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 <<
71 def_bool $(success,$(srctree)/scripts/ <<
72 help <<
73 This shows whether a suitable Rust t <<
74 <<
75 Please see Documentation/rust/quick- <<
76 to satisfy the build requirements of <<
77 <<
78 In particular, the Makefile target ' <<
79 why the Rust toolchain is not being <<
80 <<
81 config RUSTC_LLVM_VERSION <<
82 int <<
83 default $(rustc-llvm-version) <<
84 <<
85 config CC_CAN_LINK 63 config CC_CAN_LINK
86 bool 64 bool
87 default $(success,$(srctree)/scripts/c 65 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
88 default $(success,$(srctree)/scripts/c 66 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
89 67
90 config CC_CAN_LINK_STATIC 68 config CC_CAN_LINK_STATIC
91 bool 69 bool
92 default $(success,$(srctree)/scripts/c 70 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
93 default $(success,$(srctree)/scripts/c 71 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
94 72
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5 !! 73 config CC_HAS_ASM_GOTO
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id !! 74 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
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 75
104 config CC_HAS_ASM_GOTO_OUTPUT 76 config CC_HAS_ASM_GOTO_OUTPUT
105 def_bool y !! 77 depends on CC_HAS_ASM_GOTO
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN !! 78 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)
107 depends on $(success,echo 'int foo(int <<
108 79
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT 80 config CC_HAS_ASM_GOTO_TIED_OUTPUT
110 depends on CC_HAS_ASM_GOTO_OUTPUT 81 depends on CC_HAS_ASM_GOTO_OUTPUT
111 # Detect buggy gcc and clang, fixed in 82 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
112 def_bool $(success,echo 'int foo(int * !! 83 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .\n": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
113 84
114 config TOOLS_SUPPORT_RELR 85 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 86 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 87
117 config CC_HAS_ASM_INLINE 88 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 89 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 90
120 config CC_HAS_NO_PROFILE_FN_ATTR 91 config CC_HAS_NO_PROFILE_FN_ATTR
121 def_bool $(success,echo '__attribute__ 92 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
122 93
123 config PAHOLE_VERSION 94 config PAHOLE_VERSION
124 int 95 int
125 default $(shell,$(srctree)/scripts/pah 96 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
126 97
127 config CONSTRUCTORS 98 config CONSTRUCTORS
128 bool 99 bool
129 100
130 config IRQ_WORK 101 config IRQ_WORK
131 def_bool y if SMP !! 102 bool
132 103
133 config BUILDTIME_TABLE_SORT 104 config BUILDTIME_TABLE_SORT
134 bool 105 bool
135 106
136 config THREAD_INFO_IN_TASK 107 config THREAD_INFO_IN_TASK
137 bool 108 bool
138 help 109 help
139 Select this to move thread_info off 110 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 111 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 112 except flags and fix any runtime bugs.
142 113
143 One subtle change that will be neede 114 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 115 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 116
146 menu "General setup" 117 menu "General setup"
147 118
148 config BROKEN 119 config BROKEN
149 bool 120 bool
150 121
151 config BROKEN_ON_SMP 122 config BROKEN_ON_SMP
152 bool 123 bool
153 depends on BROKEN || !SMP 124 depends on BROKEN || !SMP
154 default y 125 default y
155 126
156 config INIT_ENV_ARG_LIMIT 127 config INIT_ENV_ARG_LIMIT
157 int 128 int
158 default 32 if !UML 129 default 32 if !UML
159 default 128 if UML 130 default 128 if UML
160 help 131 help
161 Maximum of each of the number of arg 132 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 133 variables passed to init from the kernel command line.
163 134
164 config COMPILE_TEST 135 config COMPILE_TEST
165 bool "Compile also drivers which will 136 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 137 depends on HAS_IOMEM
167 help 138 help
168 Some drivers can be compiled on a di 139 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 140 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 141 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 142 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 143 drivers to compile-test them.
173 144
174 If you are a developer and want to b 145 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 146 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 147 drivers to be distributed.
177 148
178 config WERROR 149 config WERROR
179 bool "Compile the kernel with warnings 150 bool "Compile the kernel with warnings as errors"
180 default COMPILE_TEST 151 default COMPILE_TEST
181 help 152 help
182 A kernel build should not cause any 153 A kernel build should not cause any compiler warnings, and this
183 enables the '-Werror' (for C) and '- !! 154 enables the '-Werror' flag to enforce that rule by default.
184 to enforce that rule by default. Cer <<
185 such as the linker may be upgraded t <<
186 well. <<
187 155
188 However, if you have a new (or very !! 156 However, if you have a new (or very old) compiler with odd and
189 and unusual warnings, or you have so !! 157 unusual warnings, or you have some architecture with problems,
190 you may need to disable this config 158 you may need to disable this config option in order to
191 successfully build the kernel. 159 successfully build the kernel.
192 160
193 If in doubt, say Y. 161 If in doubt, say Y.
194 162
195 config UAPI_HEADER_TEST 163 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 164 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 165 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 166 help
199 Compile test headers exported to use 167 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 168 self-contained, i.e. compilable as standalone units.
201 169
202 If you are a developer or tester and 170 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 171 headers are self-contained, say Y here. Otherwise, choose N.
204 172
205 config LOCALVERSION 173 config LOCALVERSION
206 string "Local version - append to kern 174 string "Local version - append to kernel release"
207 help 175 help
208 Append an extra string to the end of 176 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 177 This will show up when you type uname, for example.
210 The string you set here will be appe 178 The string you set here will be appended after the contents of
211 any files with a filename matching l 179 any files with a filename matching localversion* in your
212 object and source tree, in that orde 180 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 181 be a maximum of 64 characters.
214 182
215 config LOCALVERSION_AUTO 183 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 184 bool "Automatically append version information to the version string"
217 default y 185 default y
218 depends on !COMPILE_TEST 186 depends on !COMPILE_TEST
219 help 187 help
220 This will try to automatically deter 188 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 189 release tree by looking for git tags that belong to the current
222 top of tree revision. 190 top of tree revision.
223 191
224 A string of the format -gxxxxxxxx wi 192 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 193 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 194 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 195 set in CONFIG_LOCALVERSION.
228 196
229 (The actual string used here is the !! 197 (The actual string used here is the first eight characters produced
230 by running the command: 198 by running the command:
231 199
232 $ git rev-parse --verify HEAD 200 $ git rev-parse --verify HEAD
233 201
234 which is done within the script "scr 202 which is done within the script "scripts/setlocalversion".)
235 203
236 config BUILD_SALT 204 config BUILD_SALT
237 string "Build ID Salt" 205 string "Build ID Salt"
238 default "" 206 default ""
239 help 207 help
240 The build ID is used to link binarie 208 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 209 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 210 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 211 build is unique between builds. It's safe to leave the default.
244 212
245 config HAVE_KERNEL_GZIP 213 config HAVE_KERNEL_GZIP
246 bool 214 bool
247 215
248 config HAVE_KERNEL_BZIP2 216 config HAVE_KERNEL_BZIP2
249 bool 217 bool
250 218
251 config HAVE_KERNEL_LZMA 219 config HAVE_KERNEL_LZMA
252 bool 220 bool
253 221
254 config HAVE_KERNEL_XZ 222 config HAVE_KERNEL_XZ
255 bool 223 bool
256 224
257 config HAVE_KERNEL_LZO 225 config HAVE_KERNEL_LZO
258 bool 226 bool
259 227
260 config HAVE_KERNEL_LZ4 228 config HAVE_KERNEL_LZ4
261 bool 229 bool
262 230
263 config HAVE_KERNEL_ZSTD 231 config HAVE_KERNEL_ZSTD
264 bool 232 bool
265 233
266 config HAVE_KERNEL_UNCOMPRESSED 234 config HAVE_KERNEL_UNCOMPRESSED
267 bool 235 bool
268 236
269 choice 237 choice
270 prompt "Kernel compression mode" 238 prompt "Kernel compression mode"
271 default KERNEL_GZIP 239 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE 240 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 241 help
274 The linux kernel is a kind of self-e 242 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 243 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 244 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 245 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 246 Decompression speed is relevant at each boot.
279 247
280 If you have any problems with bzip2 248 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 249 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 250 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 251 supplied by Christian Ludwig)
284 252
285 High compression options are mostly 253 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 254 are low on disk space (embedded systems), but for whom ram
287 size matters less. 255 size matters less.
288 256
289 If in doubt, select 'gzip' 257 If in doubt, select 'gzip'
290 258
291 config KERNEL_GZIP 259 config KERNEL_GZIP
292 bool "Gzip" 260 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 261 depends on HAVE_KERNEL_GZIP
294 help 262 help
295 The old and tried gzip compression. 263 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 264 between compression ratio and decompression speed.
297 265
298 config KERNEL_BZIP2 266 config KERNEL_BZIP2
299 bool "Bzip2" 267 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 268 depends on HAVE_KERNEL_BZIP2
301 help 269 help
302 Its compression ratio and speed is i 270 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 271 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 272 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 273 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 274 will need at least 8MB RAM or more for booting.
307 275
308 config KERNEL_LZMA 276 config KERNEL_LZMA
309 bool "LZMA" 277 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 278 depends on HAVE_KERNEL_LZMA
311 help 279 help
312 This compression algorithm's ratio i 280 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 281 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 282 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 283
316 config KERNEL_XZ 284 config KERNEL_XZ
317 bool "XZ" 285 bool "XZ"
318 depends on HAVE_KERNEL_XZ 286 depends on HAVE_KERNEL_XZ
319 help 287 help
320 XZ uses the LZMA2 algorithm and inst 288 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 289 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 290 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 291 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 292 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 293 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 294
328 The speed is about the same as with 295 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 296 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 297 and LZO. Compression is slow.
331 298
332 config KERNEL_LZO 299 config KERNEL_LZO
333 bool "LZO" 300 bool "LZO"
334 depends on HAVE_KERNEL_LZO 301 depends on HAVE_KERNEL_LZO
335 help 302 help
336 Its compression ratio is the poorest 303 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 304 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 305 (both compression and decompression) is the fastest.
339 306
340 config KERNEL_LZ4 307 config KERNEL_LZ4
341 bool "LZ4" 308 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 309 depends on HAVE_KERNEL_LZ4
343 help 310 help
344 LZ4 is an LZ77-type compressor with 311 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 312 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 313 <https://code.google.com/p/lz4/>.
347 314
348 Its compression ratio is worse than 315 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 316 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 317 faster than LZO.
351 318
352 config KERNEL_ZSTD 319 config KERNEL_ZSTD
353 bool "ZSTD" 320 bool "ZSTD"
354 depends on HAVE_KERNEL_ZSTD 321 depends on HAVE_KERNEL_ZSTD
355 help 322 help
356 ZSTD is a compression algorithm targ 323 ZSTD is a compression algorithm targeting intermediate compression
357 with fast decompression speed. It wi 324 with fast decompression speed. It will compress better than GZIP and
358 decompress around the same speed as 325 decompress around the same speed as LZO, but slower than LZ4. You
359 will need at least 192 KB RAM or mor 326 will need at least 192 KB RAM or more for booting. The zstd command
360 line tool is required for compressio 327 line tool is required for compression.
361 328
362 config KERNEL_UNCOMPRESSED 329 config KERNEL_UNCOMPRESSED
363 bool "None" 330 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 331 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 332 help
366 Produce uncompressed kernel image. T 333 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 334 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 335 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 336 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 337 and jump right at uncompressed kernel image.
371 338
372 endchoice 339 endchoice
373 340
374 config DEFAULT_INIT 341 config DEFAULT_INIT
375 string "Default init path" 342 string "Default init path"
376 default "" 343 default ""
377 help 344 help
378 This option determines the default i 345 This option determines the default init for the system if no init=
379 option is passed on the kernel comma 346 option is passed on the kernel command line. If the requested path is
380 not present, we will still then move 347 not present, we will still then move on to attempting further
381 locations (e.g. /sbin/init, etc). If 348 locations (e.g. /sbin/init, etc). If this is empty, we will just use
382 the fallback list when init= is not 349 the fallback list when init= is not passed.
383 350
384 config DEFAULT_HOSTNAME 351 config DEFAULT_HOSTNAME
385 string "Default hostname" 352 string "Default hostname"
386 default "(none)" 353 default "(none)"
387 help 354 help
388 This option determines the default s 355 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 356 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 357 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 358 system more usable with less configuration.
392 359
393 config SYSVIPC 360 config SYSVIPC
394 bool "System V IPC" 361 bool "System V IPC"
395 help 362 help
396 Inter Process Communication is a sui 363 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 364 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 365 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 366 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 367 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 368 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 369 you'll need to say Y here.
403 370
404 You can find documentation about IPC 371 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 372 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 373 <http://www.tldp.org/guides.html>.
407 374
408 config SYSVIPC_SYSCTL 375 config SYSVIPC_SYSCTL
409 bool 376 bool
410 depends on SYSVIPC 377 depends on SYSVIPC
411 depends on SYSCTL 378 depends on SYSCTL
412 default y 379 default y
413 380
414 config SYSVIPC_COMPAT 381 config SYSVIPC_COMPAT
415 def_bool y 382 def_bool y
416 depends on COMPAT && SYSVIPC 383 depends on COMPAT && SYSVIPC
417 384
418 config POSIX_MQUEUE 385 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 386 bool "POSIX Message Queues"
420 depends on NET 387 depends on NET
421 help 388 help
422 POSIX variant of message queues is a 389 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 390 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 391 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 392 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 393 queues (functions mq_*) say Y here.
427 394
428 POSIX message queues are visible as 395 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 396 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 397 operations on message queues.
431 398
432 If unsure, say Y. 399 If unsure, say Y.
433 400
434 config POSIX_MQUEUE_SYSCTL 401 config POSIX_MQUEUE_SYSCTL
435 bool 402 bool
436 depends on POSIX_MQUEUE 403 depends on POSIX_MQUEUE
437 depends on SYSCTL 404 depends on SYSCTL
438 default y 405 default y
439 406
440 config WATCH_QUEUE 407 config WATCH_QUEUE
441 bool "General notification queue" 408 bool "General notification queue"
442 default n 409 default n
443 help 410 help
444 411
445 This is a general notification queue 412 This is a general notification queue for the kernel to pass events to
446 userspace by splicing them into pipe 413 userspace by splicing them into pipes. It can be used in conjunction
447 with watches for key/keyring change 414 with watches for key/keyring change notifications and device
448 notifications. 415 notifications.
449 416
450 See Documentation/core-api/watch_que !! 417 See Documentation/watch_queue.rst
451 418
452 config CROSS_MEMORY_ATTACH 419 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 420 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 421 depends on MMU
455 default y 422 default y
456 help 423 help
457 Enabling this option adds the system 424 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 425 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 426 to directly read from or write to another process' address space.
460 See the man page for more details. 427 See the man page for more details.
461 428
462 config USELIB 429 config USELIB
463 bool "uselib syscall (for libc5 and ea 430 bool "uselib syscall (for libc5 and earlier)"
464 default ALPHA || M68K || SPARC 431 default ALPHA || M68K || SPARC
465 help 432 help
466 This option enables the uselib sysca 433 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 434 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 435 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 436 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 437 running glibc can safely disable this.
471 438
472 config AUDIT 439 config AUDIT
473 bool "Auditing support" 440 bool "Auditing support"
474 depends on NET 441 depends on NET
475 help 442 help
476 Enable auditing infrastructure that 443 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 444 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 445 logging of avc messages output). System call auditing is included
479 on architectures which support it. 446 on architectures which support it.
480 447
481 config HAVE_ARCH_AUDITSYSCALL 448 config HAVE_ARCH_AUDITSYSCALL
482 bool 449 bool
483 450
484 config AUDITSYSCALL 451 config AUDITSYSCALL
485 def_bool y 452 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 453 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 454 select FSNOTIFY
488 455
489 source "kernel/irq/Kconfig" 456 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 457 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" 458 source "kernel/bpf/Kconfig"
492 source "kernel/Kconfig.preempt" 459 source "kernel/Kconfig.preempt"
493 460
494 menu "CPU/Task time and stats accounting" 461 menu "CPU/Task time and stats accounting"
495 462
496 config VIRT_CPU_ACCOUNTING 463 config VIRT_CPU_ACCOUNTING
497 bool 464 bool
498 465
499 choice 466 choice
500 prompt "Cputime accounting" 467 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 468 default TICK_CPU_ACCOUNTING if !PPC64
>> 469 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 470
503 # Kind of a stub config for the pure tick base 471 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 472 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 473 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 474 depends on !S390 && !NO_HZ_FULL
507 help 475 help
508 This is the basic tick based cputime 476 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 477 statistics about user, system and idle time spent on per jiffies
510 granularity. 478 granularity.
511 479
512 If unsure, say Y. 480 If unsure, say Y.
513 481
514 config VIRT_CPU_ACCOUNTING_NATIVE 482 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 483 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 484 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 485 select VIRT_CPU_ACCOUNTING
518 help 486 help
519 Select this option to enable more ac 487 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 488 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 489 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 490 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 491 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 492 this also enables accounting of stolen time on logically-partitioned
525 systems. 493 systems.
526 494
527 config VIRT_CPU_ACCOUNTING_GEN 495 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 496 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 497 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 498 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 499 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 500 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 501 select CONTEXT_TRACKING
534 help 502 help
535 Select this option to enable task an 503 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 504 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 505 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 506 The accounting is thus performed at the expense of some significant
539 overhead. 507 overhead.
540 508
541 For now this is only useful if you a 509 For now this is only useful if you are working on the full
542 dynticks subsystem development. 510 dynticks subsystem development.
543 511
544 If unsure, say N. 512 If unsure, say N.
545 513
546 endchoice 514 endchoice
547 515
548 config IRQ_TIME_ACCOUNTING 516 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 517 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 518 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 519 help
552 Select this option to enable fine gr 520 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 521 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 522 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 523 small performance impact.
556 524
557 If in doubt, say N here. 525 If in doubt, say N here.
558 526
559 config HAVE_SCHED_AVG_IRQ 527 config HAVE_SCHED_AVG_IRQ
560 def_bool y 528 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 529 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 530 depends on SMP
563 531
564 config SCHED_HW_PRESSURE !! 532 config SCHED_THERMAL_PRESSURE
565 bool 533 bool
566 default y if ARM && ARM_CPU_TOPOLOGY 534 default y if ARM && ARM_CPU_TOPOLOGY
567 default y if ARM64 535 default y if ARM64
568 depends on SMP 536 depends on SMP
569 depends on CPU_FREQ_THERMAL 537 depends on CPU_FREQ_THERMAL
570 help 538 help
571 Select this option to enable HW pres !! 539 Select this option to enable thermal pressure accounting in the
572 scheduler. HW pressure is the value !! 540 scheduler. Thermal pressure is the value conveyed to the scheduler
573 that reflects the reduction in CPU c 541 that reflects the reduction in CPU compute capacity resulted from
574 HW throttling. HW throttling occurs !! 542 thermal throttling. Thermal throttling occurs when the performance of
575 a CPU is capped due to high operatin !! 543 a CPU is capped due to high operating temperatures.
576 544
577 If selected, the scheduler will be a 545 If selected, the scheduler will be able to balance tasks accordingly,
578 i.e. put less load on throttled CPUs 546 i.e. put less load on throttled CPUs than on non/less throttled ones.
579 547
580 This requires the architecture to im 548 This requires the architecture to implement
581 arch_update_hw_pressure() and arch_s !! 549 arch_update_thermal_pressure() and arch_scale_thermal_pressure().
582 550
583 config BSD_PROCESS_ACCT 551 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 552 bool "BSD Process Accounting"
585 depends on MULTIUSER 553 depends on MULTIUSER
586 help 554 help
587 If you say Y here, a user level prog 555 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 556 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 557 information to a file: whenever a process exits, information about
590 that process will be appended to the 558 that process will be appended to the file by the kernel. The
591 information includes things such as 559 information includes things such as creation time, owning user,
592 command name, memory usage, controll 560 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 561 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 562 up to the user level program to do useful things with this
595 information. This is generally a go 563 information. This is generally a good idea, so say Y.
596 564
597 config BSD_PROCESS_ACCT_V3 565 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 566 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 567 depends on BSD_PROCESS_ACCT
600 default n 568 default n
601 help 569 help
602 If you say Y here, the process accou 570 If you say Y here, the process accounting information is written
603 in a new file format that also logs 571 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 572 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 573 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 574 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 575 at <http://www.gnu.org/software/acct/>.
608 576
609 config TASKSTATS 577 config TASKSTATS
610 bool "Export task/process statistics t 578 bool "Export task/process statistics through netlink"
611 depends on NET 579 depends on NET
612 depends on MULTIUSER 580 depends on MULTIUSER
613 default n 581 default n
614 help 582 help
615 Export selected statistics for tasks 583 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 584 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 585 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 586 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 587 space on task exit.
620 588
621 Say N if unsure. 589 Say N if unsure.
622 590
623 config TASK_DELAY_ACCT 591 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 592 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 593 depends on TASKSTATS
626 select SCHED_INFO 594 select SCHED_INFO
627 help 595 help
628 Collect information on time spent by 596 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 597 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 598 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 599 relative to other tasks for cpu, io, rss limits etc.
632 600
633 Say N if unsure. 601 Say N if unsure.
634 602
635 config TASK_XACCT 603 config TASK_XACCT
636 bool "Enable extended accounting over 604 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 605 depends on TASKSTATS
638 help 606 help
639 Collect extended task accounting dat 607 Collect extended task accounting data and send the data
640 to userland for processing over the 608 to userland for processing over the taskstats interface.
641 609
642 Say N if unsure. 610 Say N if unsure.
643 611
644 config TASK_IO_ACCOUNTING 612 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 613 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 614 depends on TASK_XACCT
647 help 615 help
648 Collect information on the number of 616 Collect information on the number of bytes of storage I/O which this
649 task has caused. 617 task has caused.
650 618
651 Say N if unsure. 619 Say N if unsure.
652 620
653 config PSI 621 config PSI
654 bool "Pressure stall information track 622 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 623 help
657 Collect metrics that indicate how ov 624 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 625 and IO capacity are in the system.
659 626
660 If you say Y here, the kernel will c 627 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 628 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 629 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 630 delayed due to contention of the respective resource.
664 631
665 In kernels with cgroup support, cgro 632 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 633 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 634 which aggregate pressure stalls for the grouped tasks only.
668 635
669 For more details see Documentation/a 636 For more details see Documentation/accounting/psi.rst.
670 637
671 Say N if unsure. 638 Say N if unsure.
672 639
673 config PSI_DEFAULT_DISABLED 640 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 641 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 642 default n
676 depends on PSI 643 depends on PSI
677 help 644 help
678 If set, pressure stall information t 645 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 646 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 647 kernel commandline during boot.
681 648
682 This feature adds some code to the t 649 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 650 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 651 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 652 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 653 scheduler stress tests, such as hackbench.
687 654
688 If you are paranoid and not sure wha 655 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 656 used for, say Y.
690 657
691 Say N if unsure. 658 Say N if unsure.
692 659
693 endmenu # "CPU/Task time and stats accounting" 660 endmenu # "CPU/Task time and stats accounting"
694 661
695 config CPU_ISOLATION 662 config CPU_ISOLATION
696 bool "CPU isolation" 663 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 664 depends on SMP || COMPILE_TEST
698 default y 665 default y
699 help 666 help
700 Make sure that CPUs running critical 667 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 668 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 669 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 670 the "isolcpus=" boot parameter.
704 671
705 Say Y if unsure. 672 Say Y if unsure.
706 673
707 source "kernel/rcu/Kconfig" 674 source "kernel/rcu/Kconfig"
708 675
>> 676 config BUILD_BIN2C
>> 677 bool
>> 678 default n
>> 679
709 config IKCONFIG 680 config IKCONFIG
710 tristate "Kernel .config support" 681 tristate "Kernel .config support"
711 help 682 help
712 This option enables the complete Lin 683 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 684 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 685 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 686 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 687 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 688 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 689 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 690 /proc/config.gz if enabled (below).
720 691
721 config IKCONFIG_PROC 692 config IKCONFIG_PROC
722 bool "Enable access to .config through 693 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 694 depends on IKCONFIG && PROC_FS
724 help 695 help
725 This option enables access to the ke 696 This option enables access to the kernel configuration file
726 through /proc/config.gz. 697 through /proc/config.gz.
727 698
728 config IKHEADERS 699 config IKHEADERS
729 tristate "Enable kernel headers throug 700 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 701 depends on SYSFS
731 help 702 help
732 This option enables access to the in 703 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 704 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 705 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 706 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 707
737 config LOG_BUF_SHIFT 708 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 709 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 710 range 12 25
740 default 17 711 default 17
741 depends on PRINTK 712 depends on PRINTK
742 help 713 help
743 Select the minimal kernel log buffer 714 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 715 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 716 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 717 by "log_buf_len" boot parameter.
747 718
748 Examples: 719 Examples:
749 17 => 128 KB 720 17 => 128 KB
750 16 => 64 KB 721 16 => 64 KB
751 15 => 32 KB 722 15 => 32 KB
752 14 => 16 KB 723 14 => 16 KB
753 13 => 8 KB 724 13 => 8 KB
754 12 => 4 KB 725 12 => 4 KB
755 726
756 config LOG_CPU_MAX_BUF_SHIFT 727 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 728 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 729 depends on SMP
759 range 0 21 730 range 0 21
>> 731 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 732 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 733 depends on PRINTK
763 help 734 help
764 This option allows to increase the d 735 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 736 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 737 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 738 lines however it might be much more when problems are reported,
768 e.g. backtraces. 739 e.g. backtraces.
769 740
770 The increased size means that a new 741 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 742 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 743 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 744 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 745 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed 746 so that more than 16 CPUs are needed to trigger the allocation.
776 747
777 Also this option is ignored when "lo 748 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 749 used as it forces an exact (power of two) size of the ring buffer.
779 750
780 The number of possible CPUs is used 751 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 752 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 753 scenario while allowing a simple algorithm to be used from bootup.
783 754
784 Examples shift values and their mean 755 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 756 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 757 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 758 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 759 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 760 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 761 12 => 4 KB for each CPU
791 762
>> 763 config PRINTK_SAFE_LOG_BUF_SHIFT
>> 764 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
>> 765 range 10 21
>> 766 default 13
>> 767 depends on PRINTK
>> 768 help
>> 769 Select the size of an alternate printk per-CPU buffer where messages
>> 770 printed from usafe contexts are temporary stored. One example would
>> 771 be NMI messages, another one - printk recursion. The messages are
>> 772 copied to the main log buffer in a safe context to avoid a deadlock.
>> 773 The value defines the size as a power of 2.
>> 774
>> 775 Those messages are rare and limited. The largest one is when
>> 776 a backtrace is printed. It usually fits into 4KB. Select
>> 777 8KB if you want to be on the safe side.
>> 778
>> 779 Examples:
>> 780 17 => 128 KB for each CPU
>> 781 16 => 64 KB for each CPU
>> 782 15 => 32 KB for each CPU
>> 783 14 => 16 KB for each CPU
>> 784 13 => 8 KB for each CPU
>> 785 12 => 4 KB for each CPU
>> 786
792 config PRINTK_INDEX 787 config PRINTK_INDEX
793 bool "Printk indexing debugfs interfac 788 bool "Printk indexing debugfs interface"
794 depends on PRINTK && DEBUG_FS 789 depends on PRINTK && DEBUG_FS
795 help 790 help
796 Add support for indexing of all prin 791 Add support for indexing of all printk formats known at compile time
797 at <debugfs>/printk/index/<module>. 792 at <debugfs>/printk/index/<module>.
798 793
799 This can be used as part of maintain 794 This can be used as part of maintaining daemons which monitor
800 /dev/kmsg, as it permits auditing th 795 /dev/kmsg, as it permits auditing the printk formats present in a
801 kernel, allowing detection of cases 796 kernel, allowing detection of cases where monitored printks are
802 changed or no longer present. 797 changed or no longer present.
803 798
804 There is no additional runtime cost 799 There is no additional runtime cost to printk with this enabled.
805 800
806 # 801 #
807 # Architectures with an unreliable sched_clock 802 # Architectures with an unreliable sched_clock() should select this:
808 # 803 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 804 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 805 bool
811 806
812 config GENERIC_SCHED_CLOCK 807 config GENERIC_SCHED_CLOCK
813 bool 808 bool
814 809
815 menu "Scheduler features" 810 menu "Scheduler features"
816 811
817 config UCLAMP_TASK 812 config UCLAMP_TASK
818 bool "Enable utilization clamping for 813 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 814 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 815 help
821 This feature enables the scheduler t 816 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 817 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 818
824 With this option, the user can speci 819 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 820 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 821 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 822 defines the minimum frequency it should use.
828 823
829 Both min and max utilization clamp v 824 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 825 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 826 enforce or grant any specific bandwidth for tasks.
832 827
833 If in doubt, say N. 828 If in doubt, say N.
834 829
835 config UCLAMP_BUCKETS_COUNT 830 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 831 int "Number of supported utilization clamp buckets"
837 range 5 20 832 range 5 20
838 default 5 833 default 5
839 depends on UCLAMP_TASK 834 depends on UCLAMP_TASK
840 help 835 help
841 Defines the number of clamp buckets 836 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 837 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 838 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 839 the precision of clamping aggregation and tracking at run-time.
845 840
846 For example, with the minimum config 841 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 842 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 843 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 844 effective value to 25%.
850 If a second 30% boosted task should 845 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 846 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 847 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 848 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 849 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 850 that bucket.
856 851
857 An additional boost/capping margin c 852 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 853 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 854 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 855 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 856 clamp buckets to trade off used memory for run-time tracking
862 precision. 857 precision.
863 858
864 If in doubt, use the default value. 859 If in doubt, use the default value.
865 860
866 endmenu 861 endmenu
867 862
868 # 863 #
869 # For architectures that want to enable the su 864 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 865 # balancing logic:
871 # 866 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 867 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 868 bool
874 869
875 # 870 #
876 # For architectures that prefer to flush all T 871 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 872 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 873 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 874 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 875 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 876 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 877 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 878 bool
884 879
885 config CC_HAS_INT128 880 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 881 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 882
888 config CC_IMPLICIT_FALLTHROUGH 883 config CC_IMPLICIT_FALLTHROUGH
889 string 884 string
890 default "-Wimplicit-fallthrough=5" if 885 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
891 default "-Wimplicit-fallthrough" if CC 886 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
892 887
893 # Currently, disable gcc-10+ array-bounds glob !! 888 # Currently, disable gcc-12 array-bounds globally.
894 # It's still broken in gcc-13, so no upper bou !! 889 # We may want to target only particular configurations some day.
895 config GCC10_NO_ARRAY_BOUNDS !! 890 config GCC12_NO_ARRAY_BOUNDS
896 def_bool y 891 def_bool y
897 892
898 config CC_NO_ARRAY_BOUNDS 893 config CC_NO_ARRAY_BOUNDS
899 bool 894 bool
900 default y if CC_IS_GCC && GCC_VERSION !! 895 default y if CC_IS_GCC && GCC_VERSION >= 120000 && GCC_VERSION < 130000 && GCC12_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 <<
913 896
914 # 897 #
915 # For architectures that know their GCC __int1 898 # For architectures that know their GCC __int128 support is sound
916 # 899 #
917 config ARCH_SUPPORTS_INT128 900 config ARCH_SUPPORTS_INT128
918 bool 901 bool
919 902
920 # For architectures that (ab)use NUMA to repre 903 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 904 # all cpu-local but of different latencies, such as SuperH.
922 # 905 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 906 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 907 bool
925 908
926 config NUMA_BALANCING 909 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 910 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 911 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 912 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && 913 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
931 help 914 help
932 This option adds support for automat 915 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 916 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 917 it has references to the node the task is running on.
935 918
936 This system will be inactive on UMA 919 This system will be inactive on UMA systems.
937 920
938 config NUMA_BALANCING_DEFAULT_ENABLED 921 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 922 bool "Automatically enable NUMA aware memory/task placement"
940 default y 923 default y
941 depends on NUMA_BALANCING 924 depends on NUMA_BALANCING
942 help 925 help
943 If set, automatic NUMA balancing wil 926 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 927 machine.
945 928
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 929 menuconfig CGROUPS
950 bool "Control Group support" 930 bool "Control Group support"
951 select KERNFS 931 select KERNFS
952 help 932 help
953 This option adds support for groupin 933 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 934 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 935 controls or device isolation.
956 See 936 See
957 - Documentation/scheduler/sche 937 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 938 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 939 and resource control)
960 940
961 Say N if unsure. 941 Say N if unsure.
962 942
963 if CGROUPS 943 if CGROUPS
964 944
965 config PAGE_COUNTER 945 config PAGE_COUNTER
966 bool 946 bool
967 947
968 config CGROUP_FAVOR_DYNMODS <<
969 bool "Favor dynamic modification laten <<
970 help <<
971 This option enables the "favordynmod <<
972 which reduces the latencies of dynam <<
973 as task migrations and controller on <<
974 hot path operations such as forks an <<
975 <<
976 Say N if unsure. <<
977 <<
978 config MEMCG 948 config MEMCG
979 bool "Memory controller" 949 bool "Memory controller"
980 select PAGE_COUNTER 950 select PAGE_COUNTER
981 select EVENTFD 951 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 952 help
984 Provides control over the memory foo 953 Provides control over the memory footprint of tasks in a cgroup.
985 954
986 config MEMCG_V1 !! 955 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 956 bool
988 depends on MEMCG !! 957 depends on MEMCG && SWAP
989 default n !! 958 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 959
1001 Say N if unsure. !! 960 config MEMCG_KMEM
>> 961 bool
>> 962 depends on MEMCG && !SLOB
>> 963 default y
1002 964
1003 config BLK_CGROUP 965 config BLK_CGROUP
1004 bool "IO controller" 966 bool "IO controller"
1005 depends on BLOCK 967 depends on BLOCK
1006 default n 968 default n
1007 help 969 help
1008 Generic block IO controller cgroup in 970 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 971 cgroup interface which should be used by various IO controlling
1010 policies. 972 policies.
1011 973
1012 Currently, CFQ IO scheduler uses it t 974 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 975 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 976 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 977 block layer to implement upper limit in IO rates on a device.
1016 978
1017 This option only enables generic Bloc 979 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 980 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 981 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl 982 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 983 CONFIG_BLK_DEV_THROTTLING=y.
1022 984
1023 See Documentation/admin-guide/cgroup- 985 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 986
1025 config CGROUP_WRITEBACK 987 config CGROUP_WRITEBACK
1026 bool 988 bool
1027 depends on MEMCG && BLK_CGROUP 989 depends on MEMCG && BLK_CGROUP
1028 default y 990 default y
1029 991
1030 menuconfig CGROUP_SCHED 992 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 993 bool "CPU controller"
1032 default n 994 default n
1033 help 995 help
1034 This feature lets CPU scheduler rec 996 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 997 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 998 tasks.
1037 999
1038 if CGROUP_SCHED 1000 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 1001 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 1002 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 1003 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1004 default CGROUP_SCHED
1047 1005
1048 config CFS_BANDWIDTH 1006 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1007 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1008 depends on FAIR_GROUP_SCHED
1051 default n 1009 default n
1052 help 1010 help
1053 This option allows users to define 1011 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1012 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1013 set are considered to be unconstrained and will run with no
1056 restriction. 1014 restriction.
1057 See Documentation/scheduler/sched-b 1015 See Documentation/scheduler/sched-bwc.rst for more information.
1058 1016
1059 config RT_GROUP_SCHED 1017 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1018 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1019 depends on CGROUP_SCHED
1062 default n 1020 default n
1063 help 1021 help
1064 This feature lets you explicitly al 1022 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1023 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1024 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1025 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 1026 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 1027
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 1028 endif #CGROUP_SCHED
1077 1029
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 1030 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 1031 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 1032 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 1033 depends on UCLAMP_TASK
1086 default n 1034 default n
1087 help 1035 help
1088 This feature enables the scheduler 1036 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 1037 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 1038
1091 When this option is enabled, the us 1039 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 1040 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 1041 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 1042 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 1043 frequency a task will always use.
1096 1044
1097 When task group based utilization c 1045 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 1046 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 1047 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 1048 be bigger than the corresponding clamping defined at task group level.
1101 1049
1102 If in doubt, say N. 1050 If in doubt, say N.
1103 1051
1104 config CGROUP_PIDS 1052 config CGROUP_PIDS
1105 bool "PIDs controller" 1053 bool "PIDs controller"
1106 help 1054 help
1107 Provides enforcement of process num 1055 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1056 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1057 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1058 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1059 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1060 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1061 PIDs controller is designed to stop this from happening.
1114 1062
1115 It should be noted that organisatio 1063 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 1064 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 1065 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1066 attach to a cgroup.
1119 1067
1120 config CGROUP_RDMA 1068 config CGROUP_RDMA
1121 bool "RDMA controller" 1069 bool "RDMA controller"
1122 help 1070 help
1123 Provides enforcement of RDMA resour 1071 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1072 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1073 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1074 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1075 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1076 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1077
1130 config CGROUP_FREEZER 1078 config CGROUP_FREEZER
1131 bool "Freezer controller" 1079 bool "Freezer controller"
1132 help 1080 help
1133 Provides a way to freeze and unfree 1081 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1082 cgroup.
1135 1083
1136 This option affects the ORIGINAL cg 1084 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1085 controller includes important in-kernel memory consumers per default.
1138 1086
1139 If you're using cgroup2, say N. 1087 If you're using cgroup2, say N.
1140 1088
1141 config CGROUP_HUGETLB 1089 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1090 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1091 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1092 select PAGE_COUNTER
1145 default n 1093 default n
1146 help 1094 help
1147 Provides a cgroup controller for Hu 1095 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1096 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1097 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1098 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1099 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1100 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1101 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1102 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1103 that we cannot use the controller with huge page less than 3 pages.
1156 1104
1157 config CPUSETS 1105 config CPUSETS
1158 bool "Cpuset controller" 1106 bool "Cpuset controller"
1159 depends on SMP 1107 depends on SMP
1160 help 1108 help
1161 This option will let you create and 1109 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1110 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1111 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1112 This is primarily useful on large SMP or NUMA systems.
1165 1113
1166 Say N if unsure. 1114 Say N if unsure.
1167 1115
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 1116 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1117 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1118 depends on CPUSETS
1184 default y 1119 default y
1185 1120
1186 config CGROUP_DEVICE 1121 config CGROUP_DEVICE
1187 bool "Device controller" 1122 bool "Device controller"
1188 help 1123 help
1189 Provides a cgroup controller implem 1124 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1125 devices which a process in the cgroup can mknod or open.
1191 1126
1192 config CGROUP_CPUACCT 1127 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1128 bool "Simple CPU accounting controller"
1194 help 1129 help
1195 Provides a simple controller for mo 1130 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1131 total CPU consumed by the tasks in a cgroup.
1197 1132
1198 config CGROUP_PERF 1133 config CGROUP_PERF
1199 bool "Perf controller" 1134 bool "Perf controller"
1200 depends on PERF_EVENTS 1135 depends on PERF_EVENTS
1201 help 1136 help
1202 This option extends the perf per-cp 1137 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1138 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use 1139 designated cpu. Or this can be used to have cgroup ID in samples
1205 so that it can monitor performance 1140 so that it can monitor performance events among cgroups.
1206 1141
1207 Say N if unsure. 1142 Say N if unsure.
1208 1143
1209 config CGROUP_BPF 1144 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1145 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1146 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1147 select SOCK_CGROUP_DATA
1213 help 1148 help
1214 Allow attaching eBPF programs to a 1149 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1150 syscall command BPF_PROG_ATTACH.
1216 1151
1217 In which context these programs are 1152 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1153 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1154 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1155 inet sockets.
1221 1156
1222 config CGROUP_MISC 1157 config CGROUP_MISC
1223 bool "Misc resource controller" 1158 bool "Misc resource controller"
1224 default n 1159 default n
1225 help 1160 help
1226 Provides a controller for miscellan 1161 Provides a controller for miscellaneous resources on a host.
1227 1162
1228 Miscellaneous scalar resources are 1163 Miscellaneous scalar resources are the resources on the host system
1229 which cannot be abstracted like the 1164 which cannot be abstracted like the other cgroups. This controller
1230 tracks and limits the miscellaneous 1165 tracks and limits the miscellaneous resources used by a process
1231 attached to a cgroup hierarchy. 1166 attached to a cgroup hierarchy.
1232 1167
1233 For more information, please check 1168 For more information, please check misc cgroup section in
1234 /Documentation/admin-guide/cgroup-v 1169 /Documentation/admin-guide/cgroup-v2.rst.
1235 1170
1236 config CGROUP_DEBUG 1171 config CGROUP_DEBUG
1237 bool "Debug controller" 1172 bool "Debug controller"
1238 default n 1173 default n
1239 depends on DEBUG_KERNEL 1174 depends on DEBUG_KERNEL
1240 help 1175 help
1241 This option enables a simple contro 1176 This option enables a simple controller that exports
1242 debugging information about the cgr 1177 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1178 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1179 interfaces are not stable.
1245 1180
1246 Say N. 1181 Say N.
1247 1182
1248 config SOCK_CGROUP_DATA 1183 config SOCK_CGROUP_DATA
1249 bool 1184 bool
1250 default n 1185 default n
1251 1186
1252 endif # CGROUPS 1187 endif # CGROUPS
1253 1188
1254 menuconfig NAMESPACES 1189 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1190 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1191 depends on MULTIUSER
1257 default !EXPERT 1192 default !EXPERT
1258 help 1193 help
1259 Provides the way to make tasks work 1194 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1195 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1196 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1197 different namespaces.
1263 1198
1264 if NAMESPACES 1199 if NAMESPACES
1265 1200
1266 config UTS_NS 1201 config UTS_NS
1267 bool "UTS namespace" 1202 bool "UTS namespace"
1268 default y 1203 default y
1269 help 1204 help
1270 In this namespace tasks see differe 1205 In this namespace tasks see different info provided with the
1271 uname() system call 1206 uname() system call
1272 1207
1273 config TIME_NS 1208 config TIME_NS
1274 bool "TIME namespace" 1209 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1210 depends on GENERIC_VDSO_TIME_NS
1276 default y 1211 default y
1277 help 1212 help
1278 In this namespace boottime and mono 1213 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1214 The time will keep going with the same pace.
1280 1215
1281 config IPC_NS 1216 config IPC_NS
1282 bool "IPC namespace" 1217 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1218 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1219 default y
1285 help 1220 help
1286 In this namespace tasks work with I 1221 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1222 different IPC objects in different namespaces.
1288 1223
1289 config USER_NS 1224 config USER_NS
1290 bool "User namespace" 1225 bool "User namespace"
1291 default n 1226 default n
1292 help 1227 help
1293 This allows containers, i.e. vserve 1228 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1229 to provide different user info for different servers.
1295 1230
1296 When user namespaces are enabled in 1231 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1232 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1233 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1234 of memory a memory unprivileged users can use.
1300 1235
1301 If unsure, say N. 1236 If unsure, say N.
1302 1237
1303 config PID_NS 1238 config PID_NS
1304 bool "PID Namespaces" 1239 bool "PID Namespaces"
1305 default y 1240 default y
1306 help 1241 help
1307 Support process id namespaces. Thi 1242 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1243 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1244 pid namespaces. This is a building block of containers.
1310 1245
1311 config NET_NS 1246 config NET_NS
1312 bool "Network namespace" 1247 bool "Network namespace"
1313 depends on NET 1248 depends on NET
1314 default y 1249 default y
1315 help 1250 help
1316 Allow user space to create what app 1251 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1252 of the network stack.
1318 1253
1319 endif # NAMESPACES 1254 endif # NAMESPACES
1320 1255
1321 config CHECKPOINT_RESTORE 1256 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1257 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1258 select PROC_CHILDREN
1325 select KCMP 1259 select KCMP
1326 default n 1260 default n
1327 help 1261 help
1328 Enables additional kernel features 1262 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1263 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1264 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1265 entries.
1332 1266
1333 If unsure, say N here. 1267 If unsure, say N here.
1334 1268
1335 config SCHED_AUTOGROUP 1269 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1270 bool "Automatic process group scheduling"
1337 select CGROUPS 1271 select CGROUPS
1338 select CGROUP_SCHED 1272 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1273 select FAIR_GROUP_SCHED
1340 help 1274 help
1341 This option optimizes the scheduler 1275 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1276 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1277 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1278 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1279 upon task session.
1346 1280
>> 1281 config SYSFS_DEPRECATED
>> 1282 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1283 depends on SYSFS
>> 1284 default n
>> 1285 help
>> 1286 This option adds code that switches the layout of the "block" class
>> 1287 devices, to not show up in /sys/class/block/, but only in
>> 1288 /sys/block/.
>> 1289
>> 1290 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1291 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1292
>> 1293 This option allows new kernels to run on old distributions and tools,
>> 1294 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1295 major distributions and tools handle this just fine.
>> 1296
>> 1297 Recent distributions and userspace tools after 2009/2010 depend on
>> 1298 the existence of /sys/class/block/, and will not work with this
>> 1299 option enabled.
>> 1300
>> 1301 Only if you are using a new kernel on an old distribution, you might
>> 1302 need to say Y here.
>> 1303
>> 1304 config SYSFS_DEPRECATED_V2
>> 1305 bool "Enable deprecated sysfs features by default"
>> 1306 default n
>> 1307 depends on SYSFS
>> 1308 depends on SYSFS_DEPRECATED
>> 1309 help
>> 1310 Enable deprecated sysfs by default.
>> 1311
>> 1312 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1313 option.
>> 1314
>> 1315 Only if you are using a new kernel on an old distribution, you might
>> 1316 need to say Y here. Even then, odds are you would not need it
>> 1317 enabled, you can always pass the boot option if absolutely necessary.
>> 1318
1347 config RELAY 1319 config RELAY
1348 bool "Kernel->user space relay suppor 1320 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1321 select IRQ_WORK
1350 help 1322 help
1351 This option enables support for rel 1323 This option enables support for relay interface support in
1352 certain file systems (such as debug 1324 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1325 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1326 facilities to relay large amounts of data from kernel space to
1355 user space. 1327 user space.
1356 1328
1357 If unsure, say N. 1329 If unsure, say N.
1358 1330
1359 config BLK_DEV_INITRD 1331 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1332 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1333 help
1362 The initial RAM filesystem is a ram 1334 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1335 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1336 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1337 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1338 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1339
1368 If RAM disk support (BLK_DEV_RAM) i 1340 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1341 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1342 15 Kbytes (more on some other architectures) to the kernel size.
1371 1343
1372 If unsure say Y. 1344 If unsure say Y.
1373 1345
1374 if BLK_DEV_INITRD 1346 if BLK_DEV_INITRD
1375 1347
1376 source "usr/Kconfig" 1348 source "usr/Kconfig"
1377 1349
1378 endif 1350 endif
1379 1351
1380 config BOOT_CONFIG 1352 config BOOT_CONFIG
1381 bool "Boot config support" 1353 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG 1354 select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
1383 help 1355 help
1384 Extra boot config allows system adm 1356 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1357 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1358 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1359 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1360 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1361
1390 If unsure, say Y. 1362 If unsure, say Y.
1391 1363
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 1364 config BOOT_CONFIG_EMBED
1406 bool "Embed bootconfig file in the ke 1365 bool "Embed bootconfig file in the kernel"
1407 depends on BOOT_CONFIG 1366 depends on BOOT_CONFIG
1408 help 1367 help
1409 Embed a bootconfig file given by BO 1368 Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
1410 kernel. Usually, the bootconfig fil 1369 kernel. Usually, the bootconfig file is loaded with the initrd
1411 image. But if the system doesn't su 1370 image. But if the system doesn't support initrd, this option will
1412 help you by embedding a bootconfig 1371 help you by embedding a bootconfig file while building the kernel.
1413 1372
1414 If unsure, say N. 1373 If unsure, say N.
1415 1374
1416 config BOOT_CONFIG_EMBED_FILE 1375 config BOOT_CONFIG_EMBED_FILE
1417 string "Embedded bootconfig file path 1376 string "Embedded bootconfig file path"
1418 depends on BOOT_CONFIG_EMBED 1377 depends on BOOT_CONFIG_EMBED
1419 help 1378 help
1420 Specify a bootconfig file which wil 1379 Specify a bootconfig file which will be embedded to the kernel.
1421 This bootconfig will be used if the 1380 This bootconfig will be used if there is no initrd or no other
1422 bootconfig in the initrd. 1381 bootconfig in the initrd.
1423 1382
1424 config INITRAMFS_PRESERVE_MTIME 1383 config INITRAMFS_PRESERVE_MTIME
1425 bool "Preserve cpio archive mtimes in 1384 bool "Preserve cpio archive mtimes in initramfs"
1426 default y 1385 default y
1427 help 1386 help
1428 Each entry in an initramfs cpio arc 1387 Each entry in an initramfs cpio archive carries an mtime value. When
1429 enabled, extracted cpio items take 1388 enabled, extracted cpio items take this mtime, with directory mtime
1430 setting deferred until after creati 1389 setting deferred until after creation of any child entries.
1431 1390
1432 If unsure, say Y. 1391 If unsure, say Y.
1433 1392
1434 choice 1393 choice
1435 prompt "Compiler optimization level" 1394 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1395 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1396
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1397 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1398 bool "Optimize for performance (-O2)"
1440 help 1399 help
1441 This is the default optimization le 1400 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1401 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1402 helpful compile-time warnings.
1444 1403
>> 1404 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1405 bool "Optimize more for performance (-O3)"
>> 1406 depends on ARC
>> 1407 help
>> 1408 Choosing this option will pass "-O3" to your compiler to optimize
>> 1409 the kernel yet more for performance.
>> 1410
1445 config CC_OPTIMIZE_FOR_SIZE 1411 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1412 bool "Optimize for size (-Os)"
1447 help 1413 help
1448 Choosing this option will pass "-Os 1414 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1415 in a smaller kernel.
1450 1416
1451 endchoice 1417 endchoice
1452 1418
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1419 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1420 bool
1455 help 1421 help
1456 This requires that the arch annotat 1422 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1423 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1424 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1425 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1426 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1427 is used to distinguish them from label names / C identifiers.
1462 1428
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1429 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1430 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1431 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1432 depends on EXPERT
1467 depends on $(cc-option,-ffunction-sec 1433 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1434 depends on $(ld-option,--gc-sections)
1469 help 1435 help
1470 Enable this if you want to do dead 1436 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1437 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1438 and linking with --gc-sections.
1473 1439
1474 This can reduce on disk and in-memo 1440 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1441 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1442 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1443 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1444 present. This option is not well tested yet, so use at your
1479 own risk. 1445 own risk.
1480 1446
1481 config LD_ORPHAN_WARN 1447 config LD_ORPHAN_WARN
1482 def_bool y 1448 def_bool y
1483 depends on ARCH_WANT_LD_ORPHAN_WARN 1449 depends on ARCH_WANT_LD_ORPHAN_WARN
1484 depends on $(ld-option,--orphan-handl 1450 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 1451
1493 config SYSCTL 1452 config SYSCTL
1494 bool 1453 bool
1495 1454
1496 config HAVE_UID16 1455 config HAVE_UID16
1497 bool 1456 bool
1498 1457
1499 config SYSCTL_EXCEPTION_TRACE 1458 config SYSCTL_EXCEPTION_TRACE
1500 bool 1459 bool
1501 help 1460 help
1502 Enable support for /proc/sys/debug/ 1461 Enable support for /proc/sys/debug/exception-trace.
1503 1462
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1463 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1464 bool
1506 help 1465 help
1507 Enable support for /proc/sys/kernel 1466 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1467 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1468 about unaligned access emulation going on under the hood.
1510 1469
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1470 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1471 bool
1513 help 1472 help
1514 Enable support for /proc/sys/kernel 1473 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1474 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1475 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1476 see arch/parisc/kernel/unaligned.c for reference
1518 1477
1519 config HAVE_PCSPKR_PLATFORM 1478 config HAVE_PCSPKR_PLATFORM
1520 bool 1479 bool
1521 1480
>> 1481 # interpreter that classic socket filters depend on
>> 1482 config BPF
>> 1483 bool
>> 1484
1522 menuconfig EXPERT 1485 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1486 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1487 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1488 select DEBUG_KERNEL
1526 help 1489 help
1527 This option allows certain base ker 1490 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1491 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1492 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1493 Only use this if you really know what you are doing.
1531 1494
1532 config UID16 1495 config UID16
1533 bool "Enable 16-bit UID system calls" 1496 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1497 depends on HAVE_UID16 && MULTIUSER
1535 default y 1498 default y
1536 help 1499 help
1537 This enables the legacy 16-bit UID 1500 This enables the legacy 16-bit UID syscall wrappers.
1538 1501
1539 config MULTIUSER 1502 config MULTIUSER
1540 bool "Multiple users, groups and capa 1503 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1504 default y
1542 help 1505 help
1543 This option enables support for non 1506 This option enables support for non-root users, groups and
1544 capabilities. 1507 capabilities.
1545 1508
1546 If you say N here, all processes wi 1509 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1510 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1511 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1512 setgid, and capset.
1550 1513
1551 If unsure, say Y here. 1514 If unsure, say Y here.
1552 1515
1553 config SGETMASK_SYSCALL 1516 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1517 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1518 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help 1519 help
1557 sys_sgetmask and sys_ssetmask are o 1520 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1521 no longer supported in libc but still enabled by default in some
1559 architectures. 1522 architectures.
1560 1523
1561 If unsure, leave the default option 1524 If unsure, leave the default option here.
1562 1525
1563 config SYSFS_SYSCALL 1526 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1527 bool "Sysfs syscall support" if EXPERT
1565 default y 1528 default y
1566 help 1529 help
1567 sys_sysfs is an obsolete system cal 1530 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1531 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1532 compatibility with some systems.
1570 1533
1571 If unsure say Y here. 1534 If unsure say Y here.
1572 1535
1573 config FHANDLE 1536 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1537 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1538 select EXPORTFS
1576 default y 1539 default y
1577 help 1540 help
1578 If you say Y here, a user level pro 1541 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1542 file names to handle and then later use the handle for
1580 different file system operations. T 1543 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1544 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1545 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1546 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1547 syscalls.
1585 1548
1586 config POSIX_TIMERS 1549 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1550 bool "Posix Clocks & timers" if EXPERT
1588 default y 1551 default y
1589 help 1552 help
1590 This includes native support for PO 1553 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1554 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1555 can be configured out to reduce the size of the kernel image.
1593 1556
1594 When this option is disabled, the f 1557 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1558 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1559 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1560 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1561 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1562 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1563
1601 If unsure say y. 1564 If unsure say y.
1602 1565
1603 config PRINTK 1566 config PRINTK
1604 default y 1567 default y
1605 bool "Enable support for printk" if E 1568 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1569 select IRQ_WORK
1607 help 1570 help
1608 This option enables normal printk s 1571 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1572 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1573 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1574 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1575 strongly discouraged.
1613 1576
1614 config BUG 1577 config BUG
1615 bool "BUG() support" if EXPERT 1578 bool "BUG() support" if EXPERT
1616 default y 1579 default y
1617 help 1580 help
1618 Disabling this option eliminates su 1581 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1582 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1583 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1584 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1585 Just say Y.
1623 1586
1624 config ELF_CORE 1587 config ELF_CORE
1625 depends on COREDUMP 1588 depends on COREDUMP
1626 default y 1589 default y
1627 bool "Enable ELF core dumps" if EXPER 1590 bool "Enable ELF core dumps" if EXPERT
1628 help 1591 help
1629 Enable support for generating core 1592 Enable support for generating core dumps. Disabling saves about 4k.
1630 1593
1631 1594
1632 config PCSPKR_PLATFORM 1595 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1596 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1597 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1598 select I8253_LOCK
1636 default y 1599 default y
1637 help 1600 help
1638 This option allows to disable the i 1601 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1602 support, saving some memory.
1640 1603
1641 config BASE_SMALL !! 1604 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1605 default y
>> 1606 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1607 help
1644 Enabling this option reduces the si !! 1608 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1609 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1610 but may reduce performance.
1647 1611
1648 config FUTEX 1612 config FUTEX
1649 bool "Enable futex support" if EXPERT 1613 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) 1614 depends on !(SPARC32 && SMP)
1651 default y 1615 default y
1652 imply RT_MUTEXES 1616 imply RT_MUTEXES
1653 help 1617 help
1654 Disabling this option will cause th 1618 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1619 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1620 run glibc-based applications correctly.
1657 1621
1658 config FUTEX_PI 1622 config FUTEX_PI
1659 bool 1623 bool
1660 depends on FUTEX && RT_MUTEXES 1624 depends on FUTEX && RT_MUTEXES
1661 default y 1625 default y
1662 1626
1663 config EPOLL 1627 config EPOLL
1664 bool "Enable eventpoll support" if EX 1628 bool "Enable eventpoll support" if EXPERT
1665 default y 1629 default y
1666 help 1630 help
1667 Disabling this option will cause th 1631 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1632 support for epoll family of system calls.
1669 1633
1670 config SIGNALFD 1634 config SIGNALFD
1671 bool "Enable signalfd() system call" 1635 bool "Enable signalfd() system call" if EXPERT
1672 default y 1636 default y
1673 help 1637 help
1674 Enable the signalfd() system call t 1638 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1639 on a file descriptor.
1676 1640
1677 If unsure, say Y. 1641 If unsure, say Y.
1678 1642
1679 config TIMERFD 1643 config TIMERFD
1680 bool "Enable timerfd() system call" i 1644 bool "Enable timerfd() system call" if EXPERT
1681 default y 1645 default y
1682 help 1646 help
1683 Enable the timerfd() system call th 1647 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1648 events on a file descriptor.
1685 1649
1686 If unsure, say Y. 1650 If unsure, say Y.
1687 1651
1688 config EVENTFD 1652 config EVENTFD
1689 bool "Enable eventfd() system call" i 1653 bool "Enable eventfd() system call" if EXPERT
1690 default y 1654 default y
1691 help 1655 help
1692 Enable the eventfd() system call th 1656 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1657 kernel notification (ie. KAIO) or userspace notifications.
1694 1658
1695 If unsure, say Y. 1659 If unsure, say Y.
1696 1660
1697 config SHMEM 1661 config SHMEM
1698 bool "Use full shmem filesystem" if E 1662 bool "Use full shmem filesystem" if EXPERT
1699 default y 1663 default y
1700 depends on MMU 1664 depends on MMU
1701 help 1665 help
1702 The shmem is an internal filesystem 1666 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1667 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1668 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1669 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1670 which may be appropriate on small systems without swap.
1707 1671
1708 config AIO 1672 config AIO
1709 bool "Enable AIO support" if EXPERT 1673 bool "Enable AIO support" if EXPERT
1710 default y 1674 default y
1711 help 1675 help
1712 This option enables POSIX asynchron 1676 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1677 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1678 this option saves about 7k.
1715 1679
1716 config IO_URING 1680 config IO_URING
1717 bool "Enable IO uring support" if EXP 1681 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ 1682 select IO_WQ
1719 default y 1683 default y
1720 help 1684 help
1721 This option enables support for the 1685 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1686 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1687 completion rings that are shared between the kernel and application.
1724 1688
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 1689 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1690 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1691 default y
1741 help 1692 help
1742 This option enables the madvise and 1693 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1694 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1695 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1696 applications use these syscalls, you can disable this option to save
1746 space. 1697 space.
1747 1698
1748 config MEMBARRIER 1699 config MEMBARRIER
1749 bool "Enable membarrier() system call 1700 bool "Enable membarrier() system call" if EXPERT
1750 default y 1701 default y
1751 help 1702 help
1752 Enable the membarrier() system call 1703 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1704 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1705 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1706 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1707 compiler barrier.
1757 1708
1758 If unsure, say Y. 1709 If unsure, say Y.
1759 1710
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 1711 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1712 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1713 default y
1813 help 1714 help
1814 Say Y here to let the kernel print 1715 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1716 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1717 somewhat, as all symbols have to be loaded into the kernel image.
1817 1718
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 1719 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1720 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1721 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1722 help
1835 Normally kallsyms only contains the 1723 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1724 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m !! 1725 sections). This is sufficient for most cases. And only in very rare
1838 enable kernel live patching, or oth !! 1726 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1839 when a debugger is used) all symbol !! 1727 names of variables from the data sections, etc).
1840 variables from the data sections, e <<
1841 1728
1842 This option makes sure that all sym 1729 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1730 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1731 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1732 something like this).
1846 1733
1847 Say N unless you really need all sy !! 1734 Say N unless you really need all symbols.
1848 1735
1849 config KALLSYMS_ABSOLUTE_PERCPU 1736 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1737 bool
1851 depends on KALLSYMS 1738 depends on KALLSYMS
1852 default X86_64 && SMP 1739 default X86_64 && SMP
1853 1740
>> 1741 config KALLSYMS_BASE_RELATIVE
>> 1742 bool
>> 1743 depends on KALLSYMS
>> 1744 default !IA64
>> 1745 help
>> 1746 Instead of emitting them as absolute values in the native word size,
>> 1747 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1748 each containing a relative value in the range [base, base + U32_MAX]
>> 1749 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1750 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1751 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1752 address encountered in the image.
>> 1753
>> 1754 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1755 but more importantly, it results in entries whose values are build
>> 1756 time constants, and no relocation pass is required at runtime to fix
>> 1757 up the entries based on the runtime load address of the kernel.
>> 1758
1854 # end of the "standard kernel features (exper 1759 # end of the "standard kernel features (expert users)" menu
1855 1760
>> 1761 # syscall, maps, verifier
>> 1762
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1763 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1764 bool
1858 1765
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1766 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1767 bool
1861 1768
>> 1769 config KCMP
>> 1770 bool "Enable kcmp() system call" if EXPERT
>> 1771 help
>> 1772 Enable the kernel resource comparison system call. It provides
>> 1773 user-space with the ability to compare two processes to see if they
>> 1774 share a common resource, such as a file descriptor or even virtual
>> 1775 memory space.
>> 1776
>> 1777 If unsure, say N.
>> 1778
>> 1779 config RSEQ
>> 1780 bool "Enable rseq() system call" if EXPERT
>> 1781 default y
>> 1782 depends on HAVE_RSEQ
>> 1783 select MEMBARRIER
>> 1784 help
>> 1785 Enable the restartable sequences system call. It provides a
>> 1786 user-space cache for the current CPU number value, which
>> 1787 speeds up getting the current CPU number from user-space,
>> 1788 as well as an ABI to speed up user-space operations on
>> 1789 per-CPU data.
>> 1790
>> 1791 If unsure, say Y.
>> 1792
>> 1793 config DEBUG_RSEQ
>> 1794 default n
>> 1795 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1796 depends on RSEQ && DEBUG_KERNEL
>> 1797 help
>> 1798 Enable extra debugging checks for the rseq system call.
>> 1799
>> 1800 If unsure, say N.
>> 1801
>> 1802 config EMBEDDED
>> 1803 bool "Embedded system"
>> 1804 select EXPERT
>> 1805 help
>> 1806 This option should be enabled if compiling the kernel for
>> 1807 an embedded system so certain expert options are available
>> 1808 for configuration.
>> 1809
1862 config HAVE_PERF_EVENTS 1810 config HAVE_PERF_EVENTS
1863 bool 1811 bool
1864 help 1812 help
1865 See tools/perf/design.txt for detai 1813 See tools/perf/design.txt for details.
1866 1814
1867 config GUEST_PERF_EVENTS 1815 config GUEST_PERF_EVENTS
1868 bool 1816 bool
1869 depends on HAVE_PERF_EVENTS 1817 depends on HAVE_PERF_EVENTS
1870 1818
1871 config PERF_USE_VMALLOC 1819 config PERF_USE_VMALLOC
1872 bool 1820 bool
1873 help 1821 help
1874 See tools/perf/design.txt for detai 1822 See tools/perf/design.txt for details
1875 1823
>> 1824 config PC104
>> 1825 bool "PC/104 support" if EXPERT
>> 1826 help
>> 1827 Expose PC/104 form factor device drivers and options available for
>> 1828 selection and configuration. Enable this option if your target
>> 1829 machine has a PC/104 bus.
>> 1830
1876 menu "Kernel Performance Events And Counters" 1831 menu "Kernel Performance Events And Counters"
1877 1832
1878 config PERF_EVENTS 1833 config PERF_EVENTS
1879 bool "Kernel performance events and c 1834 bool "Kernel performance events and counters"
1880 default y if PROFILING 1835 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1836 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1837 select IRQ_WORK
>> 1838 select SRCU
1883 help 1839 help
1884 Enable kernel support for various p 1840 Enable kernel support for various performance events provided
1885 by software and hardware. 1841 by software and hardware.
1886 1842
1887 Software events are supported eithe 1843 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1844 use of generic tracepoints.
1889 1845
1890 Most modern CPUs support performanc 1846 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1847 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1848 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1849 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1850 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1851 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1852 used to profile the code that runs on that CPU.
1897 1853
1898 The Linux Performance Event subsyst 1854 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1855 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1856 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1857 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1858 capabilities on top of those.
1903 1859
1904 Say Y if unsure. 1860 Say Y if unsure.
1905 1861
1906 config DEBUG_PERF_USE_VMALLOC 1862 config DEBUG_PERF_USE_VMALLOC
1907 default n 1863 default n
1908 bool "Debug: use vmalloc to back perf 1864 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1865 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1866 select PERF_USE_VMALLOC
1911 help 1867 help
1912 Use vmalloc memory to back perf mma 1868 Use vmalloc memory to back perf mmap() buffers.
1913 1869
1914 Mostly useful for debugging the vma 1870 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1871 that don't require it.
1916 1872
1917 Say N if unsure. 1873 Say N if unsure.
1918 1874
1919 endmenu 1875 endmenu
1920 1876
1921 config SYSTEM_DATA_VERIFICATION 1877 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1878 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1879 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1880 select KEYS
1925 select CRYPTO 1881 select CRYPTO
1926 select CRYPTO_RSA 1882 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1883 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1884 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1885 select ASN1
1930 select OID_REGISTRY 1886 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1887 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1888 select PKCS7_MESSAGE_PARSER
1933 help 1889 help
1934 Provide PKCS#7 message verification 1890 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1891 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1892 module verification, kexec image verification and firmware blob
1937 verification. 1893 verification.
1938 1894
1939 config PROFILING 1895 config PROFILING
1940 bool "Profiling support" 1896 bool "Profiling support"
1941 help 1897 help
1942 Say Y here to enable the extended p 1898 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. 1899 by profilers.
1944 1900
1945 config RUST <<
1946 bool "Rust support" <<
1947 depends on HAVE_RUST <<
1948 depends on RUST_IS_AVAILABLE <<
1949 depends on !MODVERSIONS <<
1950 depends on !GCC_PLUGIN_RANDSTRUCT <<
1951 depends on !RANDSTRUCT <<
1952 depends on !DEBUG_INFO_BTF || PAHOLE_ <<
1953 depends on !CFI_CLANG || HAVE_CFI_ICA <<
1954 select CFI_ICALL_NORMALIZE_INTEGERS i <<
1955 depends on !CALL_PADDING || RUSTC_VER <<
1956 depends on !KASAN_SW_TAGS <<
1957 depends on !(MITIGATION_RETHUNK && KA <<
1958 help <<
1959 Enables Rust support in the kernel. <<
1960 <<
1961 This allows other Rust-related opti <<
1962 to be selected. <<
1963 <<
1964 It is also required to be able to l <<
1965 written in Rust. <<
1966 <<
1967 See Documentation/rust/ for more in <<
1968 <<
1969 If unsure, say N. <<
1970 <<
1971 config RUSTC_VERSION_TEXT <<
1972 string <<
1973 depends on RUST <<
1974 default "$(RUSTC_VERSION_TEXT)" <<
1975 help <<
1976 See `CC_VERSION_TEXT`. <<
1977 <<
1978 config BINDGEN_VERSION_TEXT <<
1979 string <<
1980 depends on RUST <<
1981 # The dummy parameter `workaround-for <<
1982 # (https://github.com/rust-lang/rust- <<
1983 # the minimum version is upgraded pas <<
1984 default "$(shell,$(BINDGEN) --version <<
1985 <<
1986 # 1901 #
1987 # Place an empty function call at each tracep 1902 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1903 # dynamically changed for a probe function.
1989 # 1904 #
1990 config TRACEPOINTS 1905 config TRACEPOINTS
1991 bool 1906 bool
1992 1907
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1908 endmenu # General setup
1996 1909
1997 source "arch/Kconfig" 1910 source "arch/Kconfig"
1998 1911
1999 config RT_MUTEXES 1912 config RT_MUTEXES
2000 bool 1913 bool
2001 default y if PREEMPT_RT 1914 default y if PREEMPT_RT
2002 1915
>> 1916 config BASE_SMALL
>> 1917 int
>> 1918 default 0 if BASE_FULL
>> 1919 default 1 if !BASE_FULL
>> 1920
2003 config MODULE_SIG_FORMAT 1921 config MODULE_SIG_FORMAT
2004 def_bool n 1922 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 1923 select SYSTEM_DATA_VERIFICATION
2006 1924
2007 source "kernel/module/Kconfig" !! 1925 menuconfig MODULES
>> 1926 bool "Enable loadable module support"
>> 1927 modules
>> 1928 help
>> 1929 Kernel modules are small pieces of compiled code which can
>> 1930 be inserted in the running kernel, rather than being
>> 1931 permanently built into the kernel. You use the "modprobe"
>> 1932 tool to add (and sometimes remove) them. If you say Y here,
>> 1933 many parts of the kernel can be built as modules (by
>> 1934 answering M instead of Y where indicated): this is most
>> 1935 useful for infrequently used options which are not required
>> 1936 for booting. For more information, see the man pages for
>> 1937 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1938
>> 1939 If you say Y here, you will need to run "make
>> 1940 modules_install" to put the modules under /lib/modules/
>> 1941 where modprobe can find them (you may need to be root to do
>> 1942 this).
>> 1943
>> 1944 If unsure, say Y.
>> 1945
>> 1946 if MODULES
>> 1947
>> 1948 config MODULE_FORCE_LOAD
>> 1949 bool "Forced module loading"
>> 1950 default n
>> 1951 help
>> 1952 Allow loading of modules without version information (ie. modprobe
>> 1953 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1954 is usually a really bad idea.
>> 1955
>> 1956 config MODULE_UNLOAD
>> 1957 bool "Module unloading"
>> 1958 help
>> 1959 Without this option you will not be able to unload any
>> 1960 modules (note that some modules may not be unloadable
>> 1961 anyway), which makes your kernel smaller, faster
>> 1962 and simpler. If unsure, say Y.
>> 1963
>> 1964 config MODULE_FORCE_UNLOAD
>> 1965 bool "Forced module unloading"
>> 1966 depends on MODULE_UNLOAD
>> 1967 help
>> 1968 This option allows you to force a module to unload, even if the
>> 1969 kernel believes it is unsafe: the kernel will remove the module
>> 1970 without waiting for anyone to stop using it (using the -f option to
>> 1971 rmmod). This is mainly for kernel developers and desperate users.
>> 1972 If unsure, say N.
>> 1973
>> 1974 config MODULE_UNLOAD_TAINT_TRACKING
>> 1975 bool "Tainted module unload tracking"
>> 1976 depends on MODULE_UNLOAD
>> 1977 default n
>> 1978 help
>> 1979 This option allows you to maintain a record of each unloaded
>> 1980 module that tainted the kernel. In addition to displaying a
>> 1981 list of linked (or loaded) modules e.g. on detection of a bad
>> 1982 page (see bad_page()), the aforementioned details are also
>> 1983 shown. If unsure, say N.
>> 1984
>> 1985 config MODVERSIONS
>> 1986 bool "Module versioning support"
>> 1987 help
>> 1988 Usually, you have to use modules compiled with your kernel.
>> 1989 Saying Y here makes it sometimes possible to use modules
>> 1990 compiled for different kernels, by adding enough information
>> 1991 to the modules to (hopefully) spot any changes which would
>> 1992 make them incompatible with the kernel you are running. If
>> 1993 unsure, say N.
>> 1994
>> 1995 config ASM_MODVERSIONS
>> 1996 bool
>> 1997 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 1998 help
>> 1999 This enables module versioning for exported symbols also from
>> 2000 assembly. This can be enabled only when the target architecture
>> 2001 supports it.
>> 2002
>> 2003 config MODULE_SRCVERSION_ALL
>> 2004 bool "Source checksum for all modules"
>> 2005 help
>> 2006 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2007 field inserted into their modinfo section, which contains a
>> 2008 sum of the source files which made it. This helps maintainers
>> 2009 see exactly which source was used to build a module (since
>> 2010 others sometimes change the module source without updating
>> 2011 the version). With this option, such a "srcversion" field
>> 2012 will be created for all modules. If unsure, say N.
>> 2013
>> 2014 config MODULE_SIG
>> 2015 bool "Module signature verification"
>> 2016 select MODULE_SIG_FORMAT
>> 2017 help
>> 2018 Check modules for valid signatures upon load: the signature
>> 2019 is simply appended to the module. For more information see
>> 2020 <file:Documentation/admin-guide/module-signing.rst>.
>> 2021
>> 2022 Note that this option adds the OpenSSL development packages as a
>> 2023 kernel build dependency so that the signing tool can use its crypto
>> 2024 library.
>> 2025
>> 2026 You should enable this option if you wish to use either
>> 2027 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2028 another LSM - otherwise unsigned modules will be loadable regardless
>> 2029 of the lockdown policy.
>> 2030
>> 2031 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2032 module DOES NOT get stripped after being signed. This includes the
>> 2033 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2034 inclusion into an initramfs that wants the module size reduced.
>> 2035
>> 2036 config MODULE_SIG_FORCE
>> 2037 bool "Require modules to be validly signed"
>> 2038 depends on MODULE_SIG
>> 2039 help
>> 2040 Reject unsigned modules or signed modules for which we don't have a
>> 2041 key. Without this, such modules will simply taint the kernel.
>> 2042
>> 2043 config MODULE_SIG_ALL
>> 2044 bool "Automatically sign all modules"
>> 2045 default y
>> 2046 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2047 help
>> 2048 Sign all modules during make modules_install. Without this option,
>> 2049 modules must be signed manually, using the scripts/sign-file tool.
>> 2050
>> 2051 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2052 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2053
>> 2054 choice
>> 2055 prompt "Which hash algorithm should modules be signed with?"
>> 2056 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2057 help
>> 2058 This determines which sort of hashing algorithm will be used during
>> 2059 signature generation. This algorithm _must_ be built into the kernel
>> 2060 directly so that signature verification can take place. It is not
>> 2061 possible to load a signed module containing the algorithm to check
>> 2062 the signature on that module.
>> 2063
>> 2064 config MODULE_SIG_SHA1
>> 2065 bool "Sign modules with SHA-1"
>> 2066 select CRYPTO_SHA1
>> 2067
>> 2068 config MODULE_SIG_SHA224
>> 2069 bool "Sign modules with SHA-224"
>> 2070 select CRYPTO_SHA256
>> 2071
>> 2072 config MODULE_SIG_SHA256
>> 2073 bool "Sign modules with SHA-256"
>> 2074 select CRYPTO_SHA256
>> 2075
>> 2076 config MODULE_SIG_SHA384
>> 2077 bool "Sign modules with SHA-384"
>> 2078 select CRYPTO_SHA512
>> 2079
>> 2080 config MODULE_SIG_SHA512
>> 2081 bool "Sign modules with SHA-512"
>> 2082 select CRYPTO_SHA512
>> 2083
>> 2084 endchoice
>> 2085
>> 2086 config MODULE_SIG_HASH
>> 2087 string
>> 2088 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2089 default "sha1" if MODULE_SIG_SHA1
>> 2090 default "sha224" if MODULE_SIG_SHA224
>> 2091 default "sha256" if MODULE_SIG_SHA256
>> 2092 default "sha384" if MODULE_SIG_SHA384
>> 2093 default "sha512" if MODULE_SIG_SHA512
>> 2094
>> 2095 choice
>> 2096 prompt "Module compression mode"
>> 2097 help
>> 2098 This option allows you to choose the algorithm which will be used to
>> 2099 compress modules when 'make modules_install' is run. (or, you can
>> 2100 choose to not compress modules at all.)
>> 2101
>> 2102 External modules will also be compressed in the same way during the
>> 2103 installation.
>> 2104
>> 2105 For modules inside an initrd or initramfs, it's more efficient to
>> 2106 compress the whole initrd or initramfs instead.
>> 2107
>> 2108 This is fully compatible with signed modules.
>> 2109
>> 2110 Please note that the tool used to load modules needs to support the
>> 2111 corresponding algorithm. module-init-tools MAY support gzip, and kmod
>> 2112 MAY support gzip, xz and zstd.
>> 2113
>> 2114 Your build system needs to provide the appropriate compression tool
>> 2115 to compress the modules.
>> 2116
>> 2117 If in doubt, select 'None'.
>> 2118
>> 2119 config MODULE_COMPRESS_NONE
>> 2120 bool "None"
>> 2121 help
>> 2122 Do not compress modules. The installed modules are suffixed
>> 2123 with .ko.
>> 2124
>> 2125 config MODULE_COMPRESS_GZIP
>> 2126 bool "GZIP"
>> 2127 help
>> 2128 Compress modules with GZIP. The installed modules are suffixed
>> 2129 with .ko.gz.
>> 2130
>> 2131 config MODULE_COMPRESS_XZ
>> 2132 bool "XZ"
>> 2133 help
>> 2134 Compress modules with XZ. The installed modules are suffixed
>> 2135 with .ko.xz.
>> 2136
>> 2137 config MODULE_COMPRESS_ZSTD
>> 2138 bool "ZSTD"
>> 2139 help
>> 2140 Compress modules with ZSTD. The installed modules are suffixed
>> 2141 with .ko.zst.
>> 2142
>> 2143 endchoice
>> 2144
>> 2145 config MODULE_DECOMPRESS
>> 2146 bool "Support in-kernel module decompression"
>> 2147 depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ
>> 2148 select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
>> 2149 select XZ_DEC if MODULE_COMPRESS_XZ
>> 2150 help
>> 2151
>> 2152 Support for decompressing kernel modules by the kernel itself
>> 2153 instead of relying on userspace to perform this task. Useful when
>> 2154 load pinning security policy is enabled.
>> 2155
>> 2156 If unsure, say N.
>> 2157
>> 2158 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2159 bool "Allow loading of modules with missing namespace imports"
>> 2160 help
>> 2161 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2162 a namespace. A module that makes use of a symbol exported with such a
>> 2163 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2164 There is no technical reason to enforce correct namespace imports,
>> 2165 but it creates consistency between symbols defining namespaces and
>> 2166 users importing namespaces they make use of. This option relaxes this
>> 2167 requirement and lifts the enforcement when loading a module.
>> 2168
>> 2169 If unsure, say N.
>> 2170
>> 2171 config MODPROBE_PATH
>> 2172 string "Path to modprobe binary"
>> 2173 default "/sbin/modprobe"
>> 2174 help
>> 2175 When kernel code requests a module, it does so by calling
>> 2176 the "modprobe" userspace utility. This option allows you to
>> 2177 set the path where that binary is found. This can be changed
>> 2178 at runtime via the sysctl file
>> 2179 /proc/sys/kernel/modprobe. Setting this to the empty string
>> 2180 removes the kernel's ability to request modules (but
>> 2181 userspace can still load modules explicitly).
>> 2182
>> 2183 config TRIM_UNUSED_KSYMS
>> 2184 bool "Trim unused exported kernel symbols" if EXPERT
>> 2185 depends on !COMPILE_TEST
>> 2186 help
>> 2187 The kernel and some modules make many symbols available for
>> 2188 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2189 on the set of modules being selected in your kernel configuration,
>> 2190 many of those exported symbols might never be used.
>> 2191
>> 2192 This option allows for unused exported symbols to be dropped from
>> 2193 the build. In turn, this provides the compiler more opportunities
>> 2194 (especially when using LTO) for optimizing the code and reducing
>> 2195 binary size. This might have some security advantages as well.
>> 2196
>> 2197 If unsure, or if you need to build out-of-tree modules, say N.
>> 2198
>> 2199 config UNUSED_KSYMS_WHITELIST
>> 2200 string "Whitelist of symbols to keep in ksymtab"
>> 2201 depends on TRIM_UNUSED_KSYMS
>> 2202 help
>> 2203 By default, all unused exported symbols will be un-exported from the
>> 2204 build when TRIM_UNUSED_KSYMS is selected.
>> 2205
>> 2206 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
>> 2207 exported at all times, even in absence of in-tree users. The value to
>> 2208 set here is the path to a text file containing the list of symbols,
>> 2209 one per line. The path can be absolute, or relative to the kernel
>> 2210 source tree.
>> 2211
>> 2212 endif # MODULES
>> 2213
>> 2214 config MODULES_TREE_LOOKUP
>> 2215 def_bool y
>> 2216 depends on PERF_EVENTS || TRACING || CFI_CLANG
2008 2217
2009 config INIT_ALL_POSSIBLE 2218 config INIT_ALL_POSSIBLE
2010 bool 2219 bool
2011 help 2220 help
2012 Back when each arch used to define 2221 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2222 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2223 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2224 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2225 and have several arch maintainers pursuing me down dark alleys.
2017 2226
2018 source "block/Kconfig" 2227 source "block/Kconfig"
2019 2228
2020 config PREEMPT_NOTIFIERS 2229 config PREEMPT_NOTIFIERS
2021 bool 2230 bool
2022 2231
2023 config PADATA 2232 config PADATA
2024 depends on SMP 2233 depends on SMP
2025 bool 2234 bool
2026 2235
2027 config ASN1 2236 config ASN1
2028 tristate 2237 tristate
2029 help 2238 help
2030 Build a simple ASN.1 grammar compil 2239 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2240 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2241 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2242 functions to call on what tags.
2034 2243
2035 source "kernel/Kconfig.locks" 2244 source "kernel/Kconfig.locks"
2036 2245
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2246 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2247 bool
2042 2248
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2249 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2250 bool
2045 2251
2046 # It may be useful for an architecture to ove 2252 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2253 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2254 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2255 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2256 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2257 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2258 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2259 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2260 def_bool n
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