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 79
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT 80 config CC_HAS_ASM_GOTO_TIED_OUTPUT
110 depends on CC_HAS_ASM_GOTO_OUTPUT 81 depends on CC_HAS_ASM_GOTO_OUTPUT
111 # Detect buggy gcc and clang, fixed in 82 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
112 def_bool $(success,echo 'int foo(int * !! 83 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .\n": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
113 84
114 config TOOLS_SUPPORT_RELR 85 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 86 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 87
117 config CC_HAS_ASM_INLINE 88 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 89 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 90
120 config CC_HAS_NO_PROFILE_FN_ATTR 91 config CC_HAS_NO_PROFILE_FN_ATTR
121 def_bool $(success,echo '__attribute__ 92 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
122 93
123 config PAHOLE_VERSION <<
124 int <<
125 default $(shell,$(srctree)/scripts/pah <<
126 <<
127 config CONSTRUCTORS 94 config CONSTRUCTORS
128 bool 95 bool
129 96
130 config IRQ_WORK 97 config IRQ_WORK
131 def_bool y if SMP !! 98 bool
132 99
133 config BUILDTIME_TABLE_SORT 100 config BUILDTIME_TABLE_SORT
134 bool 101 bool
135 102
136 config THREAD_INFO_IN_TASK 103 config THREAD_INFO_IN_TASK
137 bool 104 bool
138 help 105 help
139 Select this to move thread_info off 106 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 107 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 108 except flags and fix any runtime bugs.
142 109
143 One subtle change that will be neede 110 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 111 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 112
146 menu "General setup" 113 menu "General setup"
147 114
148 config BROKEN 115 config BROKEN
149 bool 116 bool
150 117
151 config BROKEN_ON_SMP 118 config BROKEN_ON_SMP
152 bool 119 bool
153 depends on BROKEN || !SMP 120 depends on BROKEN || !SMP
154 default y 121 default y
155 122
156 config INIT_ENV_ARG_LIMIT 123 config INIT_ENV_ARG_LIMIT
157 int 124 int
158 default 32 if !UML 125 default 32 if !UML
159 default 128 if UML 126 default 128 if UML
160 help 127 help
161 Maximum of each of the number of arg 128 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 129 variables passed to init from the kernel command line.
163 130
164 config COMPILE_TEST 131 config COMPILE_TEST
165 bool "Compile also drivers which will 132 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 133 depends on HAS_IOMEM
167 help 134 help
168 Some drivers can be compiled on a di 135 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 136 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 137 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 138 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 139 drivers to compile-test them.
173 140
174 If you are a developer and want to b 141 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 142 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 143 drivers to be distributed.
177 144
178 config WERROR 145 config WERROR
179 bool "Compile the kernel with warnings 146 bool "Compile the kernel with warnings as errors"
180 default COMPILE_TEST 147 default COMPILE_TEST
181 help 148 help
182 A kernel build should not cause any 149 A kernel build should not cause any compiler warnings, and this
183 enables the '-Werror' (for C) and '- !! 150 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. <<
187 151
188 However, if you have a new (or very !! 152 However, if you have a new (or very old) compiler with odd and
189 and unusual warnings, or you have so !! 153 unusual warnings, or you have some architecture with problems,
190 you may need to disable this config 154 you may need to disable this config option in order to
191 successfully build the kernel. 155 successfully build the kernel.
192 156
193 If in doubt, say Y. 157 If in doubt, say Y.
194 158
195 config UAPI_HEADER_TEST 159 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 160 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 161 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 162 help
199 Compile test headers exported to use 163 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 164 self-contained, i.e. compilable as standalone units.
201 165
202 If you are a developer or tester and 166 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 167 headers are self-contained, say Y here. Otherwise, choose N.
204 168
205 config LOCALVERSION 169 config LOCALVERSION
206 string "Local version - append to kern 170 string "Local version - append to kernel release"
207 help 171 help
208 Append an extra string to the end of 172 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 173 This will show up when you type uname, for example.
210 The string you set here will be appe 174 The string you set here will be appended after the contents of
211 any files with a filename matching l 175 any files with a filename matching localversion* in your
212 object and source tree, in that orde 176 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 177 be a maximum of 64 characters.
214 178
215 config LOCALVERSION_AUTO 179 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 180 bool "Automatically append version information to the version string"
217 default y 181 default y
218 depends on !COMPILE_TEST 182 depends on !COMPILE_TEST
219 help 183 help
220 This will try to automatically deter 184 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 185 release tree by looking for git tags that belong to the current
222 top of tree revision. 186 top of tree revision.
223 187
224 A string of the format -gxxxxxxxx wi 188 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 189 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 190 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 191 set in CONFIG_LOCALVERSION.
228 192
229 (The actual string used here is the !! 193 (The actual string used here is the first eight characters produced
230 by running the command: 194 by running the command:
231 195
232 $ git rev-parse --verify HEAD 196 $ git rev-parse --verify HEAD
233 197
234 which is done within the script "scr 198 which is done within the script "scripts/setlocalversion".)
235 199
236 config BUILD_SALT 200 config BUILD_SALT
237 string "Build ID Salt" 201 string "Build ID Salt"
238 default "" 202 default ""
239 help 203 help
240 The build ID is used to link binarie 204 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 205 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 206 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 207 build is unique between builds. It's safe to leave the default.
244 208
245 config HAVE_KERNEL_GZIP 209 config HAVE_KERNEL_GZIP
246 bool 210 bool
247 211
248 config HAVE_KERNEL_BZIP2 212 config HAVE_KERNEL_BZIP2
249 bool 213 bool
250 214
251 config HAVE_KERNEL_LZMA 215 config HAVE_KERNEL_LZMA
252 bool 216 bool
253 217
254 config HAVE_KERNEL_XZ 218 config HAVE_KERNEL_XZ
255 bool 219 bool
256 220
257 config HAVE_KERNEL_LZO 221 config HAVE_KERNEL_LZO
258 bool 222 bool
259 223
260 config HAVE_KERNEL_LZ4 224 config HAVE_KERNEL_LZ4
261 bool 225 bool
262 226
263 config HAVE_KERNEL_ZSTD 227 config HAVE_KERNEL_ZSTD
264 bool 228 bool
265 229
266 config HAVE_KERNEL_UNCOMPRESSED 230 config HAVE_KERNEL_UNCOMPRESSED
267 bool 231 bool
268 232
269 choice 233 choice
270 prompt "Kernel compression mode" 234 prompt "Kernel compression mode"
271 default KERNEL_GZIP 235 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE 236 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 237 help
274 The linux kernel is a kind of self-e 238 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 239 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 240 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 241 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 242 Decompression speed is relevant at each boot.
279 243
280 If you have any problems with bzip2 244 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 245 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 246 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 247 supplied by Christian Ludwig)
284 248
285 High compression options are mostly 249 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 250 are low on disk space (embedded systems), but for whom ram
287 size matters less. 251 size matters less.
288 252
289 If in doubt, select 'gzip' 253 If in doubt, select 'gzip'
290 254
291 config KERNEL_GZIP 255 config KERNEL_GZIP
292 bool "Gzip" 256 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 257 depends on HAVE_KERNEL_GZIP
294 help 258 help
295 The old and tried gzip compression. 259 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 260 between compression ratio and decompression speed.
297 261
298 config KERNEL_BZIP2 262 config KERNEL_BZIP2
299 bool "Bzip2" 263 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 264 depends on HAVE_KERNEL_BZIP2
301 help 265 help
302 Its compression ratio and speed is i 266 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 267 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 268 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 269 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 270 will need at least 8MB RAM or more for booting.
307 271
308 config KERNEL_LZMA 272 config KERNEL_LZMA
309 bool "LZMA" 273 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 274 depends on HAVE_KERNEL_LZMA
311 help 275 help
312 This compression algorithm's ratio i 276 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 277 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 278 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 279
316 config KERNEL_XZ 280 config KERNEL_XZ
317 bool "XZ" 281 bool "XZ"
318 depends on HAVE_KERNEL_XZ 282 depends on HAVE_KERNEL_XZ
319 help 283 help
320 XZ uses the LZMA2 algorithm and inst 284 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 285 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 286 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 287 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 288 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 289 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 290
328 The speed is about the same as with 291 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 292 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 293 and LZO. Compression is slow.
331 294
332 config KERNEL_LZO 295 config KERNEL_LZO
333 bool "LZO" 296 bool "LZO"
334 depends on HAVE_KERNEL_LZO 297 depends on HAVE_KERNEL_LZO
335 help 298 help
336 Its compression ratio is the poorest 299 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 300 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 301 (both compression and decompression) is the fastest.
339 302
340 config KERNEL_LZ4 303 config KERNEL_LZ4
341 bool "LZ4" 304 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 305 depends on HAVE_KERNEL_LZ4
343 help 306 help
344 LZ4 is an LZ77-type compressor with 307 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 308 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 309 <https://code.google.com/p/lz4/>.
347 310
348 Its compression ratio is worse than 311 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 312 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 313 faster than LZO.
351 314
352 config KERNEL_ZSTD 315 config KERNEL_ZSTD
353 bool "ZSTD" 316 bool "ZSTD"
354 depends on HAVE_KERNEL_ZSTD 317 depends on HAVE_KERNEL_ZSTD
355 help 318 help
356 ZSTD is a compression algorithm targ 319 ZSTD is a compression algorithm targeting intermediate compression
357 with fast decompression speed. It wi 320 with fast decompression speed. It will compress better than GZIP and
358 decompress around the same speed as 321 decompress around the same speed as LZO, but slower than LZ4. You
359 will need at least 192 KB RAM or mor 322 will need at least 192 KB RAM or more for booting. The zstd command
360 line tool is required for compressio 323 line tool is required for compression.
361 324
362 config KERNEL_UNCOMPRESSED 325 config KERNEL_UNCOMPRESSED
363 bool "None" 326 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 327 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 328 help
366 Produce uncompressed kernel image. T 329 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 330 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 331 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 332 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 333 and jump right at uncompressed kernel image.
371 334
372 endchoice 335 endchoice
373 336
374 config DEFAULT_INIT 337 config DEFAULT_INIT
375 string "Default init path" 338 string "Default init path"
376 default "" 339 default ""
377 help 340 help
378 This option determines the default i 341 This option determines the default init for the system if no init=
379 option is passed on the kernel comma 342 option is passed on the kernel command line. If the requested path is
380 not present, we will still then move 343 not present, we will still then move on to attempting further
381 locations (e.g. /sbin/init, etc). If 344 locations (e.g. /sbin/init, etc). If this is empty, we will just use
382 the fallback list when init= is not 345 the fallback list when init= is not passed.
383 346
384 config DEFAULT_HOSTNAME 347 config DEFAULT_HOSTNAME
385 string "Default hostname" 348 string "Default hostname"
386 default "(none)" 349 default "(none)"
387 help 350 help
388 This option determines the default s 351 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 352 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 353 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 354 system more usable with less configuration.
392 355
>> 356 #
>> 357 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 358 # add proper SWAP support to them, in which case this can be remove.
>> 359 #
>> 360 config ARCH_NO_SWAP
>> 361 bool
>> 362
>> 363 config SWAP
>> 364 bool "Support for paging of anonymous memory (swap)"
>> 365 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 366 default y
>> 367 help
>> 368 This option allows you to choose whether you want to have support
>> 369 for so called swap devices or swap files in your kernel that are
>> 370 used to provide more virtual memory than the actual RAM present
>> 371 in your computer. If unsure say Y.
>> 372
393 config SYSVIPC 373 config SYSVIPC
394 bool "System V IPC" 374 bool "System V IPC"
395 help 375 help
396 Inter Process Communication is a sui 376 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 377 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 378 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 379 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 380 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 381 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 382 you'll need to say Y here.
403 383
404 You can find documentation about IPC 384 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 385 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 386 <http://www.tldp.org/guides.html>.
407 387
408 config SYSVIPC_SYSCTL 388 config SYSVIPC_SYSCTL
409 bool 389 bool
410 depends on SYSVIPC 390 depends on SYSVIPC
411 depends on SYSCTL 391 depends on SYSCTL
412 default y 392 default y
413 393
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 394 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 395 bool "POSIX Message Queues"
420 depends on NET 396 depends on NET
421 help 397 help
422 POSIX variant of message queues is a 398 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 399 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 400 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 401 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 402 queues (functions mq_*) say Y here.
427 403
428 POSIX message queues are visible as 404 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 405 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 406 operations on message queues.
431 407
432 If unsure, say Y. 408 If unsure, say Y.
433 409
434 config POSIX_MQUEUE_SYSCTL 410 config POSIX_MQUEUE_SYSCTL
435 bool 411 bool
436 depends on POSIX_MQUEUE 412 depends on POSIX_MQUEUE
437 depends on SYSCTL 413 depends on SYSCTL
438 default y 414 default y
439 415
440 config WATCH_QUEUE 416 config WATCH_QUEUE
441 bool "General notification queue" 417 bool "General notification queue"
442 default n 418 default n
443 help 419 help
444 420
445 This is a general notification queue 421 This is a general notification queue for the kernel to pass events to
446 userspace by splicing them into pipe 422 userspace by splicing them into pipes. It can be used in conjunction
447 with watches for key/keyring change 423 with watches for key/keyring change notifications and device
448 notifications. 424 notifications.
449 425
450 See Documentation/core-api/watch_que !! 426 See Documentation/watch_queue.rst
451 427
452 config CROSS_MEMORY_ATTACH 428 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 429 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 430 depends on MMU
455 default y 431 default y
456 help 432 help
457 Enabling this option adds the system 433 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 434 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 435 to directly read from or write to another process' address space.
460 See the man page for more details. 436 See the man page for more details.
461 437
462 config USELIB 438 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 439 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 440 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 441 help
466 This option enables the uselib sysca 442 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 443 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 444 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 445 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 446 running glibc can safely disable this.
471 447
472 config AUDIT 448 config AUDIT
473 bool "Auditing support" 449 bool "Auditing support"
474 depends on NET 450 depends on NET
475 help 451 help
476 Enable auditing infrastructure that 452 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 453 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 454 logging of avc messages output). System call auditing is included
479 on architectures which support it. 455 on architectures which support it.
480 456
481 config HAVE_ARCH_AUDITSYSCALL 457 config HAVE_ARCH_AUDITSYSCALL
482 bool 458 bool
483 459
484 config AUDITSYSCALL 460 config AUDITSYSCALL
485 def_bool y 461 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 462 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 463 select FSNOTIFY
488 464
489 source "kernel/irq/Kconfig" 465 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 466 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" 467 source "kernel/bpf/Kconfig"
492 source "kernel/Kconfig.preempt" 468 source "kernel/Kconfig.preempt"
493 469
494 menu "CPU/Task time and stats accounting" 470 menu "CPU/Task time and stats accounting"
495 471
496 config VIRT_CPU_ACCOUNTING 472 config VIRT_CPU_ACCOUNTING
497 bool 473 bool
498 474
499 choice 475 choice
500 prompt "Cputime accounting" 476 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 477 default TICK_CPU_ACCOUNTING if !PPC64
>> 478 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 479
503 # Kind of a stub config for the pure tick base 480 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 481 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 482 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 483 depends on !S390 && !NO_HZ_FULL
507 help 484 help
508 This is the basic tick based cputime 485 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 486 statistics about user, system and idle time spent on per jiffies
510 granularity. 487 granularity.
511 488
512 If unsure, say Y. 489 If unsure, say Y.
513 490
514 config VIRT_CPU_ACCOUNTING_NATIVE 491 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 492 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 493 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 494 select VIRT_CPU_ACCOUNTING
518 help 495 help
519 Select this option to enable more ac 496 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 497 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 498 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 499 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 500 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 501 this also enables accounting of stolen time on logically-partitioned
525 systems. 502 systems.
526 503
527 config VIRT_CPU_ACCOUNTING_GEN 504 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 505 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 506 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 507 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 508 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 509 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 510 select CONTEXT_TRACKING
534 help 511 help
535 Select this option to enable task an 512 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 513 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 514 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 515 The accounting is thus performed at the expense of some significant
539 overhead. 516 overhead.
540 517
541 For now this is only useful if you a 518 For now this is only useful if you are working on the full
542 dynticks subsystem development. 519 dynticks subsystem development.
543 520
544 If unsure, say N. 521 If unsure, say N.
545 522
546 endchoice 523 endchoice
547 524
548 config IRQ_TIME_ACCOUNTING 525 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 526 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 527 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 528 help
552 Select this option to enable fine gr 529 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 530 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 531 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 532 small performance impact.
556 533
557 If in doubt, say N here. 534 If in doubt, say N here.
558 535
559 config HAVE_SCHED_AVG_IRQ 536 config HAVE_SCHED_AVG_IRQ
560 def_bool y 537 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 538 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 539 depends on SMP
563 540
564 config SCHED_HW_PRESSURE !! 541 config SCHED_THERMAL_PRESSURE
565 bool 542 bool
566 default y if ARM && ARM_CPU_TOPOLOGY 543 default y if ARM && ARM_CPU_TOPOLOGY
567 default y if ARM64 544 default y if ARM64
568 depends on SMP 545 depends on SMP
569 depends on CPU_FREQ_THERMAL 546 depends on CPU_FREQ_THERMAL
570 help 547 help
571 Select this option to enable HW pres !! 548 Select this option to enable thermal pressure accounting in the
572 scheduler. HW pressure is the value !! 549 scheduler. Thermal pressure is the value conveyed to the scheduler
573 that reflects the reduction in CPU c 550 that reflects the reduction in CPU compute capacity resulted from
574 HW throttling. HW throttling occurs !! 551 thermal throttling. Thermal throttling occurs when the performance of
575 a CPU is capped due to high operatin !! 552 a CPU is capped due to high operating temperatures.
576 553
577 If selected, the scheduler will be a 554 If selected, the scheduler will be able to balance tasks accordingly,
578 i.e. put less load on throttled CPUs 555 i.e. put less load on throttled CPUs than on non/less throttled ones.
579 556
580 This requires the architecture to im 557 This requires the architecture to implement
581 arch_update_hw_pressure() and arch_s !! 558 arch_update_thermal_pressure() and arch_scale_thermal_pressure().
582 559
583 config BSD_PROCESS_ACCT 560 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 561 bool "BSD Process Accounting"
585 depends on MULTIUSER 562 depends on MULTIUSER
586 help 563 help
587 If you say Y here, a user level prog 564 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 565 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 566 information to a file: whenever a process exits, information about
590 that process will be appended to the 567 that process will be appended to the file by the kernel. The
591 information includes things such as 568 information includes things such as creation time, owning user,
592 command name, memory usage, controll 569 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 570 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 571 up to the user level program to do useful things with this
595 information. This is generally a go 572 information. This is generally a good idea, so say Y.
596 573
597 config BSD_PROCESS_ACCT_V3 574 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 575 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 576 depends on BSD_PROCESS_ACCT
600 default n 577 default n
601 help 578 help
602 If you say Y here, the process accou 579 If you say Y here, the process accounting information is written
603 in a new file format that also logs 580 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 581 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 582 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 583 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 584 at <http://www.gnu.org/software/acct/>.
608 585
609 config TASKSTATS 586 config TASKSTATS
610 bool "Export task/process statistics t 587 bool "Export task/process statistics through netlink"
611 depends on NET 588 depends on NET
612 depends on MULTIUSER 589 depends on MULTIUSER
613 default n 590 default n
614 help 591 help
615 Export selected statistics for tasks 592 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 593 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 594 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 595 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 596 space on task exit.
620 597
621 Say N if unsure. 598 Say N if unsure.
622 599
623 config TASK_DELAY_ACCT 600 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 601 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 602 depends on TASKSTATS
626 select SCHED_INFO 603 select SCHED_INFO
627 help 604 help
628 Collect information on time spent by 605 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 606 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 607 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 608 relative to other tasks for cpu, io, rss limits etc.
632 609
633 Say N if unsure. 610 Say N if unsure.
634 611
635 config TASK_XACCT 612 config TASK_XACCT
636 bool "Enable extended accounting over 613 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 614 depends on TASKSTATS
638 help 615 help
639 Collect extended task accounting dat 616 Collect extended task accounting data and send the data
640 to userland for processing over the 617 to userland for processing over the taskstats interface.
641 618
642 Say N if unsure. 619 Say N if unsure.
643 620
644 config TASK_IO_ACCOUNTING 621 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 622 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 623 depends on TASK_XACCT
647 help 624 help
648 Collect information on the number of 625 Collect information on the number of bytes of storage I/O which this
649 task has caused. 626 task has caused.
650 627
651 Say N if unsure. 628 Say N if unsure.
652 629
653 config PSI 630 config PSI
654 bool "Pressure stall information track 631 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 632 help
657 Collect metrics that indicate how ov 633 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 634 and IO capacity are in the system.
659 635
660 If you say Y here, the kernel will c 636 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 637 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 638 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 639 delayed due to contention of the respective resource.
664 640
665 In kernels with cgroup support, cgro 641 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 642 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 643 which aggregate pressure stalls for the grouped tasks only.
668 644
669 For more details see Documentation/a 645 For more details see Documentation/accounting/psi.rst.
670 646
671 Say N if unsure. 647 Say N if unsure.
672 648
673 config PSI_DEFAULT_DISABLED 649 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 650 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 651 default n
676 depends on PSI 652 depends on PSI
677 help 653 help
678 If set, pressure stall information t 654 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 655 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 656 kernel commandline during boot.
681 657
682 This feature adds some code to the t 658 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 659 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 660 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 661 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 662 scheduler stress tests, such as hackbench.
687 663
688 If you are paranoid and not sure wha 664 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 665 used for, say Y.
690 666
691 Say N if unsure. 667 Say N if unsure.
692 668
693 endmenu # "CPU/Task time and stats accounting" 669 endmenu # "CPU/Task time and stats accounting"
694 670
695 config CPU_ISOLATION 671 config CPU_ISOLATION
696 bool "CPU isolation" 672 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 673 depends on SMP || COMPILE_TEST
698 default y 674 default y
699 help 675 help
700 Make sure that CPUs running critical 676 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 677 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 678 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 679 the "isolcpus=" boot parameter.
704 680
705 Say Y if unsure. 681 Say Y if unsure.
706 682
707 source "kernel/rcu/Kconfig" 683 source "kernel/rcu/Kconfig"
708 684
>> 685 config BUILD_BIN2C
>> 686 bool
>> 687 default n
>> 688
709 config IKCONFIG 689 config IKCONFIG
710 tristate "Kernel .config support" 690 tristate "Kernel .config support"
711 help 691 help
712 This option enables the complete Lin 692 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 693 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 694 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 695 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 696 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 697 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 698 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 699 /proc/config.gz if enabled (below).
720 700
721 config IKCONFIG_PROC 701 config IKCONFIG_PROC
722 bool "Enable access to .config through 702 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 703 depends on IKCONFIG && PROC_FS
724 help 704 help
725 This option enables access to the ke 705 This option enables access to the kernel configuration file
726 through /proc/config.gz. 706 through /proc/config.gz.
727 707
728 config IKHEADERS 708 config IKHEADERS
729 tristate "Enable kernel headers throug 709 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 710 depends on SYSFS
731 help 711 help
732 This option enables access to the in 712 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 713 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 714 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 715 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 716
737 config LOG_BUF_SHIFT 717 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 718 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 !! 719 range 12 25 if !H8300
>> 720 range 12 19 if H8300
740 default 17 721 default 17
741 depends on PRINTK 722 depends on PRINTK
742 help 723 help
743 Select the minimal kernel log buffer 724 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 725 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 726 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 727 by "log_buf_len" boot parameter.
747 728
748 Examples: 729 Examples:
749 17 => 128 KB 730 17 => 128 KB
750 16 => 64 KB 731 16 => 64 KB
751 15 => 32 KB 732 15 => 32 KB
752 14 => 16 KB 733 14 => 16 KB
753 13 => 8 KB 734 13 => 8 KB
754 12 => 4 KB 735 12 => 4 KB
755 736
756 config LOG_CPU_MAX_BUF_SHIFT 737 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 738 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 739 depends on SMP
759 range 0 21 740 range 0 21
>> 741 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 742 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 743 depends on PRINTK
763 help 744 help
764 This option allows to increase the d 745 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 746 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 747 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 748 lines however it might be much more when problems are reported,
768 e.g. backtraces. 749 e.g. backtraces.
769 750
770 The increased size means that a new 751 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 752 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 753 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 754 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 755 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed 756 so that more than 16 CPUs are needed to trigger the allocation.
776 757
777 Also this option is ignored when "lo 758 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 759 used as it forces an exact (power of two) size of the ring buffer.
779 760
780 The number of possible CPUs is used 761 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 762 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 763 scenario while allowing a simple algorithm to be used from bootup.
783 764
784 Examples shift values and their mean 765 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 766 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 767 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 768 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 769 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 770 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 771 12 => 4 KB for each CPU
791 772
>> 773 config PRINTK_SAFE_LOG_BUF_SHIFT
>> 774 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
>> 775 range 10 21
>> 776 default 13
>> 777 depends on PRINTK
>> 778 help
>> 779 Select the size of an alternate printk per-CPU buffer where messages
>> 780 printed from usafe contexts are temporary stored. One example would
>> 781 be NMI messages, another one - printk recursion. The messages are
>> 782 copied to the main log buffer in a safe context to avoid a deadlock.
>> 783 The value defines the size as a power of 2.
>> 784
>> 785 Those messages are rare and limited. The largest one is when
>> 786 a backtrace is printed. It usually fits into 4KB. Select
>> 787 8KB if you want to be on the safe side.
>> 788
>> 789 Examples:
>> 790 17 => 128 KB for each CPU
>> 791 16 => 64 KB for each CPU
>> 792 15 => 32 KB for each CPU
>> 793 14 => 16 KB for each CPU
>> 794 13 => 8 KB for each CPU
>> 795 12 => 4 KB for each CPU
>> 796
792 config PRINTK_INDEX 797 config PRINTK_INDEX
793 bool "Printk indexing debugfs interfac 798 bool "Printk indexing debugfs interface"
794 depends on PRINTK && DEBUG_FS 799 depends on PRINTK && DEBUG_FS
795 help 800 help
796 Add support for indexing of all prin 801 Add support for indexing of all printk formats known at compile time
797 at <debugfs>/printk/index/<module>. 802 at <debugfs>/printk/index/<module>.
798 803
799 This can be used as part of maintain 804 This can be used as part of maintaining daemons which monitor
800 /dev/kmsg, as it permits auditing th 805 /dev/kmsg, as it permits auditing the printk formats present in a
801 kernel, allowing detection of cases 806 kernel, allowing detection of cases where monitored printks are
802 changed or no longer present. 807 changed or no longer present.
803 808
804 There is no additional runtime cost 809 There is no additional runtime cost to printk with this enabled.
805 810
806 # 811 #
807 # Architectures with an unreliable sched_clock 812 # Architectures with an unreliable sched_clock() should select this:
808 # 813 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 814 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 815 bool
811 816
812 config GENERIC_SCHED_CLOCK 817 config GENERIC_SCHED_CLOCK
813 bool 818 bool
814 819
815 menu "Scheduler features" 820 menu "Scheduler features"
816 821
817 config UCLAMP_TASK 822 config UCLAMP_TASK
818 bool "Enable utilization clamping for 823 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 824 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 825 help
821 This feature enables the scheduler t 826 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 827 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 828
824 With this option, the user can speci 829 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 830 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 831 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 832 defines the minimum frequency it should use.
828 833
829 Both min and max utilization clamp v 834 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 835 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 836 enforce or grant any specific bandwidth for tasks.
832 837
833 If in doubt, say N. 838 If in doubt, say N.
834 839
835 config UCLAMP_BUCKETS_COUNT 840 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 841 int "Number of supported utilization clamp buckets"
837 range 5 20 842 range 5 20
838 default 5 843 default 5
839 depends on UCLAMP_TASK 844 depends on UCLAMP_TASK
840 help 845 help
841 Defines the number of clamp buckets 846 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 847 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 848 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 849 the precision of clamping aggregation and tracking at run-time.
845 850
846 For example, with the minimum config 851 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 852 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 853 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 854 effective value to 25%.
850 If a second 30% boosted task should 855 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 856 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 857 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 858 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 859 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 860 that bucket.
856 861
857 An additional boost/capping margin c 862 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 863 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 864 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 865 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 866 clamp buckets to trade off used memory for run-time tracking
862 precision. 867 precision.
863 868
864 If in doubt, use the default value. 869 If in doubt, use the default value.
865 870
866 endmenu 871 endmenu
867 872
868 # 873 #
869 # For architectures that want to enable the su 874 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 875 # balancing logic:
871 # 876 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 877 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 878 bool
874 879
875 # 880 #
876 # For architectures that prefer to flush all T 881 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 882 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 883 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 884 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 885 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 886 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 887 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 888 bool
884 889
885 config CC_HAS_INT128 890 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 891 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 892
888 config CC_IMPLICIT_FALLTHROUGH 893 config CC_IMPLICIT_FALLTHROUGH
889 string 894 string
890 default "-Wimplicit-fallthrough=5" if 895 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
891 default "-Wimplicit-fallthrough" if CC 896 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
892 897
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 # 898 #
915 # For architectures that know their GCC __int1 899 # For architectures that know their GCC __int128 support is sound
916 # 900 #
917 config ARCH_SUPPORTS_INT128 901 config ARCH_SUPPORTS_INT128
918 bool 902 bool
919 903
920 # For architectures that (ab)use NUMA to repre 904 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 905 # all cpu-local but of different latencies, such as SuperH.
922 # 906 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 907 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 908 bool
925 909
926 config NUMA_BALANCING 910 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 911 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 912 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 913 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && 914 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
931 help 915 help
932 This option adds support for automat 916 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 917 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 918 it has references to the node the task is running on.
935 919
936 This system will be inactive on UMA 920 This system will be inactive on UMA systems.
937 921
938 config NUMA_BALANCING_DEFAULT_ENABLED 922 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 923 bool "Automatically enable NUMA aware memory/task placement"
940 default y 924 default y
941 depends on NUMA_BALANCING 925 depends on NUMA_BALANCING
942 help 926 help
943 If set, automatic NUMA balancing wil 927 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 928 machine.
945 929
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 930 menuconfig CGROUPS
950 bool "Control Group support" 931 bool "Control Group support"
951 select KERNFS 932 select KERNFS
952 help 933 help
953 This option adds support for groupin 934 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 935 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 936 controls or device isolation.
956 See 937 See
957 - Documentation/scheduler/sche 938 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 939 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 940 and resource control)
960 941
961 Say N if unsure. 942 Say N if unsure.
962 943
963 if CGROUPS 944 if CGROUPS
964 945
965 config PAGE_COUNTER 946 config PAGE_COUNTER
966 bool 947 bool
967 948
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 949 config MEMCG
979 bool "Memory controller" 950 bool "Memory controller"
980 select PAGE_COUNTER 951 select PAGE_COUNTER
981 select EVENTFD 952 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 953 help
984 Provides control over the memory foo 954 Provides control over the memory footprint of tasks in a cgroup.
985 955
986 config MEMCG_V1 !! 956 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 957 bool
988 depends on MEMCG !! 958 depends on MEMCG && SWAP
989 default n !! 959 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 960
1001 Say N if unsure. !! 961 config MEMCG_KMEM
>> 962 bool
>> 963 depends on MEMCG && !SLOB
>> 964 default y
1002 965
1003 config BLK_CGROUP 966 config BLK_CGROUP
1004 bool "IO controller" 967 bool "IO controller"
1005 depends on BLOCK 968 depends on BLOCK
1006 default n 969 default n
1007 help 970 help
1008 Generic block IO controller cgroup in 971 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 972 cgroup interface which should be used by various IO controlling
1010 policies. 973 policies.
1011 974
1012 Currently, CFQ IO scheduler uses it t 975 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 976 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 977 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 978 block layer to implement upper limit in IO rates on a device.
1016 979
1017 This option only enables generic Bloc 980 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 981 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 982 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl 983 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 984 CONFIG_BLK_DEV_THROTTLING=y.
1022 985
1023 See Documentation/admin-guide/cgroup- 986 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 987
1025 config CGROUP_WRITEBACK 988 config CGROUP_WRITEBACK
1026 bool 989 bool
1027 depends on MEMCG && BLK_CGROUP 990 depends on MEMCG && BLK_CGROUP
1028 default y 991 default y
1029 992
1030 menuconfig CGROUP_SCHED 993 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 994 bool "CPU controller"
1032 default n 995 default n
1033 help 996 help
1034 This feature lets CPU scheduler rec 997 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 998 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 999 tasks.
1037 1000
1038 if CGROUP_SCHED 1001 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 1002 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 1003 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 1004 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1005 default CGROUP_SCHED
1047 1006
1048 config CFS_BANDWIDTH 1007 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1008 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1009 depends on FAIR_GROUP_SCHED
1051 default n 1010 default n
1052 help 1011 help
1053 This option allows users to define 1012 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1013 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1014 set are considered to be unconstrained and will run with no
1056 restriction. 1015 restriction.
1057 See Documentation/scheduler/sched-b 1016 See Documentation/scheduler/sched-bwc.rst for more information.
1058 1017
1059 config RT_GROUP_SCHED 1018 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1019 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1020 depends on CGROUP_SCHED
1062 default n 1021 default n
1063 help 1022 help
1064 This feature lets you explicitly al 1023 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1024 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1025 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1026 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 1027 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 1028
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 1029 endif #CGROUP_SCHED
1077 1030
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 1031 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 1032 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 1033 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 1034 depends on UCLAMP_TASK
1086 default n 1035 default n
1087 help 1036 help
1088 This feature enables the scheduler 1037 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 1038 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 1039
1091 When this option is enabled, the us 1040 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 1041 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 1042 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 1043 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 1044 frequency a task will always use.
1096 1045
1097 When task group based utilization c 1046 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 1047 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 1048 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 1049 be bigger than the corresponding clamping defined at task group level.
1101 1050
1102 If in doubt, say N. 1051 If in doubt, say N.
1103 1052
1104 config CGROUP_PIDS 1053 config CGROUP_PIDS
1105 bool "PIDs controller" 1054 bool "PIDs controller"
1106 help 1055 help
1107 Provides enforcement of process num 1056 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1057 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1058 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1059 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1060 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1061 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1062 PIDs controller is designed to stop this from happening.
1114 1063
1115 It should be noted that organisatio 1064 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 1065 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 1066 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1067 attach to a cgroup.
1119 1068
1120 config CGROUP_RDMA 1069 config CGROUP_RDMA
1121 bool "RDMA controller" 1070 bool "RDMA controller"
1122 help 1071 help
1123 Provides enforcement of RDMA resour 1072 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1073 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1074 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1075 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1076 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1077 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1078
1130 config CGROUP_FREEZER 1079 config CGROUP_FREEZER
1131 bool "Freezer controller" 1080 bool "Freezer controller"
1132 help 1081 help
1133 Provides a way to freeze and unfree 1082 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1083 cgroup.
1135 1084
1136 This option affects the ORIGINAL cg 1085 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1086 controller includes important in-kernel memory consumers per default.
1138 1087
1139 If you're using cgroup2, say N. 1088 If you're using cgroup2, say N.
1140 1089
1141 config CGROUP_HUGETLB 1090 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1091 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1092 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1093 select PAGE_COUNTER
1145 default n 1094 default n
1146 help 1095 help
1147 Provides a cgroup controller for Hu 1096 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1097 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1098 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1099 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1100 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1101 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1102 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1103 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1104 that we cannot use the controller with huge page less than 3 pages.
1156 1105
1157 config CPUSETS 1106 config CPUSETS
1158 bool "Cpuset controller" 1107 bool "Cpuset controller"
1159 depends on SMP 1108 depends on SMP
1160 help 1109 help
1161 This option will let you create and 1110 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1111 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1112 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1113 This is primarily useful on large SMP or NUMA systems.
1165 1114
1166 Say N if unsure. 1115 Say N if unsure.
1167 1116
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 1117 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1118 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1119 depends on CPUSETS
1184 default y 1120 default y
1185 1121
1186 config CGROUP_DEVICE 1122 config CGROUP_DEVICE
1187 bool "Device controller" 1123 bool "Device controller"
1188 help 1124 help
1189 Provides a cgroup controller implem 1125 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1126 devices which a process in the cgroup can mknod or open.
1191 1127
1192 config CGROUP_CPUACCT 1128 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1129 bool "Simple CPU accounting controller"
1194 help 1130 help
1195 Provides a simple controller for mo 1131 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1132 total CPU consumed by the tasks in a cgroup.
1197 1133
1198 config CGROUP_PERF 1134 config CGROUP_PERF
1199 bool "Perf controller" 1135 bool "Perf controller"
1200 depends on PERF_EVENTS 1136 depends on PERF_EVENTS
1201 help 1137 help
1202 This option extends the perf per-cp 1138 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1139 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use 1140 designated cpu. Or this can be used to have cgroup ID in samples
1205 so that it can monitor performance 1141 so that it can monitor performance events among cgroups.
1206 1142
1207 Say N if unsure. 1143 Say N if unsure.
1208 1144
1209 config CGROUP_BPF 1145 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1146 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1147 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1148 select SOCK_CGROUP_DATA
1213 help 1149 help
1214 Allow attaching eBPF programs to a 1150 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1151 syscall command BPF_PROG_ATTACH.
1216 1152
1217 In which context these programs are 1153 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1154 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1155 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1156 inet sockets.
1221 1157
1222 config CGROUP_MISC 1158 config CGROUP_MISC
1223 bool "Misc resource controller" 1159 bool "Misc resource controller"
1224 default n 1160 default n
1225 help 1161 help
1226 Provides a controller for miscellan 1162 Provides a controller for miscellaneous resources on a host.
1227 1163
1228 Miscellaneous scalar resources are 1164 Miscellaneous scalar resources are the resources on the host system
1229 which cannot be abstracted like the 1165 which cannot be abstracted like the other cgroups. This controller
1230 tracks and limits the miscellaneous 1166 tracks and limits the miscellaneous resources used by a process
1231 attached to a cgroup hierarchy. 1167 attached to a cgroup hierarchy.
1232 1168
1233 For more information, please check 1169 For more information, please check misc cgroup section in
1234 /Documentation/admin-guide/cgroup-v 1170 /Documentation/admin-guide/cgroup-v2.rst.
1235 1171
1236 config CGROUP_DEBUG 1172 config CGROUP_DEBUG
1237 bool "Debug controller" 1173 bool "Debug controller"
1238 default n 1174 default n
1239 depends on DEBUG_KERNEL 1175 depends on DEBUG_KERNEL
1240 help 1176 help
1241 This option enables a simple contro 1177 This option enables a simple controller that exports
1242 debugging information about the cgr 1178 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1179 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1180 interfaces are not stable.
1245 1181
1246 Say N. 1182 Say N.
1247 1183
1248 config SOCK_CGROUP_DATA 1184 config SOCK_CGROUP_DATA
1249 bool 1185 bool
1250 default n 1186 default n
1251 1187
1252 endif # CGROUPS 1188 endif # CGROUPS
1253 1189
1254 menuconfig NAMESPACES 1190 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1191 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1192 depends on MULTIUSER
1257 default !EXPERT 1193 default !EXPERT
1258 help 1194 help
1259 Provides the way to make tasks work 1195 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1196 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1197 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1198 different namespaces.
1263 1199
1264 if NAMESPACES 1200 if NAMESPACES
1265 1201
1266 config UTS_NS 1202 config UTS_NS
1267 bool "UTS namespace" 1203 bool "UTS namespace"
1268 default y 1204 default y
1269 help 1205 help
1270 In this namespace tasks see differe 1206 In this namespace tasks see different info provided with the
1271 uname() system call 1207 uname() system call
1272 1208
1273 config TIME_NS 1209 config TIME_NS
1274 bool "TIME namespace" 1210 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1211 depends on GENERIC_VDSO_TIME_NS
1276 default y 1212 default y
1277 help 1213 help
1278 In this namespace boottime and mono 1214 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1215 The time will keep going with the same pace.
1280 1216
1281 config IPC_NS 1217 config IPC_NS
1282 bool "IPC namespace" 1218 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1219 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1220 default y
1285 help 1221 help
1286 In this namespace tasks work with I 1222 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1223 different IPC objects in different namespaces.
1288 1224
1289 config USER_NS 1225 config USER_NS
1290 bool "User namespace" 1226 bool "User namespace"
1291 default n 1227 default n
1292 help 1228 help
1293 This allows containers, i.e. vserve 1229 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1230 to provide different user info for different servers.
1295 1231
1296 When user namespaces are enabled in 1232 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1233 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1234 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1235 of memory a memory unprivileged users can use.
1300 1236
1301 If unsure, say N. 1237 If unsure, say N.
1302 1238
1303 config PID_NS 1239 config PID_NS
1304 bool "PID Namespaces" 1240 bool "PID Namespaces"
1305 default y 1241 default y
1306 help 1242 help
1307 Support process id namespaces. Thi 1243 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1244 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1245 pid namespaces. This is a building block of containers.
1310 1246
1311 config NET_NS 1247 config NET_NS
1312 bool "Network namespace" 1248 bool "Network namespace"
1313 depends on NET 1249 depends on NET
1314 default y 1250 default y
1315 help 1251 help
1316 Allow user space to create what app 1252 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1253 of the network stack.
1318 1254
1319 endif # NAMESPACES 1255 endif # NAMESPACES
1320 1256
1321 config CHECKPOINT_RESTORE 1257 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1258 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1259 select PROC_CHILDREN
1325 select KCMP 1260 select KCMP
1326 default n 1261 default n
1327 help 1262 help
1328 Enables additional kernel features 1263 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1264 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1265 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1266 entries.
1332 1267
1333 If unsure, say N here. 1268 If unsure, say N here.
1334 1269
1335 config SCHED_AUTOGROUP 1270 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1271 bool "Automatic process group scheduling"
1337 select CGROUPS 1272 select CGROUPS
1338 select CGROUP_SCHED 1273 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1274 select FAIR_GROUP_SCHED
1340 help 1275 help
1341 This option optimizes the scheduler 1276 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1277 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1278 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1279 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1280 upon task session.
1346 1281
>> 1282 config SYSFS_DEPRECATED
>> 1283 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1284 depends on SYSFS
>> 1285 default n
>> 1286 help
>> 1287 This option adds code that switches the layout of the "block" class
>> 1288 devices, to not show up in /sys/class/block/, but only in
>> 1289 /sys/block/.
>> 1290
>> 1291 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1292 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1293
>> 1294 This option allows new kernels to run on old distributions and tools,
>> 1295 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1296 major distributions and tools handle this just fine.
>> 1297
>> 1298 Recent distributions and userspace tools after 2009/2010 depend on
>> 1299 the existence of /sys/class/block/, and will not work with this
>> 1300 option enabled.
>> 1301
>> 1302 Only if you are using a new kernel on an old distribution, you might
>> 1303 need to say Y here.
>> 1304
>> 1305 config SYSFS_DEPRECATED_V2
>> 1306 bool "Enable deprecated sysfs features by default"
>> 1307 default n
>> 1308 depends on SYSFS
>> 1309 depends on SYSFS_DEPRECATED
>> 1310 help
>> 1311 Enable deprecated sysfs by default.
>> 1312
>> 1313 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1314 option.
>> 1315
>> 1316 Only if you are using a new kernel on an old distribution, you might
>> 1317 need to say Y here. Even then, odds are you would not need it
>> 1318 enabled, you can always pass the boot option if absolutely necessary.
>> 1319
1347 config RELAY 1320 config RELAY
1348 bool "Kernel->user space relay suppor 1321 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1322 select IRQ_WORK
1350 help 1323 help
1351 This option enables support for rel 1324 This option enables support for relay interface support in
1352 certain file systems (such as debug 1325 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1326 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1327 facilities to relay large amounts of data from kernel space to
1355 user space. 1328 user space.
1356 1329
1357 If unsure, say N. 1330 If unsure, say N.
1358 1331
1359 config BLK_DEV_INITRD 1332 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1333 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1334 help
1362 The initial RAM filesystem is a ram 1335 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1336 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1337 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1338 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1339 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1340
1368 If RAM disk support (BLK_DEV_RAM) i 1341 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1342 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1343 15 Kbytes (more on some other architectures) to the kernel size.
1371 1344
1372 If unsure say Y. 1345 If unsure say Y.
1373 1346
1374 if BLK_DEV_INITRD 1347 if BLK_DEV_INITRD
1375 1348
1376 source "usr/Kconfig" 1349 source "usr/Kconfig"
1377 1350
1378 endif 1351 endif
1379 1352
1380 config BOOT_CONFIG 1353 config BOOT_CONFIG
1381 bool "Boot config support" 1354 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG !! 1355 select BLK_DEV_INITRD
1383 help 1356 help
1384 Extra boot config allows system adm 1357 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1358 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1359 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1360 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1361 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1362
1390 If unsure, say Y. 1363 If unsure, say Y.
1391 1364
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 1365 choice
1435 prompt "Compiler optimization level" 1366 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1367 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1368
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1369 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1370 bool "Optimize for performance (-O2)"
1440 help 1371 help
1441 This is the default optimization le 1372 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1373 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1374 helpful compile-time warnings.
1444 1375
>> 1376 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1377 bool "Optimize more for performance (-O3)"
>> 1378 depends on ARC
>> 1379 help
>> 1380 Choosing this option will pass "-O3" to your compiler to optimize
>> 1381 the kernel yet more for performance.
>> 1382
1445 config CC_OPTIMIZE_FOR_SIZE 1383 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1384 bool "Optimize for size (-Os)"
1447 help 1385 help
1448 Choosing this option will pass "-Os 1386 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1387 in a smaller kernel.
1450 1388
1451 endchoice 1389 endchoice
1452 1390
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1391 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1392 bool
1455 help 1393 help
1456 This requires that the arch annotat 1394 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1395 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1396 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1397 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1398 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1399 is used to distinguish them from label names / C identifiers.
1462 1400
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1401 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1402 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1403 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1404 depends on EXPERT
1467 depends on $(cc-option,-ffunction-sec 1405 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1406 depends on $(ld-option,--gc-sections)
1469 help 1407 help
1470 Enable this if you want to do dead 1408 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1409 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1410 and linking with --gc-sections.
1473 1411
1474 This can reduce on disk and in-memo 1412 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1413 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1414 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1415 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1416 present. This option is not well tested yet, so use at your
1479 own risk. 1417 own risk.
1480 1418
1481 config LD_ORPHAN_WARN 1419 config LD_ORPHAN_WARN
1482 def_bool y 1420 def_bool y
1483 depends on ARCH_WANT_LD_ORPHAN_WARN 1421 depends on ARCH_WANT_LD_ORPHAN_WARN
1484 depends on $(ld-option,--orphan-handl 1422 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 1423
1493 config SYSCTL 1424 config SYSCTL
1494 bool 1425 bool
1495 1426
1496 config HAVE_UID16 1427 config HAVE_UID16
1497 bool 1428 bool
1498 1429
1499 config SYSCTL_EXCEPTION_TRACE 1430 config SYSCTL_EXCEPTION_TRACE
1500 bool 1431 bool
1501 help 1432 help
1502 Enable support for /proc/sys/debug/ 1433 Enable support for /proc/sys/debug/exception-trace.
1503 1434
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1435 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1436 bool
1506 help 1437 help
1507 Enable support for /proc/sys/kernel 1438 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1439 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1440 about unaligned access emulation going on under the hood.
1510 1441
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1442 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1443 bool
1513 help 1444 help
1514 Enable support for /proc/sys/kernel 1445 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1446 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1447 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1448 see arch/parisc/kernel/unaligned.c for reference
1518 1449
1519 config HAVE_PCSPKR_PLATFORM 1450 config HAVE_PCSPKR_PLATFORM
1520 bool 1451 bool
1521 1452
>> 1453 # interpreter that classic socket filters depend on
>> 1454 config BPF
>> 1455 bool
>> 1456
1522 menuconfig EXPERT 1457 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1458 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1459 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1460 select DEBUG_KERNEL
1526 help 1461 help
1527 This option allows certain base ker 1462 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1463 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1464 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1465 Only use this if you really know what you are doing.
1531 1466
1532 config UID16 1467 config UID16
1533 bool "Enable 16-bit UID system calls" 1468 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1469 depends on HAVE_UID16 && MULTIUSER
1535 default y 1470 default y
1536 help 1471 help
1537 This enables the legacy 16-bit UID 1472 This enables the legacy 16-bit UID syscall wrappers.
1538 1473
1539 config MULTIUSER 1474 config MULTIUSER
1540 bool "Multiple users, groups and capa 1475 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1476 default y
1542 help 1477 help
1543 This option enables support for non 1478 This option enables support for non-root users, groups and
1544 capabilities. 1479 capabilities.
1545 1480
1546 If you say N here, all processes wi 1481 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1482 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1483 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1484 setgid, and capset.
1550 1485
1551 If unsure, say Y here. 1486 If unsure, say Y here.
1552 1487
1553 config SGETMASK_SYSCALL 1488 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1489 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1490 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help 1491 help
1557 sys_sgetmask and sys_ssetmask are o 1492 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1493 no longer supported in libc but still enabled by default in some
1559 architectures. 1494 architectures.
1560 1495
1561 If unsure, leave the default option 1496 If unsure, leave the default option here.
1562 1497
1563 config SYSFS_SYSCALL 1498 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1499 bool "Sysfs syscall support" if EXPERT
1565 default y 1500 default y
1566 help 1501 help
1567 sys_sysfs is an obsolete system cal 1502 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1503 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1504 compatibility with some systems.
1570 1505
1571 If unsure say Y here. 1506 If unsure say Y here.
1572 1507
1573 config FHANDLE 1508 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1509 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1510 select EXPORTFS
1576 default y 1511 default y
1577 help 1512 help
1578 If you say Y here, a user level pro 1513 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1514 file names to handle and then later use the handle for
1580 different file system operations. T 1515 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1516 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1517 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1518 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1519 syscalls.
1585 1520
1586 config POSIX_TIMERS 1521 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1522 bool "Posix Clocks & timers" if EXPERT
1588 default y 1523 default y
1589 help 1524 help
1590 This includes native support for PO 1525 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1526 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1527 can be configured out to reduce the size of the kernel image.
1593 1528
1594 When this option is disabled, the f 1529 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1530 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1531 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1532 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1533 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1534 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1535
1601 If unsure say y. 1536 If unsure say y.
1602 1537
1603 config PRINTK 1538 config PRINTK
1604 default y 1539 default y
1605 bool "Enable support for printk" if E 1540 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1541 select IRQ_WORK
1607 help 1542 help
1608 This option enables normal printk s 1543 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1544 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1545 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1546 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1547 strongly discouraged.
1613 1548
1614 config BUG 1549 config BUG
1615 bool "BUG() support" if EXPERT 1550 bool "BUG() support" if EXPERT
1616 default y 1551 default y
1617 help 1552 help
1618 Disabling this option eliminates su 1553 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1554 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1555 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1556 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1557 Just say Y.
1623 1558
1624 config ELF_CORE 1559 config ELF_CORE
1625 depends on COREDUMP 1560 depends on COREDUMP
1626 default y 1561 default y
1627 bool "Enable ELF core dumps" if EXPER 1562 bool "Enable ELF core dumps" if EXPERT
1628 help 1563 help
1629 Enable support for generating core 1564 Enable support for generating core dumps. Disabling saves about 4k.
1630 1565
1631 1566
1632 config PCSPKR_PLATFORM 1567 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1568 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1569 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1570 select I8253_LOCK
1636 default y 1571 default y
1637 help 1572 help
1638 This option allows to disable the i 1573 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1574 support, saving some memory.
1640 1575
1641 config BASE_SMALL !! 1576 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1577 default y
>> 1578 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1579 help
1644 Enabling this option reduces the si !! 1580 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1581 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1582 but may reduce performance.
1647 1583
1648 config FUTEX 1584 config FUTEX
1649 bool "Enable futex support" if EXPERT 1585 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) 1586 depends on !(SPARC32 && SMP)
1651 default y 1587 default y
1652 imply RT_MUTEXES 1588 imply RT_MUTEXES
1653 help 1589 help
1654 Disabling this option will cause th 1590 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1591 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1592 run glibc-based applications correctly.
1657 1593
1658 config FUTEX_PI 1594 config FUTEX_PI
1659 bool 1595 bool
1660 depends on FUTEX && RT_MUTEXES 1596 depends on FUTEX && RT_MUTEXES
1661 default y 1597 default y
1662 1598
1663 config EPOLL 1599 config EPOLL
1664 bool "Enable eventpoll support" if EX 1600 bool "Enable eventpoll support" if EXPERT
1665 default y 1601 default y
1666 help 1602 help
1667 Disabling this option will cause th 1603 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1604 support for epoll family of system calls.
1669 1605
1670 config SIGNALFD 1606 config SIGNALFD
1671 bool "Enable signalfd() system call" 1607 bool "Enable signalfd() system call" if EXPERT
1672 default y 1608 default y
1673 help 1609 help
1674 Enable the signalfd() system call t 1610 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1611 on a file descriptor.
1676 1612
1677 If unsure, say Y. 1613 If unsure, say Y.
1678 1614
1679 config TIMERFD 1615 config TIMERFD
1680 bool "Enable timerfd() system call" i 1616 bool "Enable timerfd() system call" if EXPERT
1681 default y 1617 default y
1682 help 1618 help
1683 Enable the timerfd() system call th 1619 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1620 events on a file descriptor.
1685 1621
1686 If unsure, say Y. 1622 If unsure, say Y.
1687 1623
1688 config EVENTFD 1624 config EVENTFD
1689 bool "Enable eventfd() system call" i 1625 bool "Enable eventfd() system call" if EXPERT
1690 default y 1626 default y
1691 help 1627 help
1692 Enable the eventfd() system call th 1628 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1629 kernel notification (ie. KAIO) or userspace notifications.
1694 1630
1695 If unsure, say Y. 1631 If unsure, say Y.
1696 1632
1697 config SHMEM 1633 config SHMEM
1698 bool "Use full shmem filesystem" if E 1634 bool "Use full shmem filesystem" if EXPERT
1699 default y 1635 default y
1700 depends on MMU 1636 depends on MMU
1701 help 1637 help
1702 The shmem is an internal filesystem 1638 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1639 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1640 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1641 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1642 which may be appropriate on small systems without swap.
1707 1643
1708 config AIO 1644 config AIO
1709 bool "Enable AIO support" if EXPERT 1645 bool "Enable AIO support" if EXPERT
1710 default y 1646 default y
1711 help 1647 help
1712 This option enables POSIX asynchron 1648 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1649 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1650 this option saves about 7k.
1715 1651
1716 config IO_URING 1652 config IO_URING
1717 bool "Enable IO uring support" if EXP 1653 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ 1654 select IO_WQ
1719 default y 1655 default y
1720 help 1656 help
1721 This option enables support for the 1657 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1658 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1659 completion rings that are shared between the kernel and application.
1724 1660
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 1661 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1662 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1663 default y
1741 help 1664 help
1742 This option enables the madvise and 1665 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1666 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1667 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1668 applications use these syscalls, you can disable this option to save
1746 space. 1669 space.
1747 1670
>> 1671 config HAVE_ARCH_USERFAULTFD_WP
>> 1672 bool
>> 1673 help
>> 1674 Arch has userfaultfd write protection support
>> 1675
>> 1676 config HAVE_ARCH_USERFAULTFD_MINOR
>> 1677 bool
>> 1678 help
>> 1679 Arch has userfaultfd minor fault support
>> 1680
1748 config MEMBARRIER 1681 config MEMBARRIER
1749 bool "Enable membarrier() system call 1682 bool "Enable membarrier() system call" if EXPERT
1750 default y 1683 default y
1751 help 1684 help
1752 Enable the membarrier() system call 1685 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1686 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1687 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1688 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1689 compiler barrier.
1757 1690
1758 If unsure, say Y. 1691 If unsure, say Y.
1759 1692
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 1693 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1694 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1695 default y
1813 help 1696 help
1814 Say Y here to let the kernel print 1697 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1698 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1699 somewhat, as all symbols have to be loaded into the kernel image.
1817 1700
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 1701 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1702 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1703 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1704 help
1835 Normally kallsyms only contains the 1705 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1706 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m !! 1707 sections). This is sufficient for most cases. And only in very rare
1838 enable kernel live patching, or oth !! 1708 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1839 when a debugger is used) all symbol !! 1709 names of variables from the data sections, etc).
1840 variables from the data sections, e <<
1841 1710
1842 This option makes sure that all sym 1711 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1712 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1713 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1714 something like this).
1846 1715
1847 Say N unless you really need all sy !! 1716 Say N unless you really need all symbols.
1848 1717
1849 config KALLSYMS_ABSOLUTE_PERCPU 1718 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1719 bool
1851 depends on KALLSYMS 1720 depends on KALLSYMS
1852 default X86_64 && SMP 1721 default X86_64 && SMP
1853 1722
>> 1723 config KALLSYMS_BASE_RELATIVE
>> 1724 bool
>> 1725 depends on KALLSYMS
>> 1726 default !IA64
>> 1727 help
>> 1728 Instead of emitting them as absolute values in the native word size,
>> 1729 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1730 each containing a relative value in the range [base, base + U32_MAX]
>> 1731 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1732 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1733 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1734 address encountered in the image.
>> 1735
>> 1736 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1737 but more importantly, it results in entries whose values are build
>> 1738 time constants, and no relocation pass is required at runtime to fix
>> 1739 up the entries based on the runtime load address of the kernel.
>> 1740
1854 # end of the "standard kernel features (exper 1741 # end of the "standard kernel features (expert users)" menu
1855 1742
>> 1743 # syscall, maps, verifier
>> 1744
>> 1745 config USERFAULTFD
>> 1746 bool "Enable userfaultfd() system call"
>> 1747 depends on MMU
>> 1748 help
>> 1749 Enable the userfaultfd() system call that allows to intercept and
>> 1750 handle page faults in userland.
>> 1751
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1752 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1753 bool
1858 1754
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1755 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1756 bool
1861 1757
>> 1758 config KCMP
>> 1759 bool "Enable kcmp() system call" if EXPERT
>> 1760 help
>> 1761 Enable the kernel resource comparison system call. It provides
>> 1762 user-space with the ability to compare two processes to see if they
>> 1763 share a common resource, such as a file descriptor or even virtual
>> 1764 memory space.
>> 1765
>> 1766 If unsure, say N.
>> 1767
>> 1768 config RSEQ
>> 1769 bool "Enable rseq() system call" if EXPERT
>> 1770 default y
>> 1771 depends on HAVE_RSEQ
>> 1772 select MEMBARRIER
>> 1773 help
>> 1774 Enable the restartable sequences system call. It provides a
>> 1775 user-space cache for the current CPU number value, which
>> 1776 speeds up getting the current CPU number from user-space,
>> 1777 as well as an ABI to speed up user-space operations on
>> 1778 per-CPU data.
>> 1779
>> 1780 If unsure, say Y.
>> 1781
>> 1782 config DEBUG_RSEQ
>> 1783 default n
>> 1784 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1785 depends on RSEQ && DEBUG_KERNEL
>> 1786 help
>> 1787 Enable extra debugging checks for the rseq system call.
>> 1788
>> 1789 If unsure, say N.
>> 1790
>> 1791 config EMBEDDED
>> 1792 bool "Embedded system"
>> 1793 select EXPERT
>> 1794 help
>> 1795 This option should be enabled if compiling the kernel for
>> 1796 an embedded system so certain expert options are available
>> 1797 for configuration.
>> 1798
1862 config HAVE_PERF_EVENTS 1799 config HAVE_PERF_EVENTS
1863 bool 1800 bool
1864 help 1801 help
1865 See tools/perf/design.txt for detai 1802 See tools/perf/design.txt for details.
1866 1803
1867 config GUEST_PERF_EVENTS 1804 config GUEST_PERF_EVENTS
1868 bool 1805 bool
1869 depends on HAVE_PERF_EVENTS 1806 depends on HAVE_PERF_EVENTS
1870 1807
1871 config PERF_USE_VMALLOC 1808 config PERF_USE_VMALLOC
1872 bool 1809 bool
1873 help 1810 help
1874 See tools/perf/design.txt for detai 1811 See tools/perf/design.txt for details
1875 1812
>> 1813 config PC104
>> 1814 bool "PC/104 support" if EXPERT
>> 1815 help
>> 1816 Expose PC/104 form factor device drivers and options available for
>> 1817 selection and configuration. Enable this option if your target
>> 1818 machine has a PC/104 bus.
>> 1819
1876 menu "Kernel Performance Events And Counters" 1820 menu "Kernel Performance Events And Counters"
1877 1821
1878 config PERF_EVENTS 1822 config PERF_EVENTS
1879 bool "Kernel performance events and c 1823 bool "Kernel performance events and counters"
1880 default y if PROFILING 1824 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1825 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1826 select IRQ_WORK
>> 1827 select SRCU
1883 help 1828 help
1884 Enable kernel support for various p 1829 Enable kernel support for various performance events provided
1885 by software and hardware. 1830 by software and hardware.
1886 1831
1887 Software events are supported eithe 1832 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1833 use of generic tracepoints.
1889 1834
1890 Most modern CPUs support performanc 1835 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1836 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1837 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1838 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1839 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1840 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1841 used to profile the code that runs on that CPU.
1897 1842
1898 The Linux Performance Event subsyst 1843 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1844 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1845 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1846 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1847 capabilities on top of those.
1903 1848
1904 Say Y if unsure. 1849 Say Y if unsure.
1905 1850
1906 config DEBUG_PERF_USE_VMALLOC 1851 config DEBUG_PERF_USE_VMALLOC
1907 default n 1852 default n
1908 bool "Debug: use vmalloc to back perf 1853 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1854 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1855 select PERF_USE_VMALLOC
1911 help 1856 help
1912 Use vmalloc memory to back perf mma 1857 Use vmalloc memory to back perf mmap() buffers.
1913 1858
1914 Mostly useful for debugging the vma 1859 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1860 that don't require it.
1916 1861
1917 Say N if unsure. 1862 Say N if unsure.
1918 1863
1919 endmenu 1864 endmenu
1920 1865
>> 1866 config VM_EVENT_COUNTERS
>> 1867 default y
>> 1868 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1869 help
>> 1870 VM event counters are needed for event counts to be shown.
>> 1871 This option allows the disabling of the VM event counters
>> 1872 on EXPERT systems. /proc/vmstat will only show page counts
>> 1873 if VM event counters are disabled.
>> 1874
>> 1875 config SLUB_DEBUG
>> 1876 default y
>> 1877 bool "Enable SLUB debugging support" if EXPERT
>> 1878 depends on SLUB && SYSFS
>> 1879 help
>> 1880 SLUB has extensive debug support features. Disabling these can
>> 1881 result in significant savings in code size. This also disables
>> 1882 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1883 no support for cache validation etc.
>> 1884
>> 1885 config COMPAT_BRK
>> 1886 bool "Disable heap randomization"
>> 1887 default y
>> 1888 help
>> 1889 Randomizing heap placement makes heap exploits harder, but it
>> 1890 also breaks ancient binaries (including anything libc5 based).
>> 1891 This option changes the bootup default to heap randomization
>> 1892 disabled, and can be overridden at runtime by setting
>> 1893 /proc/sys/kernel/randomize_va_space to 2.
>> 1894
>> 1895 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1896
>> 1897 choice
>> 1898 prompt "Choose SLAB allocator"
>> 1899 default SLUB
>> 1900 help
>> 1901 This option allows to select a slab allocator.
>> 1902
>> 1903 config SLAB
>> 1904 bool "SLAB"
>> 1905 depends on !PREEMPT_RT
>> 1906 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1907 help
>> 1908 The regular slab allocator that is established and known to work
>> 1909 well in all environments. It organizes cache hot objects in
>> 1910 per cpu and per node queues.
>> 1911
>> 1912 config SLUB
>> 1913 bool "SLUB (Unqueued Allocator)"
>> 1914 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1915 help
>> 1916 SLUB is a slab allocator that minimizes cache line usage
>> 1917 instead of managing queues of cached objects (SLAB approach).
>> 1918 Per cpu caching is realized using slabs of objects instead
>> 1919 of queues of objects. SLUB can use memory efficiently
>> 1920 and has enhanced diagnostics. SLUB is the default choice for
>> 1921 a slab allocator.
>> 1922
>> 1923 config SLOB
>> 1924 depends on EXPERT
>> 1925 bool "SLOB (Simple Allocator)"
>> 1926 depends on !PREEMPT_RT
>> 1927 help
>> 1928 SLOB replaces the stock allocator with a drastically simpler
>> 1929 allocator. SLOB is generally more space efficient but
>> 1930 does not perform as well on large systems.
>> 1931
>> 1932 endchoice
>> 1933
>> 1934 config SLAB_MERGE_DEFAULT
>> 1935 bool "Allow slab caches to be merged"
>> 1936 default y
>> 1937 depends on SLAB || SLUB
>> 1938 help
>> 1939 For reduced kernel memory fragmentation, slab caches can be
>> 1940 merged when they share the same size and other characteristics.
>> 1941 This carries a risk of kernel heap overflows being able to
>> 1942 overwrite objects from merged caches (and more easily control
>> 1943 cache layout), which makes such heap attacks easier to exploit
>> 1944 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1945 can usually only damage objects in the same cache. To disable
>> 1946 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1947 command line.
>> 1948
>> 1949 config SLAB_FREELIST_RANDOM
>> 1950 bool "Randomize slab freelist"
>> 1951 depends on SLAB || SLUB
>> 1952 help
>> 1953 Randomizes the freelist order used on creating new pages. This
>> 1954 security feature reduces the predictability of the kernel slab
>> 1955 allocator against heap overflows.
>> 1956
>> 1957 config SLAB_FREELIST_HARDENED
>> 1958 bool "Harden slab freelist metadata"
>> 1959 depends on SLAB || SLUB
>> 1960 help
>> 1961 Many kernel heap attacks try to target slab cache metadata and
>> 1962 other infrastructure. This options makes minor performance
>> 1963 sacrifices to harden the kernel slab allocator against common
>> 1964 freelist exploit methods. Some slab implementations have more
>> 1965 sanity-checking than others. This option is most effective with
>> 1966 CONFIG_SLUB.
>> 1967
>> 1968 config SHUFFLE_PAGE_ALLOCATOR
>> 1969 bool "Page allocator randomization"
>> 1970 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1971 help
>> 1972 Randomization of the page allocator improves the average
>> 1973 utilization of a direct-mapped memory-side-cache. See section
>> 1974 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1975 6.2a specification for an example of how a platform advertises
>> 1976 the presence of a memory-side-cache. There are also incidental
>> 1977 security benefits as it reduces the predictability of page
>> 1978 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1979 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1980 10th order of pages is selected based on cache utilization
>> 1981 benefits on x86.
>> 1982
>> 1983 While the randomization improves cache utilization it may
>> 1984 negatively impact workloads on platforms without a cache. For
>> 1985 this reason, by default, the randomization is enabled only
>> 1986 after runtime detection of a direct-mapped memory-side-cache.
>> 1987 Otherwise, the randomization may be force enabled with the
>> 1988 'page_alloc.shuffle' kernel command line parameter.
>> 1989
>> 1990 Say Y if unsure.
>> 1991
>> 1992 config SLUB_CPU_PARTIAL
>> 1993 default y
>> 1994 depends on SLUB && SMP
>> 1995 bool "SLUB per cpu partial cache"
>> 1996 help
>> 1997 Per cpu partial caches accelerate objects allocation and freeing
>> 1998 that is local to a processor at the price of more indeterminism
>> 1999 in the latency of the free. On overflow these caches will be cleared
>> 2000 which requires the taking of locks that may cause latency spikes.
>> 2001 Typically one would choose no for a realtime system.
>> 2002
>> 2003 config MMAP_ALLOW_UNINITIALIZED
>> 2004 bool "Allow mmapped anonymous memory to be uninitialized"
>> 2005 depends on EXPERT && !MMU
>> 2006 default n
>> 2007 help
>> 2008 Normally, and according to the Linux spec, anonymous memory obtained
>> 2009 from mmap() has its contents cleared before it is passed to
>> 2010 userspace. Enabling this config option allows you to request that
>> 2011 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 2012 providing a huge performance boost. If this option is not enabled,
>> 2013 then the flag will be ignored.
>> 2014
>> 2015 This is taken advantage of by uClibc's malloc(), and also by
>> 2016 ELF-FDPIC binfmt's brk and stack allocator.
>> 2017
>> 2018 Because of the obvious security issues, this option should only be
>> 2019 enabled on embedded devices where you control what is run in
>> 2020 userspace. Since that isn't generally a problem on no-MMU systems,
>> 2021 it is normally safe to say Y here.
>> 2022
>> 2023 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
>> 2024
1921 config SYSTEM_DATA_VERIFICATION 2025 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 2026 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 2027 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 2028 select KEYS
1925 select CRYPTO 2029 select CRYPTO
1926 select CRYPTO_RSA 2030 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 2031 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2032 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 2033 select ASN1
1930 select OID_REGISTRY 2034 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 2035 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 2036 select PKCS7_MESSAGE_PARSER
1933 help 2037 help
1934 Provide PKCS#7 message verification 2038 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 2039 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 2040 module verification, kexec image verification and firmware blob
1937 verification. 2041 verification.
1938 2042
1939 config PROFILING 2043 config PROFILING
1940 bool "Profiling support" 2044 bool "Profiling support"
1941 help 2045 help
1942 Say Y here to enable the extended p 2046 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. 2047 by profilers.
1944 2048
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 # 2049 #
1987 # Place an empty function call at each tracep 2050 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 2051 # dynamically changed for a probe function.
1989 # 2052 #
1990 config TRACEPOINTS 2053 config TRACEPOINTS
1991 bool 2054 bool
1992 2055
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 2056 endmenu # General setup
1996 2057
1997 source "arch/Kconfig" 2058 source "arch/Kconfig"
1998 2059
1999 config RT_MUTEXES 2060 config RT_MUTEXES
2000 bool 2061 bool
2001 default y if PREEMPT_RT !! 2062
>> 2063 config BASE_SMALL
>> 2064 int
>> 2065 default 0 if BASE_FULL
>> 2066 default 1 if !BASE_FULL
2002 2067
2003 config MODULE_SIG_FORMAT 2068 config MODULE_SIG_FORMAT
2004 def_bool n 2069 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 2070 select SYSTEM_DATA_VERIFICATION
2006 2071
2007 source "kernel/module/Kconfig" !! 2072 menuconfig MODULES
>> 2073 bool "Enable loadable module support"
>> 2074 modules
>> 2075 help
>> 2076 Kernel modules are small pieces of compiled code which can
>> 2077 be inserted in the running kernel, rather than being
>> 2078 permanently built into the kernel. You use the "modprobe"
>> 2079 tool to add (and sometimes remove) them. If you say Y here,
>> 2080 many parts of the kernel can be built as modules (by
>> 2081 answering M instead of Y where indicated): this is most
>> 2082 useful for infrequently used options which are not required
>> 2083 for booting. For more information, see the man pages for
>> 2084 modprobe, lsmod, modinfo, insmod and rmmod.
>> 2085
>> 2086 If you say Y here, you will need to run "make
>> 2087 modules_install" to put the modules under /lib/modules/
>> 2088 where modprobe can find them (you may need to be root to do
>> 2089 this).
>> 2090
>> 2091 If unsure, say Y.
>> 2092
>> 2093 if MODULES
>> 2094
>> 2095 config MODULE_FORCE_LOAD
>> 2096 bool "Forced module loading"
>> 2097 default n
>> 2098 help
>> 2099 Allow loading of modules without version information (ie. modprobe
>> 2100 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 2101 is usually a really bad idea.
>> 2102
>> 2103 config MODULE_UNLOAD
>> 2104 bool "Module unloading"
>> 2105 help
>> 2106 Without this option you will not be able to unload any
>> 2107 modules (note that some modules may not be unloadable
>> 2108 anyway), which makes your kernel smaller, faster
>> 2109 and simpler. If unsure, say Y.
>> 2110
>> 2111 config MODULE_FORCE_UNLOAD
>> 2112 bool "Forced module unloading"
>> 2113 depends on MODULE_UNLOAD
>> 2114 help
>> 2115 This option allows you to force a module to unload, even if the
>> 2116 kernel believes it is unsafe: the kernel will remove the module
>> 2117 without waiting for anyone to stop using it (using the -f option to
>> 2118 rmmod). This is mainly for kernel developers and desperate users.
>> 2119 If unsure, say N.
>> 2120
>> 2121 config MODVERSIONS
>> 2122 bool "Module versioning support"
>> 2123 help
>> 2124 Usually, you have to use modules compiled with your kernel.
>> 2125 Saying Y here makes it sometimes possible to use modules
>> 2126 compiled for different kernels, by adding enough information
>> 2127 to the modules to (hopefully) spot any changes which would
>> 2128 make them incompatible with the kernel you are running. If
>> 2129 unsure, say N.
>> 2130
>> 2131 config ASM_MODVERSIONS
>> 2132 bool
>> 2133 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 2134 help
>> 2135 This enables module versioning for exported symbols also from
>> 2136 assembly. This can be enabled only when the target architecture
>> 2137 supports it.
>> 2138
>> 2139 config MODULE_REL_CRCS
>> 2140 bool
>> 2141 depends on MODVERSIONS
>> 2142
>> 2143 config MODULE_SRCVERSION_ALL
>> 2144 bool "Source checksum for all modules"
>> 2145 help
>> 2146 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2147 field inserted into their modinfo section, which contains a
>> 2148 sum of the source files which made it. This helps maintainers
>> 2149 see exactly which source was used to build a module (since
>> 2150 others sometimes change the module source without updating
>> 2151 the version). With this option, such a "srcversion" field
>> 2152 will be created for all modules. If unsure, say N.
>> 2153
>> 2154 config MODULE_SIG
>> 2155 bool "Module signature verification"
>> 2156 select MODULE_SIG_FORMAT
>> 2157 help
>> 2158 Check modules for valid signatures upon load: the signature
>> 2159 is simply appended to the module. For more information see
>> 2160 <file:Documentation/admin-guide/module-signing.rst>.
>> 2161
>> 2162 Note that this option adds the OpenSSL development packages as a
>> 2163 kernel build dependency so that the signing tool can use its crypto
>> 2164 library.
>> 2165
>> 2166 You should enable this option if you wish to use either
>> 2167 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2168 another LSM - otherwise unsigned modules will be loadable regardless
>> 2169 of the lockdown policy.
>> 2170
>> 2171 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2172 module DOES NOT get stripped after being signed. This includes the
>> 2173 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2174 inclusion into an initramfs that wants the module size reduced.
>> 2175
>> 2176 config MODULE_SIG_FORCE
>> 2177 bool "Require modules to be validly signed"
>> 2178 depends on MODULE_SIG
>> 2179 help
>> 2180 Reject unsigned modules or signed modules for which we don't have a
>> 2181 key. Without this, such modules will simply taint the kernel.
>> 2182
>> 2183 config MODULE_SIG_ALL
>> 2184 bool "Automatically sign all modules"
>> 2185 default y
>> 2186 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2187 help
>> 2188 Sign all modules during make modules_install. Without this option,
>> 2189 modules must be signed manually, using the scripts/sign-file tool.
>> 2190
>> 2191 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2192 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2193
>> 2194 choice
>> 2195 prompt "Which hash algorithm should modules be signed with?"
>> 2196 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2197 help
>> 2198 This determines which sort of hashing algorithm will be used during
>> 2199 signature generation. This algorithm _must_ be built into the kernel
>> 2200 directly so that signature verification can take place. It is not
>> 2201 possible to load a signed module containing the algorithm to check
>> 2202 the signature on that module.
>> 2203
>> 2204 config MODULE_SIG_SHA1
>> 2205 bool "Sign modules with SHA-1"
>> 2206 select CRYPTO_SHA1
>> 2207
>> 2208 config MODULE_SIG_SHA224
>> 2209 bool "Sign modules with SHA-224"
>> 2210 select CRYPTO_SHA256
>> 2211
>> 2212 config MODULE_SIG_SHA256
>> 2213 bool "Sign modules with SHA-256"
>> 2214 select CRYPTO_SHA256
>> 2215
>> 2216 config MODULE_SIG_SHA384
>> 2217 bool "Sign modules with SHA-384"
>> 2218 select CRYPTO_SHA512
>> 2219
>> 2220 config MODULE_SIG_SHA512
>> 2221 bool "Sign modules with SHA-512"
>> 2222 select CRYPTO_SHA512
>> 2223
>> 2224 endchoice
>> 2225
>> 2226 config MODULE_SIG_HASH
>> 2227 string
>> 2228 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2229 default "sha1" if MODULE_SIG_SHA1
>> 2230 default "sha224" if MODULE_SIG_SHA224
>> 2231 default "sha256" if MODULE_SIG_SHA256
>> 2232 default "sha384" if MODULE_SIG_SHA384
>> 2233 default "sha512" if MODULE_SIG_SHA512
>> 2234
>> 2235 choice
>> 2236 prompt "Module compression mode"
>> 2237 help
>> 2238 This option allows you to choose the algorithm which will be used to
>> 2239 compress modules when 'make modules_install' is run. (or, you can
>> 2240 choose to not compress modules at all.)
>> 2241
>> 2242 External modules will also be compressed in the same way during the
>> 2243 installation.
>> 2244
>> 2245 For modules inside an initrd or initramfs, it's more efficient to
>> 2246 compress the whole initrd or initramfs instead.
>> 2247
>> 2248 This is fully compatible with signed modules.
>> 2249
>> 2250 Please note that the tool used to load modules needs to support the
>> 2251 corresponding algorithm. module-init-tools MAY support gzip, and kmod
>> 2252 MAY support gzip, xz and zstd.
>> 2253
>> 2254 Your build system needs to provide the appropriate compression tool
>> 2255 to compress the modules.
>> 2256
>> 2257 If in doubt, select 'None'.
>> 2258
>> 2259 config MODULE_COMPRESS_NONE
>> 2260 bool "None"
>> 2261 help
>> 2262 Do not compress modules. The installed modules are suffixed
>> 2263 with .ko.
>> 2264
>> 2265 config MODULE_COMPRESS_GZIP
>> 2266 bool "GZIP"
>> 2267 help
>> 2268 Compress modules with GZIP. The installed modules are suffixed
>> 2269 with .ko.gz.
>> 2270
>> 2271 config MODULE_COMPRESS_XZ
>> 2272 bool "XZ"
>> 2273 help
>> 2274 Compress modules with XZ. The installed modules are suffixed
>> 2275 with .ko.xz.
>> 2276
>> 2277 config MODULE_COMPRESS_ZSTD
>> 2278 bool "ZSTD"
>> 2279 help
>> 2280 Compress modules with ZSTD. The installed modules are suffixed
>> 2281 with .ko.zst.
>> 2282
>> 2283 endchoice
>> 2284
>> 2285 config MODULE_DECOMPRESS
>> 2286 bool "Support in-kernel module decompression"
>> 2287 depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ
>> 2288 select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
>> 2289 select XZ_DEC if MODULE_COMPRESS_XZ
>> 2290 help
>> 2291
>> 2292 Support for decompressing kernel modules by the kernel itself
>> 2293 instead of relying on userspace to perform this task. Useful when
>> 2294 load pinning security policy is enabled.
>> 2295
>> 2296 If unsure, say N.
>> 2297
>> 2298 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2299 bool "Allow loading of modules with missing namespace imports"
>> 2300 help
>> 2301 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2302 a namespace. A module that makes use of a symbol exported with such a
>> 2303 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2304 There is no technical reason to enforce correct namespace imports,
>> 2305 but it creates consistency between symbols defining namespaces and
>> 2306 users importing namespaces they make use of. This option relaxes this
>> 2307 requirement and lifts the enforcement when loading a module.
>> 2308
>> 2309 If unsure, say N.
>> 2310
>> 2311 config MODPROBE_PATH
>> 2312 string "Path to modprobe binary"
>> 2313 default "/sbin/modprobe"
>> 2314 help
>> 2315 When kernel code requests a module, it does so by calling
>> 2316 the "modprobe" userspace utility. This option allows you to
>> 2317 set the path where that binary is found. This can be changed
>> 2318 at runtime via the sysctl file
>> 2319 /proc/sys/kernel/modprobe. Setting this to the empty string
>> 2320 removes the kernel's ability to request modules (but
>> 2321 userspace can still load modules explicitly).
>> 2322
>> 2323 config TRIM_UNUSED_KSYMS
>> 2324 bool "Trim unused exported kernel symbols" if EXPERT
>> 2325 depends on !COMPILE_TEST
>> 2326 help
>> 2327 The kernel and some modules make many symbols available for
>> 2328 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2329 on the set of modules being selected in your kernel configuration,
>> 2330 many of those exported symbols might never be used.
>> 2331
>> 2332 This option allows for unused exported symbols to be dropped from
>> 2333 the build. In turn, this provides the compiler more opportunities
>> 2334 (especially when using LTO) for optimizing the code and reducing
>> 2335 binary size. This might have some security advantages as well.
>> 2336
>> 2337 If unsure, or if you need to build out-of-tree modules, say N.
>> 2338
>> 2339 config UNUSED_KSYMS_WHITELIST
>> 2340 string "Whitelist of symbols to keep in ksymtab"
>> 2341 depends on TRIM_UNUSED_KSYMS
>> 2342 help
>> 2343 By default, all unused exported symbols will be un-exported from the
>> 2344 build when TRIM_UNUSED_KSYMS is selected.
>> 2345
>> 2346 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
>> 2347 exported at all times, even in absence of in-tree users. The value to
>> 2348 set here is the path to a text file containing the list of symbols,
>> 2349 one per line. The path can be absolute, or relative to the kernel
>> 2350 source tree.
>> 2351
>> 2352 endif # MODULES
>> 2353
>> 2354 config MODULES_TREE_LOOKUP
>> 2355 def_bool y
>> 2356 depends on PERF_EVENTS || TRACING || CFI_CLANG
2008 2357
2009 config INIT_ALL_POSSIBLE 2358 config INIT_ALL_POSSIBLE
2010 bool 2359 bool
2011 help 2360 help
2012 Back when each arch used to define 2361 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2362 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2363 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2364 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2365 and have several arch maintainers pursuing me down dark alleys.
2017 2366
2018 source "block/Kconfig" 2367 source "block/Kconfig"
2019 2368
2020 config PREEMPT_NOTIFIERS 2369 config PREEMPT_NOTIFIERS
2021 bool 2370 bool
2022 2371
2023 config PADATA 2372 config PADATA
2024 depends on SMP 2373 depends on SMP
2025 bool 2374 bool
2026 2375
2027 config ASN1 2376 config ASN1
2028 tristate 2377 tristate
2029 help 2378 help
2030 Build a simple ASN.1 grammar compil 2379 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2380 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2381 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2382 functions to call on what tags.
2034 2383
2035 source "kernel/Kconfig.locks" 2384 source "kernel/Kconfig.locks"
2036 2385
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2386 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2387 bool
2042 2388
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2389 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2390 bool
2045 2391
2046 # It may be useful for an architecture to ove 2392 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2393 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2394 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2395 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2396 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2397 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2398 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2399 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2400 def_bool n
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