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
>> 92 config GCC_ASM_GOTO_OUTPUT_WORKAROUND
>> 93 bool
>> 94 depends on CC_IS_GCC && CC_HAS_ASM_GOTO_OUTPUT
>> 95 # Fixed in GCC 14, 13.3, 12.4 and 11.5
>> 96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
>> 97 default y if GCC_VERSION < 110500
>> 98 default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
>> 99 default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
>> 100
114 config TOOLS_SUPPORT_RELR 101 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 102 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 103
117 config CC_HAS_ASM_INLINE 104 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 105 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 106
120 config CC_HAS_NO_PROFILE_FN_ATTR 107 config CC_HAS_NO_PROFILE_FN_ATTR
121 def_bool $(success,echo '__attribute__ 108 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
122 109
123 config PAHOLE_VERSION 110 config PAHOLE_VERSION
124 int 111 int
125 default $(shell,$(srctree)/scripts/pah 112 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
126 113
127 config CONSTRUCTORS 114 config CONSTRUCTORS
128 bool 115 bool
129 116
130 config IRQ_WORK 117 config IRQ_WORK
131 def_bool y if SMP !! 118 bool
132 119
133 config BUILDTIME_TABLE_SORT 120 config BUILDTIME_TABLE_SORT
134 bool 121 bool
135 122
136 config THREAD_INFO_IN_TASK 123 config THREAD_INFO_IN_TASK
137 bool 124 bool
138 help 125 help
139 Select this to move thread_info off 126 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 127 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 128 except flags and fix any runtime bugs.
142 129
143 One subtle change that will be neede 130 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 131 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 132
146 menu "General setup" 133 menu "General setup"
147 134
148 config BROKEN 135 config BROKEN
149 bool 136 bool
150 137
151 config BROKEN_ON_SMP 138 config BROKEN_ON_SMP
152 bool 139 bool
153 depends on BROKEN || !SMP 140 depends on BROKEN || !SMP
154 default y 141 default y
155 142
156 config INIT_ENV_ARG_LIMIT 143 config INIT_ENV_ARG_LIMIT
157 int 144 int
158 default 32 if !UML 145 default 32 if !UML
159 default 128 if UML 146 default 128 if UML
160 help 147 help
161 Maximum of each of the number of arg 148 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 149 variables passed to init from the kernel command line.
163 150
164 config COMPILE_TEST 151 config COMPILE_TEST
165 bool "Compile also drivers which will 152 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 153 depends on HAS_IOMEM
167 help 154 help
168 Some drivers can be compiled on a di 155 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 156 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 157 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 158 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 159 drivers to compile-test them.
173 160
174 If you are a developer and want to b 161 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 162 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 163 drivers to be distributed.
177 164
178 config WERROR 165 config WERROR
179 bool "Compile the kernel with warnings 166 bool "Compile the kernel with warnings as errors"
180 default COMPILE_TEST 167 default COMPILE_TEST
181 help 168 help
182 A kernel build should not cause any 169 A kernel build should not cause any compiler warnings, and this
183 enables the '-Werror' (for C) and '- 170 enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
184 to enforce that rule by default. Cer !! 171 to enforce that rule by default.
185 such as the linker may be upgraded t <<
186 well. <<
187 172
188 However, if you have a new (or very !! 173 However, if you have a new (or very old) compiler with odd and
189 and unusual warnings, or you have so !! 174 unusual warnings, or you have some architecture with problems,
190 you may need to disable this config 175 you may need to disable this config option in order to
191 successfully build the kernel. 176 successfully build the kernel.
192 177
193 If in doubt, say Y. 178 If in doubt, say Y.
194 179
195 config UAPI_HEADER_TEST 180 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 181 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 182 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 183 help
199 Compile test headers exported to use 184 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 185 self-contained, i.e. compilable as standalone units.
201 186
202 If you are a developer or tester and 187 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 188 headers are self-contained, say Y here. Otherwise, choose N.
204 189
205 config LOCALVERSION 190 config LOCALVERSION
206 string "Local version - append to kern 191 string "Local version - append to kernel release"
207 help 192 help
208 Append an extra string to the end of 193 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 194 This will show up when you type uname, for example.
210 The string you set here will be appe 195 The string you set here will be appended after the contents of
211 any files with a filename matching l 196 any files with a filename matching localversion* in your
212 object and source tree, in that orde 197 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 198 be a maximum of 64 characters.
214 199
215 config LOCALVERSION_AUTO 200 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 201 bool "Automatically append version information to the version string"
217 default y 202 default y
218 depends on !COMPILE_TEST 203 depends on !COMPILE_TEST
219 help 204 help
220 This will try to automatically deter 205 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 206 release tree by looking for git tags that belong to the current
222 top of tree revision. 207 top of tree revision.
223 208
224 A string of the format -gxxxxxxxx wi 209 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 210 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 211 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 212 set in CONFIG_LOCALVERSION.
228 213
229 (The actual string used here is the !! 214 (The actual string used here is the first eight characters produced
230 by running the command: 215 by running the command:
231 216
232 $ git rev-parse --verify HEAD 217 $ git rev-parse --verify HEAD
233 218
234 which is done within the script "scr 219 which is done within the script "scripts/setlocalversion".)
235 220
236 config BUILD_SALT 221 config BUILD_SALT
237 string "Build ID Salt" 222 string "Build ID Salt"
238 default "" 223 default ""
239 help 224 help
240 The build ID is used to link binarie 225 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 226 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 227 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 228 build is unique between builds. It's safe to leave the default.
244 229
245 config HAVE_KERNEL_GZIP 230 config HAVE_KERNEL_GZIP
246 bool 231 bool
247 232
248 config HAVE_KERNEL_BZIP2 233 config HAVE_KERNEL_BZIP2
249 bool 234 bool
250 235
251 config HAVE_KERNEL_LZMA 236 config HAVE_KERNEL_LZMA
252 bool 237 bool
253 238
254 config HAVE_KERNEL_XZ 239 config HAVE_KERNEL_XZ
255 bool 240 bool
256 241
257 config HAVE_KERNEL_LZO 242 config HAVE_KERNEL_LZO
258 bool 243 bool
259 244
260 config HAVE_KERNEL_LZ4 245 config HAVE_KERNEL_LZ4
261 bool 246 bool
262 247
263 config HAVE_KERNEL_ZSTD 248 config HAVE_KERNEL_ZSTD
264 bool 249 bool
265 250
266 config HAVE_KERNEL_UNCOMPRESSED 251 config HAVE_KERNEL_UNCOMPRESSED
267 bool 252 bool
268 253
269 choice 254 choice
270 prompt "Kernel compression mode" 255 prompt "Kernel compression mode"
271 default KERNEL_GZIP 256 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE 257 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 258 help
274 The linux kernel is a kind of self-e 259 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 260 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 261 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 262 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 263 Decompression speed is relevant at each boot.
279 264
280 If you have any problems with bzip2 265 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 266 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 267 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 268 supplied by Christian Ludwig)
284 269
285 High compression options are mostly 270 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 271 are low on disk space (embedded systems), but for whom ram
287 size matters less. 272 size matters less.
288 273
289 If in doubt, select 'gzip' 274 If in doubt, select 'gzip'
290 275
291 config KERNEL_GZIP 276 config KERNEL_GZIP
292 bool "Gzip" 277 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 278 depends on HAVE_KERNEL_GZIP
294 help 279 help
295 The old and tried gzip compression. 280 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 281 between compression ratio and decompression speed.
297 282
298 config KERNEL_BZIP2 283 config KERNEL_BZIP2
299 bool "Bzip2" 284 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 285 depends on HAVE_KERNEL_BZIP2
301 help 286 help
302 Its compression ratio and speed is i 287 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 288 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 289 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 290 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 291 will need at least 8MB RAM or more for booting.
307 292
308 config KERNEL_LZMA 293 config KERNEL_LZMA
309 bool "LZMA" 294 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 295 depends on HAVE_KERNEL_LZMA
311 help 296 help
312 This compression algorithm's ratio i 297 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 298 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 299 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 300
316 config KERNEL_XZ 301 config KERNEL_XZ
317 bool "XZ" 302 bool "XZ"
318 depends on HAVE_KERNEL_XZ 303 depends on HAVE_KERNEL_XZ
319 help 304 help
320 XZ uses the LZMA2 algorithm and inst 305 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 306 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 307 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 308 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 309 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 310 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 311
328 The speed is about the same as with 312 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 313 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 314 and LZO. Compression is slow.
331 315
332 config KERNEL_LZO 316 config KERNEL_LZO
333 bool "LZO" 317 bool "LZO"
334 depends on HAVE_KERNEL_LZO 318 depends on HAVE_KERNEL_LZO
335 help 319 help
336 Its compression ratio is the poorest 320 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 321 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 322 (both compression and decompression) is the fastest.
339 323
340 config KERNEL_LZ4 324 config KERNEL_LZ4
341 bool "LZ4" 325 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 326 depends on HAVE_KERNEL_LZ4
343 help 327 help
344 LZ4 is an LZ77-type compressor with 328 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 329 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 330 <https://code.google.com/p/lz4/>.
347 331
348 Its compression ratio is worse than 332 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 333 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 334 faster than LZO.
351 335
352 config KERNEL_ZSTD 336 config KERNEL_ZSTD
353 bool "ZSTD" 337 bool "ZSTD"
354 depends on HAVE_KERNEL_ZSTD 338 depends on HAVE_KERNEL_ZSTD
355 help 339 help
356 ZSTD is a compression algorithm targ 340 ZSTD is a compression algorithm targeting intermediate compression
357 with fast decompression speed. It wi 341 with fast decompression speed. It will compress better than GZIP and
358 decompress around the same speed as 342 decompress around the same speed as LZO, but slower than LZ4. You
359 will need at least 192 KB RAM or mor 343 will need at least 192 KB RAM or more for booting. The zstd command
360 line tool is required for compressio 344 line tool is required for compression.
361 345
362 config KERNEL_UNCOMPRESSED 346 config KERNEL_UNCOMPRESSED
363 bool "None" 347 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 348 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 349 help
366 Produce uncompressed kernel image. T 350 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 351 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 352 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 353 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 354 and jump right at uncompressed kernel image.
371 355
372 endchoice 356 endchoice
373 357
374 config DEFAULT_INIT 358 config DEFAULT_INIT
375 string "Default init path" 359 string "Default init path"
376 default "" 360 default ""
377 help 361 help
378 This option determines the default i 362 This option determines the default init for the system if no init=
379 option is passed on the kernel comma 363 option is passed on the kernel command line. If the requested path is
380 not present, we will still then move 364 not present, we will still then move on to attempting further
381 locations (e.g. /sbin/init, etc). If 365 locations (e.g. /sbin/init, etc). If this is empty, we will just use
382 the fallback list when init= is not 366 the fallback list when init= is not passed.
383 367
384 config DEFAULT_HOSTNAME 368 config DEFAULT_HOSTNAME
385 string "Default hostname" 369 string "Default hostname"
386 default "(none)" 370 default "(none)"
387 help 371 help
388 This option determines the default s 372 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 373 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 374 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 375 system more usable with less configuration.
392 376
393 config SYSVIPC 377 config SYSVIPC
394 bool "System V IPC" 378 bool "System V IPC"
395 help 379 help
396 Inter Process Communication is a sui 380 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 381 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 382 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 383 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 384 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 385 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 386 you'll need to say Y here.
403 387
404 You can find documentation about IPC 388 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 389 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 390 <http://www.tldp.org/guides.html>.
407 391
408 config SYSVIPC_SYSCTL 392 config SYSVIPC_SYSCTL
409 bool 393 bool
410 depends on SYSVIPC 394 depends on SYSVIPC
411 depends on SYSCTL 395 depends on SYSCTL
412 default y 396 default y
413 397
414 config SYSVIPC_COMPAT 398 config SYSVIPC_COMPAT
415 def_bool y 399 def_bool y
416 depends on COMPAT && SYSVIPC 400 depends on COMPAT && SYSVIPC
417 401
418 config POSIX_MQUEUE 402 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 403 bool "POSIX Message Queues"
420 depends on NET 404 depends on NET
421 help 405 help
422 POSIX variant of message queues is a 406 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 407 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 408 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 409 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 410 queues (functions mq_*) say Y here.
427 411
428 POSIX message queues are visible as 412 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 413 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 414 operations on message queues.
431 415
432 If unsure, say Y. 416 If unsure, say Y.
433 417
434 config POSIX_MQUEUE_SYSCTL 418 config POSIX_MQUEUE_SYSCTL
435 bool 419 bool
436 depends on POSIX_MQUEUE 420 depends on POSIX_MQUEUE
437 depends on SYSCTL 421 depends on SYSCTL
438 default y 422 default y
439 423
440 config WATCH_QUEUE 424 config WATCH_QUEUE
441 bool "General notification queue" 425 bool "General notification queue"
442 default n 426 default n
443 help 427 help
444 428
445 This is a general notification queue 429 This is a general notification queue for the kernel to pass events to
446 userspace by splicing them into pipe 430 userspace by splicing them into pipes. It can be used in conjunction
447 with watches for key/keyring change 431 with watches for key/keyring change notifications and device
448 notifications. 432 notifications.
449 433
450 See Documentation/core-api/watch_que 434 See Documentation/core-api/watch_queue.rst
451 435
452 config CROSS_MEMORY_ATTACH 436 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 437 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 438 depends on MMU
455 default y 439 default y
456 help 440 help
457 Enabling this option adds the system 441 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 442 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 443 to directly read from or write to another process' address space.
460 See the man page for more details. 444 See the man page for more details.
461 445
462 config USELIB 446 config USELIB
463 bool "uselib syscall (for libc5 and ea 447 bool "uselib syscall (for libc5 and earlier)"
464 default ALPHA || M68K || SPARC 448 default ALPHA || M68K || SPARC
465 help 449 help
466 This option enables the uselib sysca 450 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 451 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 452 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 453 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 454 running glibc can safely disable this.
471 455
472 config AUDIT 456 config AUDIT
473 bool "Auditing support" 457 bool "Auditing support"
474 depends on NET 458 depends on NET
475 help 459 help
476 Enable auditing infrastructure that 460 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 461 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 462 logging of avc messages output). System call auditing is included
479 on architectures which support it. 463 on architectures which support it.
480 464
481 config HAVE_ARCH_AUDITSYSCALL 465 config HAVE_ARCH_AUDITSYSCALL
482 bool 466 bool
483 467
484 config AUDITSYSCALL 468 config AUDITSYSCALL
485 def_bool y 469 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 470 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 471 select FSNOTIFY
488 472
489 source "kernel/irq/Kconfig" 473 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 474 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" 475 source "kernel/bpf/Kconfig"
492 source "kernel/Kconfig.preempt" 476 source "kernel/Kconfig.preempt"
493 477
494 menu "CPU/Task time and stats accounting" 478 menu "CPU/Task time and stats accounting"
495 479
496 config VIRT_CPU_ACCOUNTING 480 config VIRT_CPU_ACCOUNTING
497 bool 481 bool
498 482
499 choice 483 choice
500 prompt "Cputime accounting" 484 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING 485 default TICK_CPU_ACCOUNTING
502 486
503 # Kind of a stub config for the pure tick base 487 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 488 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 489 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 490 depends on !S390 && !NO_HZ_FULL
507 help 491 help
508 This is the basic tick based cputime 492 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 493 statistics about user, system and idle time spent on per jiffies
510 granularity. 494 granularity.
511 495
512 If unsure, say Y. 496 If unsure, say Y.
513 497
514 config VIRT_CPU_ACCOUNTING_NATIVE 498 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 499 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 500 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 501 select VIRT_CPU_ACCOUNTING
518 help 502 help
519 Select this option to enable more ac 503 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 504 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 505 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 506 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 507 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 508 this also enables accounting of stolen time on logically-partitioned
525 systems. 509 systems.
526 510
527 config VIRT_CPU_ACCOUNTING_GEN 511 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 512 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER 513 depends on HAVE_CONTEXT_TRACKING_USER
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 514 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 515 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 516 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER 517 select CONTEXT_TRACKING_USER
534 help 518 help
535 Select this option to enable task an 519 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 520 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 521 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 522 The accounting is thus performed at the expense of some significant
539 overhead. 523 overhead.
540 524
541 For now this is only useful if you a 525 For now this is only useful if you are working on the full
542 dynticks subsystem development. 526 dynticks subsystem development.
543 527
544 If unsure, say N. 528 If unsure, say N.
545 529
546 endchoice 530 endchoice
547 531
548 config IRQ_TIME_ACCOUNTING 532 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 533 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 534 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 535 help
552 Select this option to enable fine gr 536 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 537 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 538 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 539 small performance impact.
556 540
557 If in doubt, say N here. 541 If in doubt, say N here.
558 542
559 config HAVE_SCHED_AVG_IRQ 543 config HAVE_SCHED_AVG_IRQ
560 def_bool y 544 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 545 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 546 depends on SMP
563 547
564 config SCHED_HW_PRESSURE !! 548 config SCHED_THERMAL_PRESSURE
565 bool 549 bool
566 default y if ARM && ARM_CPU_TOPOLOGY 550 default y if ARM && ARM_CPU_TOPOLOGY
567 default y if ARM64 551 default y if ARM64
568 depends on SMP 552 depends on SMP
569 depends on CPU_FREQ_THERMAL 553 depends on CPU_FREQ_THERMAL
570 help 554 help
571 Select this option to enable HW pres !! 555 Select this option to enable thermal pressure accounting in the
572 scheduler. HW pressure is the value !! 556 scheduler. Thermal pressure is the value conveyed to the scheduler
573 that reflects the reduction in CPU c 557 that reflects the reduction in CPU compute capacity resulted from
574 HW throttling. HW throttling occurs !! 558 thermal throttling. Thermal throttling occurs when the performance of
575 a CPU is capped due to high operatin !! 559 a CPU is capped due to high operating temperatures.
576 560
577 If selected, the scheduler will be a 561 If selected, the scheduler will be able to balance tasks accordingly,
578 i.e. put less load on throttled CPUs 562 i.e. put less load on throttled CPUs than on non/less throttled ones.
579 563
580 This requires the architecture to im 564 This requires the architecture to implement
581 arch_update_hw_pressure() and arch_s !! 565 arch_update_thermal_pressure() and arch_scale_thermal_pressure().
582 566
583 config BSD_PROCESS_ACCT 567 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 568 bool "BSD Process Accounting"
585 depends on MULTIUSER 569 depends on MULTIUSER
586 help 570 help
587 If you say Y here, a user level prog 571 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 572 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 573 information to a file: whenever a process exits, information about
590 that process will be appended to the 574 that process will be appended to the file by the kernel. The
591 information includes things such as 575 information includes things such as creation time, owning user,
592 command name, memory usage, controll 576 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 577 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 578 up to the user level program to do useful things with this
595 information. This is generally a go 579 information. This is generally a good idea, so say Y.
596 580
597 config BSD_PROCESS_ACCT_V3 581 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 582 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 583 depends on BSD_PROCESS_ACCT
600 default n 584 default n
601 help 585 help
602 If you say Y here, the process accou 586 If you say Y here, the process accounting information is written
603 in a new file format that also logs 587 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 588 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 589 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 590 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 591 at <http://www.gnu.org/software/acct/>.
608 592
609 config TASKSTATS 593 config TASKSTATS
610 bool "Export task/process statistics t 594 bool "Export task/process statistics through netlink"
611 depends on NET 595 depends on NET
612 depends on MULTIUSER 596 depends on MULTIUSER
613 default n 597 default n
614 help 598 help
615 Export selected statistics for tasks 599 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 600 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 601 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 602 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 603 space on task exit.
620 604
621 Say N if unsure. 605 Say N if unsure.
622 606
623 config TASK_DELAY_ACCT 607 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 608 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 609 depends on TASKSTATS
626 select SCHED_INFO 610 select SCHED_INFO
627 help 611 help
628 Collect information on time spent by 612 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 613 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 614 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 615 relative to other tasks for cpu, io, rss limits etc.
632 616
633 Say N if unsure. 617 Say N if unsure.
634 618
635 config TASK_XACCT 619 config TASK_XACCT
636 bool "Enable extended accounting over 620 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 621 depends on TASKSTATS
638 help 622 help
639 Collect extended task accounting dat 623 Collect extended task accounting data and send the data
640 to userland for processing over the 624 to userland for processing over the taskstats interface.
641 625
642 Say N if unsure. 626 Say N if unsure.
643 627
644 config TASK_IO_ACCOUNTING 628 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 629 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 630 depends on TASK_XACCT
647 help 631 help
648 Collect information on the number of 632 Collect information on the number of bytes of storage I/O which this
649 task has caused. 633 task has caused.
650 634
651 Say N if unsure. 635 Say N if unsure.
652 636
653 config PSI 637 config PSI
654 bool "Pressure stall information track 638 bool "Pressure stall information tracking"
655 select KERNFS 639 select KERNFS
656 help 640 help
657 Collect metrics that indicate how ov 641 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 642 and IO capacity are in the system.
659 643
660 If you say Y here, the kernel will c 644 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 645 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 646 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 647 delayed due to contention of the respective resource.
664 648
665 In kernels with cgroup support, cgro 649 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 650 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 651 which aggregate pressure stalls for the grouped tasks only.
668 652
669 For more details see Documentation/a 653 For more details see Documentation/accounting/psi.rst.
670 654
671 Say N if unsure. 655 Say N if unsure.
672 656
673 config PSI_DEFAULT_DISABLED 657 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 658 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 659 default n
676 depends on PSI 660 depends on PSI
677 help 661 help
678 If set, pressure stall information t 662 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 663 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 664 kernel commandline during boot.
681 665
682 This feature adds some code to the t 666 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 667 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 668 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 669 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 670 scheduler stress tests, such as hackbench.
687 671
688 If you are paranoid and not sure wha 672 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 673 used for, say Y.
690 674
691 Say N if unsure. 675 Say N if unsure.
692 676
693 endmenu # "CPU/Task time and stats accounting" 677 endmenu # "CPU/Task time and stats accounting"
694 678
695 config CPU_ISOLATION 679 config CPU_ISOLATION
696 bool "CPU isolation" 680 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 681 depends on SMP || COMPILE_TEST
698 default y 682 default y
699 help 683 help
700 Make sure that CPUs running critical 684 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 685 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 686 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 687 the "isolcpus=" boot parameter.
704 688
705 Say Y if unsure. 689 Say Y if unsure.
706 690
707 source "kernel/rcu/Kconfig" 691 source "kernel/rcu/Kconfig"
708 692
>> 693 config BUILD_BIN2C
>> 694 bool
>> 695 default n
>> 696
709 config IKCONFIG 697 config IKCONFIG
710 tristate "Kernel .config support" 698 tristate "Kernel .config support"
711 help 699 help
712 This option enables the complete Lin 700 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 701 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 702 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 703 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 704 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 705 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 706 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 707 /proc/config.gz if enabled (below).
720 708
721 config IKCONFIG_PROC 709 config IKCONFIG_PROC
722 bool "Enable access to .config through 710 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 711 depends on IKCONFIG && PROC_FS
724 help 712 help
725 This option enables access to the ke 713 This option enables access to the kernel configuration file
726 through /proc/config.gz. 714 through /proc/config.gz.
727 715
728 config IKHEADERS 716 config IKHEADERS
729 tristate "Enable kernel headers throug 717 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 718 depends on SYSFS
731 help 719 help
732 This option enables access to the in 720 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 721 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 722 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 723 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 724
737 config LOG_BUF_SHIFT 725 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 726 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 727 range 12 25
740 default 17 728 default 17
741 depends on PRINTK 729 depends on PRINTK
742 help 730 help
743 Select the minimal kernel log buffer 731 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 732 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 733 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 734 by "log_buf_len" boot parameter.
747 735
748 Examples: 736 Examples:
749 17 => 128 KB 737 17 => 128 KB
750 16 => 64 KB 738 16 => 64 KB
751 15 => 32 KB 739 15 => 32 KB
752 14 => 16 KB 740 14 => 16 KB
753 13 => 8 KB 741 13 => 8 KB
754 12 => 4 KB 742 12 => 4 KB
755 743
756 config LOG_CPU_MAX_BUF_SHIFT 744 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 745 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 746 depends on SMP
759 range 0 21 747 range 0 21
>> 748 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 749 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 750 depends on PRINTK
763 help 751 help
764 This option allows to increase the d 752 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 753 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 754 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 755 lines however it might be much more when problems are reported,
768 e.g. backtraces. 756 e.g. backtraces.
769 757
770 The increased size means that a new 758 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 759 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 760 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 761 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 762 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed 763 so that more than 16 CPUs are needed to trigger the allocation.
776 764
777 Also this option is ignored when "lo 765 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 766 used as it forces an exact (power of two) size of the ring buffer.
779 767
780 The number of possible CPUs is used 768 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 769 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 770 scenario while allowing a simple algorithm to be used from bootup.
783 771
784 Examples shift values and their mean 772 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 773 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 774 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 775 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 776 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 777 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 778 12 => 4 KB for each CPU
791 779
>> 780 config PRINTK_SAFE_LOG_BUF_SHIFT
>> 781 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
>> 782 range 10 21
>> 783 default 13
>> 784 depends on PRINTK
>> 785 help
>> 786 Select the size of an alternate printk per-CPU buffer where messages
>> 787 printed from usafe contexts are temporary stored. One example would
>> 788 be NMI messages, another one - printk recursion. The messages are
>> 789 copied to the main log buffer in a safe context to avoid a deadlock.
>> 790 The value defines the size as a power of 2.
>> 791
>> 792 Those messages are rare and limited. The largest one is when
>> 793 a backtrace is printed. It usually fits into 4KB. Select
>> 794 8KB if you want to be on the safe side.
>> 795
>> 796 Examples:
>> 797 17 => 128 KB for each CPU
>> 798 16 => 64 KB for each CPU
>> 799 15 => 32 KB for each CPU
>> 800 14 => 16 KB for each CPU
>> 801 13 => 8 KB for each CPU
>> 802 12 => 4 KB for each CPU
>> 803
792 config PRINTK_INDEX 804 config PRINTK_INDEX
793 bool "Printk indexing debugfs interfac 805 bool "Printk indexing debugfs interface"
794 depends on PRINTK && DEBUG_FS 806 depends on PRINTK && DEBUG_FS
795 help 807 help
796 Add support for indexing of all prin 808 Add support for indexing of all printk formats known at compile time
797 at <debugfs>/printk/index/<module>. 809 at <debugfs>/printk/index/<module>.
798 810
799 This can be used as part of maintain 811 This can be used as part of maintaining daemons which monitor
800 /dev/kmsg, as it permits auditing th 812 /dev/kmsg, as it permits auditing the printk formats present in a
801 kernel, allowing detection of cases 813 kernel, allowing detection of cases where monitored printks are
802 changed or no longer present. 814 changed or no longer present.
803 815
804 There is no additional runtime cost 816 There is no additional runtime cost to printk with this enabled.
805 817
806 # 818 #
807 # Architectures with an unreliable sched_clock 819 # Architectures with an unreliable sched_clock() should select this:
808 # 820 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 821 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 822 bool
811 823
812 config GENERIC_SCHED_CLOCK 824 config GENERIC_SCHED_CLOCK
813 bool 825 bool
814 826
815 menu "Scheduler features" 827 menu "Scheduler features"
816 828
817 config UCLAMP_TASK 829 config UCLAMP_TASK
818 bool "Enable utilization clamping for 830 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 831 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 832 help
821 This feature enables the scheduler t 833 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 834 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 835
824 With this option, the user can speci 836 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 837 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 838 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 839 defines the minimum frequency it should use.
828 840
829 Both min and max utilization clamp v 841 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 842 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 843 enforce or grant any specific bandwidth for tasks.
832 844
833 If in doubt, say N. 845 If in doubt, say N.
834 846
835 config UCLAMP_BUCKETS_COUNT 847 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 848 int "Number of supported utilization clamp buckets"
837 range 5 20 849 range 5 20
838 default 5 850 default 5
839 depends on UCLAMP_TASK 851 depends on UCLAMP_TASK
840 help 852 help
841 Defines the number of clamp buckets 853 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 854 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 855 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 856 the precision of clamping aggregation and tracking at run-time.
845 857
846 For example, with the minimum config 858 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 859 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 860 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 861 effective value to 25%.
850 If a second 30% boosted task should 862 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 863 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 864 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 865 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 866 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 867 that bucket.
856 868
857 An additional boost/capping margin c 869 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 870 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 871 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 872 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 873 clamp buckets to trade off used memory for run-time tracking
862 precision. 874 precision.
863 875
864 If in doubt, use the default value. 876 If in doubt, use the default value.
865 877
866 endmenu 878 endmenu
867 879
868 # 880 #
869 # For architectures that want to enable the su 881 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 882 # balancing logic:
871 # 883 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 884 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 885 bool
874 886
875 # 887 #
876 # For architectures that prefer to flush all T 888 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 889 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 890 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 891 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 892 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 893 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 894 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 895 bool
884 896
885 config CC_HAS_INT128 897 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 898 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 899
888 config CC_IMPLICIT_FALLTHROUGH 900 config CC_IMPLICIT_FALLTHROUGH
889 string 901 string
890 default "-Wimplicit-fallthrough=5" if 902 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
891 default "-Wimplicit-fallthrough" if CC 903 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
892 904
893 # Currently, disable gcc-10+ array-bounds glob 905 # Currently, disable gcc-10+ array-bounds globally.
894 # It's still broken in gcc-13, so no upper bou 906 # It's still broken in gcc-13, so no upper bound yet.
895 config GCC10_NO_ARRAY_BOUNDS 907 config GCC10_NO_ARRAY_BOUNDS
896 def_bool y 908 def_bool y
897 909
898 config CC_NO_ARRAY_BOUNDS 910 config CC_NO_ARRAY_BOUNDS
899 bool 911 bool
900 default y if CC_IS_GCC && GCC_VERSION !! 912 default y if CC_IS_GCC && GCC_VERSION >= 100000 && GCC10_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 <<
913 913
914 # 914 #
915 # For architectures that know their GCC __int1 915 # For architectures that know their GCC __int128 support is sound
916 # 916 #
917 config ARCH_SUPPORTS_INT128 917 config ARCH_SUPPORTS_INT128
918 bool 918 bool
919 919
920 # For architectures that (ab)use NUMA to repre 920 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 921 # all cpu-local but of different latencies, such as SuperH.
922 # 922 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 924 bool
925 925
926 config NUMA_BALANCING 926 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 927 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 928 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 929 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && 930 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
931 help 931 help
932 This option adds support for automat 932 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 933 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 934 it has references to the node the task is running on.
935 935
936 This system will be inactive on UMA 936 This system will be inactive on UMA systems.
937 937
938 config NUMA_BALANCING_DEFAULT_ENABLED 938 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 939 bool "Automatically enable NUMA aware memory/task placement"
940 default y 940 default y
941 depends on NUMA_BALANCING 941 depends on NUMA_BALANCING
942 help 942 help
943 If set, automatic NUMA balancing wil 943 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 944 machine.
945 945
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 946 menuconfig CGROUPS
950 bool "Control Group support" 947 bool "Control Group support"
951 select KERNFS 948 select KERNFS
952 help 949 help
953 This option adds support for groupin 950 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 951 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 952 controls or device isolation.
956 See 953 See
957 - Documentation/scheduler/sche 954 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 955 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 956 and resource control)
960 957
961 Say N if unsure. 958 Say N if unsure.
962 959
963 if CGROUPS 960 if CGROUPS
964 961
965 config PAGE_COUNTER 962 config PAGE_COUNTER
966 bool 963 bool
967 964
968 config CGROUP_FAVOR_DYNMODS 965 config CGROUP_FAVOR_DYNMODS
969 bool "Favor dynamic modification laten 966 bool "Favor dynamic modification latency reduction by default"
970 help 967 help
971 This option enables the "favordynmod 968 This option enables the "favordynmods" mount option by default
972 which reduces the latencies of dynam 969 which reduces the latencies of dynamic cgroup modifications such
973 as task migrations and controller on 970 as task migrations and controller on/offs at the cost of making
974 hot path operations such as forks an 971 hot path operations such as forks and exits more expensive.
975 972
976 Say N if unsure. 973 Say N if unsure.
977 974
978 config MEMCG 975 config MEMCG
979 bool "Memory controller" 976 bool "Memory controller"
980 select PAGE_COUNTER 977 select PAGE_COUNTER
981 select EVENTFD 978 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 979 help
984 Provides control over the memory foo 980 Provides control over the memory footprint of tasks in a cgroup.
985 981
986 config MEMCG_V1 !! 982 config MEMCG_KMEM
987 bool "Legacy cgroup v1 memory controll !! 983 bool
988 depends on MEMCG !! 984 depends on MEMCG && !SLOB
989 default n !! 985 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 986
1003 config BLK_CGROUP 987 config BLK_CGROUP
1004 bool "IO controller" 988 bool "IO controller"
1005 depends on BLOCK 989 depends on BLOCK
1006 default n 990 default n
1007 help 991 help
1008 Generic block IO controller cgroup in 992 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 993 cgroup interface which should be used by various IO controlling
1010 policies. 994 policies.
1011 995
1012 Currently, CFQ IO scheduler uses it t 996 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 997 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 998 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 999 block layer to implement upper limit in IO rates on a device.
1016 1000
1017 This option only enables generic Bloc 1001 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 1002 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 1003 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl 1004 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 1005 CONFIG_BLK_DEV_THROTTLING=y.
1022 1006
1023 See Documentation/admin-guide/cgroup- 1007 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 1008
1025 config CGROUP_WRITEBACK 1009 config CGROUP_WRITEBACK
1026 bool 1010 bool
1027 depends on MEMCG && BLK_CGROUP 1011 depends on MEMCG && BLK_CGROUP
1028 default y 1012 default y
1029 1013
1030 menuconfig CGROUP_SCHED 1014 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 1015 bool "CPU controller"
1032 default n 1016 default n
1033 help 1017 help
1034 This feature lets CPU scheduler rec 1018 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 1019 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 1020 tasks.
1037 1021
1038 if CGROUP_SCHED 1022 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 1023 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 1024 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 1025 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1026 default CGROUP_SCHED
1047 1027
1048 config CFS_BANDWIDTH 1028 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1029 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1030 depends on FAIR_GROUP_SCHED
1051 default n 1031 default n
1052 help 1032 help
1053 This option allows users to define 1033 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1034 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1035 set are considered to be unconstrained and will run with no
1056 restriction. 1036 restriction.
1057 See Documentation/scheduler/sched-b 1037 See Documentation/scheduler/sched-bwc.rst for more information.
1058 1038
1059 config RT_GROUP_SCHED 1039 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1040 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1041 depends on CGROUP_SCHED
1062 default n 1042 default n
1063 help 1043 help
1064 This feature lets you explicitly al 1044 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1045 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1046 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1047 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 1048 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 1049
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 1050 endif #CGROUP_SCHED
1077 1051
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 1052 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 1053 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 1054 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 1055 depends on UCLAMP_TASK
1086 default n 1056 default n
1087 help 1057 help
1088 This feature enables the scheduler 1058 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 1059 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 1060
1091 When this option is enabled, the us 1061 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 1062 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 1063 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 1064 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 1065 frequency a task will always use.
1096 1066
1097 When task group based utilization c 1067 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 1068 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 1069 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 1070 be bigger than the corresponding clamping defined at task group level.
1101 1071
1102 If in doubt, say N. 1072 If in doubt, say N.
1103 1073
1104 config CGROUP_PIDS 1074 config CGROUP_PIDS
1105 bool "PIDs controller" 1075 bool "PIDs controller"
1106 help 1076 help
1107 Provides enforcement of process num 1077 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1078 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1079 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1080 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1081 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1082 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1083 PIDs controller is designed to stop this from happening.
1114 1084
1115 It should be noted that organisatio 1085 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 1086 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 1087 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1088 attach to a cgroup.
1119 1089
1120 config CGROUP_RDMA 1090 config CGROUP_RDMA
1121 bool "RDMA controller" 1091 bool "RDMA controller"
1122 help 1092 help
1123 Provides enforcement of RDMA resour 1093 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1094 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1095 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1096 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1097 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1098 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1099
1130 config CGROUP_FREEZER 1100 config CGROUP_FREEZER
1131 bool "Freezer controller" 1101 bool "Freezer controller"
1132 help 1102 help
1133 Provides a way to freeze and unfree 1103 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1104 cgroup.
1135 1105
1136 This option affects the ORIGINAL cg 1106 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1107 controller includes important in-kernel memory consumers per default.
1138 1108
1139 If you're using cgroup2, say N. 1109 If you're using cgroup2, say N.
1140 1110
1141 config CGROUP_HUGETLB 1111 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1112 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1113 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1114 select PAGE_COUNTER
1145 default n 1115 default n
1146 help 1116 help
1147 Provides a cgroup controller for Hu 1117 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1118 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1119 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1120 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1121 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1122 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1123 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1124 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1125 that we cannot use the controller with huge page less than 3 pages.
1156 1126
1157 config CPUSETS 1127 config CPUSETS
1158 bool "Cpuset controller" 1128 bool "Cpuset controller"
1159 depends on SMP 1129 depends on SMP
1160 help 1130 help
1161 This option will let you create and 1131 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1132 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1133 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1134 This is primarily useful on large SMP or NUMA systems.
1165 1135
1166 Say N if unsure. 1136 Say N if unsure.
1167 1137
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 1138 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1139 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1140 depends on CPUSETS
1184 default y 1141 default y
1185 1142
1186 config CGROUP_DEVICE 1143 config CGROUP_DEVICE
1187 bool "Device controller" 1144 bool "Device controller"
1188 help 1145 help
1189 Provides a cgroup controller implem 1146 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1147 devices which a process in the cgroup can mknod or open.
1191 1148
1192 config CGROUP_CPUACCT 1149 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1150 bool "Simple CPU accounting controller"
1194 help 1151 help
1195 Provides a simple controller for mo 1152 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1153 total CPU consumed by the tasks in a cgroup.
1197 1154
1198 config CGROUP_PERF 1155 config CGROUP_PERF
1199 bool "Perf controller" 1156 bool "Perf controller"
1200 depends on PERF_EVENTS 1157 depends on PERF_EVENTS
1201 help 1158 help
1202 This option extends the perf per-cp 1159 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1160 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use 1161 designated cpu. Or this can be used to have cgroup ID in samples
1205 so that it can monitor performance 1162 so that it can monitor performance events among cgroups.
1206 1163
1207 Say N if unsure. 1164 Say N if unsure.
1208 1165
1209 config CGROUP_BPF 1166 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1167 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1168 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1169 select SOCK_CGROUP_DATA
1213 help 1170 help
1214 Allow attaching eBPF programs to a 1171 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1172 syscall command BPF_PROG_ATTACH.
1216 1173
1217 In which context these programs are 1174 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1175 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1176 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1177 inet sockets.
1221 1178
1222 config CGROUP_MISC 1179 config CGROUP_MISC
1223 bool "Misc resource controller" 1180 bool "Misc resource controller"
1224 default n 1181 default n
1225 help 1182 help
1226 Provides a controller for miscellan 1183 Provides a controller for miscellaneous resources on a host.
1227 1184
1228 Miscellaneous scalar resources are 1185 Miscellaneous scalar resources are the resources on the host system
1229 which cannot be abstracted like the 1186 which cannot be abstracted like the other cgroups. This controller
1230 tracks and limits the miscellaneous 1187 tracks and limits the miscellaneous resources used by a process
1231 attached to a cgroup hierarchy. 1188 attached to a cgroup hierarchy.
1232 1189
1233 For more information, please check 1190 For more information, please check misc cgroup section in
1234 /Documentation/admin-guide/cgroup-v 1191 /Documentation/admin-guide/cgroup-v2.rst.
1235 1192
1236 config CGROUP_DEBUG 1193 config CGROUP_DEBUG
1237 bool "Debug controller" 1194 bool "Debug controller"
1238 default n 1195 default n
1239 depends on DEBUG_KERNEL 1196 depends on DEBUG_KERNEL
1240 help 1197 help
1241 This option enables a simple contro 1198 This option enables a simple controller that exports
1242 debugging information about the cgr 1199 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1200 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1201 interfaces are not stable.
1245 1202
1246 Say N. 1203 Say N.
1247 1204
1248 config SOCK_CGROUP_DATA 1205 config SOCK_CGROUP_DATA
1249 bool 1206 bool
1250 default n 1207 default n
1251 1208
1252 endif # CGROUPS 1209 endif # CGROUPS
1253 1210
1254 menuconfig NAMESPACES 1211 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1212 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1213 depends on MULTIUSER
1257 default !EXPERT 1214 default !EXPERT
1258 help 1215 help
1259 Provides the way to make tasks work 1216 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1217 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1218 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1219 different namespaces.
1263 1220
1264 if NAMESPACES 1221 if NAMESPACES
1265 1222
1266 config UTS_NS 1223 config UTS_NS
1267 bool "UTS namespace" 1224 bool "UTS namespace"
1268 default y 1225 default y
1269 help 1226 help
1270 In this namespace tasks see differe 1227 In this namespace tasks see different info provided with the
1271 uname() system call 1228 uname() system call
1272 1229
1273 config TIME_NS 1230 config TIME_NS
1274 bool "TIME namespace" 1231 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1232 depends on GENERIC_VDSO_TIME_NS
1276 default y 1233 default y
1277 help 1234 help
1278 In this namespace boottime and mono 1235 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1236 The time will keep going with the same pace.
1280 1237
1281 config IPC_NS 1238 config IPC_NS
1282 bool "IPC namespace" 1239 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1240 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1241 default y
1285 help 1242 help
1286 In this namespace tasks work with I 1243 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1244 different IPC objects in different namespaces.
1288 1245
1289 config USER_NS 1246 config USER_NS
1290 bool "User namespace" 1247 bool "User namespace"
1291 default n 1248 default n
1292 help 1249 help
1293 This allows containers, i.e. vserve 1250 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1251 to provide different user info for different servers.
1295 1252
1296 When user namespaces are enabled in 1253 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1254 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1255 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1256 of memory a memory unprivileged users can use.
1300 1257
1301 If unsure, say N. 1258 If unsure, say N.
1302 1259
1303 config PID_NS 1260 config PID_NS
1304 bool "PID Namespaces" 1261 bool "PID Namespaces"
1305 default y 1262 default y
1306 help 1263 help
1307 Support process id namespaces. Thi 1264 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1265 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1266 pid namespaces. This is a building block of containers.
1310 1267
1311 config NET_NS 1268 config NET_NS
1312 bool "Network namespace" 1269 bool "Network namespace"
1313 depends on NET 1270 depends on NET
1314 default y 1271 default y
1315 help 1272 help
1316 Allow user space to create what app 1273 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1274 of the network stack.
1318 1275
1319 endif # NAMESPACES 1276 endif # NAMESPACES
1320 1277
1321 config CHECKPOINT_RESTORE 1278 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1279 bool "Checkpoint/restore support"
1323 depends on PROC_FS 1280 depends on PROC_FS
1324 select PROC_CHILDREN 1281 select PROC_CHILDREN
1325 select KCMP 1282 select KCMP
1326 default n 1283 default n
1327 help 1284 help
1328 Enables additional kernel features 1285 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1286 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1287 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1288 entries.
1332 1289
1333 If unsure, say N here. 1290 If unsure, say N here.
1334 1291
1335 config SCHED_AUTOGROUP 1292 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1293 bool "Automatic process group scheduling"
1337 select CGROUPS 1294 select CGROUPS
1338 select CGROUP_SCHED 1295 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1296 select FAIR_GROUP_SCHED
1340 help 1297 help
1341 This option optimizes the scheduler 1298 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1299 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1300 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1301 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1302 upon task session.
1346 1303
>> 1304 config SYSFS_DEPRECATED
>> 1305 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1306 depends on SYSFS
>> 1307 default n
>> 1308 help
>> 1309 This option adds code that switches the layout of the "block" class
>> 1310 devices, to not show up in /sys/class/block/, but only in
>> 1311 /sys/block/.
>> 1312
>> 1313 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1314 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1315
>> 1316 This option allows new kernels to run on old distributions and tools,
>> 1317 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1318 major distributions and tools handle this just fine.
>> 1319
>> 1320 Recent distributions and userspace tools after 2009/2010 depend on
>> 1321 the existence of /sys/class/block/, and will not work with this
>> 1322 option enabled.
>> 1323
>> 1324 Only if you are using a new kernel on an old distribution, you might
>> 1325 need to say Y here.
>> 1326
>> 1327 config SYSFS_DEPRECATED_V2
>> 1328 bool "Enable deprecated sysfs features by default"
>> 1329 default n
>> 1330 depends on SYSFS
>> 1331 depends on SYSFS_DEPRECATED
>> 1332 help
>> 1333 Enable deprecated sysfs by default.
>> 1334
>> 1335 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1336 option.
>> 1337
>> 1338 Only if you are using a new kernel on an old distribution, you might
>> 1339 need to say Y here. Even then, odds are you would not need it
>> 1340 enabled, you can always pass the boot option if absolutely necessary.
>> 1341
1347 config RELAY 1342 config RELAY
1348 bool "Kernel->user space relay suppor 1343 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1344 select IRQ_WORK
1350 help 1345 help
1351 This option enables support for rel 1346 This option enables support for relay interface support in
1352 certain file systems (such as debug 1347 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1348 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1349 facilities to relay large amounts of data from kernel space to
1355 user space. 1350 user space.
1356 1351
1357 If unsure, say N. 1352 If unsure, say N.
1358 1353
1359 config BLK_DEV_INITRD 1354 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1355 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1356 help
1362 The initial RAM filesystem is a ram 1357 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1358 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1359 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1360 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1361 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1362
1368 If RAM disk support (BLK_DEV_RAM) i 1363 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1364 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1365 15 Kbytes (more on some other architectures) to the kernel size.
1371 1366
1372 If unsure say Y. 1367 If unsure say Y.
1373 1368
1374 if BLK_DEV_INITRD 1369 if BLK_DEV_INITRD
1375 1370
1376 source "usr/Kconfig" 1371 source "usr/Kconfig"
1377 1372
1378 endif 1373 endif
1379 1374
1380 config BOOT_CONFIG 1375 config BOOT_CONFIG
1381 bool "Boot config support" 1376 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG 1377 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1383 help 1378 help
1384 Extra boot config allows system adm 1379 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1380 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1381 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1382 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1383 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1384
1390 If unsure, say Y. 1385 If unsure, say Y.
1391 1386
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 1387 config BOOT_CONFIG_EMBED
1406 bool "Embed bootconfig file in the ke 1388 bool "Embed bootconfig file in the kernel"
1407 depends on BOOT_CONFIG 1389 depends on BOOT_CONFIG
1408 help 1390 help
1409 Embed a bootconfig file given by BO 1391 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1410 kernel. Usually, the bootconfig fil 1392 kernel. Usually, the bootconfig file is loaded with the initrd
1411 image. But if the system doesn't su 1393 image. But if the system doesn't support initrd, this option will
1412 help you by embedding a bootconfig 1394 help you by embedding a bootconfig file while building the kernel.
1413 1395
1414 If unsure, say N. 1396 If unsure, say N.
1415 1397
1416 config BOOT_CONFIG_EMBED_FILE 1398 config BOOT_CONFIG_EMBED_FILE
1417 string "Embedded bootconfig file path 1399 string "Embedded bootconfig file path"
1418 depends on BOOT_CONFIG_EMBED 1400 depends on BOOT_CONFIG_EMBED
1419 help 1401 help
1420 Specify a bootconfig file which wil 1402 Specify a bootconfig file which will be embedded to the kernel.
1421 This bootconfig will be used if the 1403 This bootconfig will be used if there is no initrd or no other
1422 bootconfig in the initrd. 1404 bootconfig in the initrd.
1423 1405
1424 config INITRAMFS_PRESERVE_MTIME 1406 config INITRAMFS_PRESERVE_MTIME
1425 bool "Preserve cpio archive mtimes in 1407 bool "Preserve cpio archive mtimes in initramfs"
1426 default y 1408 default y
1427 help 1409 help
1428 Each entry in an initramfs cpio arc 1410 Each entry in an initramfs cpio archive carries an mtime value. When
1429 enabled, extracted cpio items take 1411 enabled, extracted cpio items take this mtime, with directory mtime
1430 setting deferred until after creati 1412 setting deferred until after creation of any child entries.
1431 1413
1432 If unsure, say Y. 1414 If unsure, say Y.
1433 1415
1434 choice 1416 choice
1435 prompt "Compiler optimization level" 1417 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1418 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1419
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1420 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1421 bool "Optimize for performance (-O2)"
1440 help 1422 help
1441 This is the default optimization le 1423 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1424 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1425 helpful compile-time warnings.
1444 1426
1445 config CC_OPTIMIZE_FOR_SIZE 1427 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1428 bool "Optimize for size (-Os)"
1447 help 1429 help
1448 Choosing this option will pass "-Os 1430 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1431 in a smaller kernel.
1450 1432
1451 endchoice 1433 endchoice
1452 1434
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1435 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1436 bool
1455 help 1437 help
1456 This requires that the arch annotat 1438 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1439 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1440 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1441 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1442 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1443 is used to distinguish them from label names / C identifiers.
1462 1444
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1445 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1446 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1447 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1448 depends on EXPERT
1467 depends on $(cc-option,-ffunction-sec 1449 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1450 depends on $(ld-option,--gc-sections)
1469 help 1451 help
1470 Enable this if you want to do dead 1452 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1453 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1454 and linking with --gc-sections.
1473 1455
1474 This can reduce on disk and in-memo 1456 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1457 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1458 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1459 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1460 present. This option is not well tested yet, so use at your
1479 own risk. 1461 own risk.
1480 1462
1481 config LD_ORPHAN_WARN 1463 config LD_ORPHAN_WARN
1482 def_bool y 1464 def_bool y
1483 depends on ARCH_WANT_LD_ORPHAN_WARN 1465 depends on ARCH_WANT_LD_ORPHAN_WARN
1484 depends on $(ld-option,--orphan-handl 1466 depends on $(ld-option,--orphan-handling=warn)
1485 depends on $(ld-option,--orphan-handl <<
1486 <<
1487 config LD_ORPHAN_WARN_LEVEL <<
1488 string <<
1489 depends on LD_ORPHAN_WARN <<
1490 default "error" if WERROR <<
1491 default "warn" <<
1492 1467
1493 config SYSCTL 1468 config SYSCTL
1494 bool 1469 bool
1495 1470
1496 config HAVE_UID16 1471 config HAVE_UID16
1497 bool 1472 bool
1498 1473
1499 config SYSCTL_EXCEPTION_TRACE 1474 config SYSCTL_EXCEPTION_TRACE
1500 bool 1475 bool
1501 help 1476 help
1502 Enable support for /proc/sys/debug/ 1477 Enable support for /proc/sys/debug/exception-trace.
1503 1478
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1479 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1480 bool
1506 help 1481 help
1507 Enable support for /proc/sys/kernel 1482 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1483 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1484 about unaligned access emulation going on under the hood.
1510 1485
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1486 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1487 bool
1513 help 1488 help
1514 Enable support for /proc/sys/kernel 1489 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1490 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1491 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1492 see arch/parisc/kernel/unaligned.c for reference
1518 1493
1519 config HAVE_PCSPKR_PLATFORM 1494 config HAVE_PCSPKR_PLATFORM
1520 bool 1495 bool
1521 1496
>> 1497 # interpreter that classic socket filters depend on
>> 1498 config BPF
>> 1499 bool
>> 1500 select CRYPTO_LIB_SHA1
>> 1501
1522 menuconfig EXPERT 1502 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1503 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1504 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1505 select DEBUG_KERNEL
1526 help 1506 help
1527 This option allows certain base ker 1507 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1508 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1509 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1510 Only use this if you really know what you are doing.
1531 1511
1532 config UID16 1512 config UID16
1533 bool "Enable 16-bit UID system calls" 1513 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1514 depends on HAVE_UID16 && MULTIUSER
1535 default y 1515 default y
1536 help 1516 help
1537 This enables the legacy 16-bit UID 1517 This enables the legacy 16-bit UID syscall wrappers.
1538 1518
1539 config MULTIUSER 1519 config MULTIUSER
1540 bool "Multiple users, groups and capa 1520 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1521 default y
1542 help 1522 help
1543 This option enables support for non 1523 This option enables support for non-root users, groups and
1544 capabilities. 1524 capabilities.
1545 1525
1546 If you say N here, all processes wi 1526 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1527 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1528 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1529 setgid, and capset.
1550 1530
1551 If unsure, say Y here. 1531 If unsure, say Y here.
1552 1532
1553 config SGETMASK_SYSCALL 1533 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1534 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1535 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help 1536 help
1557 sys_sgetmask and sys_ssetmask are o 1537 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1538 no longer supported in libc but still enabled by default in some
1559 architectures. 1539 architectures.
1560 1540
1561 If unsure, leave the default option 1541 If unsure, leave the default option here.
1562 1542
1563 config SYSFS_SYSCALL 1543 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1544 bool "Sysfs syscall support" if EXPERT
1565 default y 1545 default y
1566 help 1546 help
1567 sys_sysfs is an obsolete system cal 1547 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1548 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1549 compatibility with some systems.
1570 1550
1571 If unsure say Y here. 1551 If unsure say Y here.
1572 1552
1573 config FHANDLE 1553 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1554 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1555 select EXPORTFS
1576 default y 1556 default y
1577 help 1557 help
1578 If you say Y here, a user level pro 1558 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1559 file names to handle and then later use the handle for
1580 different file system operations. T 1560 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1561 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1562 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1563 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1564 syscalls.
1585 1565
1586 config POSIX_TIMERS 1566 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1567 bool "Posix Clocks & timers" if EXPERT
1588 default y 1568 default y
1589 help 1569 help
1590 This includes native support for PO 1570 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1571 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1572 can be configured out to reduce the size of the kernel image.
1593 1573
1594 When this option is disabled, the f 1574 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1575 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1576 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1577 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1578 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1579 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1580
1601 If unsure say y. 1581 If unsure say y.
1602 1582
1603 config PRINTK 1583 config PRINTK
1604 default y 1584 default y
1605 bool "Enable support for printk" if E 1585 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1586 select IRQ_WORK
1607 help 1587 help
1608 This option enables normal printk s 1588 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1589 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1590 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1591 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1592 strongly discouraged.
1613 1593
1614 config BUG 1594 config BUG
1615 bool "BUG() support" if EXPERT 1595 bool "BUG() support" if EXPERT
1616 default y 1596 default y
1617 help 1597 help
1618 Disabling this option eliminates su 1598 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1599 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1600 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1601 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1602 Just say Y.
1623 1603
1624 config ELF_CORE 1604 config ELF_CORE
1625 depends on COREDUMP 1605 depends on COREDUMP
1626 default y 1606 default y
1627 bool "Enable ELF core dumps" if EXPER 1607 bool "Enable ELF core dumps" if EXPERT
1628 help 1608 help
1629 Enable support for generating core 1609 Enable support for generating core dumps. Disabling saves about 4k.
1630 1610
1631 1611
1632 config PCSPKR_PLATFORM 1612 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1613 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1614 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1615 select I8253_LOCK
1636 default y 1616 default y
1637 help 1617 help
1638 This option allows to disable the i 1618 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1619 support, saving some memory.
1640 1620
1641 config BASE_SMALL !! 1621 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1622 default y
>> 1623 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1624 help
1644 Enabling this option reduces the si !! 1625 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1626 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1627 but may reduce performance.
1647 1628
1648 config FUTEX 1629 config FUTEX
1649 bool "Enable futex support" if EXPERT 1630 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) 1631 depends on !(SPARC32 && SMP)
1651 default y 1632 default y
1652 imply RT_MUTEXES 1633 imply RT_MUTEXES
1653 help 1634 help
1654 Disabling this option will cause th 1635 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1636 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1637 run glibc-based applications correctly.
1657 1638
1658 config FUTEX_PI 1639 config FUTEX_PI
1659 bool 1640 bool
1660 depends on FUTEX && RT_MUTEXES 1641 depends on FUTEX && RT_MUTEXES
1661 default y 1642 default y
1662 1643
1663 config EPOLL 1644 config EPOLL
1664 bool "Enable eventpoll support" if EX 1645 bool "Enable eventpoll support" if EXPERT
1665 default y 1646 default y
1666 help 1647 help
1667 Disabling this option will cause th 1648 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1649 support for epoll family of system calls.
1669 1650
1670 config SIGNALFD 1651 config SIGNALFD
1671 bool "Enable signalfd() system call" 1652 bool "Enable signalfd() system call" if EXPERT
1672 default y 1653 default y
1673 help 1654 help
1674 Enable the signalfd() system call t 1655 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1656 on a file descriptor.
1676 1657
1677 If unsure, say Y. 1658 If unsure, say Y.
1678 1659
1679 config TIMERFD 1660 config TIMERFD
1680 bool "Enable timerfd() system call" i 1661 bool "Enable timerfd() system call" if EXPERT
1681 default y 1662 default y
1682 help 1663 help
1683 Enable the timerfd() system call th 1664 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1665 events on a file descriptor.
1685 1666
1686 If unsure, say Y. 1667 If unsure, say Y.
1687 1668
1688 config EVENTFD 1669 config EVENTFD
1689 bool "Enable eventfd() system call" i 1670 bool "Enable eventfd() system call" if EXPERT
1690 default y 1671 default y
1691 help 1672 help
1692 Enable the eventfd() system call th 1673 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1674 kernel notification (ie. KAIO) or userspace notifications.
1694 1675
1695 If unsure, say Y. 1676 If unsure, say Y.
1696 1677
1697 config SHMEM 1678 config SHMEM
1698 bool "Use full shmem filesystem" if E 1679 bool "Use full shmem filesystem" if EXPERT
1699 default y 1680 default y
1700 depends on MMU 1681 depends on MMU
1701 help 1682 help
1702 The shmem is an internal filesystem 1683 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1684 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1685 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1686 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1687 which may be appropriate on small systems without swap.
1707 1688
1708 config AIO 1689 config AIO
1709 bool "Enable AIO support" if EXPERT 1690 bool "Enable AIO support" if EXPERT
1710 default y 1691 default y
1711 help 1692 help
1712 This option enables POSIX asynchron 1693 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1694 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1695 this option saves about 7k.
1715 1696
1716 config IO_URING 1697 config IO_URING
1717 bool "Enable IO uring support" if EXP 1698 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ 1699 select IO_WQ
1719 default y 1700 default y
1720 help 1701 help
1721 This option enables support for the 1702 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1703 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1704 completion rings that are shared between the kernel and application.
1724 1705
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 1706 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1707 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1708 default y
1741 help 1709 help
1742 This option enables the madvise and 1710 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1711 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1712 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1713 applications use these syscalls, you can disable this option to save
1746 space. 1714 space.
1747 1715
1748 config MEMBARRIER 1716 config MEMBARRIER
1749 bool "Enable membarrier() system call 1717 bool "Enable membarrier() system call" if EXPERT
1750 default y 1718 default y
1751 help 1719 help
1752 Enable the membarrier() system call 1720 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1721 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1722 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1723 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1724 compiler barrier.
1757 1725
1758 If unsure, say Y. 1726 If unsure, say Y.
1759 1727
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 1728 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1729 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1730 default y
1813 help 1731 help
1814 Say Y here to let the kernel print 1732 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1733 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1734 somewhat, as all symbols have to be loaded into the kernel image.
1817 1735
1818 config KALLSYMS_SELFTEST <<
1819 bool "Test the basic functions and pe <<
1820 depends on KALLSYMS <<
1821 default n <<
1822 help <<
1823 Test the basic functions and perfor <<
1824 kallsyms_lookup_name. It also calcu <<
1825 kallsyms compression algorithm for <<
1826 <<
1827 Start self-test automatically after <<
1828 "dmesg | grep kallsyms_selftest" to <<
1829 displayed in the last line, indicat <<
1830 <<
1831 config KALLSYMS_ALL 1736 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1737 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1738 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1739 help
1835 Normally kallsyms only contains the 1740 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1741 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m 1742 sections). This is sufficient for most cases. And only if you want to
1838 enable kernel live patching, or oth 1743 enable kernel live patching, or other less common use cases (e.g.,
1839 when a debugger is used) all symbol 1744 when a debugger is used) all symbols are required (i.e., names of
1840 variables from the data sections, e 1745 variables from the data sections, etc).
1841 1746
1842 This option makes sure that all sym 1747 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1748 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1749 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1750 something like this).
1846 1751
1847 Say N unless you really need all sy 1752 Say N unless you really need all symbols, or kernel live patching.
1848 1753
1849 config KALLSYMS_ABSOLUTE_PERCPU 1754 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1755 bool
1851 depends on KALLSYMS 1756 depends on KALLSYMS
1852 default X86_64 && SMP 1757 default X86_64 && SMP
1853 1758
>> 1759 config KALLSYMS_BASE_RELATIVE
>> 1760 bool
>> 1761 depends on KALLSYMS
>> 1762 default !IA64
>> 1763 help
>> 1764 Instead of emitting them as absolute values in the native word size,
>> 1765 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1766 each containing a relative value in the range [base, base + U32_MAX]
>> 1767 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1768 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1769 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1770 address encountered in the image.
>> 1771
>> 1772 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1773 but more importantly, it results in entries whose values are build
>> 1774 time constants, and no relocation pass is required at runtime to fix
>> 1775 up the entries based on the runtime load address of the kernel.
>> 1776
1854 # end of the "standard kernel features (exper 1777 # end of the "standard kernel features (expert users)" menu
1855 1778
>> 1779 # syscall, maps, verifier
>> 1780
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1781 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1782 bool
1858 1783
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1784 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1785 bool
1861 1786
>> 1787 config KCMP
>> 1788 bool "Enable kcmp() system call" if EXPERT
>> 1789 help
>> 1790 Enable the kernel resource comparison system call. It provides
>> 1791 user-space with the ability to compare two processes to see if they
>> 1792 share a common resource, such as a file descriptor or even virtual
>> 1793 memory space.
>> 1794
>> 1795 If unsure, say N.
>> 1796
>> 1797 config RSEQ
>> 1798 bool "Enable rseq() system call" if EXPERT
>> 1799 default y
>> 1800 depends on HAVE_RSEQ
>> 1801 select MEMBARRIER
>> 1802 help
>> 1803 Enable the restartable sequences system call. It provides a
>> 1804 user-space cache for the current CPU number value, which
>> 1805 speeds up getting the current CPU number from user-space,
>> 1806 as well as an ABI to speed up user-space operations on
>> 1807 per-CPU data.
>> 1808
>> 1809 If unsure, say Y.
>> 1810
>> 1811 config DEBUG_RSEQ
>> 1812 default n
>> 1813 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1814 depends on RSEQ && DEBUG_KERNEL
>> 1815 help
>> 1816 Enable extra debugging checks for the rseq system call.
>> 1817
>> 1818 If unsure, say N.
>> 1819
>> 1820 config EMBEDDED
>> 1821 bool "Embedded system"
>> 1822 select EXPERT
>> 1823 help
>> 1824 This option should be enabled if compiling the kernel for
>> 1825 an embedded system so certain expert options are available
>> 1826 for configuration.
>> 1827
1862 config HAVE_PERF_EVENTS 1828 config HAVE_PERF_EVENTS
1863 bool 1829 bool
1864 help 1830 help
1865 See tools/perf/design.txt for detai 1831 See tools/perf/design.txt for details.
1866 1832
1867 config GUEST_PERF_EVENTS 1833 config GUEST_PERF_EVENTS
1868 bool 1834 bool
1869 depends on HAVE_PERF_EVENTS 1835 depends on HAVE_PERF_EVENTS
1870 1836
1871 config PERF_USE_VMALLOC 1837 config PERF_USE_VMALLOC
1872 bool 1838 bool
1873 help 1839 help
1874 See tools/perf/design.txt for detai 1840 See tools/perf/design.txt for details
1875 1841
>> 1842 config PC104
>> 1843 bool "PC/104 support" if EXPERT
>> 1844 help
>> 1845 Expose PC/104 form factor device drivers and options available for
>> 1846 selection and configuration. Enable this option if your target
>> 1847 machine has a PC/104 bus.
>> 1848
1876 menu "Kernel Performance Events And Counters" 1849 menu "Kernel Performance Events And Counters"
1877 1850
1878 config PERF_EVENTS 1851 config PERF_EVENTS
1879 bool "Kernel performance events and c 1852 bool "Kernel performance events and counters"
1880 default y if PROFILING 1853 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1854 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1855 select IRQ_WORK
>> 1856 select SRCU
1883 help 1857 help
1884 Enable kernel support for various p 1858 Enable kernel support for various performance events provided
1885 by software and hardware. 1859 by software and hardware.
1886 1860
1887 Software events are supported eithe 1861 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1862 use of generic tracepoints.
1889 1863
1890 Most modern CPUs support performanc 1864 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1865 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1866 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1867 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1868 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1869 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1870 used to profile the code that runs on that CPU.
1897 1871
1898 The Linux Performance Event subsyst 1872 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1873 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1874 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1875 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1876 capabilities on top of those.
1903 1877
1904 Say Y if unsure. 1878 Say Y if unsure.
1905 1879
1906 config DEBUG_PERF_USE_VMALLOC 1880 config DEBUG_PERF_USE_VMALLOC
1907 default n 1881 default n
1908 bool "Debug: use vmalloc to back perf 1882 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1883 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1884 select PERF_USE_VMALLOC
1911 help 1885 help
1912 Use vmalloc memory to back perf mma 1886 Use vmalloc memory to back perf mmap() buffers.
1913 1887
1914 Mostly useful for debugging the vma 1888 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1889 that don't require it.
1916 1890
1917 Say N if unsure. 1891 Say N if unsure.
1918 1892
1919 endmenu 1893 endmenu
1920 1894
1921 config SYSTEM_DATA_VERIFICATION 1895 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1896 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1897 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1898 select KEYS
1925 select CRYPTO 1899 select CRYPTO
1926 select CRYPTO_RSA 1900 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1901 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1902 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1903 select ASN1
1930 select OID_REGISTRY 1904 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1905 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1906 select PKCS7_MESSAGE_PARSER
1933 help 1907 help
1934 Provide PKCS#7 message verification 1908 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1909 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1910 module verification, kexec image verification and firmware blob
1937 verification. 1911 verification.
1938 1912
1939 config PROFILING 1913 config PROFILING
1940 bool "Profiling support" 1914 bool "Profiling support"
1941 help 1915 help
1942 Say Y here to enable the extended p 1916 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. 1917 by profilers.
1944 1918
1945 config RUST 1919 config RUST
1946 bool "Rust support" 1920 bool "Rust support"
1947 depends on HAVE_RUST 1921 depends on HAVE_RUST
1948 depends on RUST_IS_AVAILABLE 1922 depends on RUST_IS_AVAILABLE
>> 1923 depends on !CFI_CLANG
1949 depends on !MODVERSIONS 1924 depends on !MODVERSIONS
1950 depends on !GCC_PLUGIN_RANDSTRUCT !! 1925 depends on !GCC_PLUGINS
1951 depends on !RANDSTRUCT 1926 depends on !RANDSTRUCT
>> 1927 depends on !SHADOW_CALL_STACK
1952 depends on !DEBUG_INFO_BTF || PAHOLE_ 1928 depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
1953 depends on !CFI_CLANG || HAVE_CFI_ICA <<
1954 select CFI_ICALL_NORMALIZE_INTEGERS i <<
1955 depends on !CALL_PADDING || RUSTC_VER <<
1956 depends on !KASAN_SW_TAGS <<
1957 depends on !(MITIGATION_RETHUNK && KA <<
1958 help 1929 help
1959 Enables Rust support in the kernel. 1930 Enables Rust support in the kernel.
1960 1931
1961 This allows other Rust-related opti 1932 This allows other Rust-related options, like drivers written in Rust,
1962 to be selected. 1933 to be selected.
1963 1934
1964 It is also required to be able to l 1935 It is also required to be able to load external kernel modules
1965 written in Rust. 1936 written in Rust.
1966 1937
1967 See Documentation/rust/ for more in 1938 See Documentation/rust/ for more information.
1968 1939
1969 If unsure, say N. 1940 If unsure, say N.
1970 1941
1971 config RUSTC_VERSION_TEXT 1942 config RUSTC_VERSION_TEXT
1972 string 1943 string
1973 depends on RUST 1944 depends on RUST
1974 default "$(RUSTC_VERSION_TEXT)" !! 1945 default "$(shell,$(RUSTC) --version 2>/dev/null)"
1975 help <<
1976 See `CC_VERSION_TEXT`. <<
1977 1946
1978 config BINDGEN_VERSION_TEXT 1947 config BINDGEN_VERSION_TEXT
1979 string 1948 string
1980 depends on RUST 1949 depends on RUST
1981 # The dummy parameter `workaround-for 1950 # The dummy parameter `workaround-for-0.69.0` is required to support 0.69.0
1982 # (https://github.com/rust-lang/rust- 1951 # (https://github.com/rust-lang/rust-bindgen/pull/2678). It can be removed when
1983 # the minimum version is upgraded pas 1952 # the minimum version is upgraded past that (0.69.1 already fixed the issue).
1984 default "$(shell,$(BINDGEN) --version 1953 default "$(shell,$(BINDGEN) --version workaround-for-0.69.0 2>/dev/null)"
1985 1954
1986 # 1955 #
1987 # Place an empty function call at each tracep 1956 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1957 # dynamically changed for a probe function.
1989 # 1958 #
1990 config TRACEPOINTS 1959 config TRACEPOINTS
1991 bool 1960 bool
1992 1961
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1962 endmenu # General setup
1996 1963
1997 source "arch/Kconfig" 1964 source "arch/Kconfig"
1998 1965
1999 config RT_MUTEXES 1966 config RT_MUTEXES
2000 bool 1967 bool
2001 default y if PREEMPT_RT 1968 default y if PREEMPT_RT
2002 1969
>> 1970 config BASE_SMALL
>> 1971 int
>> 1972 default 0 if BASE_FULL
>> 1973 default 1 if !BASE_FULL
>> 1974
2003 config MODULE_SIG_FORMAT 1975 config MODULE_SIG_FORMAT
2004 def_bool n 1976 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 1977 select SYSTEM_DATA_VERIFICATION
2006 1978
2007 source "kernel/module/Kconfig" 1979 source "kernel/module/Kconfig"
2008 1980
2009 config INIT_ALL_POSSIBLE 1981 config INIT_ALL_POSSIBLE
2010 bool 1982 bool
2011 help 1983 help
2012 Back when each arch used to define 1984 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 1985 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 1986 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 1987 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 1988 and have several arch maintainers pursuing me down dark alleys.
2017 1989
2018 source "block/Kconfig" 1990 source "block/Kconfig"
2019 1991
2020 config PREEMPT_NOTIFIERS 1992 config PREEMPT_NOTIFIERS
2021 bool 1993 bool
2022 1994
2023 config PADATA 1995 config PADATA
2024 depends on SMP 1996 depends on SMP
2025 bool 1997 bool
2026 1998
2027 config ASN1 1999 config ASN1
2028 tristate 2000 tristate
2029 help 2001 help
2030 Build a simple ASN.1 grammar compil 2002 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2003 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2004 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2005 functions to call on what tags.
2034 2006
2035 source "kernel/Kconfig.locks" 2007 source "kernel/Kconfig.locks"
2036 2008
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2009 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2010 bool
2042 2011
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2012 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2013 bool
2045 2014
2046 # It may be useful for an architecture to ove 2015 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2016 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2017 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2018 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2019 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2020 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2021 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2022 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2023 def_bool n
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