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 <<
55 config LD_IS_LLD <<
56 def_bool $(success,test "$(ld-name)" = <<
57 <<
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 4
90 config CC_CAN_LINK_STATIC !! 5 config KERNELVERSION
91 bool !! 6 string
92 default $(success,$(srctree)/scripts/c !! 7 option env="KERNELVERSION"
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 depends on !UML
>> 533 select SRCU
699 help 534 help
700 Make sure that CPUs running critical !! 535 This option enables a task-based RCU implementation that uses
701 any source of "noise" such as unboun !! 536 only voluntary context switch (not preemption!), idle, and
702 Unbound jobs get offloaded to housek !! 537 user-mode execution as quiescent states.
703 the "isolcpus=" boot parameter. !! 538
>> 539 config RCU_STALL_COMMON
>> 540 def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
>> 541 help
>> 542 This option enables RCU CPU stall code that is common between
>> 543 the TINY and TREE variants of RCU. The purpose is to allow
>> 544 the tiny variants to disable RCU CPU stall warnings, while
>> 545 making these warnings mandatory for the tree variants.
>> 546
>> 547 config CONTEXT_TRACKING
>> 548 bool
>> 549
>> 550 config CONTEXT_TRACKING_FORCE
>> 551 bool "Force context tracking"
>> 552 depends on CONTEXT_TRACKING
>> 553 default y if !NO_HZ_FULL
>> 554 help
>> 555 The major pre-requirement for full dynticks to work is to
>> 556 support the context tracking subsystem. But there are also
>> 557 other dependencies to provide in order to make the full
>> 558 dynticks working.
>> 559
>> 560 This option stands for testing when an arch implements the
>> 561 context tracking backend but doesn't yet fullfill all the
>> 562 requirements to make the full dynticks feature working.
>> 563 Without the full dynticks, there is no way to test the support
>> 564 for context tracking and the subsystems that rely on it: RCU
>> 565 userspace extended quiescent state and tickless cputime
>> 566 accounting. This option copes with the absence of the full
>> 567 dynticks subsystem by forcing the context tracking on all
>> 568 CPUs in the system.
>> 569
>> 570 Say Y only if you're working on the development of an
>> 571 architecture backend for the context tracking.
>> 572
>> 573 Say N otherwise, this option brings an overhead that you
>> 574 don't want in production.
>> 575
>> 576
>> 577 config RCU_FANOUT
>> 578 int "Tree-based hierarchical RCU fanout value"
>> 579 range 2 64 if 64BIT
>> 580 range 2 32 if !64BIT
>> 581 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
>> 582 default 64 if 64BIT
>> 583 default 32 if !64BIT
>> 584 help
>> 585 This option controls the fanout of hierarchical implementations
>> 586 of RCU, allowing RCU to work efficiently on machines with
>> 587 large numbers of CPUs. This value must be at least the fourth
>> 588 root of NR_CPUS, which allows NR_CPUS to be insanely large.
>> 589 The default value of RCU_FANOUT should be used for production
>> 590 systems, but if you are stress-testing the RCU implementation
>> 591 itself, small RCU_FANOUT values allow you to test large-system
>> 592 code paths on small(er) systems.
>> 593
>> 594 Select a specific number if testing RCU itself.
>> 595 Take the default if unsure.
>> 596
>> 597 config RCU_FANOUT_LEAF
>> 598 int "Tree-based hierarchical RCU leaf-level fanout value"
>> 599 range 2 64 if 64BIT
>> 600 range 2 32 if !64BIT
>> 601 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
>> 602 default 16
>> 603 help
>> 604 This option controls the leaf-level fanout of hierarchical
>> 605 implementations of RCU, and allows trading off cache misses
>> 606 against lock contention. Systems that synchronize their
>> 607 scheduling-clock interrupts for energy-efficiency reasons will
>> 608 want the default because the smaller leaf-level fanout keeps
>> 609 lock contention levels acceptably low. Very large systems
>> 610 (hundreds or thousands of CPUs) will instead want to set this
>> 611 value to the maximum value possible in order to reduce the
>> 612 number of cache misses incurred during RCU's grace-period
>> 613 initialization. These systems tend to run CPU-bound, and thus
>> 614 are not helped by synchronized interrupts, and thus tend to
>> 615 skew them, which reduces lock contention enough that large
>> 616 leaf-level fanouts work well.
>> 617
>> 618 Select a specific number if testing RCU itself.
>> 619
>> 620 Select the maximum permissible value for large systems.
>> 621
>> 622 Take the default if unsure.
>> 623
>> 624 config RCU_FAST_NO_HZ
>> 625 bool "Accelerate last non-dyntick-idle CPU's grace periods"
>> 626 depends on NO_HZ_COMMON && SMP && RCU_EXPERT
>> 627 default n
>> 628 help
>> 629 This option permits CPUs to enter dynticks-idle state even if
>> 630 they have RCU callbacks queued, and prevents RCU from waking
>> 631 these CPUs up more than roughly once every four jiffies (by
>> 632 default, you can adjust this using the rcutree.rcu_idle_gp_delay
>> 633 parameter), thus improving energy efficiency. On the other
>> 634 hand, this option increases the duration of RCU grace periods,
>> 635 for example, slowing down synchronize_rcu().
>> 636
>> 637 Say Y if energy efficiency is critically important, and you
>> 638 don't care about increased grace-period durations.
>> 639
>> 640 Say N if you are unsure.
>> 641
>> 642 config TREE_RCU_TRACE
>> 643 def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
>> 644 select DEBUG_FS
>> 645 help
>> 646 This option provides tracing for the TREE_RCU and
>> 647 PREEMPT_RCU implementations, permitting Makefile to
>> 648 trivially select kernel/rcutree_trace.c.
>> 649
>> 650 config RCU_BOOST
>> 651 bool "Enable RCU priority boosting"
>> 652 depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
>> 653 default n
>> 654 help
>> 655 This option boosts the priority of preempted RCU readers that
>> 656 block the current preemptible RCU grace period for too long.
>> 657 This option also prevents heavy loads from blocking RCU
>> 658 callback invocation for all flavors of RCU.
>> 659
>> 660 Say Y here if you are working with real-time apps or heavy loads
>> 661 Say N here if you are unsure.
>> 662
>> 663 config RCU_KTHREAD_PRIO
>> 664 int "Real-time priority to use for RCU worker threads"
>> 665 range 1 99 if RCU_BOOST
>> 666 range 0 99 if !RCU_BOOST
>> 667 default 1 if RCU_BOOST
>> 668 default 0 if !RCU_BOOST
>> 669 depends on RCU_EXPERT
>> 670 help
>> 671 This option specifies the SCHED_FIFO priority value that will be
>> 672 assigned to the rcuc/n and rcub/n threads and is also the value
>> 673 used for RCU_BOOST (if enabled). If you are working with a
>> 674 real-time application that has one or more CPU-bound threads
>> 675 running at a real-time priority level, you should set
>> 676 RCU_KTHREAD_PRIO to a priority higher than the highest-priority
>> 677 real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO
>> 678 value of 1 is appropriate in the common case, which is real-time
>> 679 applications that do not have any CPU-bound threads.
>> 680
>> 681 Some real-time applications might not have a single real-time
>> 682 thread that saturates a given CPU, but instead might have
>> 683 multiple real-time threads that, taken together, fully utilize
>> 684 that CPU. In this case, you should set RCU_KTHREAD_PRIO to
>> 685 a priority higher than the lowest-priority thread that is
>> 686 conspiring to prevent the CPU from running any non-real-time
>> 687 tasks. For example, if one thread at priority 10 and another
>> 688 thread at priority 5 are between themselves fully consuming
>> 689 the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
>> 690 set to priority 6 or higher.
>> 691
>> 692 Specify the real-time priority, or take the default if unsure.
>> 693
>> 694 config RCU_BOOST_DELAY
>> 695 int "Milliseconds to delay boosting after RCU grace-period start"
>> 696 range 0 3000
>> 697 depends on RCU_BOOST
>> 698 default 500
>> 699 help
>> 700 This option specifies the time to wait after the beginning of
>> 701 a given grace period before priority-boosting preempted RCU
>> 702 readers blocking that grace period. Note that any RCU reader
>> 703 blocking an expedited RCU grace period is boosted immediately.
>> 704
>> 705 Accept the default if unsure.
>> 706
>> 707 config RCU_NOCB_CPU
>> 708 bool "Offload RCU callback processing from boot-selected CPUs"
>> 709 depends on TREE_RCU || PREEMPT_RCU
>> 710 depends on RCU_EXPERT || NO_HZ_FULL
>> 711 default n
>> 712 help
>> 713 Use this option to reduce OS jitter for aggressive HPC or
>> 714 real-time workloads. It can also be used to offload RCU
>> 715 callback invocation to energy-efficient CPUs in battery-powered
>> 716 asymmetric multiprocessors.
>> 717
>> 718 This option offloads callback invocation from the set of
>> 719 CPUs specified at boot time by the rcu_nocbs parameter.
>> 720 For each such CPU, a kthread ("rcuox/N") will be created to
>> 721 invoke callbacks, where the "N" is the CPU being offloaded,
>> 722 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
>> 723 "s" for RCU-sched. Nothing prevents this kthread from running
>> 724 on the specified CPUs, but (1) the kthreads may be preempted
>> 725 between each callback, and (2) affinity or cgroups can be used
>> 726 to force the kthreads to run on whatever set of CPUs is desired.
704 727
705 Say Y if unsure. !! 728 Say Y here if you want to help to debug reduced OS jitter.
>> 729 Say N here if you are unsure.
706 730
707 source "kernel/rcu/Kconfig" !! 731 choice
>> 732 prompt "Build-forced no-CBs CPUs"
>> 733 default RCU_NOCB_CPU_NONE
>> 734 depends on RCU_NOCB_CPU
>> 735 help
>> 736 This option allows no-CBs CPUs (whose RCU callbacks are invoked
>> 737 from kthreads rather than from softirq context) to be specified
>> 738 at build time. Additional no-CBs CPUs may be specified by
>> 739 the rcu_nocbs= boot parameter.
>> 740
>> 741 config RCU_NOCB_CPU_NONE
>> 742 bool "No build_forced no-CBs CPUs"
>> 743 help
>> 744 This option does not force any of the CPUs to be no-CBs CPUs.
>> 745 Only CPUs designated by the rcu_nocbs= boot parameter will be
>> 746 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
>> 747 kthreads whose names begin with "rcuo". All other CPUs will
>> 748 invoke their own RCU callbacks in softirq context.
>> 749
>> 750 Select this option if you want to choose no-CBs CPUs at
>> 751 boot time, for example, to allow testing of different no-CBs
>> 752 configurations without having to rebuild the kernel each time.
>> 753
>> 754 config RCU_NOCB_CPU_ZERO
>> 755 bool "CPU 0 is a build_forced no-CBs CPU"
>> 756 help
>> 757 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
>> 758 callbacks are invoked by a per-CPU kthread whose name begins
>> 759 with "rcuo". Additional CPUs may be designated as no-CBs
>> 760 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
>> 761 All other CPUs will invoke their own RCU callbacks in softirq
>> 762 context.
>> 763
>> 764 Select this if CPU 0 needs to be a no-CBs CPU for real-time
>> 765 or energy-efficiency reasons, but the real reason it exists
>> 766 is to ensure that randconfig testing covers mixed systems.
>> 767
>> 768 config RCU_NOCB_CPU_ALL
>> 769 bool "All CPUs are build_forced no-CBs CPUs"
>> 770 help
>> 771 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
>> 772 boot parameter will be ignored. All CPUs' RCU callbacks will
>> 773 be executed in the context of per-CPU rcuo kthreads created for
>> 774 this purpose. Assuming that the kthreads whose names start with
>> 775 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
>> 776 on the remaining CPUs, but might decrease memory locality during
>> 777 RCU-callback invocation, thus potentially degrading throughput.
>> 778
>> 779 Select this if all CPUs need to be no-CBs CPUs for real-time
>> 780 or energy-efficiency reasons.
>> 781
>> 782 endchoice
>> 783
>> 784 config RCU_EXPEDITE_BOOT
>> 785 bool
>> 786 default n
>> 787 help
>> 788 This option enables expedited grace periods at boot time,
>> 789 as if rcu_expedite_gp() had been invoked early in boot.
>> 790 The corresponding rcu_unexpedite_gp() is invoked from
>> 791 rcu_end_inkernel_boot(), which is intended to be invoked
>> 792 at the end of the kernel-only boot sequence, just before
>> 793 init is exec'ed.
>> 794
>> 795 Accept the default if unsure.
>> 796
>> 797 endmenu # "RCU Subsystem"
>> 798
>> 799 config BUILD_BIN2C
>> 800 bool
>> 801 default n
708 802
709 config IKCONFIG 803 config IKCONFIG
710 tristate "Kernel .config support" 804 tristate "Kernel .config support"
711 help !! 805 select BUILD_BIN2C
>> 806 ---help---
712 This option enables the complete Lin 807 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 808 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 809 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 810 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 811 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 812 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 813 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 814 /proc/config.gz if enabled (below).
720 815
721 config IKCONFIG_PROC 816 config IKCONFIG_PROC
722 bool "Enable access to .config through 817 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 818 depends on IKCONFIG && PROC_FS
724 help !! 819 ---help---
725 This option enables access to the ke 820 This option enables access to the kernel configuration file
726 through /proc/config.gz. 821 through /proc/config.gz.
727 822
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 823 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 824 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 825 range 12 25
740 default 17 826 default 17
741 depends on PRINTK 827 depends on PRINTK
742 help 828 help
743 Select the minimal kernel log buffer 829 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 830 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 831 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 832 by "log_buf_len" boot parameter.
747 833
748 Examples: 834 Examples:
749 17 => 128 KB 835 17 => 128 KB
750 16 => 64 KB 836 16 => 64 KB
751 15 => 32 KB 837 15 => 32 KB
752 14 => 16 KB 838 14 => 16 KB
753 13 => 8 KB 839 13 => 8 KB
754 12 => 4 KB 840 12 => 4 KB
755 841
756 config LOG_CPU_MAX_BUF_SHIFT 842 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 843 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 844 depends on SMP
759 range 0 21 845 range 0 21
>> 846 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 847 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 848 depends on PRINTK
763 help 849 help
764 This option allows to increase the d 850 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 851 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 852 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 853 lines however it might be much more when problems are reported,
768 e.g. backtraces. 854 e.g. backtraces.
769 855
770 The increased size means that a new 856 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 857 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 858 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 859 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 860 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed !! 861 so that more than 64 CPUs are needed to trigger the allocation.
776 862
777 Also this option is ignored when "lo 863 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 864 used as it forces an exact (power of two) size of the ring buffer.
779 865
780 The number of possible CPUs is used 866 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 867 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 868 scenario while allowing a simple algorithm to be used from bootup.
783 869
784 Examples shift values and their mean 870 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 871 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 872 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 873 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 874 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 875 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 876 12 => 4 KB for each CPU
791 877
792 config PRINTK_INDEX !! 878 config NMI_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 879 int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 880 range 10 21
795 help !! 881 default 13
796 Add support for indexing of all prin !! 882 depends on PRINTK_NMI
797 at <debugfs>/printk/index/<module>. !! 883 help
798 !! 884 Select the size of a per-CPU buffer where NMI messages are temporary
799 This can be used as part of maintain !! 885 stored. They are copied to the main log buffer in a safe context
800 /dev/kmsg, as it permits auditing th !! 886 to avoid a deadlock. The value defines the size as a power of 2.
801 kernel, allowing detection of cases !! 887
802 changed or no longer present. !! 888 NMI messages are rare and limited. The largest one is when
>> 889 a backtrace is printed. It usually fits into 4KB. Select
>> 890 8KB if you want to be on the safe side.
803 891
804 There is no additional runtime cost !! 892 Examples:
>> 893 17 => 128 KB for each CPU
>> 894 16 => 64 KB for each CPU
>> 895 15 => 32 KB for each CPU
>> 896 14 => 16 KB for each CPU
>> 897 13 => 8 KB for each CPU
>> 898 12 => 4 KB for each CPU
805 899
806 # 900 #
807 # Architectures with an unreliable sched_clock 901 # Architectures with an unreliable sched_clock() should select this:
808 # 902 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 903 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 904 bool
811 905
812 config GENERIC_SCHED_CLOCK 906 config GENERIC_SCHED_CLOCK
813 bool 907 bool
814 908
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 # 909 #
869 # For architectures that want to enable the su 910 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 911 # balancing logic:
871 # 912 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 913 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 914 bool
874 915
875 # 916 #
876 # For architectures that prefer to flush all T 917 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 918 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 919 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 920 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 921 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 922 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 923 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 924 bool
884 925
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 # 926 #
915 # For architectures that know their GCC __int1 927 # For architectures that know their GCC __int128 support is sound
916 # 928 #
917 config ARCH_SUPPORTS_INT128 929 config ARCH_SUPPORTS_INT128
918 bool 930 bool
919 931
920 # For architectures that (ab)use NUMA to repre 932 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 933 # all cpu-local but of different latencies, such as SuperH.
922 # 934 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 935 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 936 bool
925 937
926 config NUMA_BALANCING 938 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 939 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 940 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 941 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 942 depends on SMP && NUMA && MIGRATION
931 help 943 help
932 This option adds support for automat 944 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 945 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 946 it has references to the node the task is running on.
935 947
936 This system will be inactive on UMA 948 This system will be inactive on UMA systems.
937 949
938 config NUMA_BALANCING_DEFAULT_ENABLED 950 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 951 bool "Automatically enable NUMA aware memory/task placement"
940 default y 952 default y
941 depends on NUMA_BALANCING 953 depends on NUMA_BALANCING
942 help 954 help
943 If set, automatic NUMA balancing wil 955 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 956 machine.
945 957
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 958 menuconfig CGROUPS
950 bool "Control Group support" 959 bool "Control Group support"
951 select KERNFS 960 select KERNFS
952 help 961 help
953 This option adds support for groupin 962 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 963 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 964 controls or device isolation.
956 See 965 See
957 - Documentation/scheduler/sche !! 966 - Documentation/scheduler/sched-design-CFS.txt (CFS)
958 - Documentation/admin-guide/cg !! 967 - Documentation/cgroup-v1/ (features for grouping, isolation
959 and 968 and resource control)
960 969
961 Say N if unsure. 970 Say N if unsure.
962 971
963 if CGROUPS 972 if CGROUPS
964 973
965 config PAGE_COUNTER 974 config PAGE_COUNTER
966 bool !! 975 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. <<
977 976
978 config MEMCG 977 config MEMCG
979 bool "Memory controller" 978 bool "Memory controller"
980 select PAGE_COUNTER 979 select PAGE_COUNTER
981 select EVENTFD 980 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 981 help
984 Provides control over the memory foo 982 Provides control over the memory footprint of tasks in a cgroup.
985 983
986 config MEMCG_V1 !! 984 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 985 bool "Swap controller"
988 depends on MEMCG !! 986 depends on MEMCG && SWAP
989 default n !! 987 help
990 help !! 988 Provides control over the swap space consumed by tasks in a cgroup.
991 Legacy cgroup v1 memory controller w !! 989
992 cgroup v2 implementation. The v1 is !! 990 config MEMCG_SWAP_ENABLED
993 which haven't migrated to the new cg !! 991 bool "Swap controller enabled by default"
994 do not have any such application the !! 992 depends on MEMCG_SWAP
995 this option disabled. !! 993 default y
996 !! 994 help
997 Please note that feature set of the !! 995 Memory Resource Controller Swap Extension comes with its price in
998 going to shrink due to deprecation p !! 996 a bigger memory consumption. General purpose distribution kernels
999 controller are highly discouraged. !! 997 which want to enable the feature but keep it disabled by default
1000 !! 998 and let the user enable it by swapaccount=1 boot command line
1001 Say N if unsure. !! 999 parameter should have this option unselected.
>> 1000 For those who want to have the feature enabled by default should
>> 1001 select this option (if, for some reason, they need to disable it
>> 1002 then swapaccount=0 does the trick).
1002 1003
1003 config BLK_CGROUP 1004 config BLK_CGROUP
1004 bool "IO controller" 1005 bool "IO controller"
1005 depends on BLOCK 1006 depends on BLOCK
1006 default n 1007 default n
1007 help !! 1008 ---help---
1008 Generic block IO controller cgroup in 1009 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 1010 cgroup interface which should be used by various IO controlling
1010 policies. 1011 policies.
1011 1012
1012 Currently, CFQ IO scheduler uses it t 1013 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 1014 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 1015 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 1016 block layer to implement upper limit in IO rates on a device.
1016 1017
1017 This option only enables generic Bloc 1018 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 1019 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 1020 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl !! 1021 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 1022 CONFIG_BLK_DEV_THROTTLING=y.
1022 1023
1023 See Documentation/admin-guide/cgroup- !! 1024 See Documentation/cgroup-v1/blkio-controller.txt for more information.
>> 1025
>> 1026 config DEBUG_BLK_CGROUP
>> 1027 bool "IO controller debugging"
>> 1028 depends on BLK_CGROUP
>> 1029 default n
>> 1030 ---help---
>> 1031 Enable some debugging help. Currently it exports additional stat
>> 1032 files in a cgroup which can be useful for debugging.
1024 1033
1025 config CGROUP_WRITEBACK 1034 config CGROUP_WRITEBACK
1026 bool 1035 bool
1027 depends on MEMCG && BLK_CGROUP 1036 depends on MEMCG && BLK_CGROUP
1028 default y 1037 default y
1029 1038
1030 menuconfig CGROUP_SCHED 1039 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 1040 bool "CPU controller"
1032 default n 1041 default n
1033 help 1042 help
1034 This feature lets CPU scheduler rec 1043 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 1044 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 1045 tasks.
1037 1046
1038 if CGROUP_SCHED 1047 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 1048 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 1049 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 1050 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1051 default CGROUP_SCHED
1047 1052
1048 config CFS_BANDWIDTH 1053 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1054 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1055 depends on FAIR_GROUP_SCHED
1051 default n 1056 default n
1052 help 1057 help
1053 This option allows users to define 1058 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1059 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1060 set are considered to be unconstrained and will run with no
1056 restriction. 1061 restriction.
1057 See Documentation/scheduler/sched-b !! 1062 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1058 1063
1059 config RT_GROUP_SCHED 1064 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1065 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1066 depends on CGROUP_SCHED
1062 default n 1067 default n
1063 help 1068 help
1064 This feature lets you explicitly al 1069 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1070 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1071 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1072 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r !! 1073 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 1074
1076 endif #CGROUP_SCHED 1075 endif #CGROUP_SCHED
1077 1076
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 1077 config CGROUP_PIDS
1105 bool "PIDs controller" 1078 bool "PIDs controller"
1106 help 1079 help
1107 Provides enforcement of process num 1080 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1081 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1082 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1083 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1084 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1085 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1086 PIDs controller is designed to stop this from happening.
1114 1087
1115 It should be noted that organisatio 1088 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b !! 1089 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
1117 since the PIDs limit only affects a 1090 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1091 attach to a cgroup.
1119 1092
1120 config CGROUP_RDMA <<
1121 bool "RDMA controller" <<
1122 help <<
1123 Provides enforcement of RDMA resour <<
1124 It is fairly easy for consumers to <<
1125 can result into resource unavailabi <<
1126 RDMA controller is designed to stop <<
1127 Attaching processes with active RDM <<
1128 hierarchy is allowed even if can cr <<
1129 <<
1130 config CGROUP_FREEZER 1093 config CGROUP_FREEZER
1131 bool "Freezer controller" 1094 bool "Freezer controller"
1132 help 1095 help
1133 Provides a way to freeze and unfree 1096 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1097 cgroup.
1135 1098
1136 This option affects the ORIGINAL cg 1099 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1100 controller includes important in-kernel memory consumers per default.
1138 1101
1139 If you're using cgroup2, say N. 1102 If you're using cgroup2, say N.
1140 1103
1141 config CGROUP_HUGETLB 1104 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1105 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1106 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1107 select PAGE_COUNTER
1145 default n 1108 default n
1146 help 1109 help
1147 Provides a cgroup controller for Hu 1110 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1111 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1112 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1113 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1114 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1115 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1116 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1117 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1118 that we cannot use the controller with huge page less than 3 pages.
1156 1119
1157 config CPUSETS 1120 config CPUSETS
1158 bool "Cpuset controller" 1121 bool "Cpuset controller"
1159 depends on SMP <<
1160 help 1122 help
1161 This option will let you create and 1123 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1124 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1125 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1126 This is primarily useful on large SMP or NUMA systems.
1165 1127
1166 Say N if unsure. 1128 Say N if unsure.
1167 1129
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 1130 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1131 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1132 depends on CPUSETS
1184 default y 1133 default y
1185 1134
1186 config CGROUP_DEVICE 1135 config CGROUP_DEVICE
1187 bool "Device controller" 1136 bool "Device controller"
1188 help 1137 help
1189 Provides a cgroup controller implem 1138 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1139 devices which a process in the cgroup can mknod or open.
1191 1140
1192 config CGROUP_CPUACCT 1141 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1142 bool "Simple CPU accounting controller"
1194 help 1143 help
1195 Provides a simple controller for mo 1144 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1145 total CPU consumed by the tasks in a cgroup.
1197 1146
1198 config CGROUP_PERF 1147 config CGROUP_PERF
1199 bool "Perf controller" 1148 bool "Perf controller"
1200 depends on PERF_EVENTS 1149 depends on PERF_EVENTS
1201 help 1150 help
1202 This option extends the perf per-cp 1151 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1152 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use !! 1153 designated cpu.
1205 so that it can monitor performance <<
1206 1154
1207 Say N if unsure. 1155 Say N if unsure.
1208 1156
1209 config CGROUP_BPF 1157 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1158 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1159 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1160 select SOCK_CGROUP_DATA
1213 help 1161 help
1214 Allow attaching eBPF programs to a 1162 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1163 syscall command BPF_PROG_ATTACH.
1216 1164
1217 In which context these programs are 1165 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1166 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1167 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1168 inet sockets.
1221 1169
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 1170 config CGROUP_DEBUG
1237 bool "Debug controller" !! 1171 bool "Example controller"
1238 default n 1172 default n
1239 depends on DEBUG_KERNEL <<
1240 help 1173 help
1241 This option enables a simple contro 1174 This option enables a simple controller that exports
1242 debugging information about the cgr !! 1175 debugging information about the cgroups framework.
1243 controller is for control cgroup de <<
1244 interfaces are not stable. <<
1245 1176
1246 Say N. 1177 Say N.
1247 1178
1248 config SOCK_CGROUP_DATA 1179 config SOCK_CGROUP_DATA
1249 bool 1180 bool
1250 default n 1181 default n
1251 1182
1252 endif # CGROUPS 1183 endif # CGROUPS
1253 1184
>> 1185 config CHECKPOINT_RESTORE
>> 1186 bool "Checkpoint/restore support" if EXPERT
>> 1187 select PROC_CHILDREN
>> 1188 default n
>> 1189 help
>> 1190 Enables additional kernel features in a sake of checkpoint/restore.
>> 1191 In particular it adds auxiliary prctl codes to setup process text,
>> 1192 data and heap segment sizes, and a few additional /proc filesystem
>> 1193 entries.
>> 1194
>> 1195 If unsure, say N here.
>> 1196
1254 menuconfig NAMESPACES 1197 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1198 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1199 depends on MULTIUSER
1257 default !EXPERT 1200 default !EXPERT
1258 help 1201 help
1259 Provides the way to make tasks work 1202 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1203 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1204 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1205 different namespaces.
1263 1206
1264 if NAMESPACES 1207 if NAMESPACES
1265 1208
1266 config UTS_NS 1209 config UTS_NS
1267 bool "UTS namespace" 1210 bool "UTS namespace"
1268 default y 1211 default y
1269 help 1212 help
1270 In this namespace tasks see differe 1213 In this namespace tasks see different info provided with the
1271 uname() system call 1214 uname() system call
1272 1215
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 1216 config IPC_NS
1282 bool "IPC namespace" 1217 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1218 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1219 default y
1285 help 1220 help
1286 In this namespace tasks work with I 1221 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1222 different IPC objects in different namespaces.
1288 1223
1289 config USER_NS 1224 config USER_NS
1290 bool "User namespace" 1225 bool "User namespace"
1291 default n 1226 default n
1292 help 1227 help
1293 This allows containers, i.e. vserve 1228 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1229 to provide different user info for different servers.
1295 1230
1296 When user namespaces are enabled in 1231 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1232 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1233 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1234 of memory a memory unprivileged users can use.
1300 1235
1301 If unsure, say N. 1236 If unsure, say N.
1302 1237
1303 config PID_NS 1238 config PID_NS
1304 bool "PID Namespaces" 1239 bool "PID Namespaces"
1305 default y 1240 default y
1306 help 1241 help
1307 Support process id namespaces. Thi 1242 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1243 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1244 pid namespaces. This is a building block of containers.
1310 1245
1311 config NET_NS 1246 config NET_NS
1312 bool "Network namespace" 1247 bool "Network namespace"
1313 depends on NET 1248 depends on NET
1314 default y 1249 default y
1315 help 1250 help
1316 Allow user space to create what app 1251 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1252 of the network stack.
1318 1253
1319 endif # NAMESPACES 1254 endif # NAMESPACES
1320 1255
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 1256 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1257 bool "Automatic process group scheduling"
1337 select CGROUPS 1258 select CGROUPS
1338 select CGROUP_SCHED 1259 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1260 select FAIR_GROUP_SCHED
1340 help 1261 help
1341 This option optimizes the scheduler 1262 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1263 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1264 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1265 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1266 upon task session.
1346 1267
>> 1268 config SYSFS_DEPRECATED
>> 1269 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1270 depends on SYSFS
>> 1271 default n
>> 1272 help
>> 1273 This option adds code that switches the layout of the "block" class
>> 1274 devices, to not show up in /sys/class/block/, but only in
>> 1275 /sys/block/.
>> 1276
>> 1277 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1278 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1279
>> 1280 This option allows new kernels to run on old distributions and tools,
>> 1281 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1282 major distributions and tools handle this just fine.
>> 1283
>> 1284 Recent distributions and userspace tools after 2009/2010 depend on
>> 1285 the existence of /sys/class/block/, and will not work with this
>> 1286 option enabled.
>> 1287
>> 1288 Only if you are using a new kernel on an old distribution, you might
>> 1289 need to say Y here.
>> 1290
>> 1291 config SYSFS_DEPRECATED_V2
>> 1292 bool "Enable deprecated sysfs features by default"
>> 1293 default n
>> 1294 depends on SYSFS
>> 1295 depends on SYSFS_DEPRECATED
>> 1296 help
>> 1297 Enable deprecated sysfs by default.
>> 1298
>> 1299 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1300 option.
>> 1301
>> 1302 Only if you are using a new kernel on an old distribution, you might
>> 1303 need to say Y here. Even then, odds are you would not need it
>> 1304 enabled, you can always pass the boot option if absolutely necessary.
>> 1305
1347 config RELAY 1306 config RELAY
1348 bool "Kernel->user space relay suppor 1307 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1308 select IRQ_WORK
1350 help 1309 help
1351 This option enables support for rel 1310 This option enables support for relay interface support in
1352 certain file systems (such as debug 1311 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1312 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1313 facilities to relay large amounts of data from kernel space to
1355 user space. 1314 user space.
1356 1315
1357 If unsure, say N. 1316 If unsure, say N.
1358 1317
1359 config BLK_DEV_INITRD 1318 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1319 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
>> 1320 depends on BROKEN || !FRV
1361 help 1321 help
1362 The initial RAM filesystem is a ram 1322 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1323 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1324 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1325 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1326 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1327
1368 If RAM disk support (BLK_DEV_RAM) i 1328 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1329 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1330 15 Kbytes (more on some other architectures) to the kernel size.
1371 1331
1372 If unsure say Y. 1332 If unsure say Y.
1373 1333
1374 if BLK_DEV_INITRD 1334 if BLK_DEV_INITRD
1375 1335
1376 source "usr/Kconfig" 1336 source "usr/Kconfig"
1377 1337
1378 endif 1338 endif
1379 1339
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 1340 choice
1435 prompt "Compiler optimization level" 1341 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE !! 1342 default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
1437 1343
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1344 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" !! 1345 bool "Optimize for performance"
1440 help 1346 help
1441 This is the default optimization le 1347 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1348 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1349 helpful compile-time warnings.
1444 1350
1445 config CC_OPTIMIZE_FOR_SIZE 1351 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" !! 1352 bool "Optimize for size"
1447 help 1353 help
1448 Choosing this option will pass "-Os !! 1354 Enabling this option will pass "-Os" instead of "-O2" to
1449 in a smaller kernel. !! 1355 your compiler resulting in a smaller kernel.
>> 1356
>> 1357 If unsure, say N.
1450 1358
1451 endchoice 1359 endchoice
1452 1360
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION !! 1361 config SYSCTL
1454 bool 1362 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 1363
1493 config SYSCTL !! 1364 config ANON_INODES
1494 bool 1365 bool
1495 1366
1496 config HAVE_UID16 1367 config HAVE_UID16
1497 bool 1368 bool
1498 1369
1499 config SYSCTL_EXCEPTION_TRACE 1370 config SYSCTL_EXCEPTION_TRACE
1500 bool 1371 bool
1501 help 1372 help
1502 Enable support for /proc/sys/debug/ 1373 Enable support for /proc/sys/debug/exception-trace.
1503 1374
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1375 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1376 bool
1506 help 1377 help
1507 Enable support for /proc/sys/kernel 1378 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1379 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1380 about unaligned access emulation going on under the hood.
1510 1381
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1382 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1383 bool
1513 help 1384 help
1514 Enable support for /proc/sys/kernel 1385 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1386 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1387 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1388 see arch/parisc/kernel/unaligned.c for reference
1518 1389
1519 config HAVE_PCSPKR_PLATFORM 1390 config HAVE_PCSPKR_PLATFORM
1520 bool 1391 bool
1521 1392
>> 1393 # interpreter that classic socket filters depend on
>> 1394 config BPF
>> 1395 bool
>> 1396
1522 menuconfig EXPERT 1397 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1398 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1399 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1400 select DEBUG_KERNEL
1526 help 1401 help
1527 This option allows certain base ker 1402 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is !! 1403 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " !! 1404 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh !! 1405 Only use this if you really know what you are doing.
1531 1406
1532 config UID16 1407 config UID16
1533 bool "Enable 16-bit UID system calls" 1408 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1409 depends on HAVE_UID16 && MULTIUSER
1535 default y 1410 default y
1536 help 1411 help
1537 This enables the legacy 16-bit UID 1412 This enables the legacy 16-bit UID syscall wrappers.
1538 1413
1539 config MULTIUSER 1414 config MULTIUSER
1540 bool "Multiple users, groups and capa 1415 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1416 default y
1542 help 1417 help
1543 This option enables support for non 1418 This option enables support for non-root users, groups and
1544 capabilities. 1419 capabilities.
1545 1420
1546 If you say N here, all processes wi 1421 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1422 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1423 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1424 setgid, and capset.
1550 1425
1551 If unsure, say Y here. 1426 If unsure, say Y here.
1552 1427
1553 config SGETMASK_SYSCALL 1428 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1429 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1430 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1556 help !! 1431 ---help---
1557 sys_sgetmask and sys_ssetmask are o 1432 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1433 no longer supported in libc but still enabled by default in some
1559 architectures. 1434 architectures.
1560 1435
1561 If unsure, leave the default option 1436 If unsure, leave the default option here.
1562 1437
1563 config SYSFS_SYSCALL 1438 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1439 bool "Sysfs syscall support" if EXPERT
1565 default y 1440 default y
1566 help !! 1441 ---help---
1567 sys_sysfs is an obsolete system cal 1442 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1443 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1444 compatibility with some systems.
1570 1445
1571 If unsure say Y here. 1446 If unsure say Y here.
1572 1447
1573 config FHANDLE !! 1448 config SYSCTL_SYSCALL
1574 bool "open by fhandle syscalls" if EX !! 1449 bool "Sysctl syscall support" if EXPERT
1575 select EXPORTFS !! 1450 depends on PROC_SYSCTL
1576 default y !! 1451 default n
1577 help !! 1452 select SYSCTL
1578 If you say Y here, a user level pro !! 1453 ---help---
1579 file names to handle and then later !! 1454 sys_sysctl uses binary paths that have been found challenging
1580 different file system operations. T !! 1455 to properly maintain and use. The interface in /proc/sys
1581 userspace file servers, which now t !! 1456 using paths with ascii names is now the primary path to this
1582 of names. The handle would remain t !! 1457 information.
1583 get renamed. Enables open_by_handle !! 1458
1584 syscalls. !! 1459 Almost nothing using the binary sysctl interface so if you are
>> 1460 trying to save some space it is probably safe to disable this,
>> 1461 making your kernel marginally smaller.
>> 1462
>> 1463 If unsure say N here.
1585 1464
1586 config POSIX_TIMERS 1465 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1466 bool "Posix Clocks & timers" if EXPERT
1588 default y 1467 default y
1589 help 1468 help
1590 This includes native support for PO 1469 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1470 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1471 can be configured out to reduce the size of the kernel image.
1593 1472
1594 When this option is disabled, the f 1473 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1474 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1475 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1476 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1477 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1478 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1479
1601 If unsure say y. 1480 If unsure say y.
1602 1481
>> 1482 config KALLSYMS
>> 1483 bool "Load all symbols for debugging/ksymoops" if EXPERT
>> 1484 default y
>> 1485 help
>> 1486 Say Y here to let the kernel print out symbolic crash information and
>> 1487 symbolic stack backtraces. This increases the size of the kernel
>> 1488 somewhat, as all symbols have to be loaded into the kernel image.
>> 1489
>> 1490 config KALLSYMS_ALL
>> 1491 bool "Include all symbols in kallsyms"
>> 1492 depends on DEBUG_KERNEL && KALLSYMS
>> 1493 help
>> 1494 Normally kallsyms only contains the symbols of functions for nicer
>> 1495 OOPS messages and backtraces (i.e., symbols from the text and inittext
>> 1496 sections). This is sufficient for most cases. And only in very rare
>> 1497 cases (e.g., when a debugger is used) all symbols are required (e.g.,
>> 1498 names of variables from the data sections, etc).
>> 1499
>> 1500 This option makes sure that all symbols are loaded into the kernel
>> 1501 image (i.e., symbols from all sections) in cost of increased kernel
>> 1502 size (depending on the kernel configuration, it may be 300KiB or
>> 1503 something like this).
>> 1504
>> 1505 Say N unless you really need all symbols.
>> 1506
>> 1507 config KALLSYMS_ABSOLUTE_PERCPU
>> 1508 bool
>> 1509 depends on KALLSYMS
>> 1510 default X86_64 && SMP
>> 1511
>> 1512 config KALLSYMS_BASE_RELATIVE
>> 1513 bool
>> 1514 depends on KALLSYMS
>> 1515 default !IA64 && !(TILE && 64BIT)
>> 1516 help
>> 1517 Instead of emitting them as absolute values in the native word size,
>> 1518 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1519 each containing a relative value in the range [base, base + U32_MAX]
>> 1520 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1521 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1522 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1523 address encountered in the image.
>> 1524
>> 1525 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1526 but more importantly, it results in entries whose values are build
>> 1527 time constants, and no relocation pass is required at runtime to fix
>> 1528 up the entries based on the runtime load address of the kernel.
>> 1529
1603 config PRINTK 1530 config PRINTK
1604 default y 1531 default y
1605 bool "Enable support for printk" if E 1532 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1533 select IRQ_WORK
1607 help 1534 help
1608 This option enables normal printk s 1535 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1536 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1537 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1538 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1539 strongly discouraged.
1613 1540
>> 1541 config PRINTK_NMI
>> 1542 def_bool y
>> 1543 depends on PRINTK
>> 1544 depends on HAVE_NMI
>> 1545
1614 config BUG 1546 config BUG
1615 bool "BUG() support" if EXPERT 1547 bool "BUG() support" if EXPERT
1616 default y 1548 default y
1617 help 1549 help
1618 Disabling this option eliminates su !! 1550 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p !! 1551 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou !! 1552 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no !! 1553 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. !! 1554 Just say Y.
1623 1555
1624 config ELF_CORE 1556 config ELF_CORE
1625 depends on COREDUMP 1557 depends on COREDUMP
1626 default y 1558 default y
1627 bool "Enable ELF core dumps" if EXPER 1559 bool "Enable ELF core dumps" if EXPERT
1628 help 1560 help
1629 Enable support for generating core 1561 Enable support for generating core dumps. Disabling saves about 4k.
1630 1562
1631 1563
1632 config PCSPKR_PLATFORM 1564 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1565 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1566 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1567 select I8253_LOCK
1636 default y 1568 default y
1637 help 1569 help
1638 This option allows to disable the i !! 1570 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. !! 1571 support, saving some memory.
1640 1572
1641 config BASE_SMALL !! 1573 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1574 default y
>> 1575 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1576 help
1644 Enabling this option reduces the si !! 1577 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1578 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1579 but may reduce performance.
1647 1580
1648 config FUTEX 1581 config FUTEX
1649 bool "Enable futex support" if EXPERT 1582 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1583 default y
1652 imply RT_MUTEXES !! 1584 select RT_MUTEXES
1653 help 1585 help
1654 Disabling this option will cause th 1586 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1587 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1588 run glibc-based applications correctly.
1657 1589
1658 config FUTEX_PI !! 1590 config HAVE_FUTEX_CMPXCHG
1659 bool 1591 bool
1660 depends on FUTEX && RT_MUTEXES !! 1592 depends on FUTEX
1661 default y !! 1593 help
>> 1594 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1595 is implemented and always working. This removes a couple of runtime
>> 1596 checks.
1662 1597
1663 config EPOLL 1598 config EPOLL
1664 bool "Enable eventpoll support" if EX 1599 bool "Enable eventpoll support" if EXPERT
1665 default y 1600 default y
>> 1601 select ANON_INODES
1666 help 1602 help
1667 Disabling this option will cause th 1603 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1604 support for epoll family of system calls.
1669 1605
1670 config SIGNALFD 1606 config SIGNALFD
1671 bool "Enable signalfd() system call" 1607 bool "Enable signalfd() system call" if EXPERT
>> 1608 select ANON_INODES
1672 default y 1609 default y
1673 help 1610 help
1674 Enable the signalfd() system call t 1611 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1612 on a file descriptor.
1676 1613
1677 If unsure, say Y. 1614 If unsure, say Y.
1678 1615
1679 config TIMERFD 1616 config TIMERFD
1680 bool "Enable timerfd() system call" i 1617 bool "Enable timerfd() system call" if EXPERT
>> 1618 select ANON_INODES
1681 default y 1619 default y
1682 help 1620 help
1683 Enable the timerfd() system call th 1621 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1622 events on a file descriptor.
1685 1623
1686 If unsure, say Y. 1624 If unsure, say Y.
1687 1625
1688 config EVENTFD 1626 config EVENTFD
1689 bool "Enable eventfd() system call" i 1627 bool "Enable eventfd() system call" if EXPERT
>> 1628 select ANON_INODES
1690 default y 1629 default y
1691 help 1630 help
1692 Enable the eventfd() system call th 1631 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1632 kernel notification (ie. KAIO) or userspace notifications.
1694 1633
1695 If unsure, say Y. 1634 If unsure, say Y.
1696 1635
>> 1636 # syscall, maps, verifier
>> 1637 config BPF_SYSCALL
>> 1638 bool "Enable bpf() system call"
>> 1639 select ANON_INODES
>> 1640 select BPF
>> 1641 default n
>> 1642 help
>> 1643 Enable the bpf() system call that allows to manipulate eBPF
>> 1644 programs and maps via file descriptors.
>> 1645
1697 config SHMEM 1646 config SHMEM
1698 bool "Use full shmem filesystem" if E 1647 bool "Use full shmem filesystem" if EXPERT
1699 default y 1648 default y
1700 depends on MMU 1649 depends on MMU
1701 help 1650 help
1702 The shmem is an internal filesystem 1651 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1652 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1653 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1654 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1655 which may be appropriate on small systems without swap.
1707 1656
1708 config AIO 1657 config AIO
1709 bool "Enable AIO support" if EXPERT 1658 bool "Enable AIO support" if EXPERT
1710 default y 1659 default y
1711 help 1660 help
1712 This option enables POSIX asynchron 1661 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1662 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1663 this option saves about 7k.
1715 1664
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 1665 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1666 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1667 default y
1741 help 1668 help
1742 This option enables the madvise and 1669 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1670 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1671 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1672 applications use these syscalls, you can disable this option to save
1746 space. 1673 space.
1747 1674
>> 1675 config USERFAULTFD
>> 1676 bool "Enable userfaultfd() system call"
>> 1677 select ANON_INODES
>> 1678 depends on MMU
>> 1679 help
>> 1680 Enable the userfaultfd() system call that allows to intercept and
>> 1681 handle page faults in userland.
>> 1682
>> 1683 config PCI_QUIRKS
>> 1684 default y
>> 1685 bool "Enable PCI quirk workarounds" if EXPERT
>> 1686 depends on PCI
>> 1687 help
>> 1688 This enables workarounds for various PCI chipset
>> 1689 bugs/quirks. Disable this only if your target machine is
>> 1690 unaffected by PCI quirks.
>> 1691
1748 config MEMBARRIER 1692 config MEMBARRIER
1749 bool "Enable membarrier() system call 1693 bool "Enable membarrier() system call" if EXPERT
1750 default y 1694 default y
1751 help 1695 help
1752 Enable the membarrier() system call 1696 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1697 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1698 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1699 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1700 compiler barrier.
1757 1701
1758 If unsure, say Y. 1702 If unsure, say Y.
1759 1703
1760 config KCMP !! 1704 config EMBEDDED
1761 bool "Enable kcmp() system call" if E !! 1705 bool "Embedded system"
1762 help !! 1706 option allnoconfig_y
1763 Enable the kernel resource comparis !! 1707 select EXPERT
1764 user-space with the ability to comp !! 1708 help
1765 share a common resource, such as a !! 1709 This option should be enabled if compiling the kernel for
1766 memory space. !! 1710 an embedded system so certain expert options are available
1767 !! 1711 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 1712
1862 config HAVE_PERF_EVENTS 1713 config HAVE_PERF_EVENTS
1863 bool 1714 bool
1864 help 1715 help
1865 See tools/perf/design.txt for detai 1716 See tools/perf/design.txt for details.
1866 1717
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1718 config PERF_USE_VMALLOC
1872 bool 1719 bool
1873 help 1720 help
1874 See tools/perf/design.txt for detai 1721 See tools/perf/design.txt for details
1875 1722
1876 menu "Kernel Performance Events And Counters" 1723 menu "Kernel Performance Events And Counters"
1877 1724
1878 config PERF_EVENTS 1725 config PERF_EVENTS
1879 bool "Kernel performance events and c 1726 bool "Kernel performance events and counters"
1880 default y if PROFILING 1727 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1728 depends on HAVE_PERF_EVENTS
>> 1729 select ANON_INODES
1882 select IRQ_WORK 1730 select IRQ_WORK
>> 1731 select SRCU
1883 help 1732 help
1884 Enable kernel support for various p 1733 Enable kernel support for various performance events provided
1885 by software and hardware. 1734 by software and hardware.
1886 1735
1887 Software events are supported eithe 1736 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1737 use of generic tracepoints.
1889 1738
1890 Most modern CPUs support performanc 1739 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1740 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1741 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1742 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1743 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1744 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1745 used to profile the code that runs on that CPU.
1897 1746
1898 The Linux Performance Event subsyst 1747 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1748 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1749 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1750 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1751 capabilities on top of those.
1903 1752
1904 Say Y if unsure. 1753 Say Y if unsure.
1905 1754
1906 config DEBUG_PERF_USE_VMALLOC 1755 config DEBUG_PERF_USE_VMALLOC
1907 default n 1756 default n
1908 bool "Debug: use vmalloc to back perf 1757 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1758 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1759 select PERF_USE_VMALLOC
1911 help 1760 help
1912 Use vmalloc memory to back perf mma !! 1761 Use vmalloc memory to back perf mmap() buffers.
1913 1762
1914 Mostly useful for debugging the vma !! 1763 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. !! 1764 that don't require it.
1916 1765
1917 Say N if unsure. !! 1766 Say N if unsure.
1918 1767
1919 endmenu 1768 endmenu
1920 1769
>> 1770 config VM_EVENT_COUNTERS
>> 1771 default y
>> 1772 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1773 help
>> 1774 VM event counters are needed for event counts to be shown.
>> 1775 This option allows the disabling of the VM event counters
>> 1776 on EXPERT systems. /proc/vmstat will only show page counts
>> 1777 if VM event counters are disabled.
>> 1778
>> 1779 config SLUB_DEBUG
>> 1780 default y
>> 1781 bool "Enable SLUB debugging support" if EXPERT
>> 1782 depends on SLUB && SYSFS
>> 1783 help
>> 1784 SLUB has extensive debug support features. Disabling these can
>> 1785 result in significant savings in code size. This also disables
>> 1786 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1787 no support for cache validation etc.
>> 1788
>> 1789 config COMPAT_BRK
>> 1790 bool "Disable heap randomization"
>> 1791 default y
>> 1792 help
>> 1793 Randomizing heap placement makes heap exploits harder, but it
>> 1794 also breaks ancient binaries (including anything libc5 based).
>> 1795 This option changes the bootup default to heap randomization
>> 1796 disabled, and can be overridden at runtime by setting
>> 1797 /proc/sys/kernel/randomize_va_space to 2.
>> 1798
>> 1799 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1800
>> 1801 choice
>> 1802 prompt "Choose SLAB allocator"
>> 1803 default SLUB
>> 1804 help
>> 1805 This option allows to select a slab allocator.
>> 1806
>> 1807 config SLAB
>> 1808 bool "SLAB"
>> 1809 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1810 help
>> 1811 The regular slab allocator that is established and known to work
>> 1812 well in all environments. It organizes cache hot objects in
>> 1813 per cpu and per node queues.
>> 1814
>> 1815 config SLUB
>> 1816 bool "SLUB (Unqueued Allocator)"
>> 1817 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1818 help
>> 1819 SLUB is a slab allocator that minimizes cache line usage
>> 1820 instead of managing queues of cached objects (SLAB approach).
>> 1821 Per cpu caching is realized using slabs of objects instead
>> 1822 of queues of objects. SLUB can use memory efficiently
>> 1823 and has enhanced diagnostics. SLUB is the default choice for
>> 1824 a slab allocator.
>> 1825
>> 1826 config SLOB
>> 1827 depends on EXPERT
>> 1828 bool "SLOB (Simple Allocator)"
>> 1829 help
>> 1830 SLOB replaces the stock allocator with a drastically simpler
>> 1831 allocator. SLOB is generally more space efficient but
>> 1832 does not perform as well on large systems.
>> 1833
>> 1834 endchoice
>> 1835
>> 1836 config SLAB_FREELIST_RANDOM
>> 1837 default n
>> 1838 depends on SLAB || SLUB
>> 1839 bool "SLAB freelist randomization"
>> 1840 help
>> 1841 Randomizes the freelist order used on creating new pages. This
>> 1842 security feature reduces the predictability of the kernel slab
>> 1843 allocator against heap overflows.
>> 1844
>> 1845 config SLUB_CPU_PARTIAL
>> 1846 default y
>> 1847 depends on SLUB && SMP
>> 1848 bool "SLUB per cpu partial cache"
>> 1849 help
>> 1850 Per cpu partial caches accellerate objects allocation and freeing
>> 1851 that is local to a processor at the price of more indeterminism
>> 1852 in the latency of the free. On overflow these caches will be cleared
>> 1853 which requires the taking of locks that may cause latency spikes.
>> 1854 Typically one would choose no for a realtime system.
>> 1855
>> 1856 config MMAP_ALLOW_UNINITIALIZED
>> 1857 bool "Allow mmapped anonymous memory to be uninitialized"
>> 1858 depends on EXPERT && !MMU
>> 1859 default n
>> 1860 help
>> 1861 Normally, and according to the Linux spec, anonymous memory obtained
>> 1862 from mmap() has it's contents cleared before it is passed to
>> 1863 userspace. Enabling this config option allows you to request that
>> 1864 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 1865 providing a huge performance boost. If this option is not enabled,
>> 1866 then the flag will be ignored.
>> 1867
>> 1868 This is taken advantage of by uClibc's malloc(), and also by
>> 1869 ELF-FDPIC binfmt's brk and stack allocator.
>> 1870
>> 1871 Because of the obvious security issues, this option should only be
>> 1872 enabled on embedded devices where you control what is run in
>> 1873 userspace. Since that isn't generally a problem on no-MMU systems,
>> 1874 it is normally safe to say Y here.
>> 1875
>> 1876 See Documentation/nommu-mmap.txt for more information.
>> 1877
1921 config SYSTEM_DATA_VERIFICATION 1878 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1879 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1880 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1881 select KEYS
1925 select CRYPTO 1882 select CRYPTO
1926 select CRYPTO_RSA 1883 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1884 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1885 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1886 select ASN1
1930 select OID_REGISTRY 1887 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1888 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1889 select PKCS7_MESSAGE_PARSER
1933 help 1890 help
1934 Provide PKCS#7 message verification 1891 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1892 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1893 module verification, kexec image verification and firmware blob
1937 verification. 1894 verification.
1938 1895
1939 config PROFILING 1896 config PROFILING
1940 bool "Profiling support" 1897 bool "Profiling support"
1941 help 1898 help
1942 Say Y here to enable the extended p 1899 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 1900 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 1901
1986 # 1902 #
1987 # Place an empty function call at each tracep 1903 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1904 # dynamically changed for a probe function.
1989 # 1905 #
1990 config TRACEPOINTS 1906 config TRACEPOINTS
1991 bool 1907 bool
1992 1908
1993 source "kernel/Kconfig.kexec" !! 1909 source "arch/Kconfig"
1994 1910
1995 endmenu # General setup 1911 endmenu # General setup
1996 1912
1997 source "arch/Kconfig" !! 1913 config HAVE_GENERIC_DMA_COHERENT
>> 1914 bool
>> 1915 default n
>> 1916
>> 1917 config SLABINFO
>> 1918 bool
>> 1919 depends on PROC_FS
>> 1920 depends on SLAB || SLUB_DEBUG
>> 1921 default y
1998 1922
1999 config RT_MUTEXES 1923 config RT_MUTEXES
2000 bool 1924 bool
2001 default y if PREEMPT_RT <<
2002 1925
2003 config MODULE_SIG_FORMAT !! 1926 config BASE_SMALL
2004 def_bool n !! 1927 int
>> 1928 default 0 if BASE_FULL
>> 1929 default 1 if !BASE_FULL
>> 1930
>> 1931 menuconfig MODULES
>> 1932 bool "Enable loadable module support"
>> 1933 option modules
>> 1934 help
>> 1935 Kernel modules are small pieces of compiled code which can
>> 1936 be inserted in the running kernel, rather than being
>> 1937 permanently built into the kernel. You use the "modprobe"
>> 1938 tool to add (and sometimes remove) them. If you say Y here,
>> 1939 many parts of the kernel can be built as modules (by
>> 1940 answering M instead of Y where indicated): this is most
>> 1941 useful for infrequently used options which are not required
>> 1942 for booting. For more information, see the man pages for
>> 1943 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1944
>> 1945 If you say Y here, you will need to run "make
>> 1946 modules_install" to put the modules under /lib/modules/
>> 1947 where modprobe can find them (you may need to be root to do
>> 1948 this).
>> 1949
>> 1950 If unsure, say Y.
>> 1951
>> 1952 if MODULES
>> 1953
>> 1954 config MODULE_FORCE_LOAD
>> 1955 bool "Forced module loading"
>> 1956 default n
>> 1957 help
>> 1958 Allow loading of modules without version information (ie. modprobe
>> 1959 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1960 is usually a really bad idea.
>> 1961
>> 1962 config MODULE_UNLOAD
>> 1963 bool "Module unloading"
>> 1964 help
>> 1965 Without this option you will not be able to unload any
>> 1966 modules (note that some modules may not be unloadable
>> 1967 anyway), which makes your kernel smaller, faster
>> 1968 and simpler. If unsure, say Y.
>> 1969
>> 1970 config MODULE_FORCE_UNLOAD
>> 1971 bool "Forced module unloading"
>> 1972 depends on MODULE_UNLOAD
>> 1973 help
>> 1974 This option allows you to force a module to unload, even if the
>> 1975 kernel believes it is unsafe: the kernel will remove the module
>> 1976 without waiting for anyone to stop using it (using the -f option to
>> 1977 rmmod). This is mainly for kernel developers and desperate users.
>> 1978 If unsure, say N.
>> 1979
>> 1980 config MODVERSIONS
>> 1981 bool "Module versioning support"
>> 1982 help
>> 1983 Usually, you have to use modules compiled with your kernel.
>> 1984 Saying Y here makes it sometimes possible to use modules
>> 1985 compiled for different kernels, by adding enough information
>> 1986 to the modules to (hopefully) spot any changes which would
>> 1987 make them incompatible with the kernel you are running. If
>> 1988 unsure, say N.
>> 1989
>> 1990 config MODULE_REL_CRCS
>> 1991 bool
>> 1992 depends on MODVERSIONS
>> 1993
>> 1994 config MODULE_SRCVERSION_ALL
>> 1995 bool "Source checksum for all modules"
>> 1996 help
>> 1997 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 1998 field inserted into their modinfo section, which contains a
>> 1999 sum of the source files which made it. This helps maintainers
>> 2000 see exactly which source was used to build a module (since
>> 2001 others sometimes change the module source without updating
>> 2002 the version). With this option, such a "srcversion" field
>> 2003 will be created for all modules. If unsure, say N.
>> 2004
>> 2005 config MODULE_SIG
>> 2006 bool "Module signature verification"
>> 2007 depends on MODULES
2005 select SYSTEM_DATA_VERIFICATION 2008 select SYSTEM_DATA_VERIFICATION
>> 2009 help
>> 2010 Check modules for valid signatures upon load: the signature
>> 2011 is simply appended to the module. For more information see
>> 2012 Documentation/module-signing.txt.
>> 2013
>> 2014 Note that this option adds the OpenSSL development packages as a
>> 2015 kernel build dependency so that the signing tool can use its crypto
>> 2016 library.
>> 2017
>> 2018 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2019 module DOES NOT get stripped after being signed. This includes the
>> 2020 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2021 inclusion into an initramfs that wants the module size reduced.
>> 2022
>> 2023 config MODULE_SIG_FORCE
>> 2024 bool "Require modules to be validly signed"
>> 2025 depends on MODULE_SIG
>> 2026 help
>> 2027 Reject unsigned modules or signed modules for which we don't have a
>> 2028 key. Without this, such modules will simply taint the kernel.
>> 2029
>> 2030 config MODULE_SIG_ALL
>> 2031 bool "Automatically sign all modules"
>> 2032 default y
>> 2033 depends on MODULE_SIG
>> 2034 help
>> 2035 Sign all modules during make modules_install. Without this option,
>> 2036 modules must be signed manually, using the scripts/sign-file tool.
>> 2037
>> 2038 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2039 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2040
>> 2041 choice
>> 2042 prompt "Which hash algorithm should modules be signed with?"
>> 2043 depends on MODULE_SIG
>> 2044 help
>> 2045 This determines which sort of hashing algorithm will be used during
>> 2046 signature generation. This algorithm _must_ be built into the kernel
>> 2047 directly so that signature verification can take place. It is not
>> 2048 possible to load a signed module containing the algorithm to check
>> 2049 the signature on that module.
>> 2050
>> 2051 config MODULE_SIG_SHA1
>> 2052 bool "Sign modules with SHA-1"
>> 2053 select CRYPTO_SHA1
>> 2054
>> 2055 config MODULE_SIG_SHA224
>> 2056 bool "Sign modules with SHA-224"
>> 2057 select CRYPTO_SHA256
>> 2058
>> 2059 config MODULE_SIG_SHA256
>> 2060 bool "Sign modules with SHA-256"
>> 2061 select CRYPTO_SHA256
>> 2062
>> 2063 config MODULE_SIG_SHA384
>> 2064 bool "Sign modules with SHA-384"
>> 2065 select CRYPTO_SHA512
>> 2066
>> 2067 config MODULE_SIG_SHA512
>> 2068 bool "Sign modules with SHA-512"
>> 2069 select CRYPTO_SHA512
>> 2070
>> 2071 endchoice
>> 2072
>> 2073 config MODULE_SIG_HASH
>> 2074 string
>> 2075 depends on MODULE_SIG
>> 2076 default "sha1" if MODULE_SIG_SHA1
>> 2077 default "sha224" if MODULE_SIG_SHA224
>> 2078 default "sha256" if MODULE_SIG_SHA256
>> 2079 default "sha384" if MODULE_SIG_SHA384
>> 2080 default "sha512" if MODULE_SIG_SHA512
>> 2081
>> 2082 config MODULE_COMPRESS
>> 2083 bool "Compress modules on installation"
>> 2084 depends on MODULES
>> 2085 help
2006 2086
2007 source "kernel/module/Kconfig" !! 2087 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2088 xz depending on "Compression algorithm" below.
>> 2089
>> 2090 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2091
>> 2092 Out-of-tree kernel modules installed using Kbuild will also be
>> 2093 compressed upon installation.
>> 2094
>> 2095 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2096 to compress the whole initrd or initramfs instead.
>> 2097
>> 2098 Note: This is fully compatible with signed modules.
>> 2099
>> 2100 If in doubt, say N.
>> 2101
>> 2102 choice
>> 2103 prompt "Compression algorithm"
>> 2104 depends on MODULE_COMPRESS
>> 2105 default MODULE_COMPRESS_GZIP
>> 2106 help
>> 2107 This determines which sort of compression will be used during
>> 2108 'make modules_install'.
>> 2109
>> 2110 GZIP (default) and XZ are supported.
>> 2111
>> 2112 config MODULE_COMPRESS_GZIP
>> 2113 bool "GZIP"
>> 2114
>> 2115 config MODULE_COMPRESS_XZ
>> 2116 bool "XZ"
>> 2117
>> 2118 endchoice
>> 2119
>> 2120 config TRIM_UNUSED_KSYMS
>> 2121 bool "Trim unused exported kernel symbols"
>> 2122 depends on MODULES && !UNUSED_SYMBOLS
>> 2123 help
>> 2124 The kernel and some modules make many symbols available for
>> 2125 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2126 on the set of modules being selected in your kernel configuration,
>> 2127 many of those exported symbols might never be used.
>> 2128
>> 2129 This option allows for unused exported symbols to be dropped from
>> 2130 the build. In turn, this provides the compiler more opportunities
>> 2131 (especially when using LTO) for optimizing the code and reducing
>> 2132 binary size. This might have some security advantages as well.
>> 2133
>> 2134 If unsure, or if you need to build out-of-tree modules, say N.
>> 2135
>> 2136 endif # MODULES
>> 2137
>> 2138 config MODULES_TREE_LOOKUP
>> 2139 def_bool y
>> 2140 depends on PERF_EVENTS || TRACING
2008 2141
2009 config INIT_ALL_POSSIBLE 2142 config INIT_ALL_POSSIBLE
2010 bool 2143 bool
2011 help 2144 help
2012 Back when each arch used to define 2145 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2146 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2147 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2148 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2149 and have several arch maintainers pursuing me down dark alleys.
2017 2150
2018 source "block/Kconfig" 2151 source "block/Kconfig"
2019 2152
2020 config PREEMPT_NOTIFIERS 2153 config PREEMPT_NOTIFIERS
2021 bool 2154 bool
2022 2155
2023 config PADATA 2156 config PADATA
2024 depends on SMP 2157 depends on SMP
2025 bool 2158 bool
2026 2159
2027 config ASN1 2160 config ASN1
2028 tristate 2161 tristate
2029 help 2162 help
2030 Build a simple ASN.1 grammar compil 2163 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2164 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2165 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2166 functions to call on what tags.
2034 2167
2035 source "kernel/Kconfig.locks" 2168 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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