1 # SPDX-License-Identifier: GPL-2.0-only 1 # SPDX-License-Identifier: GPL-2.0-only
2 config CC_VERSION_TEXT 2 config CC_VERSION_TEXT
3 string 3 string
4 default "$(CC_VERSION_TEXT)" 4 default "$(CC_VERSION_TEXT)"
5 help 5 help
6 This is used in unclear ways: 6 This is used in unclear ways:
7 7
8 - Re-run Kconfig when the compiler i 8 - Re-run Kconfig when the compiler is updated
9 The 'default' property references 9 The 'default' property references the environment variable,
10 CC_VERSION_TEXT so it is recorded 10 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
11 When the compiler is updated, Kcon 11 When the compiler is updated, Kconfig will be invoked.
12 12
13 - Ensure full rebuild when the compi 13 - Ensure full rebuild when the compiler is updated
14 include/linux/compiler-version.h c 14 include/linux/compiler-version.h contains this option in the comment
15 line so fixdep adds include/config 15 line so fixdep adds include/config/CC_VERSION_TEXT into the
16 auto-generated dependency. When th 16 auto-generated dependency. When the compiler is updated, syncconfig
17 will touch it and then every file 17 will touch it and then every file will be rebuilt.
18 18
19 config CC_IS_GCC 19 config CC_IS_GCC
20 def_bool $(success,test "$(cc-name)" = 20 def_bool $(success,test "$(cc-name)" = GCC)
21 21
22 config GCC_VERSION 22 config GCC_VERSION
23 int 23 int
24 default $(cc-version) if CC_IS_GCC 24 default $(cc-version) if CC_IS_GCC
25 default 0 25 default 0
26 26
27 config CC_IS_CLANG 27 config CC_IS_CLANG
28 def_bool $(success,test "$(cc-name)" = 28 def_bool $(success,test "$(cc-name)" = Clang)
29 29
30 config CLANG_VERSION 30 config CLANG_VERSION
31 int 31 int
32 default $(cc-version) if CC_IS_CLANG 32 default $(cc-version) if CC_IS_CLANG
33 default 0 33 default 0
34 34
35 config AS_IS_GNU 35 config AS_IS_GNU
36 def_bool $(success,test "$(as-name)" = 36 def_bool $(success,test "$(as-name)" = GNU)
37 37
38 config AS_IS_LLVM 38 config AS_IS_LLVM
39 def_bool $(success,test "$(as-name)" = 39 def_bool $(success,test "$(as-name)" = LLVM)
40 40
41 config AS_VERSION 41 config AS_VERSION
42 int 42 int
43 # Use clang version if this is the int 43 # Use clang version if this is the integrated assembler
44 default CLANG_VERSION if AS_IS_LLVM 44 default CLANG_VERSION if AS_IS_LLVM
45 default $(as-version) 45 default $(as-version)
46 46
47 config LD_IS_BFD 47 config LD_IS_BFD
48 def_bool $(success,test "$(ld-name)" = 48 def_bool $(success,test "$(ld-name)" = BFD)
49 49
50 config LD_VERSION 50 config LD_VERSION
51 int 51 int
52 default $(ld-version) if LD_IS_BFD 52 default $(ld-version) if LD_IS_BFD
53 default 0 53 default 0
54 54
55 config LD_IS_LLD 55 config LD_IS_LLD
56 def_bool $(success,test "$(ld-name)" = 56 def_bool $(success,test "$(ld-name)" = LLD)
57 57
58 config LLD_VERSION 58 config LLD_VERSION
59 int 59 int
60 default $(ld-version) if LD_IS_LLD 60 default $(ld-version) if LD_IS_LLD
61 default 0 61 default 0
62 62
63 config RUSTC_VERSION <<
64 int <<
65 default $(rustc-version) <<
66 help <<
67 It does not depend on `RUST` since t <<
68 in a `depends on`. <<
69 <<
70 config RUST_IS_AVAILABLE <<
71 def_bool $(success,$(srctree)/scripts/ <<
72 help <<
73 This shows whether a suitable Rust t <<
74 <<
75 Please see Documentation/rust/quick- <<
76 to satisfy the build requirements of <<
77 <<
78 In particular, the Makefile target ' <<
79 why the Rust toolchain is not being <<
80 <<
81 config RUSTC_LLVM_VERSION <<
82 int <<
83 default $(rustc-llvm-version) <<
84 <<
85 config CC_CAN_LINK 63 config CC_CAN_LINK
86 bool 64 bool
87 default $(success,$(srctree)/scripts/c 65 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
88 default $(success,$(srctree)/scripts/c 66 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
89 67
90 config CC_CAN_LINK_STATIC 68 config CC_CAN_LINK_STATIC
91 bool 69 bool
92 default $(success,$(srctree)/scripts/c 70 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
93 default $(success,$(srctree)/scripts/c 71 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
94 72
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5 !! 73 config CC_HAS_ASM_GOTO
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id !! 74 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
97 config GCC_ASM_GOTO_OUTPUT_BROKEN <<
98 bool <<
99 depends on CC_IS_GCC <<
100 default y if GCC_VERSION < 110500 <<
101 default y if GCC_VERSION >= 120000 && <<
102 default y if GCC_VERSION >= 130000 && <<
103 75
104 config CC_HAS_ASM_GOTO_OUTPUT 76 config CC_HAS_ASM_GOTO_OUTPUT
105 def_bool y !! 77 depends on CC_HAS_ASM_GOTO
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN !! 78 def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
107 depends on $(success,echo 'int foo(int <<
108 79
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT 80 config CC_HAS_ASM_GOTO_TIED_OUTPUT
110 depends on CC_HAS_ASM_GOTO_OUTPUT 81 depends on CC_HAS_ASM_GOTO_OUTPUT
111 # Detect buggy gcc and clang, fixed in 82 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
112 def_bool $(success,echo 'int foo(int * !! 83 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .\n": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
113 84
114 config TOOLS_SUPPORT_RELR 85 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 86 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 87
117 config CC_HAS_ASM_INLINE 88 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 89 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 90
120 config CC_HAS_NO_PROFILE_FN_ATTR 91 config CC_HAS_NO_PROFILE_FN_ATTR
121 def_bool $(success,echo '__attribute__ 92 def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
122 93
123 config PAHOLE_VERSION 94 config PAHOLE_VERSION
124 int 95 int
125 default $(shell,$(srctree)/scripts/pah 96 default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
126 97
127 config CONSTRUCTORS 98 config CONSTRUCTORS
128 bool 99 bool
129 100
130 config IRQ_WORK 101 config IRQ_WORK
131 def_bool y if SMP !! 102 bool
132 103
133 config BUILDTIME_TABLE_SORT 104 config BUILDTIME_TABLE_SORT
134 bool 105 bool
135 106
136 config THREAD_INFO_IN_TASK 107 config THREAD_INFO_IN_TASK
137 bool 108 bool
138 help 109 help
139 Select this to move thread_info off 110 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 111 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 112 except flags and fix any runtime bugs.
142 113
143 One subtle change that will be neede 114 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 115 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 116
146 menu "General setup" 117 menu "General setup"
147 118
148 config BROKEN 119 config BROKEN
149 bool 120 bool
150 121
151 config BROKEN_ON_SMP 122 config BROKEN_ON_SMP
152 bool 123 bool
153 depends on BROKEN || !SMP 124 depends on BROKEN || !SMP
154 default y 125 default y
155 126
156 config INIT_ENV_ARG_LIMIT 127 config INIT_ENV_ARG_LIMIT
157 int 128 int
158 default 32 if !UML 129 default 32 if !UML
159 default 128 if UML 130 default 128 if UML
160 help 131 help
161 Maximum of each of the number of arg 132 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 133 variables passed to init from the kernel command line.
163 134
164 config COMPILE_TEST 135 config COMPILE_TEST
165 bool "Compile also drivers which will 136 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 137 depends on HAS_IOMEM
167 help 138 help
168 Some drivers can be compiled on a di 139 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 140 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 141 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 142 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 143 drivers to compile-test them.
173 144
174 If you are a developer and want to b 145 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 146 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 147 drivers to be distributed.
177 148
178 config WERROR 149 config WERROR
179 bool "Compile the kernel with warnings 150 bool "Compile the kernel with warnings as errors"
180 default COMPILE_TEST 151 default COMPILE_TEST
181 help 152 help
182 A kernel build should not cause any 153 A kernel build should not cause any compiler warnings, and this
183 enables the '-Werror' (for C) and '- !! 154 enables the '-Werror' flag to enforce that rule by default.
184 to enforce that rule by default. Cer <<
185 such as the linker may be upgraded t <<
186 well. <<
187 155
188 However, if you have a new (or very !! 156 However, if you have a new (or very old) compiler with odd and
189 and unusual warnings, or you have so !! 157 unusual warnings, or you have some architecture with problems,
190 you may need to disable this config 158 you may need to disable this config option in order to
191 successfully build the kernel. 159 successfully build the kernel.
192 160
193 If in doubt, say Y. 161 If in doubt, say Y.
194 162
195 config UAPI_HEADER_TEST 163 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 164 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 165 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 166 help
199 Compile test headers exported to use 167 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 168 self-contained, i.e. compilable as standalone units.
201 169
202 If you are a developer or tester and 170 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 171 headers are self-contained, say Y here. Otherwise, choose N.
204 172
205 config LOCALVERSION 173 config LOCALVERSION
206 string "Local version - append to kern 174 string "Local version - append to kernel release"
207 help 175 help
208 Append an extra string to the end of 176 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 177 This will show up when you type uname, for example.
210 The string you set here will be appe 178 The string you set here will be appended after the contents of
211 any files with a filename matching l 179 any files with a filename matching localversion* in your
212 object and source tree, in that orde 180 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 181 be a maximum of 64 characters.
214 182
215 config LOCALVERSION_AUTO 183 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 184 bool "Automatically append version information to the version string"
217 default y 185 default y
218 depends on !COMPILE_TEST 186 depends on !COMPILE_TEST
219 help 187 help
220 This will try to automatically deter 188 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 189 release tree by looking for git tags that belong to the current
222 top of tree revision. 190 top of tree revision.
223 191
224 A string of the format -gxxxxxxxx wi 192 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 193 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 194 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 195 set in CONFIG_LOCALVERSION.
228 196
229 (The actual string used here is the !! 197 (The actual string used here is the first eight characters produced
230 by running the command: 198 by running the command:
231 199
232 $ git rev-parse --verify HEAD 200 $ git rev-parse --verify HEAD
233 201
234 which is done within the script "scr 202 which is done within the script "scripts/setlocalversion".)
235 203
236 config BUILD_SALT 204 config BUILD_SALT
237 string "Build ID Salt" 205 string "Build ID Salt"
238 default "" 206 default ""
239 help 207 help
240 The build ID is used to link binarie 208 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 209 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 210 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 211 build is unique between builds. It's safe to leave the default.
244 212
245 config HAVE_KERNEL_GZIP 213 config HAVE_KERNEL_GZIP
246 bool 214 bool
247 215
248 config HAVE_KERNEL_BZIP2 216 config HAVE_KERNEL_BZIP2
249 bool 217 bool
250 218
251 config HAVE_KERNEL_LZMA 219 config HAVE_KERNEL_LZMA
252 bool 220 bool
253 221
254 config HAVE_KERNEL_XZ 222 config HAVE_KERNEL_XZ
255 bool 223 bool
256 224
257 config HAVE_KERNEL_LZO 225 config HAVE_KERNEL_LZO
258 bool 226 bool
259 227
260 config HAVE_KERNEL_LZ4 228 config HAVE_KERNEL_LZ4
261 bool 229 bool
262 230
263 config HAVE_KERNEL_ZSTD 231 config HAVE_KERNEL_ZSTD
264 bool 232 bool
265 233
266 config HAVE_KERNEL_UNCOMPRESSED 234 config HAVE_KERNEL_UNCOMPRESSED
267 bool 235 bool
268 236
269 choice 237 choice
270 prompt "Kernel compression mode" 238 prompt "Kernel compression mode"
271 default KERNEL_GZIP 239 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE 240 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED
273 help 241 help
274 The linux kernel is a kind of self-e 242 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 243 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 244 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 245 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 246 Decompression speed is relevant at each boot.
279 247
280 If you have any problems with bzip2 248 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 249 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 250 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 251 supplied by Christian Ludwig)
284 252
285 High compression options are mostly 253 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 254 are low on disk space (embedded systems), but for whom ram
287 size matters less. 255 size matters less.
288 256
289 If in doubt, select 'gzip' 257 If in doubt, select 'gzip'
290 258
291 config KERNEL_GZIP 259 config KERNEL_GZIP
292 bool "Gzip" 260 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 261 depends on HAVE_KERNEL_GZIP
294 help 262 help
295 The old and tried gzip compression. 263 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 264 between compression ratio and decompression speed.
297 265
298 config KERNEL_BZIP2 266 config KERNEL_BZIP2
299 bool "Bzip2" 267 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 268 depends on HAVE_KERNEL_BZIP2
301 help 269 help
302 Its compression ratio and speed is i 270 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 271 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 272 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 273 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 274 will need at least 8MB RAM or more for booting.
307 275
308 config KERNEL_LZMA 276 config KERNEL_LZMA
309 bool "LZMA" 277 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 278 depends on HAVE_KERNEL_LZMA
311 help 279 help
312 This compression algorithm's ratio i 280 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 281 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 282 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 283
316 config KERNEL_XZ 284 config KERNEL_XZ
317 bool "XZ" 285 bool "XZ"
318 depends on HAVE_KERNEL_XZ 286 depends on HAVE_KERNEL_XZ
319 help 287 help
320 XZ uses the LZMA2 algorithm and inst 288 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 289 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 290 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 291 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 292 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 293 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 294
328 The speed is about the same as with 295 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 296 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 297 and LZO. Compression is slow.
331 298
332 config KERNEL_LZO 299 config KERNEL_LZO
333 bool "LZO" 300 bool "LZO"
334 depends on HAVE_KERNEL_LZO 301 depends on HAVE_KERNEL_LZO
335 help 302 help
336 Its compression ratio is the poorest 303 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 304 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 305 (both compression and decompression) is the fastest.
339 306
340 config KERNEL_LZ4 307 config KERNEL_LZ4
341 bool "LZ4" 308 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 309 depends on HAVE_KERNEL_LZ4
343 help 310 help
344 LZ4 is an LZ77-type compressor with 311 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 312 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 313 <https://code.google.com/p/lz4/>.
347 314
348 Its compression ratio is worse than 315 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 316 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 317 faster than LZO.
351 318
352 config KERNEL_ZSTD 319 config KERNEL_ZSTD
353 bool "ZSTD" 320 bool "ZSTD"
354 depends on HAVE_KERNEL_ZSTD 321 depends on HAVE_KERNEL_ZSTD
355 help 322 help
356 ZSTD is a compression algorithm targ 323 ZSTD is a compression algorithm targeting intermediate compression
357 with fast decompression speed. It wi 324 with fast decompression speed. It will compress better than GZIP and
358 decompress around the same speed as 325 decompress around the same speed as LZO, but slower than LZ4. You
359 will need at least 192 KB RAM or mor 326 will need at least 192 KB RAM or more for booting. The zstd command
360 line tool is required for compressio 327 line tool is required for compression.
361 328
362 config KERNEL_UNCOMPRESSED 329 config KERNEL_UNCOMPRESSED
363 bool "None" 330 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 331 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 332 help
366 Produce uncompressed kernel image. T 333 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 334 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 335 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 336 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 337 and jump right at uncompressed kernel image.
371 338
372 endchoice 339 endchoice
373 340
374 config DEFAULT_INIT 341 config DEFAULT_INIT
375 string "Default init path" 342 string "Default init path"
376 default "" 343 default ""
377 help 344 help
378 This option determines the default i 345 This option determines the default init for the system if no init=
379 option is passed on the kernel comma 346 option is passed on the kernel command line. If the requested path is
380 not present, we will still then move 347 not present, we will still then move on to attempting further
381 locations (e.g. /sbin/init, etc). If 348 locations (e.g. /sbin/init, etc). If this is empty, we will just use
382 the fallback list when init= is not 349 the fallback list when init= is not passed.
383 350
384 config DEFAULT_HOSTNAME 351 config DEFAULT_HOSTNAME
385 string "Default hostname" 352 string "Default hostname"
386 default "(none)" 353 default "(none)"
387 help 354 help
388 This option determines the default s 355 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 356 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 357 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 358 system more usable with less configuration.
392 359
>> 360 #
>> 361 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 362 # add proper SWAP support to them, in which case this can be remove.
>> 363 #
>> 364 config ARCH_NO_SWAP
>> 365 bool
>> 366
>> 367 config SWAP
>> 368 bool "Support for paging of anonymous memory (swap)"
>> 369 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 370 default y
>> 371 help
>> 372 This option allows you to choose whether you want to have support
>> 373 for so called swap devices or swap files in your kernel that are
>> 374 used to provide more virtual memory than the actual RAM present
>> 375 in your computer. If unsure say Y.
>> 376
393 config SYSVIPC 377 config SYSVIPC
394 bool "System V IPC" 378 bool "System V IPC"
395 help 379 help
396 Inter Process Communication is a sui 380 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 381 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 382 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 383 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 384 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 385 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 386 you'll need to say Y here.
403 387
404 You can find documentation about IPC 388 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 389 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 390 <http://www.tldp.org/guides.html>.
407 391
408 config SYSVIPC_SYSCTL 392 config SYSVIPC_SYSCTL
409 bool 393 bool
410 depends on SYSVIPC 394 depends on SYSVIPC
411 depends on SYSCTL 395 depends on SYSCTL
412 default y 396 default y
413 397
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 398 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 399 bool "POSIX Message Queues"
420 depends on NET 400 depends on NET
421 help 401 help
422 POSIX variant of message queues is a 402 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 403 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 404 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 405 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 406 queues (functions mq_*) say Y here.
427 407
428 POSIX message queues are visible as 408 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 409 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 410 operations on message queues.
431 411
432 If unsure, say Y. 412 If unsure, say Y.
433 413
434 config POSIX_MQUEUE_SYSCTL 414 config POSIX_MQUEUE_SYSCTL
435 bool 415 bool
436 depends on POSIX_MQUEUE 416 depends on POSIX_MQUEUE
437 depends on SYSCTL 417 depends on SYSCTL
438 default y 418 default y
439 419
440 config WATCH_QUEUE 420 config WATCH_QUEUE
441 bool "General notification queue" 421 bool "General notification queue"
442 default n 422 default n
443 help 423 help
444 424
445 This is a general notification queue 425 This is a general notification queue for the kernel to pass events to
446 userspace by splicing them into pipe 426 userspace by splicing them into pipes. It can be used in conjunction
447 with watches for key/keyring change 427 with watches for key/keyring change notifications and device
448 notifications. 428 notifications.
449 429
450 See Documentation/core-api/watch_que !! 430 See Documentation/watch_queue.rst
451 431
452 config CROSS_MEMORY_ATTACH 432 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 433 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 434 depends on MMU
455 default y 435 default y
456 help 436 help
457 Enabling this option adds the system 437 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 438 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 439 to directly read from or write to another process' address space.
460 See the man page for more details. 440 See the man page for more details.
461 441
462 config USELIB 442 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 443 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 444 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 445 help
466 This option enables the uselib sysca 446 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 447 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 448 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 449 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 450 running glibc can safely disable this.
471 451
472 config AUDIT 452 config AUDIT
473 bool "Auditing support" 453 bool "Auditing support"
474 depends on NET 454 depends on NET
475 help 455 help
476 Enable auditing infrastructure that 456 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 457 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 458 logging of avc messages output). System call auditing is included
479 on architectures which support it. 459 on architectures which support it.
480 460
481 config HAVE_ARCH_AUDITSYSCALL 461 config HAVE_ARCH_AUDITSYSCALL
482 bool 462 bool
483 463
484 config AUDITSYSCALL 464 config AUDITSYSCALL
485 def_bool y 465 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 466 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 467 select FSNOTIFY
488 468
489 source "kernel/irq/Kconfig" 469 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 470 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" 471 source "kernel/bpf/Kconfig"
492 source "kernel/Kconfig.preempt" 472 source "kernel/Kconfig.preempt"
493 473
494 menu "CPU/Task time and stats accounting" 474 menu "CPU/Task time and stats accounting"
495 475
496 config VIRT_CPU_ACCOUNTING 476 config VIRT_CPU_ACCOUNTING
497 bool 477 bool
498 478
499 choice 479 choice
500 prompt "Cputime accounting" 480 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 481 default TICK_CPU_ACCOUNTING if !PPC64
>> 482 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 483
503 # Kind of a stub config for the pure tick base 484 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 485 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 486 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 487 depends on !S390 && !NO_HZ_FULL
507 help 488 help
508 This is the basic tick based cputime 489 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 490 statistics about user, system and idle time spent on per jiffies
510 granularity. 491 granularity.
511 492
512 If unsure, say Y. 493 If unsure, say Y.
513 494
514 config VIRT_CPU_ACCOUNTING_NATIVE 495 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 496 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 497 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 498 select VIRT_CPU_ACCOUNTING
518 help 499 help
519 Select this option to enable more ac 500 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 501 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 502 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 503 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 504 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 505 this also enables accounting of stolen time on logically-partitioned
525 systems. 506 systems.
526 507
527 config VIRT_CPU_ACCOUNTING_GEN 508 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 509 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 510 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 511 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 512 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 513 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 514 select CONTEXT_TRACKING
534 help 515 help
535 Select this option to enable task an 516 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 517 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 518 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 519 The accounting is thus performed at the expense of some significant
539 overhead. 520 overhead.
540 521
541 For now this is only useful if you a 522 For now this is only useful if you are working on the full
542 dynticks subsystem development. 523 dynticks subsystem development.
543 524
544 If unsure, say N. 525 If unsure, say N.
545 526
546 endchoice 527 endchoice
547 528
548 config IRQ_TIME_ACCOUNTING 529 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 530 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 531 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 532 help
552 Select this option to enable fine gr 533 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 534 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 535 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 536 small performance impact.
556 537
557 If in doubt, say N here. 538 If in doubt, say N here.
558 539
559 config HAVE_SCHED_AVG_IRQ 540 config HAVE_SCHED_AVG_IRQ
560 def_bool y 541 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 542 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 543 depends on SMP
563 544
564 config SCHED_HW_PRESSURE !! 545 config SCHED_THERMAL_PRESSURE
565 bool 546 bool
566 default y if ARM && ARM_CPU_TOPOLOGY 547 default y if ARM && ARM_CPU_TOPOLOGY
567 default y if ARM64 548 default y if ARM64
568 depends on SMP 549 depends on SMP
569 depends on CPU_FREQ_THERMAL 550 depends on CPU_FREQ_THERMAL
570 help 551 help
571 Select this option to enable HW pres !! 552 Select this option to enable thermal pressure accounting in the
572 scheduler. HW pressure is the value !! 553 scheduler. Thermal pressure is the value conveyed to the scheduler
573 that reflects the reduction in CPU c 554 that reflects the reduction in CPU compute capacity resulted from
574 HW throttling. HW throttling occurs !! 555 thermal throttling. Thermal throttling occurs when the performance of
575 a CPU is capped due to high operatin !! 556 a CPU is capped due to high operating temperatures.
576 557
577 If selected, the scheduler will be a 558 If selected, the scheduler will be able to balance tasks accordingly,
578 i.e. put less load on throttled CPUs 559 i.e. put less load on throttled CPUs than on non/less throttled ones.
579 560
580 This requires the architecture to im 561 This requires the architecture to implement
581 arch_update_hw_pressure() and arch_s !! 562 arch_update_thermal_pressure() and arch_scale_thermal_pressure().
582 563
583 config BSD_PROCESS_ACCT 564 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 565 bool "BSD Process Accounting"
585 depends on MULTIUSER 566 depends on MULTIUSER
586 help 567 help
587 If you say Y here, a user level prog 568 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 569 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 570 information to a file: whenever a process exits, information about
590 that process will be appended to the 571 that process will be appended to the file by the kernel. The
591 information includes things such as 572 information includes things such as creation time, owning user,
592 command name, memory usage, controll 573 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 574 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 575 up to the user level program to do useful things with this
595 information. This is generally a go 576 information. This is generally a good idea, so say Y.
596 577
597 config BSD_PROCESS_ACCT_V3 578 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 579 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 580 depends on BSD_PROCESS_ACCT
600 default n 581 default n
601 help 582 help
602 If you say Y here, the process accou 583 If you say Y here, the process accounting information is written
603 in a new file format that also logs 584 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 585 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 586 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 587 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 588 at <http://www.gnu.org/software/acct/>.
608 589
609 config TASKSTATS 590 config TASKSTATS
610 bool "Export task/process statistics t 591 bool "Export task/process statistics through netlink"
611 depends on NET 592 depends on NET
612 depends on MULTIUSER 593 depends on MULTIUSER
613 default n 594 default n
614 help 595 help
615 Export selected statistics for tasks 596 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 597 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 598 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 599 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 600 space on task exit.
620 601
621 Say N if unsure. 602 Say N if unsure.
622 603
623 config TASK_DELAY_ACCT 604 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 605 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 606 depends on TASKSTATS
626 select SCHED_INFO 607 select SCHED_INFO
627 help 608 help
628 Collect information on time spent by 609 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 610 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 611 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 612 relative to other tasks for cpu, io, rss limits etc.
632 613
633 Say N if unsure. 614 Say N if unsure.
634 615
635 config TASK_XACCT 616 config TASK_XACCT
636 bool "Enable extended accounting over 617 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 618 depends on TASKSTATS
638 help 619 help
639 Collect extended task accounting dat 620 Collect extended task accounting data and send the data
640 to userland for processing over the 621 to userland for processing over the taskstats interface.
641 622
642 Say N if unsure. 623 Say N if unsure.
643 624
644 config TASK_IO_ACCOUNTING 625 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 626 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 627 depends on TASK_XACCT
647 help 628 help
648 Collect information on the number of 629 Collect information on the number of bytes of storage I/O which this
649 task has caused. 630 task has caused.
650 631
651 Say N if unsure. 632 Say N if unsure.
652 633
653 config PSI 634 config PSI
654 bool "Pressure stall information track 635 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 636 help
657 Collect metrics that indicate how ov 637 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 638 and IO capacity are in the system.
659 639
660 If you say Y here, the kernel will c 640 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 641 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 642 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 643 delayed due to contention of the respective resource.
664 644
665 In kernels with cgroup support, cgro 645 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 646 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 647 which aggregate pressure stalls for the grouped tasks only.
668 648
669 For more details see Documentation/a 649 For more details see Documentation/accounting/psi.rst.
670 650
671 Say N if unsure. 651 Say N if unsure.
672 652
673 config PSI_DEFAULT_DISABLED 653 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 654 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 655 default n
676 depends on PSI 656 depends on PSI
677 help 657 help
678 If set, pressure stall information t 658 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 659 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 660 kernel commandline during boot.
681 661
682 This feature adds some code to the t 662 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 663 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 664 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 665 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 666 scheduler stress tests, such as hackbench.
687 667
688 If you are paranoid and not sure wha 668 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 669 used for, say Y.
690 670
691 Say N if unsure. 671 Say N if unsure.
692 672
693 endmenu # "CPU/Task time and stats accounting" 673 endmenu # "CPU/Task time and stats accounting"
694 674
695 config CPU_ISOLATION 675 config CPU_ISOLATION
696 bool "CPU isolation" 676 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 677 depends on SMP || COMPILE_TEST
698 default y 678 default y
699 help 679 help
700 Make sure that CPUs running critical 680 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 681 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 682 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 683 the "isolcpus=" boot parameter.
704 684
705 Say Y if unsure. 685 Say Y if unsure.
706 686
707 source "kernel/rcu/Kconfig" 687 source "kernel/rcu/Kconfig"
708 688
>> 689 config BUILD_BIN2C
>> 690 bool
>> 691 default n
>> 692
709 config IKCONFIG 693 config IKCONFIG
710 tristate "Kernel .config support" 694 tristate "Kernel .config support"
711 help 695 help
712 This option enables the complete Lin 696 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 697 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 698 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 699 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 700 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 701 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 702 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 703 /proc/config.gz if enabled (below).
720 704
721 config IKCONFIG_PROC 705 config IKCONFIG_PROC
722 bool "Enable access to .config through 706 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 707 depends on IKCONFIG && PROC_FS
724 help 708 help
725 This option enables access to the ke 709 This option enables access to the kernel configuration file
726 through /proc/config.gz. 710 through /proc/config.gz.
727 711
728 config IKHEADERS 712 config IKHEADERS
729 tristate "Enable kernel headers throug 713 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 714 depends on SYSFS
731 help 715 help
732 This option enables access to the in 716 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 717 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 718 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 719 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 720
737 config LOG_BUF_SHIFT 721 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 722 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 !! 723 range 12 25 if !H8300
>> 724 range 12 19 if H8300
740 default 17 725 default 17
741 depends on PRINTK 726 depends on PRINTK
742 help 727 help
743 Select the minimal kernel log buffer 728 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 729 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 730 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 731 by "log_buf_len" boot parameter.
747 732
748 Examples: 733 Examples:
749 17 => 128 KB 734 17 => 128 KB
750 16 => 64 KB 735 16 => 64 KB
751 15 => 32 KB 736 15 => 32 KB
752 14 => 16 KB 737 14 => 16 KB
753 13 => 8 KB 738 13 => 8 KB
754 12 => 4 KB 739 12 => 4 KB
755 740
756 config LOG_CPU_MAX_BUF_SHIFT 741 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 742 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 743 depends on SMP
759 range 0 21 744 range 0 21
>> 745 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 746 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 747 depends on PRINTK
763 help 748 help
764 This option allows to increase the d 749 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 750 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 751 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 752 lines however it might be much more when problems are reported,
768 e.g. backtraces. 753 e.g. backtraces.
769 754
770 The increased size means that a new 755 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 756 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 757 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 758 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 759 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed 760 so that more than 16 CPUs are needed to trigger the allocation.
776 761
777 Also this option is ignored when "lo 762 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 763 used as it forces an exact (power of two) size of the ring buffer.
779 764
780 The number of possible CPUs is used 765 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 766 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 767 scenario while allowing a simple algorithm to be used from bootup.
783 768
784 Examples shift values and their mean 769 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 770 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 771 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 772 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 773 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 774 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 775 12 => 4 KB for each CPU
791 776
>> 777 config PRINTK_SAFE_LOG_BUF_SHIFT
>> 778 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
>> 779 range 10 21
>> 780 default 13
>> 781 depends on PRINTK
>> 782 help
>> 783 Select the size of an alternate printk per-CPU buffer where messages
>> 784 printed from usafe contexts are temporary stored. One example would
>> 785 be NMI messages, another one - printk recursion. The messages are
>> 786 copied to the main log buffer in a safe context to avoid a deadlock.
>> 787 The value defines the size as a power of 2.
>> 788
>> 789 Those messages are rare and limited. The largest one is when
>> 790 a backtrace is printed. It usually fits into 4KB. Select
>> 791 8KB if you want to be on the safe side.
>> 792
>> 793 Examples:
>> 794 17 => 128 KB for each CPU
>> 795 16 => 64 KB for each CPU
>> 796 15 => 32 KB for each CPU
>> 797 14 => 16 KB for each CPU
>> 798 13 => 8 KB for each CPU
>> 799 12 => 4 KB for each CPU
>> 800
792 config PRINTK_INDEX 801 config PRINTK_INDEX
793 bool "Printk indexing debugfs interfac 802 bool "Printk indexing debugfs interface"
794 depends on PRINTK && DEBUG_FS 803 depends on PRINTK && DEBUG_FS
795 help 804 help
796 Add support for indexing of all prin 805 Add support for indexing of all printk formats known at compile time
797 at <debugfs>/printk/index/<module>. 806 at <debugfs>/printk/index/<module>.
798 807
799 This can be used as part of maintain 808 This can be used as part of maintaining daemons which monitor
800 /dev/kmsg, as it permits auditing th 809 /dev/kmsg, as it permits auditing the printk formats present in a
801 kernel, allowing detection of cases 810 kernel, allowing detection of cases where monitored printks are
802 changed or no longer present. 811 changed or no longer present.
803 812
804 There is no additional runtime cost 813 There is no additional runtime cost to printk with this enabled.
805 814
806 # 815 #
807 # Architectures with an unreliable sched_clock 816 # Architectures with an unreliable sched_clock() should select this:
808 # 817 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 818 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 819 bool
811 820
812 config GENERIC_SCHED_CLOCK 821 config GENERIC_SCHED_CLOCK
813 bool 822 bool
814 823
815 menu "Scheduler features" 824 menu "Scheduler features"
816 825
817 config UCLAMP_TASK 826 config UCLAMP_TASK
818 bool "Enable utilization clamping for 827 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 828 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 829 help
821 This feature enables the scheduler t 830 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 831 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 832
824 With this option, the user can speci 833 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 834 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 835 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 836 defines the minimum frequency it should use.
828 837
829 Both min and max utilization clamp v 838 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 839 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 840 enforce or grant any specific bandwidth for tasks.
832 841
833 If in doubt, say N. 842 If in doubt, say N.
834 843
835 config UCLAMP_BUCKETS_COUNT 844 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 845 int "Number of supported utilization clamp buckets"
837 range 5 20 846 range 5 20
838 default 5 847 default 5
839 depends on UCLAMP_TASK 848 depends on UCLAMP_TASK
840 help 849 help
841 Defines the number of clamp buckets 850 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 851 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 852 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 853 the precision of clamping aggregation and tracking at run-time.
845 854
846 For example, with the minimum config 855 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 856 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 857 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 858 effective value to 25%.
850 If a second 30% boosted task should 859 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 860 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 861 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 862 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 863 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 864 that bucket.
856 865
857 An additional boost/capping margin c 866 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 867 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 868 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 869 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 870 clamp buckets to trade off used memory for run-time tracking
862 precision. 871 precision.
863 872
864 If in doubt, use the default value. 873 If in doubt, use the default value.
865 874
866 endmenu 875 endmenu
867 876
868 # 877 #
869 # For architectures that want to enable the su 878 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 879 # balancing logic:
871 # 880 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 881 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 882 bool
874 883
875 # 884 #
876 # For architectures that prefer to flush all T 885 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 886 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 887 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 888 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 889 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 890 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 891 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 892 bool
884 893
885 config CC_HAS_INT128 894 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 895 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 896
888 config CC_IMPLICIT_FALLTHROUGH 897 config CC_IMPLICIT_FALLTHROUGH
889 string 898 string
890 default "-Wimplicit-fallthrough=5" if 899 default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
891 default "-Wimplicit-fallthrough" if CC 900 default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
892 901
893 # Currently, disable gcc-10+ array-bounds glob !! 902 # Currently, disable gcc-12 array-bounds globally.
894 # It's still broken in gcc-13, so no upper bou !! 903 # We may want to target only particular configurations some day.
895 config GCC10_NO_ARRAY_BOUNDS !! 904 config GCC12_NO_ARRAY_BOUNDS
896 def_bool y 905 def_bool y
897 906
898 config CC_NO_ARRAY_BOUNDS 907 config CC_NO_ARRAY_BOUNDS
899 bool 908 bool
900 default y if CC_IS_GCC && GCC_VERSION !! 909 default y if CC_IS_GCC && GCC_VERSION >= 120000 && GCC_VERSION < 130000 && GCC12_NO_ARRAY_BOUNDS
901 <<
902 # Currently, disable -Wstringop-overflow for G <<
903 config GCC_NO_STRINGOP_OVERFLOW <<
904 def_bool y <<
905 <<
906 config CC_NO_STRINGOP_OVERFLOW <<
907 bool <<
908 default y if CC_IS_GCC && GCC_NO_STRIN <<
909 <<
910 config CC_STRINGOP_OVERFLOW <<
911 bool <<
912 default y if CC_IS_GCC && !CC_NO_STRIN <<
913 910
914 # 911 #
915 # For architectures that know their GCC __int1 912 # For architectures that know their GCC __int128 support is sound
916 # 913 #
917 config ARCH_SUPPORTS_INT128 914 config ARCH_SUPPORTS_INT128
918 bool 915 bool
919 916
920 # For architectures that (ab)use NUMA to repre 917 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 918 # all cpu-local but of different latencies, such as SuperH.
922 # 919 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 920 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 921 bool
925 922
926 config NUMA_BALANCING 923 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 924 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 925 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 926 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && 927 depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
931 help 928 help
932 This option adds support for automat 929 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 930 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 931 it has references to the node the task is running on.
935 932
936 This system will be inactive on UMA 933 This system will be inactive on UMA systems.
937 934
938 config NUMA_BALANCING_DEFAULT_ENABLED 935 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 936 bool "Automatically enable NUMA aware memory/task placement"
940 default y 937 default y
941 depends on NUMA_BALANCING 938 depends on NUMA_BALANCING
942 help 939 help
943 If set, automatic NUMA balancing wil 940 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 941 machine.
945 942
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 943 menuconfig CGROUPS
950 bool "Control Group support" 944 bool "Control Group support"
951 select KERNFS 945 select KERNFS
952 help 946 help
953 This option adds support for groupin 947 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 948 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 949 controls or device isolation.
956 See 950 See
957 - Documentation/scheduler/sche 951 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 952 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 953 and resource control)
960 954
961 Say N if unsure. 955 Say N if unsure.
962 956
963 if CGROUPS 957 if CGROUPS
964 958
965 config PAGE_COUNTER 959 config PAGE_COUNTER
966 bool 960 bool
967 961
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 962 config MEMCG
979 bool "Memory controller" 963 bool "Memory controller"
980 select PAGE_COUNTER 964 select PAGE_COUNTER
981 select EVENTFD 965 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 966 help
984 Provides control over the memory foo 967 Provides control over the memory footprint of tasks in a cgroup.
985 968
986 config MEMCG_V1 !! 969 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 970 bool
988 depends on MEMCG !! 971 depends on MEMCG && SWAP
989 default n !! 972 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 973
1001 Say N if unsure. !! 974 config MEMCG_KMEM
>> 975 bool
>> 976 depends on MEMCG && !SLOB
>> 977 default y
1002 978
1003 config BLK_CGROUP 979 config BLK_CGROUP
1004 bool "IO controller" 980 bool "IO controller"
1005 depends on BLOCK 981 depends on BLOCK
1006 default n 982 default n
1007 help 983 help
1008 Generic block IO controller cgroup in 984 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 985 cgroup interface which should be used by various IO controlling
1010 policies. 986 policies.
1011 987
1012 Currently, CFQ IO scheduler uses it t 988 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 989 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 990 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 991 block layer to implement upper limit in IO rates on a device.
1016 992
1017 This option only enables generic Bloc 993 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 994 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 995 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl 996 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 997 CONFIG_BLK_DEV_THROTTLING=y.
1022 998
1023 See Documentation/admin-guide/cgroup- 999 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 1000
1025 config CGROUP_WRITEBACK 1001 config CGROUP_WRITEBACK
1026 bool 1002 bool
1027 depends on MEMCG && BLK_CGROUP 1003 depends on MEMCG && BLK_CGROUP
1028 default y 1004 default y
1029 1005
1030 menuconfig CGROUP_SCHED 1006 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 1007 bool "CPU controller"
1032 default n 1008 default n
1033 help 1009 help
1034 This feature lets CPU scheduler rec 1010 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 1011 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 1012 tasks.
1037 1013
1038 if CGROUP_SCHED 1014 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 1015 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 1016 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 1017 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 1018 default CGROUP_SCHED
1047 1019
1048 config CFS_BANDWIDTH 1020 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 1021 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 1022 depends on FAIR_GROUP_SCHED
1051 default n 1023 default n
1052 help 1024 help
1053 This option allows users to define 1025 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 1026 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 1027 set are considered to be unconstrained and will run with no
1056 restriction. 1028 restriction.
1057 See Documentation/scheduler/sched-b 1029 See Documentation/scheduler/sched-bwc.rst for more information.
1058 1030
1059 config RT_GROUP_SCHED 1031 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 1032 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 1033 depends on CGROUP_SCHED
1062 default n 1034 default n
1063 help 1035 help
1064 This feature lets you explicitly al 1036 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 1037 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 1038 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 1039 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 1040 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 1041
1070 config EXT_GROUP_SCHED <<
1071 bool <<
1072 depends on SCHED_CLASS_EXT && CGROUP_ <<
1073 select GROUP_SCHED_WEIGHT <<
1074 default y <<
1075 <<
1076 endif #CGROUP_SCHED 1042 endif #CGROUP_SCHED
1077 1043
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 1044 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 1045 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 1046 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 1047 depends on UCLAMP_TASK
1086 default n 1048 default n
1087 help 1049 help
1088 This feature enables the scheduler 1050 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 1051 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 1052
1091 When this option is enabled, the us 1053 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 1054 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 1055 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 1056 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 1057 frequency a task will always use.
1096 1058
1097 When task group based utilization c 1059 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 1060 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 1061 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 1062 be bigger than the corresponding clamping defined at task group level.
1101 1063
1102 If in doubt, say N. 1064 If in doubt, say N.
1103 1065
1104 config CGROUP_PIDS 1066 config CGROUP_PIDS
1105 bool "PIDs controller" 1067 bool "PIDs controller"
1106 help 1068 help
1107 Provides enforcement of process num 1069 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1070 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1071 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1072 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1073 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1074 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1075 PIDs controller is designed to stop this from happening.
1114 1076
1115 It should be noted that organisatio 1077 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 1078 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 1079 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1080 attach to a cgroup.
1119 1081
1120 config CGROUP_RDMA 1082 config CGROUP_RDMA
1121 bool "RDMA controller" 1083 bool "RDMA controller"
1122 help 1084 help
1123 Provides enforcement of RDMA resour 1085 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1086 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1087 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1088 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1089 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1090 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1091
1130 config CGROUP_FREEZER 1092 config CGROUP_FREEZER
1131 bool "Freezer controller" 1093 bool "Freezer controller"
1132 help 1094 help
1133 Provides a way to freeze and unfree 1095 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1096 cgroup.
1135 1097
1136 This option affects the ORIGINAL cg 1098 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1099 controller includes important in-kernel memory consumers per default.
1138 1100
1139 If you're using cgroup2, say N. 1101 If you're using cgroup2, say N.
1140 1102
1141 config CGROUP_HUGETLB 1103 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1104 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1105 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1106 select PAGE_COUNTER
1145 default n 1107 default n
1146 help 1108 help
1147 Provides a cgroup controller for Hu 1109 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1110 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1111 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1112 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1113 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1114 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1115 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1116 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1117 that we cannot use the controller with huge page less than 3 pages.
1156 1118
1157 config CPUSETS 1119 config CPUSETS
1158 bool "Cpuset controller" 1120 bool "Cpuset controller"
1159 depends on SMP 1121 depends on SMP
1160 help 1122 help
1161 This option will let you create and 1123 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1124 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1125 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1126 This is primarily useful on large SMP or NUMA systems.
1165 1127
1166 Say N if unsure. 1128 Say N if unsure.
1167 1129
1168 config CPUSETS_V1 <<
1169 bool "Legacy cgroup v1 cpusets contro <<
1170 depends on CPUSETS <<
1171 default n <<
1172 help <<
1173 Legacy cgroup v1 cpusets controller <<
1174 cgroup v2 implementation. The v1 is <<
1175 which haven't migrated to the new c <<
1176 do not have any such application th <<
1177 this option disabled. <<
1178 <<
1179 Say N if unsure. <<
1180 <<
1181 config PROC_PID_CPUSET 1130 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1131 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1132 depends on CPUSETS
1184 default y 1133 default y
1185 1134
1186 config CGROUP_DEVICE 1135 config CGROUP_DEVICE
1187 bool "Device controller" 1136 bool "Device controller"
1188 help 1137 help
1189 Provides a cgroup controller implem 1138 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1139 devices which a process in the cgroup can mknod or open.
1191 1140
1192 config CGROUP_CPUACCT 1141 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1142 bool "Simple CPU accounting controller"
1194 help 1143 help
1195 Provides a simple controller for mo 1144 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1145 total CPU consumed by the tasks in a cgroup.
1197 1146
1198 config CGROUP_PERF 1147 config CGROUP_PERF
1199 bool "Perf controller" 1148 bool "Perf controller"
1200 depends on PERF_EVENTS 1149 depends on PERF_EVENTS
1201 help 1150 help
1202 This option extends the perf per-cp 1151 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1152 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use 1153 designated cpu. Or this can be used to have cgroup ID in samples
1205 so that it can monitor performance 1154 so that it can monitor performance events among cgroups.
1206 1155
1207 Say N if unsure. 1156 Say N if unsure.
1208 1157
1209 config CGROUP_BPF 1158 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1159 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1160 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1161 select SOCK_CGROUP_DATA
1213 help 1162 help
1214 Allow attaching eBPF programs to a 1163 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1164 syscall command BPF_PROG_ATTACH.
1216 1165
1217 In which context these programs are 1166 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1167 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1168 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1169 inet sockets.
1221 1170
1222 config CGROUP_MISC 1171 config CGROUP_MISC
1223 bool "Misc resource controller" 1172 bool "Misc resource controller"
1224 default n 1173 default n
1225 help 1174 help
1226 Provides a controller for miscellan 1175 Provides a controller for miscellaneous resources on a host.
1227 1176
1228 Miscellaneous scalar resources are 1177 Miscellaneous scalar resources are the resources on the host system
1229 which cannot be abstracted like the 1178 which cannot be abstracted like the other cgroups. This controller
1230 tracks and limits the miscellaneous 1179 tracks and limits the miscellaneous resources used by a process
1231 attached to a cgroup hierarchy. 1180 attached to a cgroup hierarchy.
1232 1181
1233 For more information, please check 1182 For more information, please check misc cgroup section in
1234 /Documentation/admin-guide/cgroup-v 1183 /Documentation/admin-guide/cgroup-v2.rst.
1235 1184
1236 config CGROUP_DEBUG 1185 config CGROUP_DEBUG
1237 bool "Debug controller" 1186 bool "Debug controller"
1238 default n 1187 default n
1239 depends on DEBUG_KERNEL 1188 depends on DEBUG_KERNEL
1240 help 1189 help
1241 This option enables a simple contro 1190 This option enables a simple controller that exports
1242 debugging information about the cgr 1191 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1192 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1193 interfaces are not stable.
1245 1194
1246 Say N. 1195 Say N.
1247 1196
1248 config SOCK_CGROUP_DATA 1197 config SOCK_CGROUP_DATA
1249 bool 1198 bool
1250 default n 1199 default n
1251 1200
1252 endif # CGROUPS 1201 endif # CGROUPS
1253 1202
1254 menuconfig NAMESPACES 1203 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1204 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1205 depends on MULTIUSER
1257 default !EXPERT 1206 default !EXPERT
1258 help 1207 help
1259 Provides the way to make tasks work 1208 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1209 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1210 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1211 different namespaces.
1263 1212
1264 if NAMESPACES 1213 if NAMESPACES
1265 1214
1266 config UTS_NS 1215 config UTS_NS
1267 bool "UTS namespace" 1216 bool "UTS namespace"
1268 default y 1217 default y
1269 help 1218 help
1270 In this namespace tasks see differe 1219 In this namespace tasks see different info provided with the
1271 uname() system call 1220 uname() system call
1272 1221
1273 config TIME_NS 1222 config TIME_NS
1274 bool "TIME namespace" 1223 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1224 depends on GENERIC_VDSO_TIME_NS
1276 default y 1225 default y
1277 help 1226 help
1278 In this namespace boottime and mono 1227 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1228 The time will keep going with the same pace.
1280 1229
1281 config IPC_NS 1230 config IPC_NS
1282 bool "IPC namespace" 1231 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1232 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1233 default y
1285 help 1234 help
1286 In this namespace tasks work with I 1235 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1236 different IPC objects in different namespaces.
1288 1237
1289 config USER_NS 1238 config USER_NS
1290 bool "User namespace" 1239 bool "User namespace"
1291 default n 1240 default n
1292 help 1241 help
1293 This allows containers, i.e. vserve 1242 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1243 to provide different user info for different servers.
1295 1244
1296 When user namespaces are enabled in 1245 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1246 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1247 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1248 of memory a memory unprivileged users can use.
1300 1249
1301 If unsure, say N. 1250 If unsure, say N.
1302 1251
1303 config PID_NS 1252 config PID_NS
1304 bool "PID Namespaces" 1253 bool "PID Namespaces"
1305 default y 1254 default y
1306 help 1255 help
1307 Support process id namespaces. Thi 1256 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1257 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1258 pid namespaces. This is a building block of containers.
1310 1259
1311 config NET_NS 1260 config NET_NS
1312 bool "Network namespace" 1261 bool "Network namespace"
1313 depends on NET 1262 depends on NET
1314 default y 1263 default y
1315 help 1264 help
1316 Allow user space to create what app 1265 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1266 of the network stack.
1318 1267
1319 endif # NAMESPACES 1268 endif # NAMESPACES
1320 1269
1321 config CHECKPOINT_RESTORE 1270 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1271 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1272 select PROC_CHILDREN
1325 select KCMP 1273 select KCMP
1326 default n 1274 default n
1327 help 1275 help
1328 Enables additional kernel features 1276 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1277 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1278 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1279 entries.
1332 1280
1333 If unsure, say N here. 1281 If unsure, say N here.
1334 1282
1335 config SCHED_AUTOGROUP 1283 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1284 bool "Automatic process group scheduling"
1337 select CGROUPS 1285 select CGROUPS
1338 select CGROUP_SCHED 1286 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1287 select FAIR_GROUP_SCHED
1340 help 1288 help
1341 This option optimizes the scheduler 1289 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1290 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1291 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1292 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1293 upon task session.
1346 1294
>> 1295 config SYSFS_DEPRECATED
>> 1296 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1297 depends on SYSFS
>> 1298 default n
>> 1299 help
>> 1300 This option adds code that switches the layout of the "block" class
>> 1301 devices, to not show up in /sys/class/block/, but only in
>> 1302 /sys/block/.
>> 1303
>> 1304 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1305 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1306
>> 1307 This option allows new kernels to run on old distributions and tools,
>> 1308 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1309 major distributions and tools handle this just fine.
>> 1310
>> 1311 Recent distributions and userspace tools after 2009/2010 depend on
>> 1312 the existence of /sys/class/block/, and will not work with this
>> 1313 option enabled.
>> 1314
>> 1315 Only if you are using a new kernel on an old distribution, you might
>> 1316 need to say Y here.
>> 1317
>> 1318 config SYSFS_DEPRECATED_V2
>> 1319 bool "Enable deprecated sysfs features by default"
>> 1320 default n
>> 1321 depends on SYSFS
>> 1322 depends on SYSFS_DEPRECATED
>> 1323 help
>> 1324 Enable deprecated sysfs by default.
>> 1325
>> 1326 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1327 option.
>> 1328
>> 1329 Only if you are using a new kernel on an old distribution, you might
>> 1330 need to say Y here. Even then, odds are you would not need it
>> 1331 enabled, you can always pass the boot option if absolutely necessary.
>> 1332
1347 config RELAY 1333 config RELAY
1348 bool "Kernel->user space relay suppor 1334 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1335 select IRQ_WORK
1350 help 1336 help
1351 This option enables support for rel 1337 This option enables support for relay interface support in
1352 certain file systems (such as debug 1338 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1339 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1340 facilities to relay large amounts of data from kernel space to
1355 user space. 1341 user space.
1356 1342
1357 If unsure, say N. 1343 If unsure, say N.
1358 1344
1359 config BLK_DEV_INITRD 1345 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1346 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1347 help
1362 The initial RAM filesystem is a ram 1348 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1349 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1350 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1351 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1352 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1353
1368 If RAM disk support (BLK_DEV_RAM) i 1354 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1355 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1356 15 Kbytes (more on some other architectures) to the kernel size.
1371 1357
1372 If unsure say Y. 1358 If unsure say Y.
1373 1359
1374 if BLK_DEV_INITRD 1360 if BLK_DEV_INITRD
1375 1361
1376 source "usr/Kconfig" 1362 source "usr/Kconfig"
1377 1363
1378 endif 1364 endif
1379 1365
1380 config BOOT_CONFIG 1366 config BOOT_CONFIG
1381 bool "Boot config support" 1367 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG !! 1368 select BLK_DEV_INITRD
1383 help 1369 help
1384 Extra boot config allows system adm 1370 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1371 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1372 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1373 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1374 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1375
1390 If unsure, say Y. 1376 If unsure, say Y.
1391 1377
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 1378 choice
1435 prompt "Compiler optimization level" 1379 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1380 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1381
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1382 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1383 bool "Optimize for performance (-O2)"
1440 help 1384 help
1441 This is the default optimization le 1385 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1386 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1387 helpful compile-time warnings.
1444 1388
>> 1389 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1390 bool "Optimize more for performance (-O3)"
>> 1391 depends on ARC
>> 1392 help
>> 1393 Choosing this option will pass "-O3" to your compiler to optimize
>> 1394 the kernel yet more for performance.
>> 1395
1445 config CC_OPTIMIZE_FOR_SIZE 1396 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1397 bool "Optimize for size (-Os)"
1447 help 1398 help
1448 Choosing this option will pass "-Os 1399 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1400 in a smaller kernel.
1450 1401
1451 endchoice 1402 endchoice
1452 1403
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1404 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1405 bool
1455 help 1406 help
1456 This requires that the arch annotat 1407 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1408 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1409 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1410 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1411 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1412 is used to distinguish them from label names / C identifiers.
1462 1413
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1414 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1415 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1416 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1417 depends on EXPERT
1467 depends on $(cc-option,-ffunction-sec 1418 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1419 depends on $(ld-option,--gc-sections)
1469 help 1420 help
1470 Enable this if you want to do dead 1421 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1422 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1423 and linking with --gc-sections.
1473 1424
1474 This can reduce on disk and in-memo 1425 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1426 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1427 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1428 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1429 present. This option is not well tested yet, so use at your
1479 own risk. 1430 own risk.
1480 1431
1481 config LD_ORPHAN_WARN 1432 config LD_ORPHAN_WARN
1482 def_bool y 1433 def_bool y
1483 depends on ARCH_WANT_LD_ORPHAN_WARN 1434 depends on ARCH_WANT_LD_ORPHAN_WARN
1484 depends on $(ld-option,--orphan-handl 1435 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 1436
1493 config SYSCTL 1437 config SYSCTL
1494 bool 1438 bool
1495 1439
1496 config HAVE_UID16 1440 config HAVE_UID16
1497 bool 1441 bool
1498 1442
1499 config SYSCTL_EXCEPTION_TRACE 1443 config SYSCTL_EXCEPTION_TRACE
1500 bool 1444 bool
1501 help 1445 help
1502 Enable support for /proc/sys/debug/ 1446 Enable support for /proc/sys/debug/exception-trace.
1503 1447
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1448 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1449 bool
1506 help 1450 help
1507 Enable support for /proc/sys/kernel 1451 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1452 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1453 about unaligned access emulation going on under the hood.
1510 1454
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1455 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1456 bool
1513 help 1457 help
1514 Enable support for /proc/sys/kernel 1458 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1459 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1460 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1461 see arch/parisc/kernel/unaligned.c for reference
1518 1462
1519 config HAVE_PCSPKR_PLATFORM 1463 config HAVE_PCSPKR_PLATFORM
1520 bool 1464 bool
1521 1465
>> 1466 # interpreter that classic socket filters depend on
>> 1467 config BPF
>> 1468 bool
>> 1469
1522 menuconfig EXPERT 1470 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1471 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1472 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1473 select DEBUG_KERNEL
1526 help 1474 help
1527 This option allows certain base ker 1475 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1476 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1477 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1478 Only use this if you really know what you are doing.
1531 1479
1532 config UID16 1480 config UID16
1533 bool "Enable 16-bit UID system calls" 1481 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1482 depends on HAVE_UID16 && MULTIUSER
1535 default y 1483 default y
1536 help 1484 help
1537 This enables the legacy 16-bit UID 1485 This enables the legacy 16-bit UID syscall wrappers.
1538 1486
1539 config MULTIUSER 1487 config MULTIUSER
1540 bool "Multiple users, groups and capa 1488 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1489 default y
1542 help 1490 help
1543 This option enables support for non 1491 This option enables support for non-root users, groups and
1544 capabilities. 1492 capabilities.
1545 1493
1546 If you say N here, all processes wi 1494 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1495 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1496 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1497 setgid, and capset.
1550 1498
1551 If unsure, say Y here. 1499 If unsure, say Y here.
1552 1500
1553 config SGETMASK_SYSCALL 1501 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1502 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1503 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help 1504 help
1557 sys_sgetmask and sys_ssetmask are o 1505 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1506 no longer supported in libc but still enabled by default in some
1559 architectures. 1507 architectures.
1560 1508
1561 If unsure, leave the default option 1509 If unsure, leave the default option here.
1562 1510
1563 config SYSFS_SYSCALL 1511 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1512 bool "Sysfs syscall support" if EXPERT
1565 default y 1513 default y
1566 help 1514 help
1567 sys_sysfs is an obsolete system cal 1515 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1516 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1517 compatibility with some systems.
1570 1518
1571 If unsure say Y here. 1519 If unsure say Y here.
1572 1520
1573 config FHANDLE 1521 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1522 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1523 select EXPORTFS
1576 default y 1524 default y
1577 help 1525 help
1578 If you say Y here, a user level pro 1526 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1527 file names to handle and then later use the handle for
1580 different file system operations. T 1528 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1529 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1530 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1531 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1532 syscalls.
1585 1533
1586 config POSIX_TIMERS 1534 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1535 bool "Posix Clocks & timers" if EXPERT
1588 default y 1536 default y
1589 help 1537 help
1590 This includes native support for PO 1538 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1539 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1540 can be configured out to reduce the size of the kernel image.
1593 1541
1594 When this option is disabled, the f 1542 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1543 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1544 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1545 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1546 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1547 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1548
1601 If unsure say y. 1549 If unsure say y.
1602 1550
1603 config PRINTK 1551 config PRINTK
1604 default y 1552 default y
1605 bool "Enable support for printk" if E 1553 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1554 select IRQ_WORK
1607 help 1555 help
1608 This option enables normal printk s 1556 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1557 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1558 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1559 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1560 strongly discouraged.
1613 1561
1614 config BUG 1562 config BUG
1615 bool "BUG() support" if EXPERT 1563 bool "BUG() support" if EXPERT
1616 default y 1564 default y
1617 help 1565 help
1618 Disabling this option eliminates su 1566 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1567 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1568 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1569 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1570 Just say Y.
1623 1571
1624 config ELF_CORE 1572 config ELF_CORE
1625 depends on COREDUMP 1573 depends on COREDUMP
1626 default y 1574 default y
1627 bool "Enable ELF core dumps" if EXPER 1575 bool "Enable ELF core dumps" if EXPERT
1628 help 1576 help
1629 Enable support for generating core 1577 Enable support for generating core dumps. Disabling saves about 4k.
1630 1578
1631 1579
1632 config PCSPKR_PLATFORM 1580 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1581 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1582 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1583 select I8253_LOCK
1636 default y 1584 default y
1637 help 1585 help
1638 This option allows to disable the i 1586 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1587 support, saving some memory.
1640 1588
1641 config BASE_SMALL !! 1589 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1590 default y
>> 1591 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1592 help
1644 Enabling this option reduces the si !! 1593 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1594 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1595 but may reduce performance.
1647 1596
1648 config FUTEX 1597 config FUTEX
1649 bool "Enable futex support" if EXPERT 1598 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) 1599 depends on !(SPARC32 && SMP)
1651 default y 1600 default y
1652 imply RT_MUTEXES 1601 imply RT_MUTEXES
1653 help 1602 help
1654 Disabling this option will cause th 1603 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1604 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1605 run glibc-based applications correctly.
1657 1606
1658 config FUTEX_PI 1607 config FUTEX_PI
1659 bool 1608 bool
1660 depends on FUTEX && RT_MUTEXES 1609 depends on FUTEX && RT_MUTEXES
1661 default y 1610 default y
1662 1611
1663 config EPOLL 1612 config EPOLL
1664 bool "Enable eventpoll support" if EX 1613 bool "Enable eventpoll support" if EXPERT
1665 default y 1614 default y
1666 help 1615 help
1667 Disabling this option will cause th 1616 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1617 support for epoll family of system calls.
1669 1618
1670 config SIGNALFD 1619 config SIGNALFD
1671 bool "Enable signalfd() system call" 1620 bool "Enable signalfd() system call" if EXPERT
1672 default y 1621 default y
1673 help 1622 help
1674 Enable the signalfd() system call t 1623 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1624 on a file descriptor.
1676 1625
1677 If unsure, say Y. 1626 If unsure, say Y.
1678 1627
1679 config TIMERFD 1628 config TIMERFD
1680 bool "Enable timerfd() system call" i 1629 bool "Enable timerfd() system call" if EXPERT
1681 default y 1630 default y
1682 help 1631 help
1683 Enable the timerfd() system call th 1632 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1633 events on a file descriptor.
1685 1634
1686 If unsure, say Y. 1635 If unsure, say Y.
1687 1636
1688 config EVENTFD 1637 config EVENTFD
1689 bool "Enable eventfd() system call" i 1638 bool "Enable eventfd() system call" if EXPERT
1690 default y 1639 default y
1691 help 1640 help
1692 Enable the eventfd() system call th 1641 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1642 kernel notification (ie. KAIO) or userspace notifications.
1694 1643
1695 If unsure, say Y. 1644 If unsure, say Y.
1696 1645
1697 config SHMEM 1646 config SHMEM
1698 bool "Use full shmem filesystem" if E 1647 bool "Use full shmem filesystem" if EXPERT
1699 default y 1648 default y
1700 depends on MMU 1649 depends on MMU
1701 help 1650 help
1702 The shmem is an internal filesystem 1651 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1652 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1653 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1654 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1655 which may be appropriate on small systems without swap.
1707 1656
1708 config AIO 1657 config AIO
1709 bool "Enable AIO support" if EXPERT 1658 bool "Enable AIO support" if EXPERT
1710 default y 1659 default y
1711 help 1660 help
1712 This option enables POSIX asynchron 1661 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1662 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1663 this option saves about 7k.
1715 1664
1716 config IO_URING 1665 config IO_URING
1717 bool "Enable IO uring support" if EXP 1666 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ 1667 select IO_WQ
1719 default y 1668 default y
1720 help 1669 help
1721 This option enables support for the 1670 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1671 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1672 completion rings that are shared between the kernel and application.
1724 1673
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 1674 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1675 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1676 default y
1741 help 1677 help
1742 This option enables the madvise and 1678 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1679 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1680 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1681 applications use these syscalls, you can disable this option to save
1746 space. 1682 space.
1747 1683
>> 1684 config HAVE_ARCH_USERFAULTFD_WP
>> 1685 bool
>> 1686 help
>> 1687 Arch has userfaultfd write protection support
>> 1688
>> 1689 config HAVE_ARCH_USERFAULTFD_MINOR
>> 1690 bool
>> 1691 help
>> 1692 Arch has userfaultfd minor fault support
>> 1693
1748 config MEMBARRIER 1694 config MEMBARRIER
1749 bool "Enable membarrier() system call 1695 bool "Enable membarrier() system call" if EXPERT
1750 default y 1696 default y
1751 help 1697 help
1752 Enable the membarrier() system call 1698 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1699 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1700 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1701 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1702 compiler barrier.
1757 1703
1758 If unsure, say Y. 1704 If unsure, say Y.
1759 1705
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 1706 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1707 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1708 default y
1813 help 1709 help
1814 Say Y here to let the kernel print 1710 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1711 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1712 somewhat, as all symbols have to be loaded into the kernel image.
1817 1713
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 1714 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1715 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1716 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1717 help
1835 Normally kallsyms only contains the 1718 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1719 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m !! 1720 sections). This is sufficient for most cases. And only in very rare
1838 enable kernel live patching, or oth !! 1721 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1839 when a debugger is used) all symbol !! 1722 names of variables from the data sections, etc).
1840 variables from the data sections, e <<
1841 1723
1842 This option makes sure that all sym 1724 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1725 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1726 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1727 something like this).
1846 1728
1847 Say N unless you really need all sy !! 1729 Say N unless you really need all symbols.
1848 1730
1849 config KALLSYMS_ABSOLUTE_PERCPU 1731 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1732 bool
1851 depends on KALLSYMS 1733 depends on KALLSYMS
1852 default X86_64 && SMP 1734 default X86_64 && SMP
1853 1735
>> 1736 config KALLSYMS_BASE_RELATIVE
>> 1737 bool
>> 1738 depends on KALLSYMS
>> 1739 default !IA64
>> 1740 help
>> 1741 Instead of emitting them as absolute values in the native word size,
>> 1742 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1743 each containing a relative value in the range [base, base + U32_MAX]
>> 1744 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1745 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1746 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1747 address encountered in the image.
>> 1748
>> 1749 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1750 but more importantly, it results in entries whose values are build
>> 1751 time constants, and no relocation pass is required at runtime to fix
>> 1752 up the entries based on the runtime load address of the kernel.
>> 1753
1854 # end of the "standard kernel features (exper 1754 # end of the "standard kernel features (expert users)" menu
1855 1755
>> 1756 # syscall, maps, verifier
>> 1757
>> 1758 config USERFAULTFD
>> 1759 bool "Enable userfaultfd() system call"
>> 1760 depends on MMU
>> 1761 help
>> 1762 Enable the userfaultfd() system call that allows to intercept and
>> 1763 handle page faults in userland.
>> 1764
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1765 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1766 bool
1858 1767
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1768 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1769 bool
1861 1770
>> 1771 config KCMP
>> 1772 bool "Enable kcmp() system call" if EXPERT
>> 1773 help
>> 1774 Enable the kernel resource comparison system call. It provides
>> 1775 user-space with the ability to compare two processes to see if they
>> 1776 share a common resource, such as a file descriptor or even virtual
>> 1777 memory space.
>> 1778
>> 1779 If unsure, say N.
>> 1780
>> 1781 config RSEQ
>> 1782 bool "Enable rseq() system call" if EXPERT
>> 1783 default y
>> 1784 depends on HAVE_RSEQ
>> 1785 select MEMBARRIER
>> 1786 help
>> 1787 Enable the restartable sequences system call. It provides a
>> 1788 user-space cache for the current CPU number value, which
>> 1789 speeds up getting the current CPU number from user-space,
>> 1790 as well as an ABI to speed up user-space operations on
>> 1791 per-CPU data.
>> 1792
>> 1793 If unsure, say Y.
>> 1794
>> 1795 config DEBUG_RSEQ
>> 1796 default n
>> 1797 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1798 depends on RSEQ && DEBUG_KERNEL
>> 1799 help
>> 1800 Enable extra debugging checks for the rseq system call.
>> 1801
>> 1802 If unsure, say N.
>> 1803
>> 1804 config EMBEDDED
>> 1805 bool "Embedded system"
>> 1806 select EXPERT
>> 1807 help
>> 1808 This option should be enabled if compiling the kernel for
>> 1809 an embedded system so certain expert options are available
>> 1810 for configuration.
>> 1811
1862 config HAVE_PERF_EVENTS 1812 config HAVE_PERF_EVENTS
1863 bool 1813 bool
1864 help 1814 help
1865 See tools/perf/design.txt for detai 1815 See tools/perf/design.txt for details.
1866 1816
1867 config GUEST_PERF_EVENTS 1817 config GUEST_PERF_EVENTS
1868 bool 1818 bool
1869 depends on HAVE_PERF_EVENTS 1819 depends on HAVE_PERF_EVENTS
1870 1820
1871 config PERF_USE_VMALLOC 1821 config PERF_USE_VMALLOC
1872 bool 1822 bool
1873 help 1823 help
1874 See tools/perf/design.txt for detai 1824 See tools/perf/design.txt for details
1875 1825
>> 1826 config PC104
>> 1827 bool "PC/104 support" if EXPERT
>> 1828 help
>> 1829 Expose PC/104 form factor device drivers and options available for
>> 1830 selection and configuration. Enable this option if your target
>> 1831 machine has a PC/104 bus.
>> 1832
1876 menu "Kernel Performance Events And Counters" 1833 menu "Kernel Performance Events And Counters"
1877 1834
1878 config PERF_EVENTS 1835 config PERF_EVENTS
1879 bool "Kernel performance events and c 1836 bool "Kernel performance events and counters"
1880 default y if PROFILING 1837 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1838 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1839 select IRQ_WORK
>> 1840 select SRCU
1883 help 1841 help
1884 Enable kernel support for various p 1842 Enable kernel support for various performance events provided
1885 by software and hardware. 1843 by software and hardware.
1886 1844
1887 Software events are supported eithe 1845 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1846 use of generic tracepoints.
1889 1847
1890 Most modern CPUs support performanc 1848 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1849 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1850 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1851 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1852 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1853 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1854 used to profile the code that runs on that CPU.
1897 1855
1898 The Linux Performance Event subsyst 1856 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1857 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1858 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1859 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1860 capabilities on top of those.
1903 1861
1904 Say Y if unsure. 1862 Say Y if unsure.
1905 1863
1906 config DEBUG_PERF_USE_VMALLOC 1864 config DEBUG_PERF_USE_VMALLOC
1907 default n 1865 default n
1908 bool "Debug: use vmalloc to back perf 1866 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1867 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1868 select PERF_USE_VMALLOC
1911 help 1869 help
1912 Use vmalloc memory to back perf mma 1870 Use vmalloc memory to back perf mmap() buffers.
1913 1871
1914 Mostly useful for debugging the vma 1872 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1873 that don't require it.
1916 1874
1917 Say N if unsure. 1875 Say N if unsure.
1918 1876
1919 endmenu 1877 endmenu
1920 1878
>> 1879 config VM_EVENT_COUNTERS
>> 1880 default y
>> 1881 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1882 help
>> 1883 VM event counters are needed for event counts to be shown.
>> 1884 This option allows the disabling of the VM event counters
>> 1885 on EXPERT systems. /proc/vmstat will only show page counts
>> 1886 if VM event counters are disabled.
>> 1887
>> 1888 config SLUB_DEBUG
>> 1889 default y
>> 1890 bool "Enable SLUB debugging support" if EXPERT
>> 1891 depends on SLUB && SYSFS
>> 1892 help
>> 1893 SLUB has extensive debug support features. Disabling these can
>> 1894 result in significant savings in code size. This also disables
>> 1895 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1896 no support for cache validation etc.
>> 1897
>> 1898 config COMPAT_BRK
>> 1899 bool "Disable heap randomization"
>> 1900 default y
>> 1901 help
>> 1902 Randomizing heap placement makes heap exploits harder, but it
>> 1903 also breaks ancient binaries (including anything libc5 based).
>> 1904 This option changes the bootup default to heap randomization
>> 1905 disabled, and can be overridden at runtime by setting
>> 1906 /proc/sys/kernel/randomize_va_space to 2.
>> 1907
>> 1908 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1909
>> 1910 choice
>> 1911 prompt "Choose SLAB allocator"
>> 1912 default SLUB
>> 1913 help
>> 1914 This option allows to select a slab allocator.
>> 1915
>> 1916 config SLAB
>> 1917 bool "SLAB"
>> 1918 depends on !PREEMPT_RT
>> 1919 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1920 help
>> 1921 The regular slab allocator that is established and known to work
>> 1922 well in all environments. It organizes cache hot objects in
>> 1923 per cpu and per node queues.
>> 1924
>> 1925 config SLUB
>> 1926 bool "SLUB (Unqueued Allocator)"
>> 1927 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1928 help
>> 1929 SLUB is a slab allocator that minimizes cache line usage
>> 1930 instead of managing queues of cached objects (SLAB approach).
>> 1931 Per cpu caching is realized using slabs of objects instead
>> 1932 of queues of objects. SLUB can use memory efficiently
>> 1933 and has enhanced diagnostics. SLUB is the default choice for
>> 1934 a slab allocator.
>> 1935
>> 1936 config SLOB
>> 1937 depends on EXPERT
>> 1938 bool "SLOB (Simple Allocator)"
>> 1939 depends on !PREEMPT_RT
>> 1940 help
>> 1941 SLOB replaces the stock allocator with a drastically simpler
>> 1942 allocator. SLOB is generally more space efficient but
>> 1943 does not perform as well on large systems.
>> 1944
>> 1945 endchoice
>> 1946
>> 1947 config SLAB_MERGE_DEFAULT
>> 1948 bool "Allow slab caches to be merged"
>> 1949 default y
>> 1950 depends on SLAB || SLUB
>> 1951 help
>> 1952 For reduced kernel memory fragmentation, slab caches can be
>> 1953 merged when they share the same size and other characteristics.
>> 1954 This carries a risk of kernel heap overflows being able to
>> 1955 overwrite objects from merged caches (and more easily control
>> 1956 cache layout), which makes such heap attacks easier to exploit
>> 1957 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1958 can usually only damage objects in the same cache. To disable
>> 1959 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1960 command line.
>> 1961
>> 1962 config SLAB_FREELIST_RANDOM
>> 1963 bool "Randomize slab freelist"
>> 1964 depends on SLAB || SLUB
>> 1965 help
>> 1966 Randomizes the freelist order used on creating new pages. This
>> 1967 security feature reduces the predictability of the kernel slab
>> 1968 allocator against heap overflows.
>> 1969
>> 1970 config SLAB_FREELIST_HARDENED
>> 1971 bool "Harden slab freelist metadata"
>> 1972 depends on SLAB || SLUB
>> 1973 help
>> 1974 Many kernel heap attacks try to target slab cache metadata and
>> 1975 other infrastructure. This options makes minor performance
>> 1976 sacrifices to harden the kernel slab allocator against common
>> 1977 freelist exploit methods. Some slab implementations have more
>> 1978 sanity-checking than others. This option is most effective with
>> 1979 CONFIG_SLUB.
>> 1980
>> 1981 config SHUFFLE_PAGE_ALLOCATOR
>> 1982 bool "Page allocator randomization"
>> 1983 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1984 help
>> 1985 Randomization of the page allocator improves the average
>> 1986 utilization of a direct-mapped memory-side-cache. See section
>> 1987 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1988 6.2a specification for an example of how a platform advertises
>> 1989 the presence of a memory-side-cache. There are also incidental
>> 1990 security benefits as it reduces the predictability of page
>> 1991 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1992 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1993 10th order of pages is selected based on cache utilization
>> 1994 benefits on x86.
>> 1995
>> 1996 While the randomization improves cache utilization it may
>> 1997 negatively impact workloads on platforms without a cache. For
>> 1998 this reason, by default, the randomization is enabled only
>> 1999 after runtime detection of a direct-mapped memory-side-cache.
>> 2000 Otherwise, the randomization may be force enabled with the
>> 2001 'page_alloc.shuffle' kernel command line parameter.
>> 2002
>> 2003 Say Y if unsure.
>> 2004
>> 2005 config SLUB_CPU_PARTIAL
>> 2006 default y
>> 2007 depends on SLUB && SMP
>> 2008 bool "SLUB per cpu partial cache"
>> 2009 help
>> 2010 Per cpu partial caches accelerate objects allocation and freeing
>> 2011 that is local to a processor at the price of more indeterminism
>> 2012 in the latency of the free. On overflow these caches will be cleared
>> 2013 which requires the taking of locks that may cause latency spikes.
>> 2014 Typically one would choose no for a realtime system.
>> 2015
>> 2016 config MMAP_ALLOW_UNINITIALIZED
>> 2017 bool "Allow mmapped anonymous memory to be uninitialized"
>> 2018 depends on EXPERT && !MMU
>> 2019 default n
>> 2020 help
>> 2021 Normally, and according to the Linux spec, anonymous memory obtained
>> 2022 from mmap() has its contents cleared before it is passed to
>> 2023 userspace. Enabling this config option allows you to request that
>> 2024 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 2025 providing a huge performance boost. If this option is not enabled,
>> 2026 then the flag will be ignored.
>> 2027
>> 2028 This is taken advantage of by uClibc's malloc(), and also by
>> 2029 ELF-FDPIC binfmt's brk and stack allocator.
>> 2030
>> 2031 Because of the obvious security issues, this option should only be
>> 2032 enabled on embedded devices where you control what is run in
>> 2033 userspace. Since that isn't generally a problem on no-MMU systems,
>> 2034 it is normally safe to say Y here.
>> 2035
>> 2036 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
>> 2037
1921 config SYSTEM_DATA_VERIFICATION 2038 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 2039 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 2040 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 2041 select KEYS
1925 select CRYPTO 2042 select CRYPTO
1926 select CRYPTO_RSA 2043 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 2044 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2045 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 2046 select ASN1
1930 select OID_REGISTRY 2047 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 2048 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 2049 select PKCS7_MESSAGE_PARSER
1933 help 2050 help
1934 Provide PKCS#7 message verification 2051 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 2052 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 2053 module verification, kexec image verification and firmware blob
1937 verification. 2054 verification.
1938 2055
1939 config PROFILING 2056 config PROFILING
1940 bool "Profiling support" 2057 bool "Profiling support"
1941 help 2058 help
1942 Say Y here to enable the extended p 2059 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. 2060 by profilers.
1944 2061
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 # 2062 #
1987 # Place an empty function call at each tracep 2063 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 2064 # dynamically changed for a probe function.
1989 # 2065 #
1990 config TRACEPOINTS 2066 config TRACEPOINTS
1991 bool 2067 bool
1992 2068
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 2069 endmenu # General setup
1996 2070
1997 source "arch/Kconfig" 2071 source "arch/Kconfig"
1998 2072
1999 config RT_MUTEXES 2073 config RT_MUTEXES
2000 bool 2074 bool
2001 default y if PREEMPT_RT 2075 default y if PREEMPT_RT
2002 2076
>> 2077 config BASE_SMALL
>> 2078 int
>> 2079 default 0 if BASE_FULL
>> 2080 default 1 if !BASE_FULL
>> 2081
2003 config MODULE_SIG_FORMAT 2082 config MODULE_SIG_FORMAT
2004 def_bool n 2083 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 2084 select SYSTEM_DATA_VERIFICATION
2006 2085
2007 source "kernel/module/Kconfig" !! 2086 menuconfig MODULES
>> 2087 bool "Enable loadable module support"
>> 2088 modules
>> 2089 help
>> 2090 Kernel modules are small pieces of compiled code which can
>> 2091 be inserted in the running kernel, rather than being
>> 2092 permanently built into the kernel. You use the "modprobe"
>> 2093 tool to add (and sometimes remove) them. If you say Y here,
>> 2094 many parts of the kernel can be built as modules (by
>> 2095 answering M instead of Y where indicated): this is most
>> 2096 useful for infrequently used options which are not required
>> 2097 for booting. For more information, see the man pages for
>> 2098 modprobe, lsmod, modinfo, insmod and rmmod.
>> 2099
>> 2100 If you say Y here, you will need to run "make
>> 2101 modules_install" to put the modules under /lib/modules/
>> 2102 where modprobe can find them (you may need to be root to do
>> 2103 this).
>> 2104
>> 2105 If unsure, say Y.
>> 2106
>> 2107 if MODULES
>> 2108
>> 2109 config MODULE_FORCE_LOAD
>> 2110 bool "Forced module loading"
>> 2111 default n
>> 2112 help
>> 2113 Allow loading of modules without version information (ie. modprobe
>> 2114 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 2115 is usually a really bad idea.
>> 2116
>> 2117 config MODULE_UNLOAD
>> 2118 bool "Module unloading"
>> 2119 help
>> 2120 Without this option you will not be able to unload any
>> 2121 modules (note that some modules may not be unloadable
>> 2122 anyway), which makes your kernel smaller, faster
>> 2123 and simpler. If unsure, say Y.
>> 2124
>> 2125 config MODULE_FORCE_UNLOAD
>> 2126 bool "Forced module unloading"
>> 2127 depends on MODULE_UNLOAD
>> 2128 help
>> 2129 This option allows you to force a module to unload, even if the
>> 2130 kernel believes it is unsafe: the kernel will remove the module
>> 2131 without waiting for anyone to stop using it (using the -f option to
>> 2132 rmmod). This is mainly for kernel developers and desperate users.
>> 2133 If unsure, say N.
>> 2134
>> 2135 config MODVERSIONS
>> 2136 bool "Module versioning support"
>> 2137 help
>> 2138 Usually, you have to use modules compiled with your kernel.
>> 2139 Saying Y here makes it sometimes possible to use modules
>> 2140 compiled for different kernels, by adding enough information
>> 2141 to the modules to (hopefully) spot any changes which would
>> 2142 make them incompatible with the kernel you are running. If
>> 2143 unsure, say N.
>> 2144
>> 2145 config ASM_MODVERSIONS
>> 2146 bool
>> 2147 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 2148 help
>> 2149 This enables module versioning for exported symbols also from
>> 2150 assembly. This can be enabled only when the target architecture
>> 2151 supports it.
>> 2152
>> 2153 config MODULE_REL_CRCS
>> 2154 bool
>> 2155 depends on MODVERSIONS
>> 2156
>> 2157 config MODULE_SRCVERSION_ALL
>> 2158 bool "Source checksum for all modules"
>> 2159 help
>> 2160 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2161 field inserted into their modinfo section, which contains a
>> 2162 sum of the source files which made it. This helps maintainers
>> 2163 see exactly which source was used to build a module (since
>> 2164 others sometimes change the module source without updating
>> 2165 the version). With this option, such a "srcversion" field
>> 2166 will be created for all modules. If unsure, say N.
>> 2167
>> 2168 config MODULE_SIG
>> 2169 bool "Module signature verification"
>> 2170 select MODULE_SIG_FORMAT
>> 2171 help
>> 2172 Check modules for valid signatures upon load: the signature
>> 2173 is simply appended to the module. For more information see
>> 2174 <file:Documentation/admin-guide/module-signing.rst>.
>> 2175
>> 2176 Note that this option adds the OpenSSL development packages as a
>> 2177 kernel build dependency so that the signing tool can use its crypto
>> 2178 library.
>> 2179
>> 2180 You should enable this option if you wish to use either
>> 2181 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2182 another LSM - otherwise unsigned modules will be loadable regardless
>> 2183 of the lockdown policy.
>> 2184
>> 2185 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2186 module DOES NOT get stripped after being signed. This includes the
>> 2187 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2188 inclusion into an initramfs that wants the module size reduced.
>> 2189
>> 2190 config MODULE_SIG_FORCE
>> 2191 bool "Require modules to be validly signed"
>> 2192 depends on MODULE_SIG
>> 2193 help
>> 2194 Reject unsigned modules or signed modules for which we don't have a
>> 2195 key. Without this, such modules will simply taint the kernel.
>> 2196
>> 2197 config MODULE_SIG_ALL
>> 2198 bool "Automatically sign all modules"
>> 2199 default y
>> 2200 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2201 help
>> 2202 Sign all modules during make modules_install. Without this option,
>> 2203 modules must be signed manually, using the scripts/sign-file tool.
>> 2204
>> 2205 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2206 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2207
>> 2208 choice
>> 2209 prompt "Which hash algorithm should modules be signed with?"
>> 2210 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2211 help
>> 2212 This determines which sort of hashing algorithm will be used during
>> 2213 signature generation. This algorithm _must_ be built into the kernel
>> 2214 directly so that signature verification can take place. It is not
>> 2215 possible to load a signed module containing the algorithm to check
>> 2216 the signature on that module.
>> 2217
>> 2218 config MODULE_SIG_SHA1
>> 2219 bool "Sign modules with SHA-1"
>> 2220 select CRYPTO_SHA1
>> 2221
>> 2222 config MODULE_SIG_SHA224
>> 2223 bool "Sign modules with SHA-224"
>> 2224 select CRYPTO_SHA256
>> 2225
>> 2226 config MODULE_SIG_SHA256
>> 2227 bool "Sign modules with SHA-256"
>> 2228 select CRYPTO_SHA256
>> 2229
>> 2230 config MODULE_SIG_SHA384
>> 2231 bool "Sign modules with SHA-384"
>> 2232 select CRYPTO_SHA512
>> 2233
>> 2234 config MODULE_SIG_SHA512
>> 2235 bool "Sign modules with SHA-512"
>> 2236 select CRYPTO_SHA512
>> 2237
>> 2238 endchoice
>> 2239
>> 2240 config MODULE_SIG_HASH
>> 2241 string
>> 2242 depends on MODULE_SIG || IMA_APPRAISE_MODSIG
>> 2243 default "sha1" if MODULE_SIG_SHA1
>> 2244 default "sha224" if MODULE_SIG_SHA224
>> 2245 default "sha256" if MODULE_SIG_SHA256
>> 2246 default "sha384" if MODULE_SIG_SHA384
>> 2247 default "sha512" if MODULE_SIG_SHA512
>> 2248
>> 2249 choice
>> 2250 prompt "Module compression mode"
>> 2251 help
>> 2252 This option allows you to choose the algorithm which will be used to
>> 2253 compress modules when 'make modules_install' is run. (or, you can
>> 2254 choose to not compress modules at all.)
>> 2255
>> 2256 External modules will also be compressed in the same way during the
>> 2257 installation.
>> 2258
>> 2259 For modules inside an initrd or initramfs, it's more efficient to
>> 2260 compress the whole initrd or initramfs instead.
>> 2261
>> 2262 This is fully compatible with signed modules.
>> 2263
>> 2264 Please note that the tool used to load modules needs to support the
>> 2265 corresponding algorithm. module-init-tools MAY support gzip, and kmod
>> 2266 MAY support gzip, xz and zstd.
>> 2267
>> 2268 Your build system needs to provide the appropriate compression tool
>> 2269 to compress the modules.
>> 2270
>> 2271 If in doubt, select 'None'.
>> 2272
>> 2273 config MODULE_COMPRESS_NONE
>> 2274 bool "None"
>> 2275 help
>> 2276 Do not compress modules. The installed modules are suffixed
>> 2277 with .ko.
>> 2278
>> 2279 config MODULE_COMPRESS_GZIP
>> 2280 bool "GZIP"
>> 2281 help
>> 2282 Compress modules with GZIP. The installed modules are suffixed
>> 2283 with .ko.gz.
>> 2284
>> 2285 config MODULE_COMPRESS_XZ
>> 2286 bool "XZ"
>> 2287 help
>> 2288 Compress modules with XZ. The installed modules are suffixed
>> 2289 with .ko.xz.
>> 2290
>> 2291 config MODULE_COMPRESS_ZSTD
>> 2292 bool "ZSTD"
>> 2293 help
>> 2294 Compress modules with ZSTD. The installed modules are suffixed
>> 2295 with .ko.zst.
>> 2296
>> 2297 endchoice
>> 2298
>> 2299 config MODULE_DECOMPRESS
>> 2300 bool "Support in-kernel module decompression"
>> 2301 depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ
>> 2302 select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
>> 2303 select XZ_DEC if MODULE_COMPRESS_XZ
>> 2304 help
>> 2305
>> 2306 Support for decompressing kernel modules by the kernel itself
>> 2307 instead of relying on userspace to perform this task. Useful when
>> 2308 load pinning security policy is enabled.
>> 2309
>> 2310 If unsure, say N.
>> 2311
>> 2312 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2313 bool "Allow loading of modules with missing namespace imports"
>> 2314 help
>> 2315 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2316 a namespace. A module that makes use of a symbol exported with such a
>> 2317 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2318 There is no technical reason to enforce correct namespace imports,
>> 2319 but it creates consistency between symbols defining namespaces and
>> 2320 users importing namespaces they make use of. This option relaxes this
>> 2321 requirement and lifts the enforcement when loading a module.
>> 2322
>> 2323 If unsure, say N.
>> 2324
>> 2325 config MODPROBE_PATH
>> 2326 string "Path to modprobe binary"
>> 2327 default "/sbin/modprobe"
>> 2328 help
>> 2329 When kernel code requests a module, it does so by calling
>> 2330 the "modprobe" userspace utility. This option allows you to
>> 2331 set the path where that binary is found. This can be changed
>> 2332 at runtime via the sysctl file
>> 2333 /proc/sys/kernel/modprobe. Setting this to the empty string
>> 2334 removes the kernel's ability to request modules (but
>> 2335 userspace can still load modules explicitly).
>> 2336
>> 2337 config TRIM_UNUSED_KSYMS
>> 2338 bool "Trim unused exported kernel symbols" if EXPERT
>> 2339 depends on !COMPILE_TEST
>> 2340 help
>> 2341 The kernel and some modules make many symbols available for
>> 2342 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2343 on the set of modules being selected in your kernel configuration,
>> 2344 many of those exported symbols might never be used.
>> 2345
>> 2346 This option allows for unused exported symbols to be dropped from
>> 2347 the build. In turn, this provides the compiler more opportunities
>> 2348 (especially when using LTO) for optimizing the code and reducing
>> 2349 binary size. This might have some security advantages as well.
>> 2350
>> 2351 If unsure, or if you need to build out-of-tree modules, say N.
>> 2352
>> 2353 config UNUSED_KSYMS_WHITELIST
>> 2354 string "Whitelist of symbols to keep in ksymtab"
>> 2355 depends on TRIM_UNUSED_KSYMS
>> 2356 help
>> 2357 By default, all unused exported symbols will be un-exported from the
>> 2358 build when TRIM_UNUSED_KSYMS is selected.
>> 2359
>> 2360 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
>> 2361 exported at all times, even in absence of in-tree users. The value to
>> 2362 set here is the path to a text file containing the list of symbols,
>> 2363 one per line. The path can be absolute, or relative to the kernel
>> 2364 source tree.
>> 2365
>> 2366 endif # MODULES
>> 2367
>> 2368 config MODULES_TREE_LOOKUP
>> 2369 def_bool y
>> 2370 depends on PERF_EVENTS || TRACING || CFI_CLANG
2008 2371
2009 config INIT_ALL_POSSIBLE 2372 config INIT_ALL_POSSIBLE
2010 bool 2373 bool
2011 help 2374 help
2012 Back when each arch used to define 2375 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2376 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2377 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2378 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2379 and have several arch maintainers pursuing me down dark alleys.
2017 2380
2018 source "block/Kconfig" 2381 source "block/Kconfig"
2019 2382
2020 config PREEMPT_NOTIFIERS 2383 config PREEMPT_NOTIFIERS
2021 bool 2384 bool
2022 2385
2023 config PADATA 2386 config PADATA
2024 depends on SMP 2387 depends on SMP
2025 bool 2388 bool
2026 2389
2027 config ASN1 2390 config ASN1
2028 tristate 2391 tristate
2029 help 2392 help
2030 Build a simple ASN.1 grammar compil 2393 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2394 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2395 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2396 functions to call on what tags.
2034 2397
2035 source "kernel/Kconfig.locks" 2398 source "kernel/Kconfig.locks"
2036 2399
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2400 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2401 bool
2042 2402
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2403 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2404 bool
2045 2405
2046 # It may be useful for an architecture to ove 2406 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2407 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2408 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2409 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2410 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2411 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2412 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2413 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2414 def_bool n
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