1 # SPDX-License-Identifier: GPL-2.0-only 1 # SPDX-License-Identifier: GPL-2.0-only
2 config CC_VERSION_TEXT 2 config CC_VERSION_TEXT
3 string 3 string
4 default "$(CC_VERSION_TEXT)" 4 default "$(CC_VERSION_TEXT)"
5 help 5 help
6 This is used in unclear ways: 6 This is used in unclear ways:
7 7
8 - Re-run Kconfig when the compiler i 8 - Re-run Kconfig when the compiler is updated
9 The 'default' property references 9 The 'default' property references the environment variable,
10 CC_VERSION_TEXT so it is recorded 10 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
11 When the compiler is updated, Kcon 11 When the compiler is updated, Kconfig will be invoked.
12 12
13 - Ensure full rebuild when the compi 13 - Ensure full rebuild when the compiler is updated
14 include/linux/compiler-version.h c 14 include/linux/compiler-version.h contains this option in the comment
15 line so fixdep adds include/config 15 line so fixdep adds include/config/CC_VERSION_TEXT into the
16 auto-generated dependency. When th 16 auto-generated dependency. When the compiler is updated, syncconfig
17 will touch it and then every file 17 will touch it and then every file will be rebuilt.
18 18
19 config CC_IS_GCC 19 config CC_IS_GCC
20 def_bool $(success,test "$(cc-name)" = 20 def_bool $(success,test "$(cc-name)" = GCC)
21 21
22 config GCC_VERSION 22 config GCC_VERSION
23 int 23 int
24 default $(cc-version) if CC_IS_GCC 24 default $(cc-version) if CC_IS_GCC
25 default 0 25 default 0
26 26
27 config CC_IS_CLANG 27 config CC_IS_CLANG
28 def_bool $(success,test "$(cc-name)" = 28 def_bool $(success,test "$(cc-name)" = Clang)
29 29
30 config CLANG_VERSION 30 config CLANG_VERSION
31 int 31 int
32 default $(cc-version) if CC_IS_CLANG 32 default $(cc-version) if CC_IS_CLANG
33 default 0 33 default 0
34 34
35 config AS_IS_GNU 35 config AS_IS_GNU
36 def_bool $(success,test "$(as-name)" = 36 def_bool $(success,test "$(as-name)" = GNU)
37 37
38 config AS_IS_LLVM 38 config AS_IS_LLVM
39 def_bool $(success,test "$(as-name)" = 39 def_bool $(success,test "$(as-name)" = LLVM)
40 40
41 config AS_VERSION 41 config AS_VERSION
42 int 42 int
43 # Use clang version if this is the int 43 # Use clang version if this is the integrated assembler
44 default CLANG_VERSION if AS_IS_LLVM 44 default CLANG_VERSION if AS_IS_LLVM
45 default $(as-version) 45 default $(as-version)
46 46
47 config LD_IS_BFD 47 config LD_IS_BFD
48 def_bool $(success,test "$(ld-name)" = 48 def_bool $(success,test "$(ld-name)" = BFD)
49 49
50 config LD_VERSION 50 config LD_VERSION
51 int 51 int
52 default $(ld-version) if LD_IS_BFD 52 default $(ld-version) if LD_IS_BFD
53 default 0 53 default 0
54 54
55 config LD_IS_LLD 55 config LD_IS_LLD
56 def_bool $(success,test "$(ld-name)" = 56 def_bool $(success,test "$(ld-name)" = LLD)
57 57
58 config LLD_VERSION 58 config LLD_VERSION
59 int 59 int
60 default $(ld-version) if LD_IS_LLD 60 default $(ld-version) if LD_IS_LLD
61 default 0 61 default 0
62 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 63 config RUST_IS_AVAILABLE
71 def_bool $(success,$(srctree)/scripts/ 64 def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
72 help 65 help
73 This shows whether a suitable Rust t 66 This shows whether a suitable Rust toolchain is available (found).
74 67
75 Please see Documentation/rust/quick- 68 Please see Documentation/rust/quick-start.rst for instructions on how
76 to satisfy the build requirements of 69 to satisfy the build requirements of Rust support.
77 70
78 In particular, the Makefile target ' 71 In particular, the Makefile target 'rustavailable' is useful to check
79 why the Rust toolchain is not being 72 why the Rust toolchain is not being detected.
80 73
81 config RUSTC_LLVM_VERSION <<
82 int <<
83 default $(rustc-llvm-version) <<
84 <<
85 config CC_CAN_LINK 74 config CC_CAN_LINK
86 bool 75 bool
87 default $(success,$(srctree)/scripts/c 76 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
88 default $(success,$(srctree)/scripts/c 77 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
89 78
90 config CC_CAN_LINK_STATIC 79 config CC_CAN_LINK_STATIC
91 bool 80 bool
92 default $(success,$(srctree)/scripts/c 81 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
93 default $(success,$(srctree)/scripts/c 82 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
94 83
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 84 config CC_HAS_ASM_GOTO_OUTPUT
105 def_bool y !! 85 def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN <<
107 depends on $(success,echo 'int foo(int <<
108 86
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT 87 config CC_HAS_ASM_GOTO_TIED_OUTPUT
110 depends on CC_HAS_ASM_GOTO_OUTPUT 88 depends on CC_HAS_ASM_GOTO_OUTPUT
111 # Detect buggy gcc and clang, fixed in 89 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
112 def_bool $(success,echo 'int foo(int * 90 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
113 91
114 config TOOLS_SUPPORT_RELR 92 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 93 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 94
117 config CC_HAS_ASM_INLINE 95 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 96 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 97
120 config CC_HAS_NO_PROFILE_FN_ATTR 98 config CC_HAS_NO_PROFILE_FN_ATTR
121 def_bool $(success,echo '__attribute__ 99 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
122 100
123 config PAHOLE_VERSION 101 config PAHOLE_VERSION
124 int 102 int
125 default $(shell,$(srctree)/scripts/pah 103 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
126 104
127 config CONSTRUCTORS 105 config CONSTRUCTORS
128 bool 106 bool
129 107
130 config IRQ_WORK 108 config IRQ_WORK
131 def_bool y if SMP !! 109 bool
132 110
133 config BUILDTIME_TABLE_SORT 111 config BUILDTIME_TABLE_SORT
134 bool 112 bool
135 113
136 config THREAD_INFO_IN_TASK 114 config THREAD_INFO_IN_TASK
137 bool 115 bool
138 help 116 help
139 Select this to move thread_info off 117 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 118 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 119 except flags and fix any runtime bugs.
142 120
143 One subtle change that will be neede 121 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 122 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 123
146 menu "General setup" 124 menu "General setup"
147 125
148 config BROKEN 126 config BROKEN
149 bool 127 bool
150 128
151 config BROKEN_ON_SMP 129 config BROKEN_ON_SMP
152 bool 130 bool
153 depends on BROKEN || !SMP 131 depends on BROKEN || !SMP
154 default y 132 default y
155 133
156 config INIT_ENV_ARG_LIMIT 134 config INIT_ENV_ARG_LIMIT
157 int 135 int
158 default 32 if !UML 136 default 32 if !UML
159 default 128 if UML 137 default 128 if UML
160 help 138 help
161 Maximum of each of the number of arg 139 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 140 variables passed to init from the kernel command line.
163 141
164 config COMPILE_TEST 142 config COMPILE_TEST
165 bool "Compile also drivers which will 143 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 144 depends on HAS_IOMEM
167 help 145 help
168 Some drivers can be compiled on a di 146 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 147 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 148 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 149 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 150 drivers to compile-test them.
173 151
174 If you are a developer and want to b 152 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 153 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 154 drivers to be distributed.
177 155
178 config WERROR 156 config WERROR
179 bool "Compile the kernel with warnings 157 bool "Compile the kernel with warnings as errors"
180 default COMPILE_TEST 158 default COMPILE_TEST
181 help 159 help
182 A kernel build should not cause any 160 A kernel build should not cause any compiler warnings, and this
183 enables the '-Werror' (for C) and '- 161 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
184 to enforce that rule by default. Cer 162 to enforce that rule by default. Certain warnings from other tools
185 such as the linker may be upgraded t 163 such as the linker may be upgraded to errors with this option as
186 well. 164 well.
187 165
188 However, if you have a new (or very 166 However, if you have a new (or very old) compiler or linker with odd
189 and unusual warnings, or you have so 167 and unusual warnings, or you have some architecture with problems,
190 you may need to disable this config 168 you may need to disable this config option in order to
191 successfully build the kernel. 169 successfully build the kernel.
192 170
193 If in doubt, say Y. 171 If in doubt, say Y.
194 172
195 config UAPI_HEADER_TEST 173 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 174 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 175 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 176 help
199 Compile test headers exported to use 177 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 178 self-contained, i.e. compilable as standalone units.
201 179
202 If you are a developer or tester and 180 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 181 headers are self-contained, say Y here. Otherwise, choose N.
204 182
205 config LOCALVERSION 183 config LOCALVERSION
206 string "Local version - append to kern 184 string "Local version - append to kernel release"
207 help 185 help
208 Append an extra string to the end of 186 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 187 This will show up when you type uname, for example.
210 The string you set here will be appe 188 The string you set here will be appended after the contents of
211 any files with a filename matching l 189 any files with a filename matching localversion* in your
212 object and source tree, in that orde 190 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 191 be a maximum of 64 characters.
214 192
215 config LOCALVERSION_AUTO 193 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 194 bool "Automatically append version information to the version string"
217 default y 195 default y
218 depends on !COMPILE_TEST 196 depends on !COMPILE_TEST
219 help 197 help
220 This will try to automatically deter 198 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 199 release tree by looking for git tags that belong to the current
222 top of tree revision. 200 top of tree revision.
223 201
224 A string of the format -gxxxxxxxx wi 202 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 203 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 204 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 205 set in CONFIG_LOCALVERSION.
228 206
229 (The actual string used here is the 207 (The actual string used here is the first 12 characters produced
230 by running the command: 208 by running the command:
231 209
232 $ git rev-parse --verify HEAD 210 $ git rev-parse --verify HEAD
233 211
234 which is done within the script "scr 212 which is done within the script "scripts/setlocalversion".)
235 213
236 config BUILD_SALT 214 config BUILD_SALT
237 string "Build ID Salt" 215 string "Build ID Salt"
238 default "" 216 default ""
239 help 217 help
240 The build ID is used to link binarie 218 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 219 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 220 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 221 build is unique between builds. It's safe to leave the default.
244 222
245 config HAVE_KERNEL_GZIP 223 config HAVE_KERNEL_GZIP
246 bool 224 bool
247 225
248 config HAVE_KERNEL_BZIP2 226 config HAVE_KERNEL_BZIP2
249 bool 227 bool
250 228
251 config HAVE_KERNEL_LZMA 229 config HAVE_KERNEL_LZMA
252 bool 230 bool
253 231
254 config HAVE_KERNEL_XZ 232 config HAVE_KERNEL_XZ
255 bool 233 bool
256 234
257 config HAVE_KERNEL_LZO 235 config HAVE_KERNEL_LZO
258 bool 236 bool
259 237
260 config HAVE_KERNEL_LZ4 238 config HAVE_KERNEL_LZ4
261 bool 239 bool
262 240
263 config HAVE_KERNEL_ZSTD 241 config HAVE_KERNEL_ZSTD
264 bool 242 bool
265 243
266 config HAVE_KERNEL_UNCOMPRESSED 244 config HAVE_KERNEL_UNCOMPRESSED
267 bool 245 bool
268 246
269 choice 247 choice
270 prompt "Kernel compression mode" 248 prompt "Kernel compression mode"
271 default KERNEL_GZIP 249 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE 250 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED
273 help 251 help
274 The linux kernel is a kind of self-e 252 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 253 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 254 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 255 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 256 Decompression speed is relevant at each boot.
279 257
280 If you have any problems with bzip2 258 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 259 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 260 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 261 supplied by Christian Ludwig)
284 262
285 High compression options are mostly 263 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 264 are low on disk space (embedded systems), but for whom ram
287 size matters less. 265 size matters less.
288 266
289 If in doubt, select 'gzip' 267 If in doubt, select 'gzip'
290 268
291 config KERNEL_GZIP 269 config KERNEL_GZIP
292 bool "Gzip" 270 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 271 depends on HAVE_KERNEL_GZIP
294 help 272 help
295 The old and tried gzip compression. 273 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 274 between compression ratio and decompression speed.
297 275
298 config KERNEL_BZIP2 276 config KERNEL_BZIP2
299 bool "Bzip2" 277 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 278 depends on HAVE_KERNEL_BZIP2
301 help 279 help
302 Its compression ratio and speed is i 280 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 281 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 282 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 283 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 284 will need at least 8MB RAM or more for booting.
307 285
308 config KERNEL_LZMA 286 config KERNEL_LZMA
309 bool "LZMA" 287 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 288 depends on HAVE_KERNEL_LZMA
311 help 289 help
312 This compression algorithm's ratio i 290 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 291 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 292 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 293
316 config KERNEL_XZ 294 config KERNEL_XZ
317 bool "XZ" 295 bool "XZ"
318 depends on HAVE_KERNEL_XZ 296 depends on HAVE_KERNEL_XZ
319 help 297 help
320 XZ uses the LZMA2 algorithm and inst 298 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 299 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 300 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 301 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 302 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 303 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 304
328 The speed is about the same as with 305 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 306 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 307 and LZO. Compression is slow.
331 308
332 config KERNEL_LZO 309 config KERNEL_LZO
333 bool "LZO" 310 bool "LZO"
334 depends on HAVE_KERNEL_LZO 311 depends on HAVE_KERNEL_LZO
335 help 312 help
336 Its compression ratio is the poorest 313 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 314 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 315 (both compression and decompression) is the fastest.
339 316
340 config KERNEL_LZ4 317 config KERNEL_LZ4
341 bool "LZ4" 318 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 319 depends on HAVE_KERNEL_LZ4
343 help 320 help
344 LZ4 is an LZ77-type compressor with 321 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 322 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 323 <https://code.google.com/p/lz4/>.
347 324
348 Its compression ratio is worse than 325 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 326 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 327 faster than LZO.
351 328
352 config KERNEL_ZSTD 329 config KERNEL_ZSTD
353 bool "ZSTD" 330 bool "ZSTD"
354 depends on HAVE_KERNEL_ZSTD 331 depends on HAVE_KERNEL_ZSTD
355 help 332 help
356 ZSTD is a compression algorithm targ 333 ZSTD is a compression algorithm targeting intermediate compression
357 with fast decompression speed. It wi 334 with fast decompression speed. It will compress better than GZIP and
358 decompress around the same speed as 335 decompress around the same speed as LZO, but slower than LZ4. You
359 will need at least 192 KB RAM or mor 336 will need at least 192 KB RAM or more for booting. The zstd command
360 line tool is required for compressio 337 line tool is required for compression.
361 338
362 config KERNEL_UNCOMPRESSED 339 config KERNEL_UNCOMPRESSED
363 bool "None" 340 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 341 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 342 help
366 Produce uncompressed kernel image. T 343 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 344 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 345 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 346 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 347 and jump right at uncompressed kernel image.
371 348
372 endchoice 349 endchoice
373 350
374 config DEFAULT_INIT 351 config DEFAULT_INIT
375 string "Default init path" 352 string "Default init path"
376 default "" 353 default ""
377 help 354 help
378 This option determines the default i 355 This option determines the default init for the system if no init=
379 option is passed on the kernel comma 356 option is passed on the kernel command line. If the requested path is
380 not present, we will still then move 357 not present, we will still then move on to attempting further
381 locations (e.g. /sbin/init, etc). If 358 locations (e.g. /sbin/init, etc). If this is empty, we will just use
382 the fallback list when init= is not 359 the fallback list when init= is not passed.
383 360
384 config DEFAULT_HOSTNAME 361 config DEFAULT_HOSTNAME
385 string "Default hostname" 362 string "Default hostname"
386 default "(none)" 363 default "(none)"
387 help 364 help
388 This option determines the default s 365 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 366 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 367 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 368 system more usable with less configuration.
392 369
393 config SYSVIPC 370 config SYSVIPC
394 bool "System V IPC" 371 bool "System V IPC"
395 help 372 help
396 Inter Process Communication is a sui 373 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 374 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 375 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 376 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 377 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 378 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 379 you'll need to say Y here.
403 380
404 You can find documentation about IPC 381 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 382 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 383 <http://www.tldp.org/guides.html>.
407 384
408 config SYSVIPC_SYSCTL 385 config SYSVIPC_SYSCTL
409 bool 386 bool
410 depends on SYSVIPC 387 depends on SYSVIPC
411 depends on SYSCTL 388 depends on SYSCTL
412 default y 389 default y
413 390
414 config SYSVIPC_COMPAT 391 config SYSVIPC_COMPAT
415 def_bool y 392 def_bool y
416 depends on COMPAT && SYSVIPC 393 depends on COMPAT && SYSVIPC
417 394
418 config POSIX_MQUEUE 395 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 396 bool "POSIX Message Queues"
420 depends on NET 397 depends on NET
421 help 398 help
422 POSIX variant of message queues is a 399 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 400 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 401 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 402 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 403 queues (functions mq_*) say Y here.
427 404
428 POSIX message queues are visible as 405 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 406 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 407 operations on message queues.
431 408
432 If unsure, say Y. 409 If unsure, say Y.
433 410
434 config POSIX_MQUEUE_SYSCTL 411 config POSIX_MQUEUE_SYSCTL
435 bool 412 bool
436 depends on POSIX_MQUEUE 413 depends on POSIX_MQUEUE
437 depends on SYSCTL 414 depends on SYSCTL
438 default y 415 default y
439 416
440 config WATCH_QUEUE 417 config WATCH_QUEUE
441 bool "General notification queue" 418 bool "General notification queue"
442 default n 419 default n
443 help 420 help
444 421
445 This is a general notification queue 422 This is a general notification queue for the kernel to pass events to
446 userspace by splicing them into pipe 423 userspace by splicing them into pipes. It can be used in conjunction
447 with watches for key/keyring change 424 with watches for key/keyring change notifications and device
448 notifications. 425 notifications.
449 426
450 See Documentation/core-api/watch_que 427 See Documentation/core-api/watch_queue.rst
451 428
452 config CROSS_MEMORY_ATTACH 429 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 430 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 431 depends on MMU
455 default y 432 default y
456 help 433 help
457 Enabling this option adds the system 434 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 435 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 436 to directly read from or write to another process' address space.
460 See the man page for more details. 437 See the man page for more details.
461 438
462 config USELIB 439 config USELIB
463 bool "uselib syscall (for libc5 and ea 440 bool "uselib syscall (for libc5 and earlier)"
464 default ALPHA || M68K || SPARC 441 default ALPHA || M68K || SPARC
465 help 442 help
466 This option enables the uselib sysca 443 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 444 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 445 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 446 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 447 running glibc can safely disable this.
471 448
472 config AUDIT 449 config AUDIT
473 bool "Auditing support" 450 bool "Auditing support"
474 depends on NET 451 depends on NET
475 help 452 help
476 Enable auditing infrastructure that 453 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 454 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 455 logging of avc messages output). System call auditing is included
479 on architectures which support it. 456 on architectures which support it.
480 457
481 config HAVE_ARCH_AUDITSYSCALL 458 config HAVE_ARCH_AUDITSYSCALL
482 bool 459 bool
483 460
484 config AUDITSYSCALL 461 config AUDITSYSCALL
485 def_bool y 462 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 463 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 464 select FSNOTIFY
488 465
489 source "kernel/irq/Kconfig" 466 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 467 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" 468 source "kernel/bpf/Kconfig"
492 source "kernel/Kconfig.preempt" 469 source "kernel/Kconfig.preempt"
493 470
494 menu "CPU/Task time and stats accounting" 471 menu "CPU/Task time and stats accounting"
495 472
496 config VIRT_CPU_ACCOUNTING 473 config VIRT_CPU_ACCOUNTING
497 bool 474 bool
498 475
499 choice 476 choice
500 prompt "Cputime accounting" 477 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING 478 default TICK_CPU_ACCOUNTING
502 479
503 # Kind of a stub config for the pure tick base 480 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 481 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 482 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 483 depends on !S390 && !NO_HZ_FULL
507 help 484 help
508 This is the basic tick based cputime 485 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 486 statistics about user, system and idle time spent on per jiffies
510 granularity. 487 granularity.
511 488
512 If unsure, say Y. 489 If unsure, say Y.
513 490
514 config VIRT_CPU_ACCOUNTING_NATIVE 491 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 492 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 493 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 494 select VIRT_CPU_ACCOUNTING
518 help 495 help
519 Select this option to enable more ac 496 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 497 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 498 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 499 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 500 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 501 this also enables accounting of stolen time on logically-partitioned
525 systems. 502 systems.
526 503
527 config VIRT_CPU_ACCOUNTING_GEN 504 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 505 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER 506 depends on HAVE_CONTEXT_TRACKING_USER
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 507 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 508 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 509 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER 510 select CONTEXT_TRACKING_USER
534 help 511 help
535 Select this option to enable task an 512 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 513 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 514 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 515 The accounting is thus performed at the expense of some significant
539 overhead. 516 overhead.
540 517
541 For now this is only useful if you a 518 For now this is only useful if you are working on the full
542 dynticks subsystem development. 519 dynticks subsystem development.
543 520
544 If unsure, say N. 521 If unsure, say N.
545 522
546 endchoice 523 endchoice
547 524
548 config IRQ_TIME_ACCOUNTING 525 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 526 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 527 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 528 help
552 Select this option to enable fine gr 529 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 530 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 531 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 532 small performance impact.
556 533
557 If in doubt, say N here. 534 If in doubt, say N here.
558 535
559 config HAVE_SCHED_AVG_IRQ 536 config HAVE_SCHED_AVG_IRQ
560 def_bool y 537 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 538 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 539 depends on SMP
563 540
564 config SCHED_HW_PRESSURE !! 541 config SCHED_THERMAL_PRESSURE
565 bool 542 bool
566 default y if ARM && ARM_CPU_TOPOLOGY 543 default y if ARM && ARM_CPU_TOPOLOGY
567 default y if ARM64 544 default y if ARM64
568 depends on SMP 545 depends on SMP
569 depends on CPU_FREQ_THERMAL 546 depends on CPU_FREQ_THERMAL
570 help 547 help
571 Select this option to enable HW pres !! 548 Select this option to enable thermal pressure accounting in the
572 scheduler. HW pressure is the value !! 549 scheduler. Thermal pressure is the value conveyed to the scheduler
573 that reflects the reduction in CPU c 550 that reflects the reduction in CPU compute capacity resulted from
574 HW throttling. HW throttling occurs !! 551 thermal throttling. Thermal throttling occurs when the performance of
575 a CPU is capped due to high operatin !! 552 a CPU is capped due to high operating temperatures.
576 553
577 If selected, the scheduler will be a 554 If selected, the scheduler will be able to balance tasks accordingly,
578 i.e. put less load on throttled CPUs 555 i.e. put less load on throttled CPUs than on non/less throttled ones.
579 556
580 This requires the architecture to im 557 This requires the architecture to implement
581 arch_update_hw_pressure() and arch_s !! 558 arch_update_thermal_pressure() and arch_scale_thermal_pressure().
582 559
583 config BSD_PROCESS_ACCT 560 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 561 bool "BSD Process Accounting"
585 depends on MULTIUSER 562 depends on MULTIUSER
586 help 563 help
587 If you say Y here, a user level prog 564 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 565 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 566 information to a file: whenever a process exits, information about
590 that process will be appended to the 567 that process will be appended to the file by the kernel. The
591 information includes things such as 568 information includes things such as creation time, owning user,
592 command name, memory usage, controll 569 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 570 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 571 up to the user level program to do useful things with this
595 information. This is generally a go 572 information. This is generally a good idea, so say Y.
596 573
597 config BSD_PROCESS_ACCT_V3 574 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 575 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 576 depends on BSD_PROCESS_ACCT
600 default n 577 default n
601 help 578 help
602 If you say Y here, the process accou 579 If you say Y here, the process accounting information is written
603 in a new file format that also logs 580 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 581 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 582 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 583 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 584 at <http://www.gnu.org/software/acct/>.
608 585
609 config TASKSTATS 586 config TASKSTATS
610 bool "Export task/process statistics t 587 bool "Export task/process statistics through netlink"
611 depends on NET 588 depends on NET
612 depends on MULTIUSER 589 depends on MULTIUSER
613 default n 590 default n
614 help 591 help
615 Export selected statistics for tasks 592 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 593 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 594 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 595 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 596 space on task exit.
620 597
621 Say N if unsure. 598 Say N if unsure.
622 599
623 config TASK_DELAY_ACCT 600 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 601 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 602 depends on TASKSTATS
626 select SCHED_INFO 603 select SCHED_INFO
627 help 604 help
628 Collect information on time spent by 605 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 606 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 607 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 608 relative to other tasks for cpu, io, rss limits etc.
632 609
633 Say N if unsure. 610 Say N if unsure.
634 611
635 config TASK_XACCT 612 config TASK_XACCT
636 bool "Enable extended accounting over 613 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 614 depends on TASKSTATS
638 help 615 help
639 Collect extended task accounting dat 616 Collect extended task accounting data and send the data
640 to userland for processing over the 617 to userland for processing over the taskstats interface.
641 618
642 Say N if unsure. 619 Say N if unsure.
643 620
644 config TASK_IO_ACCOUNTING 621 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 622 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 623 depends on TASK_XACCT
647 help 624 help
648 Collect information on the number of 625 Collect information on the number of bytes of storage I/O which this
649 task has caused. 626 task has caused.
650 627
651 Say N if unsure. 628 Say N if unsure.
652 629
653 config PSI 630 config PSI
654 bool "Pressure stall information track 631 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 632 help
657 Collect metrics that indicate how ov 633 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 634 and IO capacity are in the system.
659 635
660 If you say Y here, the kernel will c 636 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 637 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 638 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 639 delayed due to contention of the respective resource.
664 640
665 In kernels with cgroup support, cgro 641 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 642 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 643 which aggregate pressure stalls for the grouped tasks only.
668 644
669 For more details see Documentation/a 645 For more details see Documentation/accounting/psi.rst.
670 646
671 Say N if unsure. 647 Say N if unsure.
672 648
673 config PSI_DEFAULT_DISABLED 649 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 650 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 651 default n
676 depends on PSI 652 depends on PSI
677 help 653 help
678 If set, pressure stall information t 654 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 655 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 656 kernel commandline during boot.
681 657
682 This feature adds some code to the t 658 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 659 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 660 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 661 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 662 scheduler stress tests, such as hackbench.
687 663
688 If you are paranoid and not sure wha 664 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 665 used for, say Y.
690 666
691 Say N if unsure. 667 Say N if unsure.
692 668
693 endmenu # "CPU/Task time and stats accounting" 669 endmenu # "CPU/Task time and stats accounting"
694 670
695 config CPU_ISOLATION 671 config CPU_ISOLATION
696 bool "CPU isolation" 672 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 673 depends on SMP || COMPILE_TEST
698 default y 674 default y
699 help 675 help
700 Make sure that CPUs running critical 676 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 677 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 678 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 679 the "isolcpus=" boot parameter.
704 680
705 Say Y if unsure. 681 Say Y if unsure.
706 682
707 source "kernel/rcu/Kconfig" 683 source "kernel/rcu/Kconfig"
708 684
>> 685 config BUILD_BIN2C
>> 686 bool
>> 687 default n
>> 688
709 config IKCONFIG 689 config IKCONFIG
710 tristate "Kernel .config support" 690 tristate "Kernel .config support"
711 help 691 help
712 This option enables the complete Lin 692 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 693 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 694 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 695 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 696 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 697 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 698 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 699 /proc/config.gz if enabled (below).
720 700
721 config IKCONFIG_PROC 701 config IKCONFIG_PROC
722 bool "Enable access to .config through 702 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 703 depends on IKCONFIG && PROC_FS
724 help 704 help
725 This option enables access to the ke 705 This option enables access to the kernel configuration file
726 through /proc/config.gz. 706 through /proc/config.gz.
727 707
728 config IKHEADERS 708 config IKHEADERS
729 tristate "Enable kernel headers throug 709 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 710 depends on SYSFS
731 help 711 help
732 This option enables access to the in 712 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 713 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 714 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 715 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 716
737 config LOG_BUF_SHIFT 717 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 718 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 719 range 12 25
740 default 17 720 default 17
741 depends on PRINTK 721 depends on PRINTK
742 help 722 help
743 Select the minimal kernel log buffer 723 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 724 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 725 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 726 by "log_buf_len" boot parameter.
747 727
748 Examples: 728 Examples:
749 17 => 128 KB 729 17 => 128 KB
750 16 => 64 KB 730 16 => 64 KB
751 15 => 32 KB 731 15 => 32 KB
752 14 => 16 KB 732 14 => 16 KB
753 13 => 8 KB 733 13 => 8 KB
754 12 => 4 KB 734 12 => 4 KB
755 735
756 config LOG_CPU_MAX_BUF_SHIFT 736 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 737 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 738 depends on SMP
759 range 0 21 739 range 0 21
>> 740 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 741 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 742 depends on PRINTK
763 help 743 help
764 This option allows to increase the d 744 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 745 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 746 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 747 lines however it might be much more when problems are reported,
768 e.g. backtraces. 748 e.g. backtraces.
769 749
770 The increased size means that a new 750 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 751 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 752 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 753 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 754 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed 755 so that more than 16 CPUs are needed to trigger the allocation.
776 756
777 Also this option is ignored when "lo 757 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 758 used as it forces an exact (power of two) size of the ring buffer.
779 759
780 The number of possible CPUs is used 760 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 761 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 762 scenario while allowing a simple algorithm to be used from bootup.
783 763
784 Examples shift values and their mean 764 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 765 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 766 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 767 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 768 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 769 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 770 12 => 4 KB for each CPU
791 771
>> 772 config PRINTK_SAFE_LOG_BUF_SHIFT
>> 773 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
>> 774 range 10 21
>> 775 default 13
>> 776 depends on PRINTK
>> 777 help
>> 778 Select the size of an alternate printk per-CPU buffer where messages
>> 779 printed from unsafe contexts are temporary stored. One example would
>> 780 be NMI messages, another one - printk recursion. The messages are
>> 781 copied to the main log buffer in a safe context to avoid a deadlock.
>> 782 The value defines the size as a power of 2.
>> 783
>> 784 Those messages are rare and limited. The largest one is when
>> 785 a backtrace is printed. It usually fits into 4KB. Select
>> 786 8KB if you want to be on the safe side.
>> 787
>> 788 Examples:
>> 789 17 => 128 KB for each CPU
>> 790 16 => 64 KB for each CPU
>> 791 15 => 32 KB for each CPU
>> 792 14 => 16 KB for each CPU
>> 793 13 => 8 KB for each CPU
>> 794 12 => 4 KB for each CPU
>> 795
792 config PRINTK_INDEX 796 config PRINTK_INDEX
793 bool "Printk indexing debugfs interfac 797 bool "Printk indexing debugfs interface"
794 depends on PRINTK && DEBUG_FS 798 depends on PRINTK && DEBUG_FS
795 help 799 help
796 Add support for indexing of all prin 800 Add support for indexing of all printk formats known at compile time
797 at <debugfs>/printk/index/<module>. 801 at <debugfs>/printk/index/<module>.
798 802
799 This can be used as part of maintain 803 This can be used as part of maintaining daemons which monitor
800 /dev/kmsg, as it permits auditing th 804 /dev/kmsg, as it permits auditing the printk formats present in a
801 kernel, allowing detection of cases 805 kernel, allowing detection of cases where monitored printks are
802 changed or no longer present. 806 changed or no longer present.
803 807
804 There is no additional runtime cost 808 There is no additional runtime cost to printk with this enabled.
805 809
806 # 810 #
807 # Architectures with an unreliable sched_clock 811 # Architectures with an unreliable sched_clock() should select this:
808 # 812 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 813 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 814 bool
811 815
812 config GENERIC_SCHED_CLOCK 816 config GENERIC_SCHED_CLOCK
813 bool 817 bool
814 818
815 menu "Scheduler features" 819 menu "Scheduler features"
816 820
817 config UCLAMP_TASK 821 config UCLAMP_TASK
818 bool "Enable utilization clamping for 822 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 823 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 824 help
821 This feature enables the scheduler t 825 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 826 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 827
824 With this option, the user can speci 828 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 829 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 830 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 831 defines the minimum frequency it should use.
828 832
829 Both min and max utilization clamp v 833 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 834 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 835 enforce or grant any specific bandwidth for tasks.
832 836
833 If in doubt, say N. 837 If in doubt, say N.
834 838
835 config UCLAMP_BUCKETS_COUNT 839 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 840 int "Number of supported utilization clamp buckets"
837 range 5 20 841 range 5 20
838 default 5 842 default 5
839 depends on UCLAMP_TASK 843 depends on UCLAMP_TASK
840 help 844 help
841 Defines the number of clamp buckets 845 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 846 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 847 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 848 the precision of clamping aggregation and tracking at run-time.
845 849
846 For example, with the minimum config 850 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 851 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 852 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 853 effective value to 25%.
850 If a second 30% boosted task should 854 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 855 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 856 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 857 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 858 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 859 that bucket.
856 860
857 An additional boost/capping margin c 861 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 862 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 863 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 864 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 865 clamp buckets to trade off used memory for run-time tracking
862 precision. 866 precision.
863 867
864 If in doubt, use the default value. 868 If in doubt, use the default value.
865 869
866 endmenu 870 endmenu
867 871
868 # 872 #
869 # For architectures that want to enable the su 873 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 874 # balancing logic:
871 # 875 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 876 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 877 bool
874 878
875 # 879 #
876 # For architectures that prefer to flush all T 880 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 881 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 882 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 883 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 884 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 885 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 886 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 887 bool
884 888
885 config CC_HAS_INT128 889 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 890 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 891
888 config CC_IMPLICIT_FALLTHROUGH 892 config CC_IMPLICIT_FALLTHROUGH
889 string 893 string
890 default "-Wimplicit-fallthrough=5" if 894 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
891 default "-Wimplicit-fallthrough" if CC 895 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
892 896
893 # Currently, disable gcc-10+ array-bounds glob !! 897 # Currently, disable gcc-11+ array-bounds globally.
894 # It's still broken in gcc-13, so no upper bou 898 # It's still broken in gcc-13, so no upper bound yet.
895 config GCC10_NO_ARRAY_BOUNDS !! 899 config GCC11_NO_ARRAY_BOUNDS
896 def_bool y 900 def_bool y
897 901
898 config CC_NO_ARRAY_BOUNDS 902 config CC_NO_ARRAY_BOUNDS
899 bool 903 bool
900 default y if CC_IS_GCC && GCC_VERSION !! 904 default y if CC_IS_GCC && GCC_VERSION >= 110000 && GCC11_NO_ARRAY_BOUNDS
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 <<
913 905
914 # 906 #
915 # For architectures that know their GCC __int1 907 # For architectures that know their GCC __int128 support is sound
916 # 908 #
917 config ARCH_SUPPORTS_INT128 909 config ARCH_SUPPORTS_INT128
918 bool 910 bool
919 911
920 # For architectures that (ab)use NUMA to repre 912 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 913 # all cpu-local but of different latencies, such as SuperH.
922 # 914 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 915 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 916 bool
925 917
926 config NUMA_BALANCING 918 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 919 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 920 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 921 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && 922 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
931 help 923 help
932 This option adds support for automat 924 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 925 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 926 it has references to the node the task is running on.
935 927
936 This system will be inactive on UMA 928 This system will be inactive on UMA systems.
937 929
938 config NUMA_BALANCING_DEFAULT_ENABLED 930 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 931 bool "Automatically enable NUMA aware memory/task placement"
940 default y 932 default y
941 depends on NUMA_BALANCING 933 depends on NUMA_BALANCING
942 help 934 help
943 If set, automatic NUMA balancing wil 935 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 936 machine.
945 937
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 938 menuconfig CGROUPS
950 bool "Control Group support" 939 bool "Control Group support"
951 select KERNFS 940 select KERNFS
952 help 941 help
953 This option adds support for groupin 942 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 943 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 944 controls or device isolation.
956 See 945 See
957 - Documentation/scheduler/sche 946 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 947 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 948 and resource control)
960 949
961 Say N if unsure. 950 Say N if unsure.
962 951
963 if CGROUPS 952 if CGROUPS
964 953
965 config PAGE_COUNTER 954 config PAGE_COUNTER
966 bool 955 bool
967 956
968 config CGROUP_FAVOR_DYNMODS 957 config CGROUP_FAVOR_DYNMODS
969 bool "Favor dynamic modification laten 958 bool "Favor dynamic modification latency reduction by default"
970 help 959 help
971 This option enables the "favordynmod 960 This option enables the "favordynmods" mount option by default
972 which reduces the latencies of dynam 961 which reduces the latencies of dynamic cgroup modifications such
973 as task migrations and controller on 962 as task migrations and controller on/offs at the cost of making
974 hot path operations such as forks an 963 hot path operations such as forks and exits more expensive.
975 964
976 Say N if unsure. 965 Say N if unsure.
977 966
978 config MEMCG 967 config MEMCG
979 bool "Memory controller" 968 bool "Memory controller"
980 select PAGE_COUNTER 969 select PAGE_COUNTER
981 select EVENTFD 970 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 971 help
984 Provides control over the memory foo 972 Provides control over the memory footprint of tasks in a cgroup.
985 973
986 config MEMCG_V1 !! 974 config MEMCG_KMEM
987 bool "Legacy cgroup v1 memory controll !! 975 bool
988 depends on MEMCG !! 976 depends on MEMCG && !SLOB
989 default n !! 977 default y
990 help <<
991 Legacy cgroup v1 memory controller w <<
992 cgroup v2 implementation. The v1 is <<
993 which haven't migrated to the new cg <<
994 do not have any such application the <<
995 this option disabled. <<
996 <<
997 Please note that feature set of the <<
998 going to shrink due to deprecation p <<
999 controller are highly discouraged. <<
1000 <<
1001 Say N if unsure. <<
1002 978
1003 config BLK_CGROUP 979 config BLK_CGROUP
1004 bool "IO controller" 980 bool "IO controller"
1005 depends on BLOCK 981 depends on BLOCK
1006 default n 982 default n
1007 help 983 help
1008 Generic block IO controller cgroup in 984 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 985 cgroup interface which should be used by various IO controlling
1010 policies. 986 policies.
1011 987
1012 Currently, CFQ IO scheduler uses it t 988 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 989 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 990 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 991 block layer to implement upper limit in IO rates on a device.
1016 992
1017 This option only enables generic Bloc 993 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 994 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 995 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl 996 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 997 CONFIG_BLK_DEV_THROTTLING=y.
1022 998
1023 See Documentation/admin-guide/cgroup- 999 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 1000
1025 config CGROUP_WRITEBACK 1001 config CGROUP_WRITEBACK
1026 bool 1002 bool
1027 depends on MEMCG && BLK_CGROUP 1003 depends on MEMCG && BLK_CGROUP
1028 default y 1004 default y
1029 1005
1030 menuconfig CGROUP_SCHED 1006 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 1007 bool "CPU controller"
1032 default n 1008 default n
1033 help 1009 help
1034 This feature lets CPU scheduler rec 1010 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 1011 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 1012 tasks.
1037 1013
1038 if CGROUP_SCHED 1014 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 1015 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 1016 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 1017 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1018 default CGROUP_SCHED
1047 1019
1048 config CFS_BANDWIDTH 1020 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1021 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1022 depends on FAIR_GROUP_SCHED
1051 default n 1023 default n
1052 help 1024 help
1053 This option allows users to define 1025 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1026 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1027 set are considered to be unconstrained and will run with no
1056 restriction. 1028 restriction.
1057 See Documentation/scheduler/sched-b 1029 See Documentation/scheduler/sched-bwc.rst for more information.
1058 1030
1059 config RT_GROUP_SCHED 1031 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1032 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1033 depends on CGROUP_SCHED
1062 default n 1034 default n
1063 help 1035 help
1064 This feature lets you explicitly al 1036 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1037 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1038 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1039 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 1040 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 1041
1070 config EXT_GROUP_SCHED <<
1071 bool <<
1072 depends on SCHED_CLASS_EXT && CGROUP_ <<
1073 select GROUP_SCHED_WEIGHT <<
1074 default y <<
1075 <<
1076 endif #CGROUP_SCHED 1042 endif #CGROUP_SCHED
1077 1043
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 1044 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 1045 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 1046 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 1047 depends on UCLAMP_TASK
1086 default n 1048 default n
1087 help 1049 help
1088 This feature enables the scheduler 1050 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 1051 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 1052
1091 When this option is enabled, the us 1053 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 1054 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 1055 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 1056 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 1057 frequency a task will always use.
1096 1058
1097 When task group based utilization c 1059 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 1060 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 1061 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 1062 be bigger than the corresponding clamping defined at task group level.
1101 1063
1102 If in doubt, say N. 1064 If in doubt, say N.
1103 1065
1104 config CGROUP_PIDS 1066 config CGROUP_PIDS
1105 bool "PIDs controller" 1067 bool "PIDs controller"
1106 help 1068 help
1107 Provides enforcement of process num 1069 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1070 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1071 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1072 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1073 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1074 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1075 PIDs controller is designed to stop this from happening.
1114 1076
1115 It should be noted that organisatio 1077 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 1078 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 1079 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1080 attach to a cgroup.
1119 1081
1120 config CGROUP_RDMA 1082 config CGROUP_RDMA
1121 bool "RDMA controller" 1083 bool "RDMA controller"
1122 help 1084 help
1123 Provides enforcement of RDMA resour 1085 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1086 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1087 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1088 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1089 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1090 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1091
1130 config CGROUP_FREEZER 1092 config CGROUP_FREEZER
1131 bool "Freezer controller" 1093 bool "Freezer controller"
1132 help 1094 help
1133 Provides a way to freeze and unfree 1095 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1096 cgroup.
1135 1097
1136 This option affects the ORIGINAL cg 1098 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1099 controller includes important in-kernel memory consumers per default.
1138 1100
1139 If you're using cgroup2, say N. 1101 If you're using cgroup2, say N.
1140 1102
1141 config CGROUP_HUGETLB 1103 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1104 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1105 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1106 select PAGE_COUNTER
1145 default n 1107 default n
1146 help 1108 help
1147 Provides a cgroup controller for Hu 1109 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1110 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1111 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1112 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1113 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1114 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1115 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1116 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1117 that we cannot use the controller with huge page less than 3 pages.
1156 1118
1157 config CPUSETS 1119 config CPUSETS
1158 bool "Cpuset controller" 1120 bool "Cpuset controller"
1159 depends on SMP 1121 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. Or this can be used to have cgroup ID in samples
1205 so that it can monitor performance 1154 so that it can monitor performance events among cgroups.
1206 1155
1207 Say N if unsure. 1156 Say N if unsure.
1208 1157
1209 config CGROUP_BPF 1158 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1159 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1160 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1161 select SOCK_CGROUP_DATA
1213 help 1162 help
1214 Allow attaching eBPF programs to a 1163 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1164 syscall command BPF_PROG_ATTACH.
1216 1165
1217 In which context these programs are 1166 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1167 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1168 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1169 inet sockets.
1221 1170
1222 config CGROUP_MISC 1171 config CGROUP_MISC
1223 bool "Misc resource controller" 1172 bool "Misc resource controller"
1224 default n 1173 default n
1225 help 1174 help
1226 Provides a controller for miscellan 1175 Provides a controller for miscellaneous resources on a host.
1227 1176
1228 Miscellaneous scalar resources are 1177 Miscellaneous scalar resources are the resources on the host system
1229 which cannot be abstracted like the 1178 which cannot be abstracted like the other cgroups. This controller
1230 tracks and limits the miscellaneous 1179 tracks and limits the miscellaneous resources used by a process
1231 attached to a cgroup hierarchy. 1180 attached to a cgroup hierarchy.
1232 1181
1233 For more information, please check 1182 For more information, please check misc cgroup section in
1234 /Documentation/admin-guide/cgroup-v 1183 /Documentation/admin-guide/cgroup-v2.rst.
1235 1184
1236 config CGROUP_DEBUG 1185 config CGROUP_DEBUG
1237 bool "Debug controller" 1186 bool "Debug controller"
1238 default n 1187 default n
1239 depends on DEBUG_KERNEL 1188 depends on DEBUG_KERNEL
1240 help 1189 help
1241 This option enables a simple contro 1190 This option enables a simple controller that exports
1242 debugging information about the cgr 1191 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1192 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1193 interfaces are not stable.
1245 1194
1246 Say N. 1195 Say N.
1247 1196
1248 config SOCK_CGROUP_DATA 1197 config SOCK_CGROUP_DATA
1249 bool 1198 bool
1250 default n 1199 default n
1251 1200
1252 endif # CGROUPS 1201 endif # CGROUPS
1253 1202
1254 menuconfig NAMESPACES 1203 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1204 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1205 depends on MULTIUSER
1257 default !EXPERT 1206 default !EXPERT
1258 help 1207 help
1259 Provides the way to make tasks work 1208 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1209 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1210 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1211 different namespaces.
1263 1212
1264 if NAMESPACES 1213 if NAMESPACES
1265 1214
1266 config UTS_NS 1215 config UTS_NS
1267 bool "UTS namespace" 1216 bool "UTS namespace"
1268 default y 1217 default y
1269 help 1218 help
1270 In this namespace tasks see differe 1219 In this namespace tasks see different info provided with the
1271 uname() system call 1220 uname() system call
1272 1221
1273 config TIME_NS 1222 config TIME_NS
1274 bool "TIME namespace" 1223 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1224 depends on GENERIC_VDSO_TIME_NS
1276 default y 1225 default y
1277 help 1226 help
1278 In this namespace boottime and mono 1227 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1228 The time will keep going with the same pace.
1280 1229
1281 config IPC_NS 1230 config IPC_NS
1282 bool "IPC namespace" 1231 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1232 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1233 default y
1285 help 1234 help
1286 In this namespace tasks work with I 1235 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1236 different IPC objects in different namespaces.
1288 1237
1289 config USER_NS 1238 config USER_NS
1290 bool "User namespace" 1239 bool "User namespace"
1291 default n 1240 default n
1292 help 1241 help
1293 This allows containers, i.e. vserve 1242 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1243 to provide different user info for different servers.
1295 1244
1296 When user namespaces are enabled in 1245 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1246 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1247 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1248 of memory a memory unprivileged users can use.
1300 1249
1301 If unsure, say N. 1250 If unsure, say N.
1302 1251
1303 config PID_NS 1252 config PID_NS
1304 bool "PID Namespaces" 1253 bool "PID Namespaces"
1305 default y 1254 default y
1306 help 1255 help
1307 Support process id namespaces. Thi 1256 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1257 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1258 pid namespaces. This is a building block of containers.
1310 1259
1311 config NET_NS 1260 config NET_NS
1312 bool "Network namespace" 1261 bool "Network namespace"
1313 depends on NET 1262 depends on NET
1314 default y 1263 default y
1315 help 1264 help
1316 Allow user space to create what app 1265 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1266 of the network stack.
1318 1267
1319 endif # NAMESPACES 1268 endif # NAMESPACES
1320 1269
1321 config CHECKPOINT_RESTORE 1270 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1271 bool "Checkpoint/restore support"
1323 depends on PROC_FS 1272 depends on PROC_FS
1324 select PROC_CHILDREN 1273 select PROC_CHILDREN
1325 select KCMP 1274 select KCMP
1326 default n 1275 default n
1327 help 1276 help
1328 Enables additional kernel features 1277 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1278 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1279 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1280 entries.
1332 1281
1333 If unsure, say N here. 1282 If unsure, say N here.
1334 1283
1335 config SCHED_AUTOGROUP 1284 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1285 bool "Automatic process group scheduling"
1337 select CGROUPS 1286 select CGROUPS
1338 select CGROUP_SCHED 1287 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1288 select FAIR_GROUP_SCHED
1340 help 1289 help
1341 This option optimizes the scheduler 1290 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1291 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1292 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1293 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1294 upon task session.
1346 1295
>> 1296 config SYSFS_DEPRECATED
>> 1297 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1298 depends on SYSFS
>> 1299 default n
>> 1300 help
>> 1301 This option adds code that switches the layout of the "block" class
>> 1302 devices, to not show up in /sys/class/block/, but only in
>> 1303 /sys/block/.
>> 1304
>> 1305 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1306 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1307
>> 1308 This option allows new kernels to run on old distributions and tools,
>> 1309 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1310 major distributions and tools handle this just fine.
>> 1311
>> 1312 Recent distributions and userspace tools after 2009/2010 depend on
>> 1313 the existence of /sys/class/block/, and will not work with this
>> 1314 option enabled.
>> 1315
>> 1316 Only if you are using a new kernel on an old distribution, you might
>> 1317 need to say Y here.
>> 1318
>> 1319 config SYSFS_DEPRECATED_V2
>> 1320 bool "Enable deprecated sysfs features by default"
>> 1321 default n
>> 1322 depends on SYSFS
>> 1323 depends on SYSFS_DEPRECATED
>> 1324 help
>> 1325 Enable deprecated sysfs by default.
>> 1326
>> 1327 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1328 option.
>> 1329
>> 1330 Only if you are using a new kernel on an old distribution, you might
>> 1331 need to say Y here. Even then, odds are you would not need it
>> 1332 enabled, you can always pass the boot option if absolutely necessary.
>> 1333
1347 config RELAY 1334 config RELAY
1348 bool "Kernel->user space relay suppor 1335 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1336 select IRQ_WORK
1350 help 1337 help
1351 This option enables support for rel 1338 This option enables support for relay interface support in
1352 certain file systems (such as debug 1339 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1340 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1341 facilities to relay large amounts of data from kernel space to
1355 user space. 1342 user space.
1356 1343
1357 If unsure, say N. 1344 If unsure, say N.
1358 1345
1359 config BLK_DEV_INITRD 1346 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1347 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1348 help
1362 The initial RAM filesystem is a ram 1349 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1350 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1351 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1352 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1353 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1354
1368 If RAM disk support (BLK_DEV_RAM) i 1355 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1356 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1357 15 Kbytes (more on some other architectures) to the kernel size.
1371 1358
1372 If unsure say Y. 1359 If unsure say Y.
1373 1360
1374 if BLK_DEV_INITRD 1361 if BLK_DEV_INITRD
1375 1362
1376 source "usr/Kconfig" 1363 source "usr/Kconfig"
1377 1364
1378 endif 1365 endif
1379 1366
1380 config BOOT_CONFIG 1367 config BOOT_CONFIG
1381 bool "Boot config support" 1368 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG 1369 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1383 help 1370 help
1384 Extra boot config allows system adm 1371 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1372 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1373 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1374 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1375 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1376
1390 If unsure, say Y. 1377 If unsure, say Y.
1391 1378
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 1379 config BOOT_CONFIG_EMBED
1406 bool "Embed bootconfig file in the ke 1380 bool "Embed bootconfig file in the kernel"
1407 depends on BOOT_CONFIG 1381 depends on BOOT_CONFIG
1408 help 1382 help
1409 Embed a bootconfig file given by BO 1383 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1410 kernel. Usually, the bootconfig fil 1384 kernel. Usually, the bootconfig file is loaded with the initrd
1411 image. But if the system doesn't su 1385 image. But if the system doesn't support initrd, this option will
1412 help you by embedding a bootconfig 1386 help you by embedding a bootconfig file while building the kernel.
1413 1387
1414 If unsure, say N. 1388 If unsure, say N.
1415 1389
1416 config BOOT_CONFIG_EMBED_FILE 1390 config BOOT_CONFIG_EMBED_FILE
1417 string "Embedded bootconfig file path 1391 string "Embedded bootconfig file path"
1418 depends on BOOT_CONFIG_EMBED 1392 depends on BOOT_CONFIG_EMBED
1419 help 1393 help
1420 Specify a bootconfig file which wil 1394 Specify a bootconfig file which will be embedded to the kernel.
1421 This bootconfig will be used if the 1395 This bootconfig will be used if there is no initrd or no other
1422 bootconfig in the initrd. 1396 bootconfig in the initrd.
1423 1397
1424 config INITRAMFS_PRESERVE_MTIME 1398 config INITRAMFS_PRESERVE_MTIME
1425 bool "Preserve cpio archive mtimes in 1399 bool "Preserve cpio archive mtimes in initramfs"
1426 default y 1400 default y
1427 help 1401 help
1428 Each entry in an initramfs cpio arc 1402 Each entry in an initramfs cpio archive carries an mtime value. When
1429 enabled, extracted cpio items take 1403 enabled, extracted cpio items take this mtime, with directory mtime
1430 setting deferred until after creati 1404 setting deferred until after creation of any child entries.
1431 1405
1432 If unsure, say Y. 1406 If unsure, say Y.
1433 1407
1434 choice 1408 choice
1435 prompt "Compiler optimization level" 1409 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1410 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1411
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1412 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1413 bool "Optimize for performance (-O2)"
1440 help 1414 help
1441 This is the default optimization le 1415 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1416 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1417 helpful compile-time warnings.
1444 1418
1445 config CC_OPTIMIZE_FOR_SIZE 1419 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1420 bool "Optimize for size (-Os)"
1447 help 1421 help
1448 Choosing this option will pass "-Os 1422 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1423 in a smaller kernel.
1450 1424
1451 endchoice 1425 endchoice
1452 1426
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1427 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1428 bool
1455 help 1429 help
1456 This requires that the arch annotat 1430 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1431 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1432 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1433 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1434 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1435 is used to distinguish them from label names / C identifiers.
1462 1436
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1437 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1438 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1439 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1440 depends on EXPERT
1467 depends on $(cc-option,-ffunction-sec 1441 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1442 depends on $(ld-option,--gc-sections)
1469 help 1443 help
1470 Enable this if you want to do dead 1444 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1445 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1446 and linking with --gc-sections.
1473 1447
1474 This can reduce on disk and in-memo 1448 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1449 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1450 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1451 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1452 present. This option is not well tested yet, so use at your
1479 own risk. 1453 own risk.
1480 1454
1481 config LD_ORPHAN_WARN 1455 config LD_ORPHAN_WARN
1482 def_bool y 1456 def_bool y
1483 depends on ARCH_WANT_LD_ORPHAN_WARN 1457 depends on ARCH_WANT_LD_ORPHAN_WARN
1484 depends on $(ld-option,--orphan-handl 1458 depends on $(ld-option,--orphan-handling=warn)
1485 depends on $(ld-option,--orphan-handl 1459 depends on $(ld-option,--orphan-handling=error)
1486 1460
1487 config LD_ORPHAN_WARN_LEVEL 1461 config LD_ORPHAN_WARN_LEVEL
1488 string 1462 string
1489 depends on LD_ORPHAN_WARN 1463 depends on LD_ORPHAN_WARN
1490 default "error" if WERROR 1464 default "error" if WERROR
1491 default "warn" 1465 default "warn"
1492 1466
1493 config SYSCTL 1467 config SYSCTL
1494 bool 1468 bool
1495 1469
1496 config HAVE_UID16 1470 config HAVE_UID16
1497 bool 1471 bool
1498 1472
1499 config SYSCTL_EXCEPTION_TRACE 1473 config SYSCTL_EXCEPTION_TRACE
1500 bool 1474 bool
1501 help 1475 help
1502 Enable support for /proc/sys/debug/ 1476 Enable support for /proc/sys/debug/exception-trace.
1503 1477
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1478 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1479 bool
1506 help 1480 help
1507 Enable support for /proc/sys/kernel 1481 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1482 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1483 about unaligned access emulation going on under the hood.
1510 1484
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1485 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1486 bool
1513 help 1487 help
1514 Enable support for /proc/sys/kernel 1488 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1489 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1490 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1491 see arch/parisc/kernel/unaligned.c for reference
1518 1492
1519 config HAVE_PCSPKR_PLATFORM 1493 config HAVE_PCSPKR_PLATFORM
1520 bool 1494 bool
1521 1495
>> 1496 # interpreter that classic socket filters depend on
>> 1497 config BPF
>> 1498 bool
>> 1499 select CRYPTO_LIB_SHA1
>> 1500
1522 menuconfig EXPERT 1501 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1502 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1503 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1504 select DEBUG_KERNEL
1526 help 1505 help
1527 This option allows certain base ker 1506 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1507 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1508 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1509 Only use this if you really know what you are doing.
1531 1510
1532 config UID16 1511 config UID16
1533 bool "Enable 16-bit UID system calls" 1512 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1513 depends on HAVE_UID16 && MULTIUSER
1535 default y 1514 default y
1536 help 1515 help
1537 This enables the legacy 16-bit UID 1516 This enables the legacy 16-bit UID syscall wrappers.
1538 1517
1539 config MULTIUSER 1518 config MULTIUSER
1540 bool "Multiple users, groups and capa 1519 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1520 default y
1542 help 1521 help
1543 This option enables support for non 1522 This option enables support for non-root users, groups and
1544 capabilities. 1523 capabilities.
1545 1524
1546 If you say N here, all processes wi 1525 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1526 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1527 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1528 setgid, and capset.
1550 1529
1551 If unsure, say Y here. 1530 If unsure, say Y here.
1552 1531
1553 config SGETMASK_SYSCALL 1532 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1533 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1534 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help 1535 help
1557 sys_sgetmask and sys_ssetmask are o 1536 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1537 no longer supported in libc but still enabled by default in some
1559 architectures. 1538 architectures.
1560 1539
1561 If unsure, leave the default option 1540 If unsure, leave the default option here.
1562 1541
1563 config SYSFS_SYSCALL 1542 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1543 bool "Sysfs syscall support" if EXPERT
1565 default y 1544 default y
1566 help 1545 help
1567 sys_sysfs is an obsolete system cal 1546 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1547 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1548 compatibility with some systems.
1570 1549
1571 If unsure say Y here. 1550 If unsure say Y here.
1572 1551
1573 config FHANDLE 1552 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1553 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1554 select EXPORTFS
1576 default y 1555 default y
1577 help 1556 help
1578 If you say Y here, a user level pro 1557 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1558 file names to handle and then later use the handle for
1580 different file system operations. T 1559 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1560 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1561 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1562 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1563 syscalls.
1585 1564
1586 config POSIX_TIMERS 1565 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1566 bool "Posix Clocks & timers" if EXPERT
1588 default y 1567 default y
1589 help 1568 help
1590 This includes native support for PO 1569 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1570 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1571 can be configured out to reduce the size of the kernel image.
1593 1572
1594 When this option is disabled, the f 1573 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1574 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1575 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1576 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1577 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1578 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1579
1601 If unsure say y. 1580 If unsure say y.
1602 1581
1603 config PRINTK 1582 config PRINTK
1604 default y 1583 default y
1605 bool "Enable support for printk" if E 1584 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1585 select IRQ_WORK
1607 help 1586 help
1608 This option enables normal printk s 1587 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1588 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1589 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1590 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1591 strongly discouraged.
1613 1592
1614 config BUG 1593 config BUG
1615 bool "BUG() support" if EXPERT 1594 bool "BUG() support" if EXPERT
1616 default y 1595 default y
1617 help 1596 help
1618 Disabling this option eliminates su 1597 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1598 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1599 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1600 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1601 Just say Y.
1623 1602
1624 config ELF_CORE 1603 config ELF_CORE
1625 depends on COREDUMP 1604 depends on COREDUMP
1626 default y 1605 default y
1627 bool "Enable ELF core dumps" if EXPER 1606 bool "Enable ELF core dumps" if EXPERT
1628 help 1607 help
1629 Enable support for generating core 1608 Enable support for generating core dumps. Disabling saves about 4k.
1630 1609
1631 1610
1632 config PCSPKR_PLATFORM 1611 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1612 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1613 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1614 select I8253_LOCK
1636 default y 1615 default y
1637 help 1616 help
1638 This option allows to disable the i 1617 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1618 support, saving some memory.
1640 1619
1641 config BASE_SMALL !! 1620 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1621 default y
>> 1622 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1623 help
1644 Enabling this option reduces the si !! 1624 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1625 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1626 but may reduce performance.
1647 1627
1648 config FUTEX 1628 config FUTEX
1649 bool "Enable futex support" if EXPERT 1629 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) 1630 depends on !(SPARC32 && SMP)
1651 default y 1631 default y
1652 imply RT_MUTEXES 1632 imply RT_MUTEXES
1653 help 1633 help
1654 Disabling this option will cause th 1634 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1635 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1636 run glibc-based applications correctly.
1657 1637
1658 config FUTEX_PI 1638 config FUTEX_PI
1659 bool 1639 bool
1660 depends on FUTEX && RT_MUTEXES 1640 depends on FUTEX && RT_MUTEXES
1661 default y 1641 default y
1662 1642
1663 config EPOLL 1643 config EPOLL
1664 bool "Enable eventpoll support" if EX 1644 bool "Enable eventpoll support" if EXPERT
1665 default y 1645 default y
1666 help 1646 help
1667 Disabling this option will cause th 1647 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1648 support for epoll family of system calls.
1669 1649
1670 config SIGNALFD 1650 config SIGNALFD
1671 bool "Enable signalfd() system call" 1651 bool "Enable signalfd() system call" if EXPERT
1672 default y 1652 default y
1673 help 1653 help
1674 Enable the signalfd() system call t 1654 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1655 on a file descriptor.
1676 1656
1677 If unsure, say Y. 1657 If unsure, say Y.
1678 1658
1679 config TIMERFD 1659 config TIMERFD
1680 bool "Enable timerfd() system call" i 1660 bool "Enable timerfd() system call" if EXPERT
1681 default y 1661 default y
1682 help 1662 help
1683 Enable the timerfd() system call th 1663 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1664 events on a file descriptor.
1685 1665
1686 If unsure, say Y. 1666 If unsure, say Y.
1687 1667
1688 config EVENTFD 1668 config EVENTFD
1689 bool "Enable eventfd() system call" i 1669 bool "Enable eventfd() system call" if EXPERT
1690 default y 1670 default y
1691 help 1671 help
1692 Enable the eventfd() system call th 1672 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1673 kernel notification (ie. KAIO) or userspace notifications.
1694 1674
1695 If unsure, say Y. 1675 If unsure, say Y.
1696 1676
1697 config SHMEM 1677 config SHMEM
1698 bool "Use full shmem filesystem" if E 1678 bool "Use full shmem filesystem" if EXPERT
1699 default y 1679 default y
1700 depends on MMU 1680 depends on MMU
1701 help 1681 help
1702 The shmem is an internal filesystem 1682 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1683 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1684 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1685 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1686 which may be appropriate on small systems without swap.
1707 1687
1708 config AIO 1688 config AIO
1709 bool "Enable AIO support" if EXPERT 1689 bool "Enable AIO support" if EXPERT
1710 default y 1690 default y
1711 help 1691 help
1712 This option enables POSIX asynchron 1692 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1693 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1694 this option saves about 7k.
1715 1695
1716 config IO_URING 1696 config IO_URING
1717 bool "Enable IO uring support" if EXP 1697 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ 1698 select IO_WQ
1719 default y 1699 default y
1720 help 1700 help
1721 This option enables support for the 1701 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1702 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1703 completion rings that are shared between the kernel and application.
1724 1704
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 1705 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1706 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1707 default y
1741 help 1708 help
1742 This option enables the madvise and 1709 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1710 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1711 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1712 applications use these syscalls, you can disable this option to save
1746 space. 1713 space.
1747 1714
1748 config MEMBARRIER 1715 config MEMBARRIER
1749 bool "Enable membarrier() system call 1716 bool "Enable membarrier() system call" if EXPERT
1750 default y 1717 default y
1751 help 1718 help
1752 Enable the membarrier() system call 1719 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1720 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1721 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1722 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1723 compiler barrier.
1757 1724
1758 If unsure, say Y. 1725 If unsure, say Y.
1759 1726
1760 config KCMP <<
1761 bool "Enable kcmp() system call" if E <<
1762 help <<
1763 Enable the kernel resource comparis <<
1764 user-space with the ability to comp <<
1765 share a common resource, such as a <<
1766 memory space. <<
1767 <<
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 1727 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1728 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1729 default y
1813 help 1730 help
1814 Say Y here to let the kernel print 1731 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1732 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1733 somewhat, as all symbols have to be loaded into the kernel image.
1817 1734
1818 config KALLSYMS_SELFTEST 1735 config KALLSYMS_SELFTEST
1819 bool "Test the basic functions and pe 1736 bool "Test the basic functions and performance of kallsyms"
1820 depends on KALLSYMS 1737 depends on KALLSYMS
1821 default n 1738 default n
1822 help 1739 help
1823 Test the basic functions and perfor 1740 Test the basic functions and performance of some interfaces, such as
1824 kallsyms_lookup_name. It also calcu 1741 kallsyms_lookup_name. It also calculates the compression rate of the
1825 kallsyms compression algorithm for 1742 kallsyms compression algorithm for the current symbol set.
1826 1743
1827 Start self-test automatically after 1744 Start self-test automatically after system startup. Suggest executing
1828 "dmesg | grep kallsyms_selftest" to 1745 "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
1829 displayed in the last line, indicat 1746 displayed in the last line, indicating that the test is complete.
1830 1747
1831 config KALLSYMS_ALL 1748 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1749 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1750 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1751 help
1835 Normally kallsyms only contains the 1752 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1753 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m 1754 sections). This is sufficient for most cases. And only if you want to
1838 enable kernel live patching, or oth 1755 enable kernel live patching, or other less common use cases (e.g.,
1839 when a debugger is used) all symbol 1756 when a debugger is used) all symbols are required (i.e., names of
1840 variables from the data sections, e 1757 variables from the data sections, etc).
1841 1758
1842 This option makes sure that all sym 1759 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1760 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1761 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1762 something like this).
1846 1763
1847 Say N unless you really need all sy 1764 Say N unless you really need all symbols, or kernel live patching.
1848 1765
1849 config KALLSYMS_ABSOLUTE_PERCPU 1766 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1767 bool
1851 depends on KALLSYMS 1768 depends on KALLSYMS
1852 default X86_64 && SMP 1769 default X86_64 && SMP
1853 1770
>> 1771 config KALLSYMS_BASE_RELATIVE
>> 1772 bool
>> 1773 depends on KALLSYMS
>> 1774 default !IA64
>> 1775 help
>> 1776 Instead of emitting them as absolute values in the native word size,
>> 1777 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1778 each containing a relative value in the range [base, base + U32_MAX]
>> 1779 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1780 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1781 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1782 address encountered in the image.
>> 1783
>> 1784 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1785 but more importantly, it results in entries whose values are build
>> 1786 time constants, and no relocation pass is required at runtime to fix
>> 1787 up the entries based on the runtime load address of the kernel.
>> 1788
1854 # end of the "standard kernel features (exper 1789 # end of the "standard kernel features (expert users)" menu
1855 1790
>> 1791 # syscall, maps, verifier
>> 1792
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1793 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1794 bool
1858 1795
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1796 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1797 bool
1861 1798
>> 1799 config KCMP
>> 1800 bool "Enable kcmp() system call" if EXPERT
>> 1801 help
>> 1802 Enable the kernel resource comparison system call. It provides
>> 1803 user-space with the ability to compare two processes to see if they
>> 1804 share a common resource, such as a file descriptor or even virtual
>> 1805 memory space.
>> 1806
>> 1807 If unsure, say N.
>> 1808
>> 1809 config RSEQ
>> 1810 bool "Enable rseq() system call" if EXPERT
>> 1811 default y
>> 1812 depends on HAVE_RSEQ
>> 1813 select MEMBARRIER
>> 1814 help
>> 1815 Enable the restartable sequences system call. It provides a
>> 1816 user-space cache for the current CPU number value, which
>> 1817 speeds up getting the current CPU number from user-space,
>> 1818 as well as an ABI to speed up user-space operations on
>> 1819 per-CPU data.
>> 1820
>> 1821 If unsure, say Y.
>> 1822
>> 1823 config DEBUG_RSEQ
>> 1824 default n
>> 1825 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1826 depends on RSEQ && DEBUG_KERNEL
>> 1827 help
>> 1828 Enable extra debugging checks for the rseq system call.
>> 1829
>> 1830 If unsure, say N.
>> 1831
>> 1832 config EMBEDDED
>> 1833 bool "Embedded system"
>> 1834 select EXPERT
>> 1835 help
>> 1836 This option should be enabled if compiling the kernel for
>> 1837 an embedded system so certain expert options are available
>> 1838 for configuration.
>> 1839
1862 config HAVE_PERF_EVENTS 1840 config HAVE_PERF_EVENTS
1863 bool 1841 bool
1864 help 1842 help
1865 See tools/perf/design.txt for detai 1843 See tools/perf/design.txt for details.
1866 1844
1867 config GUEST_PERF_EVENTS 1845 config GUEST_PERF_EVENTS
1868 bool 1846 bool
1869 depends on HAVE_PERF_EVENTS 1847 depends on HAVE_PERF_EVENTS
1870 1848
1871 config PERF_USE_VMALLOC 1849 config PERF_USE_VMALLOC
1872 bool 1850 bool
1873 help 1851 help
1874 See tools/perf/design.txt for detai 1852 See tools/perf/design.txt for details
1875 1853
>> 1854 config PC104
>> 1855 bool "PC/104 support" if EXPERT
>> 1856 help
>> 1857 Expose PC/104 form factor device drivers and options available for
>> 1858 selection and configuration. Enable this option if your target
>> 1859 machine has a PC/104 bus.
>> 1860
1876 menu "Kernel Performance Events And Counters" 1861 menu "Kernel Performance Events And Counters"
1877 1862
1878 config PERF_EVENTS 1863 config PERF_EVENTS
1879 bool "Kernel performance events and c 1864 bool "Kernel performance events and counters"
1880 default y if PROFILING 1865 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1866 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1867 select IRQ_WORK
>> 1868 select SRCU
1883 help 1869 help
1884 Enable kernel support for various p 1870 Enable kernel support for various performance events provided
1885 by software and hardware. 1871 by software and hardware.
1886 1872
1887 Software events are supported eithe 1873 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1874 use of generic tracepoints.
1889 1875
1890 Most modern CPUs support performanc 1876 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1877 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1878 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1879 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1880 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1881 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1882 used to profile the code that runs on that CPU.
1897 1883
1898 The Linux Performance Event subsyst 1884 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1885 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1886 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1887 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1888 capabilities on top of those.
1903 1889
1904 Say Y if unsure. 1890 Say Y if unsure.
1905 1891
1906 config DEBUG_PERF_USE_VMALLOC 1892 config DEBUG_PERF_USE_VMALLOC
1907 default n 1893 default n
1908 bool "Debug: use vmalloc to back perf 1894 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1895 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1896 select PERF_USE_VMALLOC
1911 help 1897 help
1912 Use vmalloc memory to back perf mma 1898 Use vmalloc memory to back perf mmap() buffers.
1913 1899
1914 Mostly useful for debugging the vma 1900 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1901 that don't require it.
1916 1902
1917 Say N if unsure. 1903 Say N if unsure.
1918 1904
1919 endmenu 1905 endmenu
1920 1906
1921 config SYSTEM_DATA_VERIFICATION 1907 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1908 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1909 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1910 select KEYS
1925 select CRYPTO 1911 select CRYPTO
1926 select CRYPTO_RSA 1912 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1913 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1914 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1915 select ASN1
1930 select OID_REGISTRY 1916 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1917 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1918 select PKCS7_MESSAGE_PARSER
1933 help 1919 help
1934 Provide PKCS#7 message verification 1920 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1921 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1922 module verification, kexec image verification and firmware blob
1937 verification. 1923 verification.
1938 1924
1939 config PROFILING 1925 config PROFILING
1940 bool "Profiling support" 1926 bool "Profiling support"
1941 help 1927 help
1942 Say Y here to enable the extended p 1928 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. 1929 by profilers.
1944 1930
1945 config RUST 1931 config RUST
1946 bool "Rust support" 1932 bool "Rust support"
1947 depends on HAVE_RUST 1933 depends on HAVE_RUST
1948 depends on RUST_IS_AVAILABLE 1934 depends on RUST_IS_AVAILABLE
1949 depends on !MODVERSIONS 1935 depends on !MODVERSIONS
1950 depends on !GCC_PLUGIN_RANDSTRUCT !! 1936 depends on !GCC_PLUGINS
1951 depends on !RANDSTRUCT 1937 depends on !RANDSTRUCT
1952 depends on !DEBUG_INFO_BTF || PAHOLE_ !! 1938 depends on !DEBUG_INFO_BTF
1953 depends on !CFI_CLANG || HAVE_CFI_ICA !! 1939 select CONSTRUCTORS
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 1940 help
1959 Enables Rust support in the kernel. 1941 Enables Rust support in the kernel.
1960 1942
1961 This allows other Rust-related opti 1943 This allows other Rust-related options, like drivers written in Rust,
1962 to be selected. 1944 to be selected.
1963 1945
1964 It is also required to be able to l 1946 It is also required to be able to load external kernel modules
1965 written in Rust. 1947 written in Rust.
1966 1948
1967 See Documentation/rust/ for more in 1949 See Documentation/rust/ for more information.
1968 1950
1969 If unsure, say N. 1951 If unsure, say N.
1970 1952
1971 config RUSTC_VERSION_TEXT 1953 config RUSTC_VERSION_TEXT
1972 string 1954 string
1973 depends on RUST 1955 depends on RUST
1974 default "$(RUSTC_VERSION_TEXT)" !! 1956 default $(shell,command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version || echo n)
1975 help <<
1976 See `CC_VERSION_TEXT`. <<
1977 1957
1978 config BINDGEN_VERSION_TEXT 1958 config BINDGEN_VERSION_TEXT
1979 string 1959 string
1980 depends on RUST 1960 depends on RUST
1981 # The dummy parameter `workaround-for !! 1961 default $(shell,command -v $(BINDGEN) >/dev/null 2>&1 && $(BINDGEN) --version || echo n)
1982 # (https://github.com/rust-lang/rust- <<
1983 # the minimum version is upgraded pas <<
1984 default "$(shell,$(BINDGEN) --version <<
1985 1962
1986 # 1963 #
1987 # Place an empty function call at each tracep 1964 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1965 # dynamically changed for a probe function.
1989 # 1966 #
1990 config TRACEPOINTS 1967 config TRACEPOINTS
1991 bool 1968 bool
1992 1969
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1970 endmenu # General setup
1996 1971
1997 source "arch/Kconfig" 1972 source "arch/Kconfig"
1998 1973
1999 config RT_MUTEXES 1974 config RT_MUTEXES
2000 bool 1975 bool
2001 default y if PREEMPT_RT 1976 default y if PREEMPT_RT
2002 1977
>> 1978 config BASE_SMALL
>> 1979 int
>> 1980 default 0 if BASE_FULL
>> 1981 default 1 if !BASE_FULL
>> 1982
2003 config MODULE_SIG_FORMAT 1983 config MODULE_SIG_FORMAT
2004 def_bool n 1984 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 1985 select SYSTEM_DATA_VERIFICATION
2006 1986
2007 source "kernel/module/Kconfig" 1987 source "kernel/module/Kconfig"
2008 1988
2009 config INIT_ALL_POSSIBLE 1989 config INIT_ALL_POSSIBLE
2010 bool 1990 bool
2011 help 1991 help
2012 Back when each arch used to define 1992 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 1993 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 1994 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 1995 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 1996 and have several arch maintainers pursuing me down dark alleys.
2017 1997
2018 source "block/Kconfig" 1998 source "block/Kconfig"
2019 1999
2020 config PREEMPT_NOTIFIERS 2000 config PREEMPT_NOTIFIERS
2021 bool 2001 bool
2022 2002
2023 config PADATA 2003 config PADATA
2024 depends on SMP 2004 depends on SMP
2025 bool 2005 bool
2026 2006
2027 config ASN1 2007 config ASN1
2028 tristate 2008 tristate
2029 help 2009 help
2030 Build a simple ASN.1 grammar compil 2010 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2011 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2012 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2013 functions to call on what tags.
2034 2014
2035 source "kernel/Kconfig.locks" 2015 source "kernel/Kconfig.locks"
2036 2016
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2017 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2018 bool
2042 2019
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2020 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2021 bool
2045 2022
2046 # It may be useful for an architecture to ove 2023 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2024 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2025 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2026 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2027 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2028 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2029 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2030 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2031 def_bool n
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