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) $(m64-flag)) if 64BIT
88 default $(success,$(srctree)/scripts/c !! 66 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(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) $(m64-flag) -static) if 64BIT
93 default $(success,$(srctree)/scripts/c !! 71 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(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 <<
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT <<
110 depends on CC_HAS_ASM_GOTO_OUTPUT <<
111 # Detect buggy gcc and clang, fixed in <<
112 def_bool $(success,echo 'int foo(int * <<
113 79
114 config TOOLS_SUPPORT_RELR 80 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 81 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 82
117 config CC_HAS_ASM_INLINE 83 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 84 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 85
120 config CC_HAS_NO_PROFILE_FN_ATTR 86 config CC_HAS_NO_PROFILE_FN_ATTR
121 def_bool $(success,echo '__attribute__ 87 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
122 88
123 config PAHOLE_VERSION <<
124 int <<
125 default $(shell,$(srctree)/scripts/pah <<
126 <<
127 config CONSTRUCTORS 89 config CONSTRUCTORS
128 bool 90 bool
129 91
130 config IRQ_WORK 92 config IRQ_WORK
131 def_bool y if SMP !! 93 bool
132 94
133 config BUILDTIME_TABLE_SORT 95 config BUILDTIME_TABLE_SORT
134 bool 96 bool
135 97
136 config THREAD_INFO_IN_TASK 98 config THREAD_INFO_IN_TASK
137 bool 99 bool
138 help 100 help
139 Select this to move thread_info off 101 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 102 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 103 except flags and fix any runtime bugs.
142 104
143 One subtle change that will be neede 105 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 106 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 107
146 menu "General setup" 108 menu "General setup"
147 109
148 config BROKEN 110 config BROKEN
149 bool 111 bool
150 112
151 config BROKEN_ON_SMP 113 config BROKEN_ON_SMP
152 bool 114 bool
153 depends on BROKEN || !SMP 115 depends on BROKEN || !SMP
154 default y 116 default y
155 117
156 config INIT_ENV_ARG_LIMIT 118 config INIT_ENV_ARG_LIMIT
157 int 119 int
158 default 32 if !UML 120 default 32 if !UML
159 default 128 if UML 121 default 128 if UML
160 help 122 help
161 Maximum of each of the number of arg 123 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 124 variables passed to init from the kernel command line.
163 125
164 config COMPILE_TEST 126 config COMPILE_TEST
165 bool "Compile also drivers which will 127 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 128 depends on HAS_IOMEM
167 help 129 help
168 Some drivers can be compiled on a di 130 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 131 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 132 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 133 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 134 drivers to compile-test them.
173 135
174 If you are a developer and want to b 136 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 137 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 138 drivers to be distributed.
177 139
178 config WERROR 140 config WERROR
179 bool "Compile the kernel with warnings 141 bool "Compile the kernel with warnings as errors"
180 default COMPILE_TEST 142 default COMPILE_TEST
181 help 143 help
182 A kernel build should not cause any 144 A kernel build should not cause any compiler warnings, and this
183 enables the '-Werror' (for C) and '- !! 145 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. <<
187 146
188 However, if you have a new (or very !! 147 However, if you have a new (or very old) compiler with odd and
189 and unusual warnings, or you have so !! 148 unusual warnings, or you have some architecture with problems,
190 you may need to disable this config 149 you may need to disable this config option in order to
191 successfully build the kernel. 150 successfully build the kernel.
192 151
193 If in doubt, say Y. 152 If in doubt, say Y.
194 153
195 config UAPI_HEADER_TEST 154 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 155 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 156 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 157 help
199 Compile test headers exported to use 158 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 159 self-contained, i.e. compilable as standalone units.
201 160
202 If you are a developer or tester and 161 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 162 headers are self-contained, say Y here. Otherwise, choose N.
204 163
205 config LOCALVERSION 164 config LOCALVERSION
206 string "Local version - append to kern 165 string "Local version - append to kernel release"
207 help 166 help
208 Append an extra string to the end of 167 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 168 This will show up when you type uname, for example.
210 The string you set here will be appe 169 The string you set here will be appended after the contents of
211 any files with a filename matching l 170 any files with a filename matching localversion* in your
212 object and source tree, in that orde 171 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 172 be a maximum of 64 characters.
214 173
215 config LOCALVERSION_AUTO 174 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 175 bool "Automatically append version information to the version string"
217 default y 176 default y
218 depends on !COMPILE_TEST 177 depends on !COMPILE_TEST
219 help 178 help
220 This will try to automatically deter 179 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 180 release tree by looking for git tags that belong to the current
222 top of tree revision. 181 top of tree revision.
223 182
224 A string of the format -gxxxxxxxx wi 183 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 184 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 185 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 186 set in CONFIG_LOCALVERSION.
228 187
229 (The actual string used here is the !! 188 (The actual string used here is the first eight characters produced
230 by running the command: 189 by running the command:
231 190
232 $ git rev-parse --verify HEAD 191 $ git rev-parse --verify HEAD
233 192
234 which is done within the script "scr 193 which is done within the script "scripts/setlocalversion".)
235 194
236 config BUILD_SALT 195 config BUILD_SALT
237 string "Build ID Salt" 196 string "Build ID Salt"
238 default "" 197 default ""
239 help 198 help
240 The build ID is used to link binarie 199 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 200 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 201 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 202 build is unique between builds. It's safe to leave the default.
244 203
245 config HAVE_KERNEL_GZIP 204 config HAVE_KERNEL_GZIP
246 bool 205 bool
247 206
248 config HAVE_KERNEL_BZIP2 207 config HAVE_KERNEL_BZIP2
249 bool 208 bool
250 209
251 config HAVE_KERNEL_LZMA 210 config HAVE_KERNEL_LZMA
252 bool 211 bool
253 212
254 config HAVE_KERNEL_XZ 213 config HAVE_KERNEL_XZ
255 bool 214 bool
256 215
257 config HAVE_KERNEL_LZO 216 config HAVE_KERNEL_LZO
258 bool 217 bool
259 218
260 config HAVE_KERNEL_LZ4 219 config HAVE_KERNEL_LZ4
261 bool 220 bool
262 221
263 config HAVE_KERNEL_ZSTD 222 config HAVE_KERNEL_ZSTD
264 bool 223 bool
265 224
266 config HAVE_KERNEL_UNCOMPRESSED 225 config HAVE_KERNEL_UNCOMPRESSED
267 bool 226 bool
268 227
269 choice 228 choice
270 prompt "Kernel compression mode" 229 prompt "Kernel compression mode"
271 default KERNEL_GZIP 230 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE 231 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 232 help
274 The linux kernel is a kind of self-e 233 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 234 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 235 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 236 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 237 Decompression speed is relevant at each boot.
279 238
280 If you have any problems with bzip2 239 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 240 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 241 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 242 supplied by Christian Ludwig)
284 243
285 High compression options are mostly 244 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 245 are low on disk space (embedded systems), but for whom ram
287 size matters less. 246 size matters less.
288 247
289 If in doubt, select 'gzip' 248 If in doubt, select 'gzip'
290 249
291 config KERNEL_GZIP 250 config KERNEL_GZIP
292 bool "Gzip" 251 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 252 depends on HAVE_KERNEL_GZIP
294 help 253 help
295 The old and tried gzip compression. 254 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 255 between compression ratio and decompression speed.
297 256
298 config KERNEL_BZIP2 257 config KERNEL_BZIP2
299 bool "Bzip2" 258 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 259 depends on HAVE_KERNEL_BZIP2
301 help 260 help
302 Its compression ratio and speed is i 261 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 262 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 263 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 264 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 265 will need at least 8MB RAM or more for booting.
307 266
308 config KERNEL_LZMA 267 config KERNEL_LZMA
309 bool "LZMA" 268 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 269 depends on HAVE_KERNEL_LZMA
311 help 270 help
312 This compression algorithm's ratio i 271 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 272 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 273 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 274
316 config KERNEL_XZ 275 config KERNEL_XZ
317 bool "XZ" 276 bool "XZ"
318 depends on HAVE_KERNEL_XZ 277 depends on HAVE_KERNEL_XZ
319 help 278 help
320 XZ uses the LZMA2 algorithm and inst 279 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 280 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 281 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 282 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 283 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 284 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 285
328 The speed is about the same as with 286 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 287 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 288 and LZO. Compression is slow.
331 289
332 config KERNEL_LZO 290 config KERNEL_LZO
333 bool "LZO" 291 bool "LZO"
334 depends on HAVE_KERNEL_LZO 292 depends on HAVE_KERNEL_LZO
335 help 293 help
336 Its compression ratio is the poorest 294 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 295 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 296 (both compression and decompression) is the fastest.
339 297
340 config KERNEL_LZ4 298 config KERNEL_LZ4
341 bool "LZ4" 299 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 300 depends on HAVE_KERNEL_LZ4
343 help 301 help
344 LZ4 is an LZ77-type compressor with 302 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 303 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 304 <https://code.google.com/p/lz4/>.
347 305
348 Its compression ratio is worse than 306 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 307 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 308 faster than LZO.
351 309
352 config KERNEL_ZSTD 310 config KERNEL_ZSTD
353 bool "ZSTD" 311 bool "ZSTD"
354 depends on HAVE_KERNEL_ZSTD 312 depends on HAVE_KERNEL_ZSTD
355 help 313 help
356 ZSTD is a compression algorithm targ 314 ZSTD is a compression algorithm targeting intermediate compression
357 with fast decompression speed. It wi 315 with fast decompression speed. It will compress better than GZIP and
358 decompress around the same speed as 316 decompress around the same speed as LZO, but slower than LZ4. You
359 will need at least 192 KB RAM or mor 317 will need at least 192 KB RAM or more for booting. The zstd command
360 line tool is required for compressio 318 line tool is required for compression.
361 319
362 config KERNEL_UNCOMPRESSED 320 config KERNEL_UNCOMPRESSED
363 bool "None" 321 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 322 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 323 help
366 Produce uncompressed kernel image. T 324 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 325 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 326 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 327 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 328 and jump right at uncompressed kernel image.
371 329
372 endchoice 330 endchoice
373 331
374 config DEFAULT_INIT 332 config DEFAULT_INIT
375 string "Default init path" 333 string "Default init path"
376 default "" 334 default ""
377 help 335 help
378 This option determines the default i 336 This option determines the default init for the system if no init=
379 option is passed on the kernel comma 337 option is passed on the kernel command line. If the requested path is
380 not present, we will still then move 338 not present, we will still then move on to attempting further
381 locations (e.g. /sbin/init, etc). If 339 locations (e.g. /sbin/init, etc). If this is empty, we will just use
382 the fallback list when init= is not 340 the fallback list when init= is not passed.
383 341
384 config DEFAULT_HOSTNAME 342 config DEFAULT_HOSTNAME
385 string "Default hostname" 343 string "Default hostname"
386 default "(none)" 344 default "(none)"
387 help 345 help
388 This option determines the default s 346 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 347 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 348 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 349 system more usable with less configuration.
392 350
>> 351 #
>> 352 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 353 # add proper SWAP support to them, in which case this can be remove.
>> 354 #
>> 355 config ARCH_NO_SWAP
>> 356 bool
>> 357
>> 358 config SWAP
>> 359 bool "Support for paging of anonymous memory (swap)"
>> 360 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 361 default y
>> 362 help
>> 363 This option allows you to choose whether you want to have support
>> 364 for so called swap devices or swap files in your kernel that are
>> 365 used to provide more virtual memory than the actual RAM present
>> 366 in your computer. If unsure say Y.
>> 367
393 config SYSVIPC 368 config SYSVIPC
394 bool "System V IPC" 369 bool "System V IPC"
395 help 370 help
396 Inter Process Communication is a sui 371 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 372 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 373 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 374 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 375 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 376 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 377 you'll need to say Y here.
403 378
404 You can find documentation about IPC 379 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 380 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 381 <http://www.tldp.org/guides.html>.
407 382
408 config SYSVIPC_SYSCTL 383 config SYSVIPC_SYSCTL
409 bool 384 bool
410 depends on SYSVIPC 385 depends on SYSVIPC
411 depends on SYSCTL 386 depends on SYSCTL
412 default y 387 default y
413 388
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 389 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 390 bool "POSIX Message Queues"
420 depends on NET 391 depends on NET
421 help 392 help
422 POSIX variant of message queues is a 393 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 394 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 395 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 396 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 397 queues (functions mq_*) say Y here.
427 398
428 POSIX message queues are visible as 399 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 400 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 401 operations on message queues.
431 402
432 If unsure, say Y. 403 If unsure, say Y.
433 404
434 config POSIX_MQUEUE_SYSCTL 405 config POSIX_MQUEUE_SYSCTL
435 bool 406 bool
436 depends on POSIX_MQUEUE 407 depends on POSIX_MQUEUE
437 depends on SYSCTL 408 depends on SYSCTL
438 default y 409 default y
439 410
440 config WATCH_QUEUE 411 config WATCH_QUEUE
441 bool "General notification queue" 412 bool "General notification queue"
442 default n 413 default n
443 help 414 help
444 415
445 This is a general notification queue 416 This is a general notification queue for the kernel to pass events to
446 userspace by splicing them into pipe 417 userspace by splicing them into pipes. It can be used in conjunction
447 with watches for key/keyring change 418 with watches for key/keyring change notifications and device
448 notifications. 419 notifications.
449 420
450 See Documentation/core-api/watch_que !! 421 See Documentation/watch_queue.rst
451 422
452 config CROSS_MEMORY_ATTACH 423 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 424 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 425 depends on MMU
455 default y 426 default y
456 help 427 help
457 Enabling this option adds the system 428 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 429 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 430 to directly read from or write to another process' address space.
460 See the man page for more details. 431 See the man page for more details.
461 432
462 config USELIB 433 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 434 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 435 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 436 help
466 This option enables the uselib sysca 437 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 438 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 439 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 440 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 441 running glibc can safely disable this.
471 442
472 config AUDIT 443 config AUDIT
473 bool "Auditing support" 444 bool "Auditing support"
474 depends on NET 445 depends on NET
475 help 446 help
476 Enable auditing infrastructure that 447 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 448 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 449 logging of avc messages output). System call auditing is included
479 on architectures which support it. 450 on architectures which support it.
480 451
481 config HAVE_ARCH_AUDITSYSCALL 452 config HAVE_ARCH_AUDITSYSCALL
482 bool 453 bool
483 454
484 config AUDITSYSCALL 455 config AUDITSYSCALL
485 def_bool y 456 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 457 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 458 select FSNOTIFY
488 459
489 source "kernel/irq/Kconfig" 460 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 461 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" 462 source "kernel/bpf/Kconfig"
492 source "kernel/Kconfig.preempt" 463 source "kernel/Kconfig.preempt"
493 464
494 menu "CPU/Task time and stats accounting" 465 menu "CPU/Task time and stats accounting"
495 466
496 config VIRT_CPU_ACCOUNTING 467 config VIRT_CPU_ACCOUNTING
497 bool 468 bool
498 469
499 choice 470 choice
500 prompt "Cputime accounting" 471 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 472 default TICK_CPU_ACCOUNTING if !PPC64
>> 473 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 474
503 # Kind of a stub config for the pure tick base 475 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 476 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 477 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 478 depends on !S390 && !NO_HZ_FULL
507 help 479 help
508 This is the basic tick based cputime 480 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 481 statistics about user, system and idle time spent on per jiffies
510 granularity. 482 granularity.
511 483
512 If unsure, say Y. 484 If unsure, say Y.
513 485
514 config VIRT_CPU_ACCOUNTING_NATIVE 486 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 487 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 488 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 489 select VIRT_CPU_ACCOUNTING
518 help 490 help
519 Select this option to enable more ac 491 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 492 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 493 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 494 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 495 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 496 this also enables accounting of stolen time on logically-partitioned
525 systems. 497 systems.
526 498
527 config VIRT_CPU_ACCOUNTING_GEN 499 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 500 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 501 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 502 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 503 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 504 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 505 select CONTEXT_TRACKING
534 help 506 help
535 Select this option to enable task an 507 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 508 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 509 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 510 The accounting is thus performed at the expense of some significant
539 overhead. 511 overhead.
540 512
541 For now this is only useful if you a 513 For now this is only useful if you are working on the full
542 dynticks subsystem development. 514 dynticks subsystem development.
543 515
544 If unsure, say N. 516 If unsure, say N.
545 517
546 endchoice 518 endchoice
547 519
548 config IRQ_TIME_ACCOUNTING 520 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 521 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 522 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 523 help
552 Select this option to enable fine gr 524 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 525 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 526 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 527 small performance impact.
556 528
557 If in doubt, say N here. 529 If in doubt, say N here.
558 530
559 config HAVE_SCHED_AVG_IRQ 531 config HAVE_SCHED_AVG_IRQ
560 def_bool y 532 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 533 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 534 depends on SMP
563 535
564 config SCHED_HW_PRESSURE !! 536 config SCHED_THERMAL_PRESSURE
565 bool 537 bool
566 default y if ARM && ARM_CPU_TOPOLOGY 538 default y if ARM && ARM_CPU_TOPOLOGY
567 default y if ARM64 539 default y if ARM64
568 depends on SMP 540 depends on SMP
569 depends on CPU_FREQ_THERMAL 541 depends on CPU_FREQ_THERMAL
570 help 542 help
571 Select this option to enable HW pres !! 543 Select this option to enable thermal pressure accounting in the
572 scheduler. HW pressure is the value !! 544 scheduler. Thermal pressure is the value conveyed to the scheduler
573 that reflects the reduction in CPU c 545 that reflects the reduction in CPU compute capacity resulted from
574 HW throttling. HW throttling occurs !! 546 thermal throttling. Thermal throttling occurs when the performance of
575 a CPU is capped due to high operatin !! 547 a CPU is capped due to high operating temperatures.
576 548
577 If selected, the scheduler will be a 549 If selected, the scheduler will be able to balance tasks accordingly,
578 i.e. put less load on throttled CPUs 550 i.e. put less load on throttled CPUs than on non/less throttled ones.
579 551
580 This requires the architecture to im 552 This requires the architecture to implement
581 arch_update_hw_pressure() and arch_s !! 553 arch_set_thermal_pressure() and arch_scale_thermal_pressure().
582 554
583 config BSD_PROCESS_ACCT 555 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 556 bool "BSD Process Accounting"
585 depends on MULTIUSER 557 depends on MULTIUSER
586 help 558 help
587 If you say Y here, a user level prog 559 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 560 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 561 information to a file: whenever a process exits, information about
590 that process will be appended to the 562 that process will be appended to the file by the kernel. The
591 information includes things such as 563 information includes things such as creation time, owning user,
592 command name, memory usage, controll 564 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 565 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 566 up to the user level program to do useful things with this
595 information. This is generally a go 567 information. This is generally a good idea, so say Y.
596 568
597 config BSD_PROCESS_ACCT_V3 569 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 570 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 571 depends on BSD_PROCESS_ACCT
600 default n 572 default n
601 help 573 help
602 If you say Y here, the process accou 574 If you say Y here, the process accounting information is written
603 in a new file format that also logs 575 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 576 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 577 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 578 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 579 at <http://www.gnu.org/software/acct/>.
608 580
609 config TASKSTATS 581 config TASKSTATS
610 bool "Export task/process statistics t 582 bool "Export task/process statistics through netlink"
611 depends on NET 583 depends on NET
612 depends on MULTIUSER 584 depends on MULTIUSER
613 default n 585 default n
614 help 586 help
615 Export selected statistics for tasks 587 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 588 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 589 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 590 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 591 space on task exit.
620 592
621 Say N if unsure. 593 Say N if unsure.
622 594
623 config TASK_DELAY_ACCT 595 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 596 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 597 depends on TASKSTATS
626 select SCHED_INFO 598 select SCHED_INFO
627 help 599 help
628 Collect information on time spent by 600 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 601 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 602 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 603 relative to other tasks for cpu, io, rss limits etc.
632 604
633 Say N if unsure. 605 Say N if unsure.
634 606
635 config TASK_XACCT 607 config TASK_XACCT
636 bool "Enable extended accounting over 608 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 609 depends on TASKSTATS
638 help 610 help
639 Collect extended task accounting dat 611 Collect extended task accounting data and send the data
640 to userland for processing over the 612 to userland for processing over the taskstats interface.
641 613
642 Say N if unsure. 614 Say N if unsure.
643 615
644 config TASK_IO_ACCOUNTING 616 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 617 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 618 depends on TASK_XACCT
647 help 619 help
648 Collect information on the number of 620 Collect information on the number of bytes of storage I/O which this
649 task has caused. 621 task has caused.
650 622
651 Say N if unsure. 623 Say N if unsure.
652 624
653 config PSI 625 config PSI
654 bool "Pressure stall information track 626 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 627 help
657 Collect metrics that indicate how ov 628 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 629 and IO capacity are in the system.
659 630
660 If you say Y here, the kernel will c 631 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 632 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 633 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 634 delayed due to contention of the respective resource.
664 635
665 In kernels with cgroup support, cgro 636 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 637 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 638 which aggregate pressure stalls for the grouped tasks only.
668 639
669 For more details see Documentation/a 640 For more details see Documentation/accounting/psi.rst.
670 641
671 Say N if unsure. 642 Say N if unsure.
672 643
673 config PSI_DEFAULT_DISABLED 644 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 645 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 646 default n
676 depends on PSI 647 depends on PSI
677 help 648 help
678 If set, pressure stall information t 649 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 650 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 651 kernel commandline during boot.
681 652
682 This feature adds some code to the t 653 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 654 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 655 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 656 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 657 scheduler stress tests, such as hackbench.
687 658
688 If you are paranoid and not sure wha 659 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 660 used for, say Y.
690 661
691 Say N if unsure. 662 Say N if unsure.
692 663
693 endmenu # "CPU/Task time and stats accounting" 664 endmenu # "CPU/Task time and stats accounting"
694 665
695 config CPU_ISOLATION 666 config CPU_ISOLATION
696 bool "CPU isolation" 667 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 668 depends on SMP || COMPILE_TEST
698 default y 669 default y
699 help 670 help
700 Make sure that CPUs running critical 671 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 672 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 673 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 674 the "isolcpus=" boot parameter.
704 675
705 Say Y if unsure. 676 Say Y if unsure.
706 677
707 source "kernel/rcu/Kconfig" 678 source "kernel/rcu/Kconfig"
708 679
>> 680 config BUILD_BIN2C
>> 681 bool
>> 682 default n
>> 683
709 config IKCONFIG 684 config IKCONFIG
710 tristate "Kernel .config support" 685 tristate "Kernel .config support"
711 help 686 help
712 This option enables the complete Lin 687 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 688 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 689 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 690 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 691 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 692 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 693 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 694 /proc/config.gz if enabled (below).
720 695
721 config IKCONFIG_PROC 696 config IKCONFIG_PROC
722 bool "Enable access to .config through 697 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 698 depends on IKCONFIG && PROC_FS
724 help 699 help
725 This option enables access to the ke 700 This option enables access to the kernel configuration file
726 through /proc/config.gz. 701 through /proc/config.gz.
727 702
728 config IKHEADERS 703 config IKHEADERS
729 tristate "Enable kernel headers throug 704 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 705 depends on SYSFS
731 help 706 help
732 This option enables access to the in 707 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 708 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 709 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 710 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 711
737 config LOG_BUF_SHIFT 712 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 713 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 !! 714 range 12 25 if !H8300
>> 715 range 12 19 if H8300
740 default 17 716 default 17
741 depends on PRINTK 717 depends on PRINTK
742 help 718 help
743 Select the minimal kernel log buffer 719 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 720 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 721 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 722 by "log_buf_len" boot parameter.
747 723
748 Examples: 724 Examples:
749 17 => 128 KB 725 17 => 128 KB
750 16 => 64 KB 726 16 => 64 KB
751 15 => 32 KB 727 15 => 32 KB
752 14 => 16 KB 728 14 => 16 KB
753 13 => 8 KB 729 13 => 8 KB
754 12 => 4 KB 730 12 => 4 KB
755 731
756 config LOG_CPU_MAX_BUF_SHIFT 732 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 733 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 734 depends on SMP
759 range 0 21 735 range 0 21
>> 736 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 737 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 738 depends on PRINTK
763 help 739 help
764 This option allows to increase the d 740 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 741 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 742 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 743 lines however it might be much more when problems are reported,
768 e.g. backtraces. 744 e.g. backtraces.
769 745
770 The increased size means that a new 746 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 747 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 748 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 749 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 750 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed 751 so that more than 16 CPUs are needed to trigger the allocation.
776 752
777 Also this option is ignored when "lo 753 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 754 used as it forces an exact (power of two) size of the ring buffer.
779 755
780 The number of possible CPUs is used 756 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 757 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 758 scenario while allowing a simple algorithm to be used from bootup.
783 759
784 Examples shift values and their mean 760 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 761 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 762 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 763 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 764 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 765 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 766 12 => 4 KB for each CPU
791 767
>> 768 config PRINTK_SAFE_LOG_BUF_SHIFT
>> 769 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
>> 770 range 10 21
>> 771 default 13
>> 772 depends on PRINTK
>> 773 help
>> 774 Select the size of an alternate printk per-CPU buffer where messages
>> 775 printed from usafe contexts are temporary stored. One example would
>> 776 be NMI messages, another one - printk recursion. The messages are
>> 777 copied to the main log buffer in a safe context to avoid a deadlock.
>> 778 The value defines the size as a power of 2.
>> 779
>> 780 Those messages are rare and limited. The largest one is when
>> 781 a backtrace is printed. It usually fits into 4KB. Select
>> 782 8KB if you want to be on the safe side.
>> 783
>> 784 Examples:
>> 785 17 => 128 KB for each CPU
>> 786 16 => 64 KB for each CPU
>> 787 15 => 32 KB for each CPU
>> 788 14 => 16 KB for each CPU
>> 789 13 => 8 KB for each CPU
>> 790 12 => 4 KB for each CPU
>> 791
792 config PRINTK_INDEX 792 config PRINTK_INDEX
793 bool "Printk indexing debugfs interfac 793 bool "Printk indexing debugfs interface"
794 depends on PRINTK && DEBUG_FS 794 depends on PRINTK && DEBUG_FS
795 help 795 help
796 Add support for indexing of all prin 796 Add support for indexing of all printk formats known at compile time
797 at <debugfs>/printk/index/<module>. 797 at <debugfs>/printk/index/<module>.
798 798
799 This can be used as part of maintain 799 This can be used as part of maintaining daemons which monitor
800 /dev/kmsg, as it permits auditing th 800 /dev/kmsg, as it permits auditing the printk formats present in a
801 kernel, allowing detection of cases 801 kernel, allowing detection of cases where monitored printks are
802 changed or no longer present. 802 changed or no longer present.
803 803
804 There is no additional runtime cost 804 There is no additional runtime cost to printk with this enabled.
805 805
806 # 806 #
807 # Architectures with an unreliable sched_clock 807 # Architectures with an unreliable sched_clock() should select this:
808 # 808 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 809 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 810 bool
811 811
812 config GENERIC_SCHED_CLOCK 812 config GENERIC_SCHED_CLOCK
813 bool 813 bool
814 814
815 menu "Scheduler features" 815 menu "Scheduler features"
816 816
817 config UCLAMP_TASK 817 config UCLAMP_TASK
818 bool "Enable utilization clamping for 818 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 819 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 820 help
821 This feature enables the scheduler t 821 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 822 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 823
824 With this option, the user can speci 824 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 825 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 826 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 827 defines the minimum frequency it should use.
828 828
829 Both min and max utilization clamp v 829 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 830 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 831 enforce or grant any specific bandwidth for tasks.
832 832
833 If in doubt, say N. 833 If in doubt, say N.
834 834
835 config UCLAMP_BUCKETS_COUNT 835 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 836 int "Number of supported utilization clamp buckets"
837 range 5 20 837 range 5 20
838 default 5 838 default 5
839 depends on UCLAMP_TASK 839 depends on UCLAMP_TASK
840 help 840 help
841 Defines the number of clamp buckets 841 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 842 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 843 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 844 the precision of clamping aggregation and tracking at run-time.
845 845
846 For example, with the minimum config 846 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 847 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 848 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 849 effective value to 25%.
850 If a second 30% boosted task should 850 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 851 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 852 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 853 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 854 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 855 that bucket.
856 856
857 An additional boost/capping margin c 857 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 858 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 859 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 860 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 861 clamp buckets to trade off used memory for run-time tracking
862 precision. 862 precision.
863 863
864 If in doubt, use the default value. 864 If in doubt, use the default value.
865 865
866 endmenu 866 endmenu
867 867
868 # 868 #
869 # For architectures that want to enable the su 869 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 870 # balancing logic:
871 # 871 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 872 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 873 bool
874 874
875 # 875 #
876 # For architectures that prefer to flush all T 876 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 877 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 878 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 879 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 880 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 881 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 883 bool
884 884
885 config CC_HAS_INT128 885 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 886 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 887
888 config CC_IMPLICIT_FALLTHROUGH 888 config CC_IMPLICIT_FALLTHROUGH
889 string 889 string
890 default "-Wimplicit-fallthrough=5" if 890 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
891 default "-Wimplicit-fallthrough" if CC 891 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
892 892
893 # Currently, disable gcc-10+ array-bounds glob <<
894 # It's still broken in gcc-13, so no upper bou <<
895 config GCC10_NO_ARRAY_BOUNDS <<
896 def_bool y <<
897 <<
898 config CC_NO_ARRAY_BOUNDS <<
899 bool <<
900 default y if CC_IS_GCC && GCC_VERSION <<
901 <<
902 # Currently, disable -Wstringop-overflow for G <<
903 config GCC_NO_STRINGOP_OVERFLOW <<
904 def_bool y <<
905 <<
906 config CC_NO_STRINGOP_OVERFLOW <<
907 bool <<
908 default y if CC_IS_GCC && GCC_NO_STRIN <<
909 <<
910 config CC_STRINGOP_OVERFLOW <<
911 bool <<
912 default y if CC_IS_GCC && !CC_NO_STRIN <<
913 <<
914 # 893 #
915 # For architectures that know their GCC __int1 894 # For architectures that know their GCC __int128 support is sound
916 # 895 #
917 config ARCH_SUPPORTS_INT128 896 config ARCH_SUPPORTS_INT128
918 bool 897 bool
919 898
920 # For architectures that (ab)use NUMA to repre 899 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 900 # all cpu-local but of different latencies, such as SuperH.
922 # 901 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 902 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 903 bool
925 904
926 config NUMA_BALANCING 905 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 906 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 907 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 908 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && 909 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
931 help 910 help
932 This option adds support for automat 911 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 912 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 913 it has references to the node the task is running on.
935 914
936 This system will be inactive on UMA 915 This system will be inactive on UMA systems.
937 916
938 config NUMA_BALANCING_DEFAULT_ENABLED 917 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 918 bool "Automatically enable NUMA aware memory/task placement"
940 default y 919 default y
941 depends on NUMA_BALANCING 920 depends on NUMA_BALANCING
942 help 921 help
943 If set, automatic NUMA balancing wil 922 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 923 machine.
945 924
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 925 menuconfig CGROUPS
950 bool "Control Group support" 926 bool "Control Group support"
951 select KERNFS 927 select KERNFS
952 help 928 help
953 This option adds support for groupin 929 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 930 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 931 controls or device isolation.
956 See 932 See
957 - Documentation/scheduler/sche 933 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 934 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 935 and resource control)
960 936
961 Say N if unsure. 937 Say N if unsure.
962 938
963 if CGROUPS 939 if CGROUPS
964 940
965 config PAGE_COUNTER 941 config PAGE_COUNTER
966 bool 942 bool
967 943
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 944 config MEMCG
979 bool "Memory controller" 945 bool "Memory controller"
980 select PAGE_COUNTER 946 select PAGE_COUNTER
981 select EVENTFD 947 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 948 help
984 Provides control over the memory foo 949 Provides control over the memory footprint of tasks in a cgroup.
985 950
986 config MEMCG_V1 !! 951 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 952 bool
988 depends on MEMCG !! 953 depends on MEMCG && SWAP
989 default n !! 954 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 955
1001 Say N if unsure. !! 956 config MEMCG_KMEM
>> 957 bool
>> 958 depends on MEMCG && !SLOB
>> 959 default y
1002 960
1003 config BLK_CGROUP 961 config BLK_CGROUP
1004 bool "IO controller" 962 bool "IO controller"
1005 depends on BLOCK 963 depends on BLOCK
1006 default n 964 default n
1007 help 965 help
1008 Generic block IO controller cgroup in 966 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 967 cgroup interface which should be used by various IO controlling
1010 policies. 968 policies.
1011 969
1012 Currently, CFQ IO scheduler uses it t 970 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 971 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 972 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 973 block layer to implement upper limit in IO rates on a device.
1016 974
1017 This option only enables generic Bloc 975 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 976 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 977 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl 978 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 979 CONFIG_BLK_DEV_THROTTLING=y.
1022 980
1023 See Documentation/admin-guide/cgroup- 981 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 982
1025 config CGROUP_WRITEBACK 983 config CGROUP_WRITEBACK
1026 bool 984 bool
1027 depends on MEMCG && BLK_CGROUP 985 depends on MEMCG && BLK_CGROUP
1028 default y 986 default y
1029 987
1030 menuconfig CGROUP_SCHED 988 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 989 bool "CPU controller"
1032 default n 990 default n
1033 help 991 help
1034 This feature lets CPU scheduler rec 992 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 993 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 994 tasks.
1037 995
1038 if CGROUP_SCHED 996 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 997 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 998 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 999 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1000 default CGROUP_SCHED
1047 1001
1048 config CFS_BANDWIDTH 1002 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1003 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1004 depends on FAIR_GROUP_SCHED
1051 default n 1005 default n
1052 help 1006 help
1053 This option allows users to define 1007 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1008 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1009 set are considered to be unconstrained and will run with no
1056 restriction. 1010 restriction.
1057 See Documentation/scheduler/sched-b 1011 See Documentation/scheduler/sched-bwc.rst for more information.
1058 1012
1059 config RT_GROUP_SCHED 1013 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1014 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1015 depends on CGROUP_SCHED
1062 default n 1016 default n
1063 help 1017 help
1064 This feature lets you explicitly al 1018 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1019 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1020 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1021 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 1022 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 1023
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 1024 endif #CGROUP_SCHED
1077 1025
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 1026 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 1027 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 1028 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 1029 depends on UCLAMP_TASK
1086 default n 1030 default n
1087 help 1031 help
1088 This feature enables the scheduler 1032 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 1033 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 1034
1091 When this option is enabled, the us 1035 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 1036 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 1037 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 1038 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 1039 frequency a task will always use.
1096 1040
1097 When task group based utilization c 1041 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 1042 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 1043 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 1044 be bigger than the corresponding clamping defined at task group level.
1101 1045
1102 If in doubt, say N. 1046 If in doubt, say N.
1103 1047
1104 config CGROUP_PIDS 1048 config CGROUP_PIDS
1105 bool "PIDs controller" 1049 bool "PIDs controller"
1106 help 1050 help
1107 Provides enforcement of process num 1051 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1052 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1053 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1054 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1055 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1056 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1057 PIDs controller is designed to stop this from happening.
1114 1058
1115 It should be noted that organisatio 1059 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 1060 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 1061 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1062 attach to a cgroup.
1119 1063
1120 config CGROUP_RDMA 1064 config CGROUP_RDMA
1121 bool "RDMA controller" 1065 bool "RDMA controller"
1122 help 1066 help
1123 Provides enforcement of RDMA resour 1067 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1068 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1069 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1070 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1071 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1072 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1073
1130 config CGROUP_FREEZER 1074 config CGROUP_FREEZER
1131 bool "Freezer controller" 1075 bool "Freezer controller"
1132 help 1076 help
1133 Provides a way to freeze and unfree 1077 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1078 cgroup.
1135 1079
1136 This option affects the ORIGINAL cg 1080 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1081 controller includes important in-kernel memory consumers per default.
1138 1082
1139 If you're using cgroup2, say N. 1083 If you're using cgroup2, say N.
1140 1084
1141 config CGROUP_HUGETLB 1085 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1086 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1087 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1088 select PAGE_COUNTER
1145 default n 1089 default n
1146 help 1090 help
1147 Provides a cgroup controller for Hu 1091 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1092 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1093 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1094 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1095 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1096 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1097 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1098 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1099 that we cannot use the controller with huge page less than 3 pages.
1156 1100
1157 config CPUSETS 1101 config CPUSETS
1158 bool "Cpuset controller" 1102 bool "Cpuset controller"
1159 depends on SMP 1103 depends on SMP
1160 help 1104 help
1161 This option will let you create and 1105 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1106 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1107 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1108 This is primarily useful on large SMP or NUMA systems.
1165 1109
1166 Say N if unsure. 1110 Say N if unsure.
1167 1111
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 1112 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1113 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1114 depends on CPUSETS
1184 default y 1115 default y
1185 1116
1186 config CGROUP_DEVICE 1117 config CGROUP_DEVICE
1187 bool "Device controller" 1118 bool "Device controller"
1188 help 1119 help
1189 Provides a cgroup controller implem 1120 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1121 devices which a process in the cgroup can mknod or open.
1191 1122
1192 config CGROUP_CPUACCT 1123 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1124 bool "Simple CPU accounting controller"
1194 help 1125 help
1195 Provides a simple controller for mo 1126 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1127 total CPU consumed by the tasks in a cgroup.
1197 1128
1198 config CGROUP_PERF 1129 config CGROUP_PERF
1199 bool "Perf controller" 1130 bool "Perf controller"
1200 depends on PERF_EVENTS 1131 depends on PERF_EVENTS
1201 help 1132 help
1202 This option extends the perf per-cp 1133 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1134 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use 1135 designated cpu. Or this can be used to have cgroup ID in samples
1205 so that it can monitor performance 1136 so that it can monitor performance events among cgroups.
1206 1137
1207 Say N if unsure. 1138 Say N if unsure.
1208 1139
1209 config CGROUP_BPF 1140 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1141 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1142 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1143 select SOCK_CGROUP_DATA
1213 help 1144 help
1214 Allow attaching eBPF programs to a 1145 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1146 syscall command BPF_PROG_ATTACH.
1216 1147
1217 In which context these programs are 1148 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1149 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1150 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1151 inet sockets.
1221 1152
1222 config CGROUP_MISC 1153 config CGROUP_MISC
1223 bool "Misc resource controller" 1154 bool "Misc resource controller"
1224 default n 1155 default n
1225 help 1156 help
1226 Provides a controller for miscellan 1157 Provides a controller for miscellaneous resources on a host.
1227 1158
1228 Miscellaneous scalar resources are 1159 Miscellaneous scalar resources are the resources on the host system
1229 which cannot be abstracted like the 1160 which cannot be abstracted like the other cgroups. This controller
1230 tracks and limits the miscellaneous 1161 tracks and limits the miscellaneous resources used by a process
1231 attached to a cgroup hierarchy. 1162 attached to a cgroup hierarchy.
1232 1163
1233 For more information, please check 1164 For more information, please check misc cgroup section in
1234 /Documentation/admin-guide/cgroup-v 1165 /Documentation/admin-guide/cgroup-v2.rst.
1235 1166
1236 config CGROUP_DEBUG 1167 config CGROUP_DEBUG
1237 bool "Debug controller" 1168 bool "Debug controller"
1238 default n 1169 default n
1239 depends on DEBUG_KERNEL 1170 depends on DEBUG_KERNEL
1240 help 1171 help
1241 This option enables a simple contro 1172 This option enables a simple controller that exports
1242 debugging information about the cgr 1173 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1174 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1175 interfaces are not stable.
1245 1176
1246 Say N. 1177 Say N.
1247 1178
1248 config SOCK_CGROUP_DATA 1179 config SOCK_CGROUP_DATA
1249 bool 1180 bool
1250 default n 1181 default n
1251 1182
1252 endif # CGROUPS 1183 endif # CGROUPS
1253 1184
1254 menuconfig NAMESPACES 1185 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1186 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1187 depends on MULTIUSER
1257 default !EXPERT 1188 default !EXPERT
1258 help 1189 help
1259 Provides the way to make tasks work 1190 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1191 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1192 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1193 different namespaces.
1263 1194
1264 if NAMESPACES 1195 if NAMESPACES
1265 1196
1266 config UTS_NS 1197 config UTS_NS
1267 bool "UTS namespace" 1198 bool "UTS namespace"
1268 default y 1199 default y
1269 help 1200 help
1270 In this namespace tasks see differe 1201 In this namespace tasks see different info provided with the
1271 uname() system call 1202 uname() system call
1272 1203
1273 config TIME_NS 1204 config TIME_NS
1274 bool "TIME namespace" 1205 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1206 depends on GENERIC_VDSO_TIME_NS
1276 default y 1207 default y
1277 help 1208 help
1278 In this namespace boottime and mono 1209 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1210 The time will keep going with the same pace.
1280 1211
1281 config IPC_NS 1212 config IPC_NS
1282 bool "IPC namespace" 1213 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1214 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1215 default y
1285 help 1216 help
1286 In this namespace tasks work with I 1217 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1218 different IPC objects in different namespaces.
1288 1219
1289 config USER_NS 1220 config USER_NS
1290 bool "User namespace" 1221 bool "User namespace"
1291 default n 1222 default n
1292 help 1223 help
1293 This allows containers, i.e. vserve 1224 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1225 to provide different user info for different servers.
1295 1226
1296 When user namespaces are enabled in 1227 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1228 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1229 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1230 of memory a memory unprivileged users can use.
1300 1231
1301 If unsure, say N. 1232 If unsure, say N.
1302 1233
1303 config PID_NS 1234 config PID_NS
1304 bool "PID Namespaces" 1235 bool "PID Namespaces"
1305 default y 1236 default y
1306 help 1237 help
1307 Support process id namespaces. Thi 1238 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1239 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1240 pid namespaces. This is a building block of containers.
1310 1241
1311 config NET_NS 1242 config NET_NS
1312 bool "Network namespace" 1243 bool "Network namespace"
1313 depends on NET 1244 depends on NET
1314 default y 1245 default y
1315 help 1246 help
1316 Allow user space to create what app 1247 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1248 of the network stack.
1318 1249
1319 endif # NAMESPACES 1250 endif # NAMESPACES
1320 1251
1321 config CHECKPOINT_RESTORE 1252 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1253 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1254 select PROC_CHILDREN
1325 select KCMP 1255 select KCMP
1326 default n 1256 default n
1327 help 1257 help
1328 Enables additional kernel features 1258 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1259 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1260 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1261 entries.
1332 1262
1333 If unsure, say N here. 1263 If unsure, say N here.
1334 1264
1335 config SCHED_AUTOGROUP 1265 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1266 bool "Automatic process group scheduling"
1337 select CGROUPS 1267 select CGROUPS
1338 select CGROUP_SCHED 1268 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1269 select FAIR_GROUP_SCHED
1340 help 1270 help
1341 This option optimizes the scheduler 1271 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1272 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1273 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1274 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1275 upon task session.
1346 1276
>> 1277 config SYSFS_DEPRECATED
>> 1278 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1279 depends on SYSFS
>> 1280 default n
>> 1281 help
>> 1282 This option adds code that switches the layout of the "block" class
>> 1283 devices, to not show up in /sys/class/block/, but only in
>> 1284 /sys/block/.
>> 1285
>> 1286 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1287 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1288
>> 1289 This option allows new kernels to run on old distributions and tools,
>> 1290 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1291 major distributions and tools handle this just fine.
>> 1292
>> 1293 Recent distributions and userspace tools after 2009/2010 depend on
>> 1294 the existence of /sys/class/block/, and will not work with this
>> 1295 option enabled.
>> 1296
>> 1297 Only if you are using a new kernel on an old distribution, you might
>> 1298 need to say Y here.
>> 1299
>> 1300 config SYSFS_DEPRECATED_V2
>> 1301 bool "Enable deprecated sysfs features by default"
>> 1302 default n
>> 1303 depends on SYSFS
>> 1304 depends on SYSFS_DEPRECATED
>> 1305 help
>> 1306 Enable deprecated sysfs by default.
>> 1307
>> 1308 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1309 option.
>> 1310
>> 1311 Only if you are using a new kernel on an old distribution, you might
>> 1312 need to say Y here. Even then, odds are you would not need it
>> 1313 enabled, you can always pass the boot option if absolutely necessary.
>> 1314
1347 config RELAY 1315 config RELAY
1348 bool "Kernel->user space relay suppor 1316 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1317 select IRQ_WORK
1350 help 1318 help
1351 This option enables support for rel 1319 This option enables support for relay interface support in
1352 certain file systems (such as debug 1320 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1321 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1322 facilities to relay large amounts of data from kernel space to
1355 user space. 1323 user space.
1356 1324
1357 If unsure, say N. 1325 If unsure, say N.
1358 1326
1359 config BLK_DEV_INITRD 1327 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1328 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1329 help
1362 The initial RAM filesystem is a ram 1330 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1331 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1332 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1333 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1334 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1335
1368 If RAM disk support (BLK_DEV_RAM) i 1336 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1337 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1338 15 Kbytes (more on some other architectures) to the kernel size.
1371 1339
1372 If unsure say Y. 1340 If unsure say Y.
1373 1341
1374 if BLK_DEV_INITRD 1342 if BLK_DEV_INITRD
1375 1343
1376 source "usr/Kconfig" 1344 source "usr/Kconfig"
1377 1345
1378 endif 1346 endif
1379 1347
1380 config BOOT_CONFIG 1348 config BOOT_CONFIG
1381 bool "Boot config support" 1349 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG !! 1350 select BLK_DEV_INITRD
1383 help 1351 help
1384 Extra boot config allows system adm 1352 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1353 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1354 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1355 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1356 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1357
1390 If unsure, say Y. 1358 If unsure, say Y.
1391 1359
1392 config BOOT_CONFIG_FORCE <<
1393 bool "Force unconditional bootconfig <<
1394 depends on BOOT_CONFIG <<
1395 default y if BOOT_CONFIG_EMBED <<
1396 help <<
1397 With this Kconfig option set, BOOT_ <<
1398 out even when the "bootconfig" kern <<
1399 In fact, with this Kconfig option s <<
1400 make the kernel ignore the BOOT_CON <<
1401 parameters. <<
1402 <<
1403 If unsure, say N. <<
1404 <<
1405 config BOOT_CONFIG_EMBED <<
1406 bool "Embed bootconfig file in the ke <<
1407 depends on BOOT_CONFIG <<
1408 help <<
1409 Embed a bootconfig file given by BO <<
1410 kernel. Usually, the bootconfig fil <<
1411 image. But if the system doesn't su <<
1412 help you by embedding a bootconfig <<
1413 <<
1414 If unsure, say N. <<
1415 <<
1416 config BOOT_CONFIG_EMBED_FILE <<
1417 string "Embedded bootconfig file path <<
1418 depends on BOOT_CONFIG_EMBED <<
1419 help <<
1420 Specify a bootconfig file which wil <<
1421 This bootconfig will be used if the <<
1422 bootconfig in the initrd. <<
1423 <<
1424 config INITRAMFS_PRESERVE_MTIME <<
1425 bool "Preserve cpio archive mtimes in <<
1426 default y <<
1427 help <<
1428 Each entry in an initramfs cpio arc <<
1429 enabled, extracted cpio items take <<
1430 setting deferred until after creati <<
1431 <<
1432 If unsure, say Y. <<
1433 <<
1434 choice 1360 choice
1435 prompt "Compiler optimization level" 1361 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1362 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1363
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1364 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1365 bool "Optimize for performance (-O2)"
1440 help 1366 help
1441 This is the default optimization le 1367 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1368 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1369 helpful compile-time warnings.
1444 1370
>> 1371 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1372 bool "Optimize more for performance (-O3)"
>> 1373 depends on ARC
>> 1374 help
>> 1375 Choosing this option will pass "-O3" to your compiler to optimize
>> 1376 the kernel yet more for performance.
>> 1377
1445 config CC_OPTIMIZE_FOR_SIZE 1378 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1379 bool "Optimize for size (-Os)"
1447 help 1380 help
1448 Choosing this option will pass "-Os 1381 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1382 in a smaller kernel.
1450 1383
1451 endchoice 1384 endchoice
1452 1385
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1386 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1387 bool
1455 help 1388 help
1456 This requires that the arch annotat 1389 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1390 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1391 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1392 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1393 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1394 is used to distinguish them from label names / C identifiers.
1462 1395
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1396 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1397 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1398 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1399 depends on EXPERT
1467 depends on $(cc-option,-ffunction-sec 1400 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1401 depends on $(ld-option,--gc-sections)
1469 help 1402 help
1470 Enable this if you want to do dead 1403 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1404 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1405 and linking with --gc-sections.
1473 1406
1474 This can reduce on disk and in-memo 1407 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1408 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1409 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1410 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1411 present. This option is not well tested yet, so use at your
1479 own risk. 1412 own risk.
1480 1413
1481 config LD_ORPHAN_WARN 1414 config LD_ORPHAN_WARN
1482 def_bool y 1415 def_bool y
1483 depends on ARCH_WANT_LD_ORPHAN_WARN 1416 depends on ARCH_WANT_LD_ORPHAN_WARN
>> 1417 depends on !LD_IS_LLD || LLD_VERSION >= 110000
1484 depends on $(ld-option,--orphan-handl 1418 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 1419
1493 config SYSCTL 1420 config SYSCTL
1494 bool 1421 bool
1495 1422
1496 config HAVE_UID16 1423 config HAVE_UID16
1497 bool 1424 bool
1498 1425
1499 config SYSCTL_EXCEPTION_TRACE 1426 config SYSCTL_EXCEPTION_TRACE
1500 bool 1427 bool
1501 help 1428 help
1502 Enable support for /proc/sys/debug/ 1429 Enable support for /proc/sys/debug/exception-trace.
1503 1430
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1431 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1432 bool
1506 help 1433 help
1507 Enable support for /proc/sys/kernel 1434 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1435 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1436 about unaligned access emulation going on under the hood.
1510 1437
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1438 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1439 bool
1513 help 1440 help
1514 Enable support for /proc/sys/kernel 1441 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1442 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1443 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1444 see arch/parisc/kernel/unaligned.c for reference
1518 1445
1519 config HAVE_PCSPKR_PLATFORM 1446 config HAVE_PCSPKR_PLATFORM
1520 bool 1447 bool
1521 1448
>> 1449 # interpreter that classic socket filters depend on
>> 1450 config BPF
>> 1451 bool
>> 1452
1522 menuconfig EXPERT 1453 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1454 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1455 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1456 select DEBUG_KERNEL
1526 help 1457 help
1527 This option allows certain base ker 1458 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1459 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1460 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1461 Only use this if you really know what you are doing.
1531 1462
1532 config UID16 1463 config UID16
1533 bool "Enable 16-bit UID system calls" 1464 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1465 depends on HAVE_UID16 && MULTIUSER
1535 default y 1466 default y
1536 help 1467 help
1537 This enables the legacy 16-bit UID 1468 This enables the legacy 16-bit UID syscall wrappers.
1538 1469
1539 config MULTIUSER 1470 config MULTIUSER
1540 bool "Multiple users, groups and capa 1471 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1472 default y
1542 help 1473 help
1543 This option enables support for non 1474 This option enables support for non-root users, groups and
1544 capabilities. 1475 capabilities.
1545 1476
1546 If you say N here, all processes wi 1477 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1478 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1479 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1480 setgid, and capset.
1550 1481
1551 If unsure, say Y here. 1482 If unsure, say Y here.
1552 1483
1553 config SGETMASK_SYSCALL 1484 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1485 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1486 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help 1487 help
1557 sys_sgetmask and sys_ssetmask are o 1488 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1489 no longer supported in libc but still enabled by default in some
1559 architectures. 1490 architectures.
1560 1491
1561 If unsure, leave the default option 1492 If unsure, leave the default option here.
1562 1493
1563 config SYSFS_SYSCALL 1494 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1495 bool "Sysfs syscall support" if EXPERT
1565 default y 1496 default y
1566 help 1497 help
1567 sys_sysfs is an obsolete system cal 1498 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1499 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1500 compatibility with some systems.
1570 1501
1571 If unsure say Y here. 1502 If unsure say Y here.
1572 1503
1573 config FHANDLE 1504 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1505 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1506 select EXPORTFS
1576 default y 1507 default y
1577 help 1508 help
1578 If you say Y here, a user level pro 1509 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1510 file names to handle and then later use the handle for
1580 different file system operations. T 1511 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1512 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1513 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1514 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1515 syscalls.
1585 1516
1586 config POSIX_TIMERS 1517 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1518 bool "Posix Clocks & timers" if EXPERT
1588 default y 1519 default y
1589 help 1520 help
1590 This includes native support for PO 1521 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1522 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1523 can be configured out to reduce the size of the kernel image.
1593 1524
1594 When this option is disabled, the f 1525 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1526 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1527 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1528 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1529 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1530 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1531
1601 If unsure say y. 1532 If unsure say y.
1602 1533
1603 config PRINTK 1534 config PRINTK
1604 default y 1535 default y
1605 bool "Enable support for printk" if E 1536 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1537 select IRQ_WORK
1607 help 1538 help
1608 This option enables normal printk s 1539 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1540 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1541 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1542 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1543 strongly discouraged.
1613 1544
1614 config BUG 1545 config BUG
1615 bool "BUG() support" if EXPERT 1546 bool "BUG() support" if EXPERT
1616 default y 1547 default y
1617 help 1548 help
1618 Disabling this option eliminates su 1549 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1550 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1551 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1552 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1553 Just say Y.
1623 1554
1624 config ELF_CORE 1555 config ELF_CORE
1625 depends on COREDUMP 1556 depends on COREDUMP
1626 default y 1557 default y
1627 bool "Enable ELF core dumps" if EXPER 1558 bool "Enable ELF core dumps" if EXPERT
1628 help 1559 help
1629 Enable support for generating core 1560 Enable support for generating core dumps. Disabling saves about 4k.
1630 1561
1631 1562
1632 config PCSPKR_PLATFORM 1563 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1564 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1565 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1566 select I8253_LOCK
1636 default y 1567 default y
1637 help 1568 help
1638 This option allows to disable the i 1569 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1570 support, saving some memory.
1640 1571
1641 config BASE_SMALL !! 1572 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1573 default y
>> 1574 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1575 help
1644 Enabling this option reduces the si !! 1576 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1577 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1578 but may reduce performance.
1647 1579
1648 config FUTEX 1580 config FUTEX
1649 bool "Enable futex support" if EXPERT 1581 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1582 default y
1652 imply RT_MUTEXES 1583 imply RT_MUTEXES
1653 help 1584 help
1654 Disabling this option will cause th 1585 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1586 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1587 run glibc-based applications correctly.
1657 1588
1658 config FUTEX_PI 1589 config FUTEX_PI
1659 bool 1590 bool
1660 depends on FUTEX && RT_MUTEXES 1591 depends on FUTEX && RT_MUTEXES
1661 default y 1592 default y
1662 1593
>> 1594 config HAVE_FUTEX_CMPXCHG
>> 1595 bool
>> 1596 depends on FUTEX
>> 1597 help
>> 1598 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1599 is implemented and always working. This removes a couple of runtime
>> 1600 checks.
>> 1601
1663 config EPOLL 1602 config EPOLL
1664 bool "Enable eventpoll support" if EX 1603 bool "Enable eventpoll support" if EXPERT
1665 default y 1604 default y
1666 help 1605 help
1667 Disabling this option will cause th 1606 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1607 support for epoll family of system calls.
1669 1608
1670 config SIGNALFD 1609 config SIGNALFD
1671 bool "Enable signalfd() system call" 1610 bool "Enable signalfd() system call" if EXPERT
1672 default y 1611 default y
1673 help 1612 help
1674 Enable the signalfd() system call t 1613 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1614 on a file descriptor.
1676 1615
1677 If unsure, say Y. 1616 If unsure, say Y.
1678 1617
1679 config TIMERFD 1618 config TIMERFD
1680 bool "Enable timerfd() system call" i 1619 bool "Enable timerfd() system call" if EXPERT
1681 default y 1620 default y
1682 help 1621 help
1683 Enable the timerfd() system call th 1622 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1623 events on a file descriptor.
1685 1624
1686 If unsure, say Y. 1625 If unsure, say Y.
1687 1626
1688 config EVENTFD 1627 config EVENTFD
1689 bool "Enable eventfd() system call" i 1628 bool "Enable eventfd() system call" if EXPERT
1690 default y 1629 default y
1691 help 1630 help
1692 Enable the eventfd() system call th 1631 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1632 kernel notification (ie. KAIO) or userspace notifications.
1694 1633
1695 If unsure, say Y. 1634 If unsure, say Y.
1696 1635
1697 config SHMEM 1636 config SHMEM
1698 bool "Use full shmem filesystem" if E 1637 bool "Use full shmem filesystem" if EXPERT
1699 default y 1638 default y
1700 depends on MMU 1639 depends on MMU
1701 help 1640 help
1702 The shmem is an internal filesystem 1641 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1642 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1643 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1644 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1645 which may be appropriate on small systems without swap.
1707 1646
1708 config AIO 1647 config AIO
1709 bool "Enable AIO support" if EXPERT 1648 bool "Enable AIO support" if EXPERT
1710 default y 1649 default y
1711 help 1650 help
1712 This option enables POSIX asynchron 1651 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1652 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1653 this option saves about 7k.
1715 1654
1716 config IO_URING 1655 config IO_URING
1717 bool "Enable IO uring support" if EXP 1656 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ 1657 select IO_WQ
1719 default y 1658 default y
1720 help 1659 help
1721 This option enables support for the 1660 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1661 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1662 completion rings that are shared between the kernel and application.
1724 1663
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 1664 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1665 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1666 default y
1741 help 1667 help
1742 This option enables the madvise and 1668 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1669 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1670 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1671 applications use these syscalls, you can disable this option to save
1746 space. 1672 space.
1747 1673
>> 1674 config HAVE_ARCH_USERFAULTFD_WP
>> 1675 bool
>> 1676 help
>> 1677 Arch has userfaultfd write protection support
>> 1678
>> 1679 config HAVE_ARCH_USERFAULTFD_MINOR
>> 1680 bool
>> 1681 help
>> 1682 Arch has userfaultfd minor fault support
>> 1683
1748 config MEMBARRIER 1684 config MEMBARRIER
1749 bool "Enable membarrier() system call 1685 bool "Enable membarrier() system call" if EXPERT
1750 default y 1686 default y
1751 help 1687 help
1752 Enable the membarrier() system call 1688 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1689 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1690 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1691 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1692 compiler barrier.
1757 1693
1758 If unsure, say Y. 1694 If unsure, say Y.
1759 1695
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 1696 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1697 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1698 default y
1813 help 1699 help
1814 Say Y here to let the kernel print 1700 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1701 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1702 somewhat, as all symbols have to be loaded into the kernel image.
1817 1703
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 1704 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1705 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1706 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1707 help
1835 Normally kallsyms only contains the 1708 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1709 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m !! 1710 sections). This is sufficient for most cases. And only in very rare
1838 enable kernel live patching, or oth !! 1711 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1839 when a debugger is used) all symbol !! 1712 names of variables from the data sections, etc).
1840 variables from the data sections, e <<
1841 1713
1842 This option makes sure that all sym 1714 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1715 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1716 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1717 something like this).
1846 1718
1847 Say N unless you really need all sy !! 1719 Say N unless you really need all symbols.
1848 1720
1849 config KALLSYMS_ABSOLUTE_PERCPU 1721 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1722 bool
1851 depends on KALLSYMS 1723 depends on KALLSYMS
1852 default X86_64 && SMP 1724 default X86_64 && SMP
1853 1725
>> 1726 config KALLSYMS_BASE_RELATIVE
>> 1727 bool
>> 1728 depends on KALLSYMS
>> 1729 default !IA64
>> 1730 help
>> 1731 Instead of emitting them as absolute values in the native word size,
>> 1732 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1733 each containing a relative value in the range [base, base + U32_MAX]
>> 1734 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1735 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1736 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1737 address encountered in the image.
>> 1738
>> 1739 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1740 but more importantly, it results in entries whose values are build
>> 1741 time constants, and no relocation pass is required at runtime to fix
>> 1742 up the entries based on the runtime load address of the kernel.
>> 1743
1854 # end of the "standard kernel features (exper 1744 # end of the "standard kernel features (expert users)" menu
1855 1745
>> 1746 # syscall, maps, verifier
>> 1747
>> 1748 config USERFAULTFD
>> 1749 bool "Enable userfaultfd() system call"
>> 1750 depends on MMU
>> 1751 help
>> 1752 Enable the userfaultfd() system call that allows to intercept and
>> 1753 handle page faults in userland.
>> 1754
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1755 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1756 bool
1858 1757
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1758 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1759 bool
1861 1760
>> 1761 config KCMP
>> 1762 bool "Enable kcmp() system call" if EXPERT
>> 1763 help
>> 1764 Enable the kernel resource comparison system call. It provides
>> 1765 user-space with the ability to compare two processes to see if they
>> 1766 share a common resource, such as a file descriptor or even virtual
>> 1767 memory space.
>> 1768
>> 1769 If unsure, say N.
>> 1770
>> 1771 config RSEQ
>> 1772 bool "Enable rseq() system call" if EXPERT
>> 1773 default y
>> 1774 depends on HAVE_RSEQ
>> 1775 select MEMBARRIER
>> 1776 help
>> 1777 Enable the restartable sequences system call. It provides a
>> 1778 user-space cache for the current CPU number value, which
>> 1779 speeds up getting the current CPU number from user-space,
>> 1780 as well as an ABI to speed up user-space operations on
>> 1781 per-CPU data.
>> 1782
>> 1783 If unsure, say Y.
>> 1784
>> 1785 config DEBUG_RSEQ
>> 1786 default n
>> 1787 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1788 depends on RSEQ && DEBUG_KERNEL
>> 1789 help
>> 1790 Enable extra debugging checks for the rseq system call.
>> 1791
>> 1792 If unsure, say N.
>> 1793
>> 1794 config EMBEDDED
>> 1795 bool "Embedded system"
>> 1796 select EXPERT
>> 1797 help
>> 1798 This option should be enabled if compiling the kernel for
>> 1799 an embedded system so certain expert options are available
>> 1800 for configuration.
>> 1801
1862 config HAVE_PERF_EVENTS 1802 config HAVE_PERF_EVENTS
1863 bool 1803 bool
1864 help 1804 help
1865 See tools/perf/design.txt for detai 1805 See tools/perf/design.txt for details.
1866 1806
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1807 config PERF_USE_VMALLOC
1872 bool 1808 bool
1873 help 1809 help
1874 See tools/perf/design.txt for detai 1810 See tools/perf/design.txt for details
1875 1811
>> 1812 config PC104
>> 1813 bool "PC/104 support" if EXPERT
>> 1814 help
>> 1815 Expose PC/104 form factor device drivers and options available for
>> 1816 selection and configuration. Enable this option if your target
>> 1817 machine has a PC/104 bus.
>> 1818
1876 menu "Kernel Performance Events And Counters" 1819 menu "Kernel Performance Events And Counters"
1877 1820
1878 config PERF_EVENTS 1821 config PERF_EVENTS
1879 bool "Kernel performance events and c 1822 bool "Kernel performance events and counters"
1880 default y if PROFILING 1823 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1824 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1825 select IRQ_WORK
>> 1826 select SRCU
1883 help 1827 help
1884 Enable kernel support for various p 1828 Enable kernel support for various performance events provided
1885 by software and hardware. 1829 by software and hardware.
1886 1830
1887 Software events are supported eithe 1831 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1832 use of generic tracepoints.
1889 1833
1890 Most modern CPUs support performanc 1834 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1835 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1836 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1837 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1838 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1839 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1840 used to profile the code that runs on that CPU.
1897 1841
1898 The Linux Performance Event subsyst 1842 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1843 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1844 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1845 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1846 capabilities on top of those.
1903 1847
1904 Say Y if unsure. 1848 Say Y if unsure.
1905 1849
1906 config DEBUG_PERF_USE_VMALLOC 1850 config DEBUG_PERF_USE_VMALLOC
1907 default n 1851 default n
1908 bool "Debug: use vmalloc to back perf 1852 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1853 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1854 select PERF_USE_VMALLOC
1911 help 1855 help
1912 Use vmalloc memory to back perf mma 1856 Use vmalloc memory to back perf mmap() buffers.
1913 1857
1914 Mostly useful for debugging the vma 1858 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1859 that don't require it.
1916 1860
1917 Say N if unsure. 1861 Say N if unsure.
1918 1862
1919 endmenu 1863 endmenu
1920 1864
>> 1865 config VM_EVENT_COUNTERS
>> 1866 default y
>> 1867 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1868 help
>> 1869 VM event counters are needed for event counts to be shown.
>> 1870 This option allows the disabling of the VM event counters
>> 1871 on EXPERT systems. /proc/vmstat will only show page counts
>> 1872 if VM event counters are disabled.
>> 1873
>> 1874 config SLUB_DEBUG
>> 1875 default y
>> 1876 bool "Enable SLUB debugging support" if EXPERT
>> 1877 depends on SLUB && SYSFS
>> 1878 help
>> 1879 SLUB has extensive debug support features. Disabling these can
>> 1880 result in significant savings in code size. This also disables
>> 1881 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1882 no support for cache validation etc.
>> 1883
>> 1884 config COMPAT_BRK
>> 1885 bool "Disable heap randomization"
>> 1886 default y
>> 1887 help
>> 1888 Randomizing heap placement makes heap exploits harder, but it
>> 1889 also breaks ancient binaries (including anything libc5 based).
>> 1890 This option changes the bootup default to heap randomization
>> 1891 disabled, and can be overridden at runtime by setting
>> 1892 /proc/sys/kernel/randomize_va_space to 2.
>> 1893
>> 1894 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1895
>> 1896 choice
>> 1897 prompt "Choose SLAB allocator"
>> 1898 default SLUB
>> 1899 help
>> 1900 This option allows to select a slab allocator.
>> 1901
>> 1902 config SLAB
>> 1903 bool "SLAB"
>> 1904 depends on !PREEMPT_RT
>> 1905 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1906 help
>> 1907 The regular slab allocator that is established and known to work
>> 1908 well in all environments. It organizes cache hot objects in
>> 1909 per cpu and per node queues.
>> 1910
>> 1911 config SLUB
>> 1912 bool "SLUB (Unqueued Allocator)"
>> 1913 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1914 help
>> 1915 SLUB is a slab allocator that minimizes cache line usage
>> 1916 instead of managing queues of cached objects (SLAB approach).
>> 1917 Per cpu caching is realized using slabs of objects instead
>> 1918 of queues of objects. SLUB can use memory efficiently
>> 1919 and has enhanced diagnostics. SLUB is the default choice for
>> 1920 a slab allocator.
>> 1921
>> 1922 config SLOB
>> 1923 depends on EXPERT
>> 1924 bool "SLOB (Simple Allocator)"
>> 1925 depends on !PREEMPT_RT
>> 1926 help
>> 1927 SLOB replaces the stock allocator with a drastically simpler
>> 1928 allocator. SLOB is generally more space efficient but
>> 1929 does not perform as well on large systems.
>> 1930
>> 1931 endchoice
>> 1932
>> 1933 config SLAB_MERGE_DEFAULT
>> 1934 bool "Allow slab caches to be merged"
>> 1935 default y
>> 1936 help
>> 1937 For reduced kernel memory fragmentation, slab caches can be
>> 1938 merged when they share the same size and other characteristics.
>> 1939 This carries a risk of kernel heap overflows being able to
>> 1940 overwrite objects from merged caches (and more easily control
>> 1941 cache layout), which makes such heap attacks easier to exploit
>> 1942 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1943 can usually only damage objects in the same cache. To disable
>> 1944 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1945 command line.
>> 1946
>> 1947 config SLAB_FREELIST_RANDOM
>> 1948 bool "Randomize slab freelist"
>> 1949 depends on SLAB || SLUB
>> 1950 help
>> 1951 Randomizes the freelist order used on creating new pages. This
>> 1952 security feature reduces the predictability of the kernel slab
>> 1953 allocator against heap overflows.
>> 1954
>> 1955 config SLAB_FREELIST_HARDENED
>> 1956 bool "Harden slab freelist metadata"
>> 1957 depends on SLAB || SLUB
>> 1958 help
>> 1959 Many kernel heap attacks try to target slab cache metadata and
>> 1960 other infrastructure. This options makes minor performance
>> 1961 sacrifices to harden the kernel slab allocator against common
>> 1962 freelist exploit methods. Some slab implementations have more
>> 1963 sanity-checking than others. This option is most effective with
>> 1964 CONFIG_SLUB.
>> 1965
>> 1966 config SHUFFLE_PAGE_ALLOCATOR
>> 1967 bool "Page allocator randomization"
>> 1968 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1969 help
>> 1970 Randomization of the page allocator improves the average
>> 1971 utilization of a direct-mapped memory-side-cache. See section
>> 1972 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1973 6.2a specification for an example of how a platform advertises
>> 1974 the presence of a memory-side-cache. There are also incidental
>> 1975 security benefits as it reduces the predictability of page
>> 1976 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1977 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1978 10th order of pages is selected based on cache utilization
>> 1979 benefits on x86.
>> 1980
>> 1981 While the randomization improves cache utilization it may
>> 1982 negatively impact workloads on platforms without a cache. For
>> 1983 this reason, by default, the randomization is enabled only
>> 1984 after runtime detection of a direct-mapped memory-side-cache.
>> 1985 Otherwise, the randomization may be force enabled with the
>> 1986 'page_alloc.shuffle' kernel command line parameter.
>> 1987
>> 1988 Say Y if unsure.
>> 1989
>> 1990 config SLUB_CPU_PARTIAL
>> 1991 default y
>> 1992 depends on SLUB && SMP
>> 1993 bool "SLUB per cpu partial cache"
>> 1994 help
>> 1995 Per cpu partial caches accelerate objects allocation and freeing
>> 1996 that is local to a processor at the price of more indeterminism
>> 1997 in the latency of the free. On overflow these caches will be cleared
>> 1998 which requires the taking of locks that may cause latency spikes.
>> 1999 Typically one would choose no for a realtime system.
>> 2000
>> 2001 config MMAP_ALLOW_UNINITIALIZED
>> 2002 bool "Allow mmapped anonymous memory to be uninitialized"
>> 2003 depends on EXPERT && !MMU
>> 2004 default n
>> 2005 help
>> 2006 Normally, and according to the Linux spec, anonymous memory obtained
>> 2007 from mmap() has its contents cleared before it is passed to
>> 2008 userspace. Enabling this config option allows you to request that
>> 2009 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 2010 providing a huge performance boost. If this option is not enabled,
>> 2011 then the flag will be ignored.
>> 2012
>> 2013 This is taken advantage of by uClibc's malloc(), and also by
>> 2014 ELF-FDPIC binfmt's brk and stack allocator.
>> 2015
>> 2016 Because of the obvious security issues, this option should only be
>> 2017 enabled on embedded devices where you control what is run in
>> 2018 userspace. Since that isn't generally a problem on no-MMU systems,
>> 2019 it is normally safe to say Y here.
>> 2020
>> 2021 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
>> 2022
1921 config SYSTEM_DATA_VERIFICATION 2023 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 2024 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 2025 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 2026 select KEYS
1925 select CRYPTO 2027 select CRYPTO
1926 select CRYPTO_RSA 2028 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 2029 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2030 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 2031 select ASN1
1930 select OID_REGISTRY 2032 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 2033 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 2034 select PKCS7_MESSAGE_PARSER
1933 help 2035 help
1934 Provide PKCS#7 message verification 2036 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 2037 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 2038 module verification, kexec image verification and firmware blob
1937 verification. 2039 verification.
1938 2040
1939 config PROFILING 2041 config PROFILING
1940 bool "Profiling support" 2042 bool "Profiling support"
1941 help 2043 help
1942 Say Y here to enable the extended p 2044 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. 2045 by profilers.
1944 2046
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 # 2047 #
1987 # Place an empty function call at each tracep 2048 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 2049 # dynamically changed for a probe function.
1989 # 2050 #
1990 config TRACEPOINTS 2051 config TRACEPOINTS
1991 bool 2052 bool
1992 2053
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 2054 endmenu # General setup
1996 2055
1997 source "arch/Kconfig" 2056 source "arch/Kconfig"
1998 2057
1999 config RT_MUTEXES 2058 config RT_MUTEXES
2000 bool 2059 bool
2001 default y if PREEMPT_RT !! 2060
>> 2061 config BASE_SMALL
>> 2062 int
>> 2063 default 0 if BASE_FULL
>> 2064 default 1 if !BASE_FULL
2002 2065
2003 config MODULE_SIG_FORMAT 2066 config MODULE_SIG_FORMAT
2004 def_bool n 2067 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 2068 select SYSTEM_DATA_VERIFICATION
2006 2069
2007 source "kernel/module/Kconfig" !! 2070 menuconfig MODULES
>> 2071 bool "Enable loadable module support"
>> 2072 modules
>> 2073 help
>> 2074 Kernel modules are small pieces of compiled code which can
>> 2075 be inserted in the running kernel, rather than being
>> 2076 permanently built into the kernel. You use the "modprobe"
>> 2077 tool to add (and sometimes remove) them. If you say Y here,
>> 2078 many parts of the kernel can be built as modules (by
>> 2079 answering M instead of Y where indicated): this is most
>> 2080 useful for infrequently used options which are not required
>> 2081 for booting. For more information, see the man pages for
>> 2082 modprobe, lsmod, modinfo, insmod and rmmod.
>> 2083
>> 2084 If you say Y here, you will need to run "make
>> 2085 modules_install" to put the modules under /lib/modules/
>> 2086 where modprobe can find them (you may need to be root to do
>> 2087 this).
>> 2088
>> 2089 If unsure, say Y.
>> 2090
>> 2091 if MODULES
>> 2092
>> 2093 config MODULE_FORCE_LOAD
>> 2094 bool "Forced module loading"
>> 2095 default n
>> 2096 help
>> 2097 Allow loading of modules without version information (ie. modprobe
>> 2098 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 2099 is usually a really bad idea.
>> 2100
>> 2101 config MODULE_UNLOAD
>> 2102 bool "Module unloading"
>> 2103 help
>> 2104 Without this option you will not be able to unload any
>> 2105 modules (note that some modules may not be unloadable
>> 2106 anyway), which makes your kernel smaller, faster
>> 2107 and simpler. If unsure, say Y.
>> 2108
>> 2109 config MODULE_FORCE_UNLOAD
>> 2110 bool "Forced module unloading"
>> 2111 depends on MODULE_UNLOAD
>> 2112 help
>> 2113 This option allows you to force a module to unload, even if the
>> 2114 kernel believes it is unsafe: the kernel will remove the module
>> 2115 without waiting for anyone to stop using it (using the -f option to
>> 2116 rmmod). This is mainly for kernel developers and desperate users.
>> 2117 If unsure, say N.
>> 2118
>> 2119 config MODVERSIONS
>> 2120 bool "Module versioning support"
>> 2121 help
>> 2122 Usually, you have to use modules compiled with your kernel.
>> 2123 Saying Y here makes it sometimes possible to use modules
>> 2124 compiled for different kernels, by adding enough information
>> 2125 to the modules to (hopefully) spot any changes which would
>> 2126 make them incompatible with the kernel you are running. If
>> 2127 unsure, say N.
>> 2128
>> 2129 config ASM_MODVERSIONS
>> 2130 bool
>> 2131 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 2132 help
>> 2133 This enables module versioning for exported symbols also from
>> 2134 assembly. This can be enabled only when the target architecture
>> 2135 supports it.
>> 2136
>> 2137 config MODULE_REL_CRCS
>> 2138 bool
>> 2139 depends on MODVERSIONS
>> 2140
>> 2141 config MODULE_SRCVERSION_ALL
>> 2142 bool "Source checksum for all modules"
>> 2143 help
>> 2144 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2145 field inserted into their modinfo section, which contains a
>> 2146 sum of the source files which made it. This helps maintainers
>> 2147 see exactly which source was used to build a module (since
>> 2148 others sometimes change the module source without updating
>> 2149 the version). With this option, such a "srcversion" field
>> 2150 will be created for all modules. If unsure, say N.
>> 2151
>> 2152 config MODULE_SIG
>> 2153 bool "Module signature verification"
>> 2154 select MODULE_SIG_FORMAT
>> 2155 help
>> 2156 Check modules for valid signatures upon load: the signature
>> 2157 is simply appended to the module. For more information see
>> 2158 <file:Documentation/admin-guide/module-signing.rst>.
>> 2159
>> 2160 Note that this option adds the OpenSSL development packages as a
>> 2161 kernel build dependency so that the signing tool can use its crypto
>> 2162 library.
>> 2163
>> 2164 You should enable this option if you wish to use either
>> 2165 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2166 another LSM - otherwise unsigned modules will be loadable regardless
>> 2167 of the lockdown policy.
>> 2168
>> 2169 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2170 module DOES NOT get stripped after being signed. This includes the
>> 2171 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2172 inclusion into an initramfs that wants the module size reduced.
>> 2173
>> 2174 config MODULE_SIG_FORCE
>> 2175 bool "Require modules to be validly signed"
>> 2176 depends on MODULE_SIG
>> 2177 help
>> 2178 Reject unsigned modules or signed modules for which we don't have a
>> 2179 key. Without this, such modules will simply taint the kernel.
>> 2180
>> 2181 config MODULE_SIG_ALL
>> 2182 bool "Automatically sign all modules"
>> 2183 default y
>> 2184 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2185 help
>> 2186 Sign all modules during make modules_install. Without this option,
>> 2187 modules must be signed manually, using the scripts/sign-file tool.
>> 2188
>> 2189 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2190 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2191
>> 2192 choice
>> 2193 prompt "Which hash algorithm should modules be signed with?"
>> 2194 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2195 help
>> 2196 This determines which sort of hashing algorithm will be used during
>> 2197 signature generation. This algorithm _must_ be built into the kernel
>> 2198 directly so that signature verification can take place. It is not
>> 2199 possible to load a signed module containing the algorithm to check
>> 2200 the signature on that module.
>> 2201
>> 2202 config MODULE_SIG_SHA1
>> 2203 bool "Sign modules with SHA-1"
>> 2204 select CRYPTO_SHA1
>> 2205
>> 2206 config MODULE_SIG_SHA224
>> 2207 bool "Sign modules with SHA-224"
>> 2208 select CRYPTO_SHA256
>> 2209
>> 2210 config MODULE_SIG_SHA256
>> 2211 bool "Sign modules with SHA-256"
>> 2212 select CRYPTO_SHA256
>> 2213
>> 2214 config MODULE_SIG_SHA384
>> 2215 bool "Sign modules with SHA-384"
>> 2216 select CRYPTO_SHA512
>> 2217
>> 2218 config MODULE_SIG_SHA512
>> 2219 bool "Sign modules with SHA-512"
>> 2220 select CRYPTO_SHA512
>> 2221
>> 2222 endchoice
>> 2223
>> 2224 config MODULE_SIG_HASH
>> 2225 string
>> 2226 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2227 default "sha1" if MODULE_SIG_SHA1
>> 2228 default "sha224" if MODULE_SIG_SHA224
>> 2229 default "sha256" if MODULE_SIG_SHA256
>> 2230 default "sha384" if MODULE_SIG_SHA384
>> 2231 default "sha512" if MODULE_SIG_SHA512
>> 2232
>> 2233 choice
>> 2234 prompt "Module compression mode"
>> 2235 help
>> 2236 This option allows you to choose the algorithm which will be used to
>> 2237 compress modules when 'make modules_install' is run. (or, you can
>> 2238 choose to not compress modules at all.)
>> 2239
>> 2240 External modules will also be compressed in the same way during the
>> 2241 installation.
>> 2242
>> 2243 For modules inside an initrd or initramfs, it's more efficient to
>> 2244 compress the whole initrd or initramfs instead.
>> 2245
>> 2246 This is fully compatible with signed modules.
>> 2247
>> 2248 Please note that the tool used to load modules needs to support the
>> 2249 corresponding algorithm. module-init-tools MAY support gzip, and kmod
>> 2250 MAY support gzip, xz and zstd.
>> 2251
>> 2252 Your build system needs to provide the appropriate compression tool
>> 2253 to compress the modules.
>> 2254
>> 2255 If in doubt, select 'None'.
>> 2256
>> 2257 config MODULE_COMPRESS_NONE
>> 2258 bool "None"
>> 2259 help
>> 2260 Do not compress modules. The installed modules are suffixed
>> 2261 with .ko.
>> 2262
>> 2263 config MODULE_COMPRESS_GZIP
>> 2264 bool "GZIP"
>> 2265 help
>> 2266 Compress modules with GZIP. The installed modules are suffixed
>> 2267 with .ko.gz.
>> 2268
>> 2269 config MODULE_COMPRESS_XZ
>> 2270 bool "XZ"
>> 2271 help
>> 2272 Compress modules with XZ. The installed modules are suffixed
>> 2273 with .ko.xz.
>> 2274
>> 2275 config MODULE_COMPRESS_ZSTD
>> 2276 bool "ZSTD"
>> 2277 help
>> 2278 Compress modules with ZSTD. The installed modules are suffixed
>> 2279 with .ko.zst.
>> 2280
>> 2281 endchoice
>> 2282
>> 2283 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2284 bool "Allow loading of modules with missing namespace imports"
>> 2285 help
>> 2286 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2287 a namespace. A module that makes use of a symbol exported with such a
>> 2288 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2289 There is no technical reason to enforce correct namespace imports,
>> 2290 but it creates consistency between symbols defining namespaces and
>> 2291 users importing namespaces they make use of. This option relaxes this
>> 2292 requirement and lifts the enforcement when loading a module.
>> 2293
>> 2294 If unsure, say N.
>> 2295
>> 2296 config MODPROBE_PATH
>> 2297 string "Path to modprobe binary"
>> 2298 default "/sbin/modprobe"
>> 2299 help
>> 2300 When kernel code requests a module, it does so by calling
>> 2301 the "modprobe" userspace utility. This option allows you to
>> 2302 set the path where that binary is found. This can be changed
>> 2303 at runtime via the sysctl file
>> 2304 /proc/sys/kernel/modprobe. Setting this to the empty string
>> 2305 removes the kernel's ability to request modules (but
>> 2306 userspace can still load modules explicitly).
>> 2307
>> 2308 config TRIM_UNUSED_KSYMS
>> 2309 bool "Trim unused exported kernel symbols" if EXPERT
>> 2310 depends on !COMPILE_TEST
>> 2311 help
>> 2312 The kernel and some modules make many symbols available for
>> 2313 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2314 on the set of modules being selected in your kernel configuration,
>> 2315 many of those exported symbols might never be used.
>> 2316
>> 2317 This option allows for unused exported symbols to be dropped from
>> 2318 the build. In turn, this provides the compiler more opportunities
>> 2319 (especially when using LTO) for optimizing the code and reducing
>> 2320 binary size. This might have some security advantages as well.
>> 2321
>> 2322 If unsure, or if you need to build out-of-tree modules, say N.
>> 2323
>> 2324 config UNUSED_KSYMS_WHITELIST
>> 2325 string "Whitelist of symbols to keep in ksymtab"
>> 2326 depends on TRIM_UNUSED_KSYMS
>> 2327 help
>> 2328 By default, all unused exported symbols will be un-exported from the
>> 2329 build when TRIM_UNUSED_KSYMS is selected.
>> 2330
>> 2331 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
>> 2332 exported at all times, even in absence of in-tree users. The value to
>> 2333 set here is the path to a text file containing the list of symbols,
>> 2334 one per line. The path can be absolute, or relative to the kernel
>> 2335 source tree.
>> 2336
>> 2337 endif # MODULES
>> 2338
>> 2339 config MODULES_TREE_LOOKUP
>> 2340 def_bool y
>> 2341 depends on PERF_EVENTS || TRACING || CFI_CLANG
2008 2342
2009 config INIT_ALL_POSSIBLE 2343 config INIT_ALL_POSSIBLE
2010 bool 2344 bool
2011 help 2345 help
2012 Back when each arch used to define 2346 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2347 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2348 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2349 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2350 and have several arch maintainers pursuing me down dark alleys.
2017 2351
2018 source "block/Kconfig" 2352 source "block/Kconfig"
2019 2353
2020 config PREEMPT_NOTIFIERS 2354 config PREEMPT_NOTIFIERS
2021 bool 2355 bool
2022 2356
2023 config PADATA 2357 config PADATA
2024 depends on SMP 2358 depends on SMP
2025 bool 2359 bool
2026 2360
2027 config ASN1 2361 config ASN1
2028 tristate 2362 tristate
2029 help 2363 help
2030 Build a simple ASN.1 grammar compil 2364 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2365 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2366 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2367 functions to call on what tags.
2034 2368
2035 source "kernel/Kconfig.locks" 2369 source "kernel/Kconfig.locks"
2036 2370
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2371 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2372 bool
2042 2373
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2374 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2375 bool
2045 2376
2046 # It may be useful for an architecture to ove 2377 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2378 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2379 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2380 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2381 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2382 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2383 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2384 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2385 def_bool n
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