select KERNFS 948 select KERNFS
952 help 949 help
953 This option adds support for groupin 950 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 951 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 952 controls or device isolation.
956 See 953 See
957 - Documentation/scheduler/sche !! 954 - Documentation/scheduler/sched-design-CFS.txt (CFS)
958 - Documentation/admin-guide/cg !! 955 - Documentation/cgroup-v1/ (features for grouping, isolation
959 and 956 and resource control)
960 957
961 Say N if unsure. 958 Say N if unsure.
962 959
963 if CGROUPS 960 if CGROUPS
964 961
965 config PAGE_COUNTER 962 config PAGE_COUNTER
966 bool !! 963 bool
967 <<
968 config CGROUP_FAVOR_DYNMODS <<
969 bool "Favor dynamic modification laten <<
970 help <<
971 This option enables the "favordynmod <<
972 which reduces the latencies of dynam <<
973 as task migrations and controller on <<
974 hot path operations such as forks an <<
975 <<
976 Say N if unsure. <<
977 964
978 config MEMCG 965 config MEMCG
979 bool "Memory controller" 966 bool "Memory controller"
980 select PAGE_COUNTER 967 select PAGE_COUNTER
981 select EVENTFD 968 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 969 help
984 Provides control over the memory foo 970 Provides control over the memory footprint of tasks in a cgroup.
985 971
986 config MEMCG_V1 !! 972 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 973 bool "Swap controller"
988 depends on MEMCG !! 974 depends on MEMCG && SWAP
989 default n !! 975 help
990 help !! 976 Provides control over the swap space consumed by tasks in a cgroup.
991 Legacy cgroup v1 memory controller w !! 977
992 cgroup v2 implementation. The v1 is !! 978 config MEMCG_SWAP_ENABLED
993 which haven't migrated to the new cg !! 979 bool "Swap controller enabled by default"
994 do not have any such application the !! 980 depends on MEMCG_SWAP
995 this option disabled. !! 981 default y
996 !! 982 help
997 Please note that feature set of the !! 983 Memory Resource Controller Swap Extension comes with its price in
998 going to shrink due to deprecation p !! 984 a bigger memory consumption. General purpose distribution kernels
999 controller are highly discouraged. !! 985 which want to enable the feature but keep it disabled by default
1000 !! 986 and let the user enable it by swapaccount=1 boot command line
1001 Say N if unsure. !! 987 parameter should have this option unselected.
>> 988 For those who want to have the feature enabled by default should
>> 989 select this option (if, for some reason, they need to disable it
>> 990 then swapaccount=0 does the trick).
1002 991
1003 config BLK_CGROUP 992 config BLK_CGROUP
1004 bool "IO controller" 993 bool "IO controller"
1005 depends on BLOCK 994 depends on BLOCK
1006 default n 995 default n
1007 help !! 996 ---help---
1008 Generic block IO controller cgroup in 997 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 998 cgroup interface which should be used by various IO controlling
1010 policies. 999 policies.
1011 1000
1012 Currently, CFQ IO scheduler uses it t 1001 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 1002 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 1003 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 1004 block layer to implement upper limit in IO rates on a device.
1016 1005
1017 This option only enables generic Bloc 1006 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 1007 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 1008 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl !! 1009 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 1010 CONFIG_BLK_DEV_THROTTLING=y.
1022 1011
1023 See Documentation/admin-guide/cgroup- !! 1012 See Documentation/cgroup-v1/blkio-controller.txt for more information.
>> 1013
>> 1014 config DEBUG_BLK_CGROUP
>> 1015 bool "IO controller debugging"
>> 1016 depends on BLK_CGROUP
>> 1017 default n
>> 1018 ---help---
>> 1019 Enable some debugging help. Currently it exports additional stat
>> 1020 files in a cgroup which can be useful for debugging.
1024 1021
1025 config CGROUP_WRITEBACK 1022 config CGROUP_WRITEBACK
1026 bool 1023 bool
1027 depends on MEMCG && BLK_CGROUP 1024 depends on MEMCG && BLK_CGROUP
1028 default y 1025 default y
1029 1026
1030 menuconfig CGROUP_SCHED 1027 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 1028 bool "CPU controller"
1032 default n 1029 default n
1033 help 1030 help
1034 This feature lets CPU scheduler rec 1031 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 1032 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 1033 tasks.
1037 1034
1038 if CGROUP_SCHED 1035 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 1036 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 1037 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 1038 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1039 default CGROUP_SCHED
1047 1040
1048 config CFS_BANDWIDTH 1041 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1042 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1043 depends on FAIR_GROUP_SCHED
1051 default n 1044 default n
1052 help 1045 help
1053 This option allows users to define 1046 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1047 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1048 set are considered to be unconstrained and will run with no
1056 restriction. 1049 restriction.
1057 See Documentation/scheduler/sched-b !! 1050 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1058 1051
1059 config RT_GROUP_SCHED 1052 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1053 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1054 depends on CGROUP_SCHED
1062 default n 1055 default n
1063 help 1056 help
1064 This feature lets you explicitly al 1057 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1058 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1059 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1060 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r !! 1061 See Documentation/scheduler/sched-rt-group.txt for more information.
1069 <<
1070 config EXT_GROUP_SCHED <<
1071 bool <<
1072 depends on SCHED_CLASS_EXT && CGROUP_ <<
1073 select GROUP_SCHED_WEIGHT <<
1074 default y <<
1075 1062
1076 endif #CGROUP_SCHED 1063 endif #CGROUP_SCHED
1077 1064
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP <<
1083 bool "Utilization clamping per group <<
1084 depends on CGROUP_SCHED <<
1085 depends on UCLAMP_TASK <<
1086 default n <<
1087 help <<
1088 This feature enables the scheduler <<
1089 of each CPU based on RUNNABLE tasks <<
1090 <<
1091 When this option is enabled, the us <<
1092 CPU bandwidth which is allowed for <<
1093 The max bandwidth allows to clamp t <<
1094 can use, while the min bandwidth al <<
1095 frequency a task will always use. <<
1096 <<
1097 When task group based utilization c <<
1098 specified task-specific clamp value <<
1099 specified clamp value. Both minimum <<
1100 be bigger than the corresponding cl <<
1101 <<
1102 If in doubt, say N. <<
1103 <<
1104 config CGROUP_PIDS 1065 config CGROUP_PIDS
1105 bool "PIDs controller" 1066 bool "PIDs controller"
1106 help 1067 help
1107 Provides enforcement of process num 1068 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1069 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1070 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1071 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1072 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1073 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1074 PIDs controller is designed to stop this from happening.
1114 1075
1115 It should be noted that organisatio 1076 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b !! 1077 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
1117 since the PIDs limit only affects a 1078 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1079 attach to a cgroup.
1119 1080
1120 config CGROUP_RDMA 1081 config CGROUP_RDMA
1121 bool "RDMA controller" 1082 bool "RDMA controller"
1122 help 1083 help
1123 Provides enforcement of RDMA resour 1084 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1085 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1086 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1087 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1088 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1089 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1090
1130 config CGROUP_FREEZER 1091 config CGROUP_FREEZER
1131 bool "Freezer controller" 1092 bool "Freezer controller"
1132 help 1093 help
1133 Provides a way to freeze and unfree 1094 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1095 cgroup.
1135 1096
1136 This option affects the ORIGINAL cg 1097 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1098 controller includes important in-kernel memory consumers per default.
1138 1099
1139 If you're using cgroup2, say N. 1100 If you're using cgroup2, say N.
1140 1101
1141 config CGROUP_HUGETLB 1102 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1103 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1104 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1105 select PAGE_COUNTER
1145 default n 1106 default n
1146 help 1107 help
1147 Provides a cgroup controller for Hu 1108 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1109 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1110 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1111 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1112 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1113 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1114 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1115 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1116 that we cannot use the controller with huge page less than 3 pages.
1156 1117
1157 config CPUSETS 1118 config CPUSETS
1158 bool "Cpuset controller" 1119 bool "Cpuset controller"
1159 depends on SMP <<
1160 help 1120 help
1161 This option will let you create and 1121 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1122 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1123 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1124 This is primarily useful on large SMP or NUMA systems.
1165 1125
1166 Say N if unsure. 1126 Say N if unsure.
1167 1127
1168 config CPUSETS_V1 <<
1169 bool "Legacy cgroup v1 cpusets contro <<
1170 depends on CPUSETS <<
1171 default n <<
1172 help <<
1173 Legacy cgroup v1 cpusets controller <<
1174 cgroup v2 implementation. The v1 is <<
1175 which haven't migrated to the new c <<
1176 do not have any such application th <<
1177 this option disabled. <<
1178 <<
1179 Say N if unsure. <<
1180 <<
1181 config PROC_PID_CPUSET 1128 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1129 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1130 depends on CPUSETS
1184 default y 1131 default y
1185 1132
1186 config CGROUP_DEVICE 1133 config CGROUP_DEVICE
1187 bool "Device controller" 1134 bool "Device controller"
1188 help 1135 help
1189 Provides a cgroup controller implem 1136 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1137 devices which a process in the cgroup can mknod or open.
1191 1138
1192 config CGROUP_CPUACCT 1139 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1140 bool "Simple CPU accounting controller"
1194 help 1141 help
1195 Provides a simple controller for mo 1142 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1143 total CPU consumed by the tasks in a cgroup.
1197 1144
1198 config CGROUP_PERF 1145 config CGROUP_PERF
1199 bool "Perf controller" 1146 bool "Perf controller"
1200 depends on PERF_EVENTS 1147 depends on PERF_EVENTS
1201 help 1148 help
1202 This option extends the perf per-cp 1149 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1150 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use !! 1151 designated cpu.
1205 so that it can monitor performance <<
1206 1152
1207 Say N if unsure. 1153 Say N if unsure.
1208 1154
1209 config CGROUP_BPF 1155 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1156 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1157 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1158 select SOCK_CGROUP_DATA
1213 help 1159 help
1214 Allow attaching eBPF programs to a 1160 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1161 syscall command BPF_PROG_ATTACH.
1216 1162
1217 In which context these programs are 1163 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1164 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1165 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1166 inet sockets.
1221 1167
1222 config CGROUP_MISC <<
1223 bool "Misc resource controller" <<
1224 default n <<
1225 help <<
1226 Provides a controller for miscellan <<
1227 <<
1228 Miscellaneous scalar resources are <<
1229 which cannot be abstracted like the <<
1230 tracks and limits the miscellaneous <<
1231 attached to a cgroup hierarchy. <<
1232 <<
1233 For more information, please check <<
1234 /Documentation/admin-guide/cgroup-v <<
1235 <<
1236 config CGROUP_DEBUG 1168 config CGROUP_DEBUG
1237 bool "Debug controller" !! 1169 bool "Example controller"
1238 default n 1170 default n
1239 depends on DEBUG_KERNEL <<
1240 help 1171 help
1241 This option enables a simple contro 1172 This option enables a simple controller that exports
1242 debugging information about the cgr !! 1173 debugging information about the cgroups framework.
1243 controller is for control cgroup de <<
1244 interfaces are not stable. <<
1245 1174
1246 Say N. 1175 Say N.
1247 1176
1248 config SOCK_CGROUP_DATA 1177 config SOCK_CGROUP_DATA
1249 bool 1178 bool
1250 default n 1179 default n
1251 1180
1252 endif # CGROUPS 1181 endif # CGROUPS
1253 1182
>> 1183 config CHECKPOINT_RESTORE
>> 1184 bool "Checkpoint/restore support" if EXPERT
>> 1185 select PROC_CHILDREN
>> 1186 default n
>> 1187 help
>> 1188 Enables additional kernel features in a sake of checkpoint/restore.
>> 1189 In particular it adds auxiliary prctl codes to setup process text,
>> 1190 data and heap segment sizes, and a few additional /proc filesystem
>> 1191 entries.
>> 1192
>> 1193 If unsure, say N here.
>> 1194
1254 menuconfig NAMESPACES 1195 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1196 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1197 depends on MULTIUSER
1257 default !EXPERT 1198 default !EXPERT
1258 help 1199 help
1259 Provides the way to make tasks work 1200 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1201 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1202 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1203 different namespaces.
1263 1204
1264 if NAMESPACES 1205 if NAMESPACES
1265 1206
1266 config UTS_NS 1207 config UTS_NS
1267 bool "UTS namespace" 1208 bool "UTS namespace"
1268 default y 1209 default y
1269 help 1210 help
1270 In this namespace tasks see differe 1211 In this namespace tasks see different info provided with the
1271 uname() system call 1212 uname() system call
1272 1213
1273 config TIME_NS <<
1274 bool "TIME namespace" <<
1275 depends on GENERIC_VDSO_TIME_NS <<
1276 default y <<
1277 help <<
1278 In this namespace boottime and mono <<
1279 The time will keep going with the s <<
1280 <<
1281 config IPC_NS 1214 config IPC_NS
1282 bool "IPC namespace" 1215 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1216 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1217 default y
1285 help 1218 help
1286 In this namespace tasks work with I 1219 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1220 different IPC objects in different namespaces.
1288 1221
1289 config USER_NS 1222 config USER_NS
1290 bool "User namespace" 1223 bool "User namespace"
1291 default n 1224 default n
1292 help 1225 help
1293 This allows containers, i.e. vserve 1226 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1227 to provide different user info for different servers.
1295 1228
1296 When user namespaces are enabled in 1229 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1230 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1231 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1232 of memory a memory unprivileged users can use.
1300 1233
1301 If unsure, say N. 1234 If unsure, say N.
1302 1235
1303 config PID_NS 1236 config PID_NS
1304 bool "PID Namespaces" 1237 bool "PID Namespaces"
1305 default y 1238 default y
1306 help 1239 help
1307 Support process id namespaces. Thi 1240 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1241 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1242 pid namespaces. This is a building block of containers.
1310 1243
1311 config NET_NS 1244 config NET_NS
1312 bool "Network namespace" 1245 bool "Network namespace"
1313 depends on NET 1246 depends on NET
1314 default y 1247 default y
1315 help 1248 help
1316 Allow user space to create what app 1249 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1250 of the network stack.
1318 1251
1319 endif # NAMESPACES 1252 endif # NAMESPACES
1320 1253
1321 config CHECKPOINT_RESTORE <<
1322 bool "Checkpoint/restore support" <<
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN <<
1325 select KCMP <<
1326 default n <<
1327 help <<
1328 Enables additional kernel features <<
1329 In particular it adds auxiliary prc <<
1330 data and heap segment sizes, and a <<
1331 entries. <<
1332 <<
1333 If unsure, say N here. <<
1334 <<
1335 config SCHED_AUTOGROUP 1254 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1255 bool "Automatic process group scheduling"
1337 select CGROUPS 1256 select CGROUPS
1338 select CGROUP_SCHED 1257 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1258 select FAIR_GROUP_SCHED
1340 help 1259 help
1341 This option optimizes the scheduler 1260 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1261 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1262 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1263 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1264 upon task session.
1346 1265
>> 1266 config SYSFS_DEPRECATED
>> 1267 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1268 depends on SYSFS
>> 1269 default n
>> 1270 help
>> 1271 This option adds code that switches the layout of the "block" class
>> 1272 devices, to not show up in /sys/class/block/, but only in
>> 1273 /sys/block/.
>> 1274
>> 1275 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1276 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1277
>> 1278 This option allows new kernels to run on old distributions and tools,
>> 1279 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1280 major distributions and tools handle this just fine.
>> 1281
>> 1282 Recent distributions and userspace tools after 2009/2010 depend on
>> 1283 the existence of /sys/class/block/, and will not work with this
>> 1284 option enabled.
>> 1285
>> 1286 Only if you are using a new kernel on an old distribution, you might
>> 1287 need to say Y here.
>> 1288
>> 1289 config SYSFS_DEPRECATED_V2
>> 1290 bool "Enable deprecated sysfs features by default"
>> 1291 default n
>> 1292 depends on SYSFS
>> 1293 depends on SYSFS_DEPRECATED
>> 1294 help
>> 1295 Enable deprecated sysfs by default.
>> 1296
>> 1297 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1298 option.
>> 1299
>> 1300 Only if you are using a new kernel on an old distribution, you might
>> 1301 need to say Y here. Even then, odds are you would not need it
>> 1302 enabled, you can always pass the boot option if absolutely necessary.
>> 1303
1347 config RELAY 1304 config RELAY
1348 bool "Kernel->user space relay suppor 1305 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1306 select IRQ_WORK
1350 help 1307 help
1351 This option enables support for rel 1308 This option enables support for relay interface support in
1352 certain file systems (such as debug 1309 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1310 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1311 facilities to relay large amounts of data from kernel space to
1355 user space. 1312 user space.
1356 1313
1357 If unsure, say N. 1314 If unsure, say N.
1358 1315
1359 config BLK_DEV_INITRD 1316 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1317 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
>> 1318 depends on BROKEN || !FRV
1361 help 1319 help
1362 The initial RAM filesystem is a ram 1320 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1321 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1322 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1323 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1324 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1325
1368 If RAM disk support (BLK_DEV_RAM) i 1326 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1327 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1328 15 Kbytes (more on some other architectures) to the kernel size.
1371 1329
1372 If unsure say Y. 1330 If unsure say Y.
1373 1331
1374 if BLK_DEV_INITRD 1332 if BLK_DEV_INITRD
1375 1333
1376 source "usr/Kconfig" 1334 source "usr/Kconfig"
1377 1335
1378 endif 1336 endif
1379 1337
1380 config BOOT_CONFIG <<
1381 bool "Boot config support" <<
1382 select BLK_DEV_INITRD if !BOOT_CONFIG <<
1383 help <<
1384 Extra boot config allows system adm <<
1385 complemental extension of kernel cm <<
1386 The boot config file must be attach <<
1387 with checksum, size and magic word. <<
1388 See <file:Documentation/admin-guide <<
1389 <<
1390 If unsure, say Y. <<
1391 <<
1392 config BOOT_CONFIG_FORCE <<
1393 bool "Force unconditional bootconfig <<
1394 depends on BOOT_CONFIG <<
1395 default y if BOOT_CONFIG_EMBED <<
1396 help <<
1397 With this Kconfig option set, BOOT_ <<
1398 out even when the "bootconfig" kern <<
1399 In fact, with this Kconfig option s <<
1400 make the kernel ignore the BOOT_CON <<
1401 parameters. <<
1402 <<
1403 If unsure, say N. <<
1404 <<
1405 config BOOT_CONFIG_EMBED <<
1406 bool "Embed bootconfig file in the ke <<
1407 depends on BOOT_CONFIG <<
1408 help <<
1409 Embed a bootconfig file given by BO <<
1410 kernel. Usually, the bootconfig fil <<
1411 image. But if the system doesn't su <<
1412 help you by embedding a bootconfig <<
1413 <<
1414 If unsure, say N. <<
1415 <<
1416 config BOOT_CONFIG_EMBED_FILE <<
1417 string "Embedded bootconfig file path <<
1418 depends on BOOT_CONFIG_EMBED <<
1419 help <<
1420 Specify a bootconfig file which wil <<
1421 This bootconfig will be used if the <<
1422 bootconfig in the initrd. <<
1423 <<
1424 config INITRAMFS_PRESERVE_MTIME <<
1425 bool "Preserve cpio archive mtimes in <<
1426 default y <<
1427 help <<
1428 Each entry in an initramfs cpio arc <<
1429 enabled, extracted cpio items take <<
1430 setting deferred until after creati <<
1431 <<
1432 If unsure, say Y. <<
1433 <<
1434 choice 1338 choice
1435 prompt "Compiler optimization level" 1339 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE !! 1340 default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
1437 1341
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1342 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" !! 1343 bool "Optimize for performance"
1440 help 1344 help
1441 This is the default optimization le 1345 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1346 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1347 helpful compile-time warnings.
1444 1348
1445 config CC_OPTIMIZE_FOR_SIZE 1349 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" !! 1350 bool "Optimize for size"
1447 help 1351 help
1448 Choosing this option will pass "-Os !! 1352 Enabling this option will pass "-Os" instead of "-O2" to
1449 in a smaller kernel. !! 1353 your compiler resulting in a smaller kernel.
>> 1354
>> 1355 If unsure, say N.
1450 1356
1451 endchoice 1357 endchoice
1452 1358
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION !! 1359 config SYSCTL
1454 bool 1360 bool
1455 help <<
1456 This requires that the arch annotat <<
1457 its external entry points from bein <<
1458 must also merge .text.*, .data.*, a <<
1459 output sections. Care must be taken <<
1460 sections (e.g., '.text.init'). Typi <<
1461 is used to distinguish them from la <<
1462 <<
1463 config LD_DEAD_CODE_DATA_ELIMINATION <<
1464 bool "Dead code and data elimination <<
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI <<
1466 depends on EXPERT <<
1467 depends on $(cc-option,-ffunction-sec <<
1468 depends on $(ld-option,--gc-sections) <<
1469 help <<
1470 Enable this if you want to do dead <<
1471 the linker by compiling with -ffunc <<
1472 and linking with --gc-sections. <<
1473 <<
1474 This can reduce on disk and in-memo <<
1475 code and static data, particularly <<
1476 on small systems. This has the poss <<
1477 silently broken kernel if the requi <<
1478 present. This option is not well te <<
1479 own risk. <<
1480 <<
1481 config LD_ORPHAN_WARN <<
1482 def_bool y <<
1483 depends on ARCH_WANT_LD_ORPHAN_WARN <<
1484 depends on $(ld-option,--orphan-handl <<
1485 depends on $(ld-option,--orphan-handl <<
1486 <<
1487 config LD_ORPHAN_WARN_LEVEL <<
1488 string <<
1489 depends on LD_ORPHAN_WARN <<
1490 default "error" if WERROR <<
1491 default "warn" <<
1492 1361
1493 config SYSCTL !! 1362 config ANON_INODES
1494 bool 1363 bool
1495 1364
1496 config HAVE_UID16 1365 config HAVE_UID16
1497 bool 1366 bool
1498 1367
1499 config SYSCTL_EXCEPTION_TRACE 1368 config SYSCTL_EXCEPTION_TRACE
1500 bool 1369 bool
1501 help 1370 help
1502 Enable support for /proc/sys/debug/ 1371 Enable support for /proc/sys/debug/exception-trace.
1503 1372
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1373 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1374 bool
1506 help 1375 help
1507 Enable support for /proc/sys/kernel 1376 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1377 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1378 about unaligned access emulation going on under the hood.
1510 1379
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1380 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1381 bool
1513 help 1382 help
1514 Enable support for /proc/sys/kernel 1383 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1384 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1385 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1386 see arch/parisc/kernel/unaligned.c for reference
1518 1387
1519 config HAVE_PCSPKR_PLATFORM 1388 config HAVE_PCSPKR_PLATFORM
1520 bool 1389 bool
1521 1390
>> 1391 # interpreter that classic socket filters depend on
>> 1392 config BPF
>> 1393 bool
>> 1394
1522 menuconfig EXPERT 1395 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1396 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1397 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1398 select DEBUG_KERNEL
1526 help 1399 help
1527 This option allows certain base ker 1400 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is !! 1401 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " !! 1402 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh !! 1403 Only use this if you really know what you are doing.
1531 1404
1532 config UID16 1405 config UID16
1533 bool "Enable 16-bit UID system calls" 1406 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1407 depends on HAVE_UID16 && MULTIUSER
1535 default y 1408 default y
1536 help 1409 help
1537 This enables the legacy 16-bit UID 1410 This enables the legacy 16-bit UID syscall wrappers.
1538 1411
1539 config MULTIUSER 1412 config MULTIUSER
1540 bool "Multiple users, groups and capa 1413 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1414 default y
1542 help 1415 help
1543 This option enables support for non 1416 This option enables support for non-root users, groups and
1544 capabilities. 1417 capabilities.
1545 1418
1546 If you say N here, all processes wi 1419 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1420 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1421 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1422 setgid, and capset.
1550 1423
1551 If unsure, say Y here. 1424 If unsure, say Y here.
1552 1425
1553 config SGETMASK_SYSCALL 1426 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1427 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1428 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1556 help !! 1429 ---help---
1557 sys_sgetmask and sys_ssetmask are o 1430 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1431 no longer supported in libc but still enabled by default in some
1559 architectures. 1432 architectures.
1560 1433
1561 If unsure, leave the default option 1434 If unsure, leave the default option here.
1562 1435
1563 config SYSFS_SYSCALL 1436 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1437 bool "Sysfs syscall support" if EXPERT
1565 default y 1438 default y
1566 help !! 1439 ---help---
1567 sys_sysfs is an obsolete system cal 1440 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1441 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1442 compatibility with some systems.
1570 1443
1571 If unsure say Y here. 1444 If unsure say Y here.
1572 1445
1573 config FHANDLE !! 1446 config SYSCTL_SYSCALL
1574 bool "open by fhandle syscalls" if EX !! 1447 bool "Sysctl syscall support" if EXPERT
1575 select EXPORTFS !! 1448 depends on PROC_SYSCTL
1576 default y !! 1449 default n
1577 help !! 1450 select SYSCTL
1578 If you say Y here, a user level pro !! 1451 ---help---
1579 file names to handle and then later !! 1452 sys_sysctl uses binary paths that have been found challenging
1580 different file system operations. T !! 1453 to properly maintain and use. The interface in /proc/sys
1581 userspace file servers, which now t !! 1454 using paths with ascii names is now the primary path to this
1582 of names. The handle would remain t !! 1455 information.
1583 get renamed. Enables open_by_handle !! 1456
1584 syscalls. !! 1457 Almost nothing using the binary sysctl interface so if you are
>> 1458 trying to save some space it is probably safe to disable this,
>> 1459 making your kernel marginally smaller.
>> 1460
>> 1461 If unsure say N here.
1585 1462
1586 config POSIX_TIMERS 1463 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1464 bool "Posix Clocks & timers" if EXPERT
1588 default y 1465 default y
1589 help 1466 help
1590 This includes native support for PO 1467 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1468 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1469 can be configured out to reduce the size of the kernel image.
1593 1470
1594 When this option is disabled, the f 1471 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1472 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1473 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1474 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1475 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1476 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1477
1601 If unsure say y. 1478 If unsure say y.
1602 1479
>> 1480 config KALLSYMS
>> 1481 bool "Load all symbols for debugging/ksymoops" if EXPERT
>> 1482 default y
>> 1483 help
>> 1484 Say Y here to let the kernel print out symbolic crash information and
>> 1485 symbolic stack backtraces. This increases the size of the kernel
>> 1486 somewhat, as all symbols have to be loaded into the kernel image.
>> 1487
>> 1488 config KALLSYMS_ALL
>> 1489 bool "Include all symbols in kallsyms"
>> 1490 depends on DEBUG_KERNEL && KALLSYMS
>> 1491 help
>> 1492 Normally kallsyms only contains the symbols of functions for nicer
>> 1493 OOPS messages and backtraces (i.e., symbols from the text and inittext
>> 1494 sections). This is sufficient for most cases. And only in very rare
>> 1495 cases (e.g., when a debugger is used) all symbols are required (e.g.,
>> 1496 names of variables from the data sections, etc).
>> 1497
>> 1498 This option makes sure that all symbols are loaded into the kernel
>> 1499 image (i.e., symbols from all sections) in cost of increased kernel
>> 1500 size (depending on the kernel configuration, it may be 300KiB or
>> 1501 something like this).
>> 1502
>> 1503 Say N unless you really need all symbols.
>> 1504
>> 1505 config KALLSYMS_ABSOLUTE_PERCPU
>> 1506 bool
>> 1507 depends on KALLSYMS
>> 1508 default X86_64 && SMP
>> 1509
>> 1510 config KALLSYMS_BASE_RELATIVE
>> 1511 bool
>> 1512 depends on KALLSYMS
>> 1513 default !IA64 && !(TILE && 64BIT)
>> 1514 help
>> 1515 Instead of emitting them as absolute values in the native word size,
>> 1516 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1517 each containing a relative value in the range [base, base + U32_MAX]
>> 1518 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1519 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1520 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1521 address encountered in the image.
>> 1522
>> 1523 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1524 but more importantly, it results in entries whose values are build
>> 1525 time constants, and no relocation pass is required at runtime to fix
>> 1526 up the entries based on the runtime load address of the kernel.
>> 1527
1603 config PRINTK 1528 config PRINTK
1604 default y 1529 default y
1605 bool "Enable support for printk" if E 1530 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1531 select IRQ_WORK
1607 help 1532 help
1608 This option enables normal printk s 1533 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1534 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1535 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1536 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1537 strongly discouraged.
1613 1538
>> 1539 config PRINTK_NMI
>> 1540 def_bool y
>> 1541 depends on PRINTK
>> 1542 depends on HAVE_NMI
>> 1543
1614 config BUG 1544 config BUG
1615 bool "BUG() support" if EXPERT 1545 bool "BUG() support" if EXPERT
1616 default y 1546 default y
1617 help 1547 help
1618 Disabling this option eliminates su !! 1548 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p !! 1549 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou !! 1550 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no !! 1551 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. !! 1552 Just say Y.
1623 1553
1624 config ELF_CORE 1554 config ELF_CORE
1625 depends on COREDUMP 1555 depends on COREDUMP
1626 default y 1556 default y
1627 bool "Enable ELF core dumps" if EXPER 1557 bool "Enable ELF core dumps" if EXPERT
1628 help 1558 help
1629 Enable support for generating core 1559 Enable support for generating core dumps. Disabling saves about 4k.
1630 1560
1631 1561
1632 config PCSPKR_PLATFORM 1562 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1563 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1564 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1565 select I8253_LOCK
1636 default y 1566 default y
1637 help 1567 help
1638 This option allows to disable the i !! 1568 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. !! 1569 support, saving some memory.
1640 1570
1641 config BASE_SMALL !! 1571 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1572 default y
>> 1573 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1574 help
1644 Enabling this option reduces the si !! 1575 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1576 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1577 but may reduce performance.
1647 1578
1648 config FUTEX 1579 config FUTEX
1649 bool "Enable futex support" if EXPERT 1580 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1581 default y
1652 imply RT_MUTEXES !! 1582 select RT_MUTEXES
1653 help 1583 help
1654 Disabling this option will cause th 1584 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1585 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1586 run glibc-based applications correctly.
1657 1587
1658 config FUTEX_PI !! 1588 config HAVE_FUTEX_CMPXCHG
1659 bool 1589 bool
1660 depends on FUTEX && RT_MUTEXES !! 1590 depends on FUTEX
1661 default y !! 1591 help
>> 1592 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1593 is implemented and always working. This removes a couple of runtime
>> 1594 checks.
1662 1595
1663 config EPOLL 1596 config EPOLL
1664 bool "Enable eventpoll support" if EX 1597 bool "Enable eventpoll support" if EXPERT
1665 default y 1598 default y
>> 1599 select ANON_INODES
1666 help 1600 help
1667 Disabling this option will cause th 1601 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1602 support for epoll family of system calls.
1669 1603
1670 config SIGNALFD 1604 config SIGNALFD
1671 bool "Enable signalfd() system call" 1605 bool "Enable signalfd() system call" if EXPERT
>> 1606 select ANON_INODES
1672 default y 1607 default y
1673 help 1608 help
1674 Enable the signalfd() system call t 1609 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1610 on a file descriptor.
1676 1611
1677 If unsure, say Y. 1612 If unsure, say Y.
1678 1613
1679 config TIMERFD 1614 config TIMERFD
1680 bool "Enable timerfd() system call" i 1615 bool "Enable timerfd() system call" if EXPERT
>> 1616 select ANON_INODES
1681 default y 1617 default y
1682 help 1618 help
1683 Enable the timerfd() system call th 1619 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1620 events on a file descriptor.
1685 1621
1686 If unsure, say Y. 1622 If unsure, say Y.
1687 1623
1688 config EVENTFD 1624 config EVENTFD
1689 bool "Enable eventfd() system call" i 1625 bool "Enable eventfd() system call" if EXPERT
>> 1626 select ANON_INODES
1690 default y 1627 default y
1691 help 1628 help
1692 Enable the eventfd() system call th 1629 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1630 kernel notification (ie. KAIO) or userspace notifications.
1694 1631
1695 If unsure, say Y. 1632 If unsure, say Y.
1696 1633
>> 1634 # syscall, maps, verifier
>> 1635 config BPF_SYSCALL
>> 1636 bool "Enable bpf() system call"
>> 1637 select ANON_INODES
>> 1638 select BPF
>> 1639 default n
>> 1640 help
>> 1641 Enable the bpf() system call that allows to manipulate eBPF
>> 1642 programs and maps via file descriptors.
>> 1643
1697 config SHMEM 1644 config SHMEM
1698 bool "Use full shmem filesystem" if E 1645 bool "Use full shmem filesystem" if EXPERT
1699 default y 1646 default y
1700 depends on MMU 1647 depends on MMU
1701 help 1648 help
1702 The shmem is an internal filesystem 1649 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1650 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1651 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1652 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1653 which may be appropriate on small systems without swap.
1707 1654
1708 config AIO 1655 config AIO
1709 bool "Enable AIO support" if EXPERT 1656 bool "Enable AIO support" if EXPERT
1710 default y 1657 default y
1711 help 1658 help
1712 This option enables POSIX asynchron 1659 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1660 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1661 this option saves about 7k.
1715 1662
1716 config IO_URING <<
1717 bool "Enable IO uring support" if EXP <<
1718 select IO_WQ <<
1719 default y <<
1720 help <<
1721 This option enables support for the <<
1722 applications to submit and complete <<
1723 completion rings that are shared be <<
1724 <<
1725 config GCOV_PROFILE_URING <<
1726 bool "Enable GCOV profiling on the io <<
1727 depends on GCOV_KERNEL <<
1728 help <<
1729 Enable GCOV profiling on the io_uri <<
1730 code coverage testing. <<
1731 <<
1732 If unsure, say N. <<
1733 <<
1734 Note that this will have a negative <<
1735 the io_uring subsystem, hence this <<
1736 specific test purposes. <<
1737 <<
1738 config ADVISE_SYSCALLS 1663 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1664 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1665 default y
1741 help 1666 help
1742 This option enables the madvise and 1667 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1668 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1669 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1670 applications use these syscalls, you can disable this option to save
1746 space. 1671 space.
1747 1672
>> 1673 config USERFAULTFD
>> 1674 bool "Enable userfaultfd() system call"
>> 1675 select ANON_INODES
>> 1676 depends on MMU
>> 1677 help
>> 1678 Enable the userfaultfd() system call that allows to intercept and
>> 1679 handle page faults in userland.
>> 1680
>> 1681 config PCI_QUIRKS
>> 1682 default y
>> 1683 bool "Enable PCI quirk workarounds" if EXPERT
>> 1684 depends on PCI
>> 1685 help
>> 1686 This enables workarounds for various PCI chipset
>> 1687 bugs/quirks. Disable this only if your target machine is
>> 1688 unaffected by PCI quirks.
>> 1689
1748 config MEMBARRIER 1690 config MEMBARRIER
1749 bool "Enable membarrier() system call 1691 bool "Enable membarrier() system call" if EXPERT
1750 default y 1692 default y
1751 help 1693 help
1752 Enable the membarrier() system call 1694 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1695 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1696 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1697 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1698 compiler barrier.
1757 1699
1758 If unsure, say Y. 1700 If unsure, say Y.
1759 1701
1760 config KCMP !! 1702 config EMBEDDED
1761 bool "Enable kcmp() system call" if E !! 1703 bool "Embedded system"
1762 help !! 1704 option allnoconfig_y
1763 Enable the kernel resource comparis !! 1705 select EXPERT
1764 user-space with the ability to comp !! 1706 help
1765 share a common resource, such as a !! 1707 This option should be enabled if compiling the kernel for
1766 memory space. !! 1708 an embedded system so certain expert options are available
1767 !! 1709 for configuration.
1768 If unsure, say N. <<
1769 <<
1770 config RSEQ <<
1771 bool "Enable rseq() system call" if E <<
1772 default y <<
1773 depends on HAVE_RSEQ <<
1774 select MEMBARRIER <<
1775 help <<
1776 Enable the restartable sequences sy <<
1777 user-space cache for the current CP <<
1778 speeds up getting the current CPU n <<
1779 as well as an ABI to speed up user- <<
1780 per-CPU data. <<
1781 <<
1782 If unsure, say Y. <<
1783 <<
1784 config DEBUG_RSEQ <<
1785 default n <<
1786 bool "Enable debugging of rseq() syst <<
1787 depends on RSEQ && DEBUG_KERNEL <<
1788 help <<
1789 Enable extra debugging checks for t <<
1790 <<
1791 If unsure, say N. <<
1792 <<
1793 config CACHESTAT_SYSCALL <<
1794 bool "Enable cachestat() system call" <<
1795 default y <<
1796 help <<
1797 Enable the cachestat system call, w <<
1798 statistics of a file (number of cac <<
1799 pages marked for writeback, (recent <<
1800 <<
1801 If unsure say Y here. <<
1802 <<
1803 config PC104 <<
1804 bool "PC/104 support" if EXPERT <<
1805 help <<
1806 Expose PC/104 form factor device dr <<
1807 selection and configuration. Enable <<
1808 machine has a PC/104 bus. <<
1809 <<
1810 config KALLSYMS <<
1811 bool "Load all symbols for debugging/ <<
1812 default y <<
1813 help <<
1814 Say Y here to let the kernel print <<
1815 symbolic stack backtraces. This inc <<
1816 somewhat, as all symbols have to be <<
1817 <<
1818 config KALLSYMS_SELFTEST <<
1819 bool "Test the basic functions and pe <<
1820 depends on KALLSYMS <<
1821 default n <<
1822 help <<
1823 Test the basic functions and perfor <<
1824 kallsyms_lookup_name. It also calcu <<
1825 kallsyms compression algorithm for <<
1826 <<
1827 Start self-test automatically after <<
1828 "dmesg | grep kallsyms_selftest" to <<
1829 displayed in the last line, indicat <<
1830 <<
1831 config KALLSYMS_ALL <<
1832 bool "Include all symbols in kallsyms <<
1833 depends on DEBUG_KERNEL && KALLSYMS <<
1834 help <<
1835 Normally kallsyms only contains the <<
1836 OOPS messages and backtraces (i.e., <<
1837 sections). This is sufficient for m <<
1838 enable kernel live patching, or oth <<
1839 when a debugger is used) all symbol <<
1840 variables from the data sections, e <<
1841 <<
1842 This option makes sure that all sym <<
1843 image (i.e., symbols from all secti <<
1844 size (depending on the kernel confi <<
1845 something like this). <<
1846 <<
1847 Say N unless you really need all sy <<
1848 <<
1849 config KALLSYMS_ABSOLUTE_PERCPU <<
1850 bool <<
1851 depends on KALLSYMS <<
1852 default X86_64 && SMP <<
1853 <<
1854 # end of the "standard kernel features (exper <<
1855 <<
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS <<
1857 bool <<
1858 <<
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE <<
1860 bool <<
1861 1710
1862 config HAVE_PERF_EVENTS 1711 config HAVE_PERF_EVENTS
1863 bool 1712 bool
1864 help 1713 help
1865 See tools/perf/design.txt for detai 1714 See tools/perf/design.txt for details.
1866 1715
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1716 config PERF_USE_VMALLOC
1872 bool 1717 bool
1873 help 1718 help
1874 See tools/perf/design.txt for detai 1719 See tools/perf/design.txt for details
1875 1720
>> 1721 config PC104
>> 1722 bool "PC/104 support"
>> 1723 help
>> 1724 Expose PC/104 form factor device drivers and options available for
>> 1725 selection and configuration. Enable this option if your target
>> 1726 machine has a PC/104 bus.
>> 1727
1876 menu "Kernel Performance Events And Counters" 1728 menu "Kernel Performance Events And Counters"
1877 1729
1878 config PERF_EVENTS 1730 config PERF_EVENTS
1879 bool "Kernel performance events and c 1731 bool "Kernel performance events and counters"
1880 default y if PROFILING 1732 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1733 depends on HAVE_PERF_EVENTS
>> 1734 select ANON_INODES
1882 select IRQ_WORK 1735 select IRQ_WORK
>> 1736 select SRCU
1883 help 1737 help
1884 Enable kernel support for various p 1738 Enable kernel support for various performance events provided
1885 by software and hardware. 1739 by software and hardware.
1886 1740
1887 Software events are supported eithe 1741 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1742 use of generic tracepoints.
1889 1743
1890 Most modern CPUs support performanc 1744 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1745 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1746 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1747 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1748 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1749 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1750 used to profile the code that runs on that CPU.
1897 1751
1898 The Linux Performance Event subsyst 1752 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1753 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1754 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1755 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1756 capabilities on top of those.
1903 1757
1904 Say Y if unsure. 1758 Say Y if unsure.
1905 1759
1906 config DEBUG_PERF_USE_VMALLOC 1760 config DEBUG_PERF_USE_VMALLOC
1907 default n 1761 default n
1908 bool "Debug: use vmalloc to back perf 1762 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1763 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1764 select PERF_USE_VMALLOC
1911 help 1765 help
1912 Use vmalloc memory to back perf mma !! 1766 Use vmalloc memory to back perf mmap() buffers.
1913 1767
1914 Mostly useful for debugging the vma !! 1768 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. !! 1769 that don't require it.
1916 1770
1917 Say N if unsure. !! 1771 Say N if unsure.
1918 1772
1919 endmenu 1773 endmenu
1920 1774
>> 1775 config VM_EVENT_COUNTERS
>> 1776 default y
>> 1777 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1778 help
>> 1779 VM event counters are needed for event counts to be shown.
>> 1780 This option allows the disabling of the VM event counters
>> 1781 on EXPERT systems. /proc/vmstat will only show page counts
>> 1782 if VM event counters are disabled.
>> 1783
>> 1784 config SLUB_DEBUG
>> 1785 default y
>> 1786 bool "Enable SLUB debugging support" if EXPERT
>> 1787 depends on SLUB && SYSFS
>> 1788 help
>> 1789 SLUB has extensive debug support features. Disabling these can
>> 1790 result in significant savings in code size. This also disables
>> 1791 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1792 no support for cache validation etc.
>> 1793
>> 1794 config SLUB_MEMCG_SYSFS_ON
>> 1795 default n
>> 1796 bool "Enable memcg SLUB sysfs support by default" if EXPERT
>> 1797 depends on SLUB && SYSFS && MEMCG
>> 1798 help
>> 1799 SLUB creates a directory under /sys/kernel/slab for each
>> 1800 allocation cache to host info and debug files. If memory
>> 1801 cgroup is enabled, each cache can have per memory cgroup
>> 1802 caches. SLUB can create the same sysfs directories for these
>> 1803 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
>> 1804 to a very high number of debug files being created. This is
>> 1805 controlled by slub_memcg_sysfs boot parameter and this
>> 1806 config option determines the parameter's default value.
>> 1807
>> 1808 config COMPAT_BRK
>> 1809 bool "Disable heap randomization"
>> 1810 default y
>> 1811 help
>> 1812 Randomizing heap placement makes heap exploits harder, but it
>> 1813 also breaks ancient binaries (including anything libc5 based).
>> 1814 This option changes the bootup default to heap randomization
>> 1815 disabled, and can be overridden at runtime by setting
>> 1816 /proc/sys/kernel/randomize_va_space to 2.
>> 1817
>> 1818 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1819
>> 1820 choice
>> 1821 prompt "Choose SLAB allocator"
>> 1822 default SLUB
>> 1823 help
>> 1824 This option allows to select a slab allocator.
>> 1825
>> 1826 config SLAB
>> 1827 bool "SLAB"
>> 1828 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1829 help
>> 1830 The regular slab allocator that is established and known to work
>> 1831 well in all environments. It organizes cache hot objects in
>> 1832 per cpu and per node queues.
>> 1833
>> 1834 config SLUB
>> 1835 bool "SLUB (Unqueued Allocator)"
>> 1836 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1837 help
>> 1838 SLUB is a slab allocator that minimizes cache line usage
>> 1839 instead of managing queues of cached objects (SLAB approach).
>> 1840 Per cpu caching is realized using slabs of objects instead
>> 1841 of queues of objects. SLUB can use memory efficiently
>> 1842 and has enhanced diagnostics. SLUB is the default choice for
>> 1843 a slab allocator.
>> 1844
>> 1845 config SLOB
>> 1846 depends on EXPERT
>> 1847 bool "SLOB (Simple Allocator)"
>> 1848 help
>> 1849 SLOB replaces the stock allocator with a drastically simpler
>> 1850 allocator. SLOB is generally more space efficient but
>> 1851 does not perform as well on large systems.
>> 1852
>> 1853 endchoice
>> 1854
>> 1855 config SLAB_FREELIST_RANDOM
>> 1856 default n
>> 1857 depends on SLAB || SLUB
>> 1858 bool "SLAB freelist randomization"
>> 1859 help
>> 1860 Randomizes the freelist order used on creating new pages. This
>> 1861 security feature reduces the predictability of the kernel slab
>> 1862 allocator against heap overflows.
>> 1863
>> 1864 config SLUB_CPU_PARTIAL
>> 1865 default y
>> 1866 depends on SLUB && SMP
>> 1867 bool "SLUB per cpu partial cache"
>> 1868 help
>> 1869 Per cpu partial caches accellerate objects allocation and freeing
>> 1870 that is local to a processor at the price of more indeterminism
>> 1871 in the latency of the free. On overflow these caches will be cleared
>> 1872 which requires the taking of locks that may cause latency spikes.
>> 1873 Typically one would choose no for a realtime system.
>> 1874
>> 1875 config MMAP_ALLOW_UNINITIALIZED
>> 1876 bool "Allow mmapped anonymous memory to be uninitialized"
>> 1877 depends on EXPERT && !MMU
>> 1878 default n
>> 1879 help
>> 1880 Normally, and according to the Linux spec, anonymous memory obtained
>> 1881 from mmap() has it's contents cleared before it is passed to
>> 1882 userspace. Enabling this config option allows you to request that
>> 1883 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 1884 providing a huge performance boost. If this option is not enabled,
>> 1885 then the flag will be ignored.
>> 1886
>> 1887 This is taken advantage of by uClibc's malloc(), and also by
>> 1888 ELF-FDPIC binfmt's brk and stack allocator.
>> 1889
>> 1890 Because of the obvious security issues, this option should only be
>> 1891 enabled on embedded devices where you control what is run in
>> 1892 userspace. Since that isn't generally a problem on no-MMU systems,
>> 1893 it is normally safe to say Y here.
>> 1894
>> 1895 See Documentation/nommu-mmap.txt for more information.
>> 1896
1921 config SYSTEM_DATA_VERIFICATION 1897 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1898 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1899 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1900 select KEYS
1925 select CRYPTO 1901 select CRYPTO
1926 select CRYPTO_RSA 1902 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1903 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1904 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1905 select ASN1
1930 select OID_REGISTRY 1906 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1907 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1908 select PKCS7_MESSAGE_PARSER
1933 help 1909 help
1934 Provide PKCS#7 message verification 1910 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1911 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1912 module verification, kexec image verification and firmware blob
1937 verification. 1913 verification.
1938 1914
1939 config PROFILING 1915 config PROFILING
1940 bool "Profiling support" 1916 bool "Profiling support"
1941 help 1917 help
1942 Say Y here to enable the extended p 1918 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 1919 by profilers such as OProfile.
1944 <<
1945 config RUST <<
1946 bool "Rust support" <<
1947 depends on HAVE_RUST <<
1948 depends on RUST_IS_AVAILABLE <<
1949 depends on !MODVERSIONS <<
1950 depends on !GCC_PLUGIN_RANDSTRUCT <<
1951 depends on !RANDSTRUCT <<
1952 depends on !DEBUG_INFO_BTF || PAHOLE_ <<
1953 depends on !CFI_CLANG || HAVE_CFI_ICA <<
1954 select CFI_ICALL_NORMALIZE_INTEGERS i <<
1955 depends on !CALL_PADDING || RUSTC_VER <<
1956 depends on !KASAN_SW_TAGS <<
1957 depends on !(MITIGATION_RETHUNK && KA <<
1958 help <<
1959 Enables Rust support in the kernel. <<
1960 <<
1961 This allows other Rust-related opti <<
1962 to be selected. <<
1963 <<
1964 It is also required to be able to l <<
1965 written in Rust. <<
1966 <<
1967 See Documentation/rust/ for more in <<
1968 <<
1969 If unsure, say N. <<
1970 <<
1971 config RUSTC_VERSION_TEXT <<
1972 string <<
1973 depends on RUST <<
1974 default "$(RUSTC_VERSION_TEXT)" <<
1975 help <<
1976 See `CC_VERSION_TEXT`. <<
1977 <<
1978 config BINDGEN_VERSION_TEXT <<
1979 string <<
1980 depends on RUST <<
1981 # The dummy parameter `workaround-for <<
1982 # (https://github.com/rust-lang/rust- <<
1983 # the minimum version is upgraded pas <<
1984 default "$(shell,$(BINDGEN) --version <<
1985 1920
1986 # 1921 #
1987 # Place an empty function call at each tracep 1922 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1923 # dynamically changed for a probe function.
1989 # 1924 #
1990 config TRACEPOINTS 1925 config TRACEPOINTS
1991 bool 1926 bool
1992 1927
1993 source "kernel/Kconfig.kexec" !! 1928 source "arch/Kconfig"
1994 1929
1995 endmenu # General setup 1930 endmenu # General setup
1996 1931
1997 source "arch/Kconfig" !! 1932 config HAVE_GENERIC_DMA_COHERENT
>> 1933 bool
>> 1934 default n
>> 1935
>> 1936 config SLABINFO
>> 1937 bool
>> 1938 depends on PROC_FS
>> 1939 depends on SLAB || SLUB_DEBUG
>> 1940 default y
1998 1941
1999 config RT_MUTEXES 1942 config RT_MUTEXES
2000 bool 1943 bool
2001 default y if PREEMPT_RT <<
2002 1944
2003 config MODULE_SIG_FORMAT !! 1945 config BASE_SMALL
2004 def_bool n !! 1946 int
>> 1947 default 0 if BASE_FULL
>> 1948 default 1 if !BASE_FULL
>> 1949
>> 1950 menuconfig MODULES
>> 1951 bool "Enable loadable module support"
>> 1952 option modules
>> 1953 help
>> 1954 Kernel modules are small pieces of compiled code which can
>> 1955 be inserted in the running kernel, rather than being
>> 1956 permanently built into the kernel. You use the "modprobe"
>> 1957 tool to add (and sometimes remove) them. If you say Y here,
>> 1958 many parts of the kernel can be built as modules (by
>> 1959 answering M instead of Y where indicated): this is most
>> 1960 useful for infrequently used options which are not required
>> 1961 for booting. For more information, see the man pages for
>> 1962 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1963
>> 1964 If you say Y here, you will need to run "make
>> 1965 modules_install" to put the modules under /lib/modules/
>> 1966 where modprobe can find them (you may need to be root to do
>> 1967 this).
>> 1968
>> 1969 If unsure, say Y.
>> 1970
>> 1971 if MODULES
>> 1972
>> 1973 config MODULE_FORCE_LOAD
>> 1974 bool "Forced module loading"
>> 1975 default n
>> 1976 help
>> 1977 Allow loading of modules without version information (ie. modprobe
>> 1978 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1979 is usually a really bad idea.
>> 1980
>> 1981 config MODULE_UNLOAD
>> 1982 bool "Module unloading"
>> 1983 help
>> 1984 Without this option you will not be able to unload any
>> 1985 modules (note that some modules may not be unloadable
>> 1986 anyway), which makes your kernel smaller, faster
>> 1987 and simpler. If unsure, say Y.
>> 1988
>> 1989 config MODULE_FORCE_UNLOAD
>> 1990 bool "Forced module unloading"
>> 1991 depends on MODULE_UNLOAD
>> 1992 help
>> 1993 This option allows you to force a module to unload, even if the
>> 1994 kernel believes it is unsafe: the kernel will remove the module
>> 1995 without waiting for anyone to stop using it (using the -f option to
>> 1996 rmmod). This is mainly for kernel developers and desperate users.
>> 1997 If unsure, say N.
>> 1998
>> 1999 config MODVERSIONS
>> 2000 bool "Module versioning support"
>> 2001 help
>> 2002 Usually, you have to use modules compiled with your kernel.
>> 2003 Saying Y here makes it sometimes possible to use modules
>> 2004 compiled for different kernels, by adding enough information
>> 2005 to the modules to (hopefully) spot any changes which would
>> 2006 make them incompatible with the kernel you are running. If
>> 2007 unsure, say N.
>> 2008
>> 2009 config MODULE_REL_CRCS
>> 2010 bool
>> 2011 depends on MODVERSIONS
>> 2012
>> 2013 config MODULE_SRCVERSION_ALL
>> 2014 bool "Source checksum for all modules"
>> 2015 help
>> 2016 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2017 field inserted into their modinfo section, which contains a
>> 2018 sum of the source files which made it. This helps maintainers
>> 2019 see exactly which source was used to build a module (since
>> 2020 others sometimes change the module source without updating
>> 2021 the version). With this option, such a "srcversion" field
>> 2022 will be created for all modules. If unsure, say N.
>> 2023
>> 2024 config MODULE_SIG
>> 2025 bool "Module signature verification"
>> 2026 depends on MODULES
2005 select SYSTEM_DATA_VERIFICATION 2027 select SYSTEM_DATA_VERIFICATION
>> 2028 help
>> 2029 Check modules for valid signatures upon load: the signature
>> 2030 is simply appended to the module. For more information see
>> 2031 Documentation/module-signing.txt.
>> 2032
>> 2033 Note that this option adds the OpenSSL development packages as a
>> 2034 kernel build dependency so that the signing tool can use its crypto
>> 2035 library.
>> 2036
>> 2037 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2038 module DOES NOT get stripped after being signed. This includes the
>> 2039 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2040 inclusion into an initramfs that wants the module size reduced.
>> 2041
>> 2042 config MODULE_SIG_FORCE
>> 2043 bool "Require modules to be validly signed"
>> 2044 depends on MODULE_SIG
>> 2045 help
>> 2046 Reject unsigned modules or signed modules for which we don't have a
>> 2047 key. Without this, such modules will simply taint the kernel.
>> 2048
>> 2049 config MODULE_SIG_ALL
>> 2050 bool "Automatically sign all modules"
>> 2051 default y
>> 2052 depends on MODULE_SIG
>> 2053 help
>> 2054 Sign all modules during make modules_install. Without this option,
>> 2055 modules must be signed manually, using the scripts/sign-file tool.
>> 2056
>> 2057 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2058 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2059
>> 2060 choice
>> 2061 prompt "Which hash algorithm should modules be signed with?"
>> 2062 depends on MODULE_SIG
>> 2063 help
>> 2064 This determines which sort of hashing algorithm will be used during
>> 2065 signature generation. This algorithm _must_ be built into the kernel
>> 2066 directly so that signature verification can take place. It is not
>> 2067 possible to load a signed module containing the algorithm to check
>> 2068 the signature on that module.
>> 2069
>> 2070 config MODULE_SIG_SHA1
>> 2071 bool "Sign modules with SHA-1"
>> 2072 select CRYPTO_SHA1
>> 2073
>> 2074 config MODULE_SIG_SHA224
>> 2075 bool "Sign modules with SHA-224"
>> 2076 select CRYPTO_SHA256
>> 2077
>> 2078 config MODULE_SIG_SHA256
>> 2079 bool "Sign modules with SHA-256"
>> 2080 select CRYPTO_SHA256
>> 2081
>> 2082 config MODULE_SIG_SHA384
>> 2083 bool "Sign modules with SHA-384"
>> 2084 select CRYPTO_SHA512
>> 2085
>> 2086 config MODULE_SIG_SHA512
>> 2087 bool "Sign modules with SHA-512"
>> 2088 select CRYPTO_SHA512
>> 2089
>> 2090 endchoice
>> 2091
>> 2092 config MODULE_SIG_HASH
>> 2093 string
>> 2094 depends on MODULE_SIG
>> 2095 default "sha1" if MODULE_SIG_SHA1
>> 2096 default "sha224" if MODULE_SIG_SHA224
>> 2097 default "sha256" if MODULE_SIG_SHA256
>> 2098 default "sha384" if MODULE_SIG_SHA384
>> 2099 default "sha512" if MODULE_SIG_SHA512
>> 2100
>> 2101 config MODULE_COMPRESS
>> 2102 bool "Compress modules on installation"
>> 2103 depends on MODULES
>> 2104 help
2006 2105
2007 source "kernel/module/Kconfig" !! 2106 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2107 xz depending on "Compression algorithm" below.
>> 2108
>> 2109 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2110
>> 2111 Out-of-tree kernel modules installed using Kbuild will also be
>> 2112 compressed upon installation.
>> 2113
>> 2114 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2115 to compress the whole initrd or initramfs instead.
>> 2116
>> 2117 Note: This is fully compatible with signed modules.
>> 2118
>> 2119 If in doubt, say N.
>> 2120
>> 2121 choice
>> 2122 prompt "Compression algorithm"
>> 2123 depends on MODULE_COMPRESS
>> 2124 default MODULE_COMPRESS_GZIP
>> 2125 help
>> 2126 This determines which sort of compression will be used during
>> 2127 'make modules_install'.
>> 2128
>> 2129 GZIP (default) and XZ are supported.
>> 2130
>> 2131 config MODULE_COMPRESS_GZIP
>> 2132 bool "GZIP"
>> 2133
>> 2134 config MODULE_COMPRESS_XZ
>> 2135 bool "XZ"
>> 2136
>> 2137 endchoice
>> 2138
>> 2139 config TRIM_UNUSED_KSYMS
>> 2140 bool "Trim unused exported kernel symbols"
>> 2141 depends on MODULES && !UNUSED_SYMBOLS
>> 2142 help
>> 2143 The kernel and some modules make many symbols available for
>> 2144 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2145 on the set of modules being selected in your kernel configuration,
>> 2146 many of those exported symbols might never be used.
>> 2147
>> 2148 This option allows for unused exported symbols to be dropped from
>> 2149 the build. In turn, this provides the compiler more opportunities
>> 2150 (especially when using LTO) for optimizing the code and reducing
>> 2151 binary size. This might have some security advantages as well.
>> 2152
>> 2153 If unsure, or if you need to build out-of-tree modules, say N.
>> 2154
>> 2155 endif # MODULES
>> 2156
>> 2157 config MODULES_TREE_LOOKUP
>> 2158 def_bool y
>> 2159 depends on PERF_EVENTS || TRACING
2008 2160
2009 config INIT_ALL_POSSIBLE 2161 config INIT_ALL_POSSIBLE
2010 bool 2162 bool
2011 help 2163 help
2012 Back when each arch used to define 2164 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2165 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2166 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2167 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2168 and have several arch maintainers pursuing me down dark alleys.
2017 2169
2018 source "block/Kconfig" 2170 source "block/Kconfig"
2019 2171
2020 config PREEMPT_NOTIFIERS 2172 config PREEMPT_NOTIFIERS
2021 bool 2173 bool
2022 2174
2023 config PADATA 2175 config PADATA
2024 depends on SMP 2176 depends on SMP
2025 bool 2177 bool
2026 2178
2027 config ASN1 2179 config ASN1
2028 tristate 2180 tristate
2029 help 2181 help
2030 Build a simple ASN.1 grammar compil 2182 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2183 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2184 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2185 functions to call on what tags.
2034 2186
2035 source "kernel/Kconfig.locks" 2187 source "kernel/Kconfig.locks"
2036 <<
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE <<
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool <<
2042 <<
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE <<
2044 bool <<
2045 <<
2046 # It may be useful for an architecture to ove <<
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma <<
2048 # and the COMPAT_ variants in <linux/compat.h <<
2049 # different calling convention for syscalls. <<
2050 # macros for not-implemented syscalls in kern <<
2051 # kernel/time/posix-stubs.c. All these overri <<
2052 # <asm/syscall_wrapper.h>. <<
2053 config ARCH_HAS_SYSCALL_WRAPPER <<
2054 def_bool n <<
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