1 # SPDX-License-Identifier: GPL-2.0-only 1 # SPDX-License-Identifier: GPL-2.0-only
>> 2 config DEFCONFIG_LIST
>> 3 string
>> 4 depends on !UML
>> 5 option defconfig_list
>> 6 default "/lib/modules/$(shell,uname -r)/.config"
>> 7 default "/etc/kernel-config"
>> 8 default "/boot/config-$(shell,uname -r)"
>> 9 default "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)"
>> 10
2 config CC_VERSION_TEXT 11 config CC_VERSION_TEXT
3 string 12 string
4 default "$(CC_VERSION_TEXT)" 13 default "$(CC_VERSION_TEXT)"
5 help 14 help
6 This is used in unclear ways: 15 This is used in unclear ways:
7 16
8 - Re-run Kconfig when the compiler i 17 - Re-run Kconfig when the compiler is updated
9 The 'default' property references 18 The 'default' property references the environment variable,
10 CC_VERSION_TEXT so it is recorded 19 CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
11 When the compiler is updated, Kcon 20 When the compiler is updated, Kconfig will be invoked.
12 21
13 - Ensure full rebuild when the compi !! 22 - Ensure full rebuild when the compier is updated
14 include/linux/compiler-version.h c !! 23 include/linux/kconfig.h contains this option in the comment line so
15 line so fixdep adds include/config !! 24 fixdep adds include/config/cc/version/text.h into the auto-generated
16 auto-generated dependency. When th !! 25 dependency. When the compiler is updated, syncconfig will touch it
17 will touch it and then every file !! 26 and then every file will be rebuilt.
18 27
19 config CC_IS_GCC 28 config CC_IS_GCC
20 def_bool $(success,test "$(cc-name)" = !! 29 def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q gcc)
21 30
22 config GCC_VERSION 31 config GCC_VERSION
23 int 32 int
24 default $(cc-version) if CC_IS_GCC !! 33 default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
25 default 0 34 default 0
26 35
>> 36 config LD_VERSION
>> 37 int
>> 38 default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh)
>> 39
27 config CC_IS_CLANG 40 config CC_IS_CLANG
28 def_bool $(success,test "$(cc-name)" = !! 41 def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q clang)
>> 42
>> 43 config LD_IS_LLD
>> 44 def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
29 45
30 config CLANG_VERSION 46 config CLANG_VERSION
31 int 47 int
32 default $(cc-version) if CC_IS_CLANG !! 48 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
33 default 0 <<
34 49
35 config AS_IS_GNU 50 config AS_IS_GNU
36 def_bool $(success,test "$(as-name)" = 51 def_bool $(success,test "$(as-name)" = GNU)
37 52
38 config AS_IS_LLVM 53 config AS_IS_LLVM
39 def_bool $(success,test "$(as-name)" = 54 def_bool $(success,test "$(as-name)" = LLVM)
40 55
41 config AS_VERSION 56 config AS_VERSION
42 int 57 int
43 # Use clang version if this is the int 58 # Use clang version if this is the integrated assembler
44 default CLANG_VERSION if AS_IS_LLVM 59 default CLANG_VERSION if AS_IS_LLVM
45 default $(as-version) 60 default $(as-version)
46 61
47 config LD_IS_BFD <<
48 def_bool $(success,test "$(ld-name)" = <<
49 <<
50 config LD_VERSION <<
51 int <<
52 default $(ld-version) if LD_IS_BFD <<
53 default 0 <<
54 <<
55 config LD_IS_LLD <<
56 def_bool $(success,test "$(ld-name)" = <<
57 <<
58 config LLD_VERSION 62 config LLD_VERSION
59 int 63 int
60 default $(ld-version) if LD_IS_LLD !! 64 default $(shell,$(srctree)/scripts/lld-version.sh $(LD))
61 default 0 <<
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 65
85 config CC_CAN_LINK 66 config CC_CAN_LINK
86 bool 67 bool
87 default $(success,$(srctree)/scripts/c !! 68 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag)) if 64BIT
88 default $(success,$(srctree)/scripts/c !! 69 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag))
89 70
90 config CC_CAN_LINK_STATIC 71 config CC_CAN_LINK_STATIC
91 bool 72 bool
92 default $(success,$(srctree)/scripts/c !! 73 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static) if 64BIT
93 default $(success,$(srctree)/scripts/c !! 74 default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static)
94 75
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5 !! 76 config CC_HAS_ASM_GOTO
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id !! 77 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 78
104 config CC_HAS_ASM_GOTO_OUTPUT 79 config CC_HAS_ASM_GOTO_OUTPUT
105 def_bool y !! 80 depends on CC_HAS_ASM_GOTO
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN !! 81 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 82
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT 83 config CC_HAS_ASM_GOTO_TIED_OUTPUT
110 depends on CC_HAS_ASM_GOTO_OUTPUT 84 depends on CC_HAS_ASM_GOTO_OUTPUT
111 # Detect buggy gcc and clang, fixed in 85 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
112 def_bool $(success,echo 'int foo(int * 86 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
113 87
114 config TOOLS_SUPPORT_RELR 88 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 89 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 90
117 config CC_HAS_ASM_INLINE 91 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 92 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 93
120 config CC_HAS_NO_PROFILE_FN_ATTR <<
121 def_bool $(success,echo '__attribute__ <<
122 <<
123 config PAHOLE_VERSION <<
124 int <<
125 default $(shell,$(srctree)/scripts/pah <<
126 <<
127 config CONSTRUCTORS 94 config CONSTRUCTORS
128 bool 95 bool
>> 96 depends on !UML
129 97
130 config IRQ_WORK 98 config IRQ_WORK
131 def_bool y if SMP !! 99 bool
132 100
133 config BUILDTIME_TABLE_SORT 101 config BUILDTIME_TABLE_SORT
134 bool 102 bool
135 103
136 config THREAD_INFO_IN_TASK 104 config THREAD_INFO_IN_TASK
137 bool 105 bool
138 help 106 help
139 Select this to move thread_info off 107 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 108 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 109 except flags and fix any runtime bugs.
142 110
143 One subtle change that will be neede 111 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 112 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 113
146 menu "General setup" 114 menu "General setup"
147 115
148 config BROKEN 116 config BROKEN
149 bool 117 bool
150 118
151 config BROKEN_ON_SMP 119 config BROKEN_ON_SMP
152 bool 120 bool
153 depends on BROKEN || !SMP 121 depends on BROKEN || !SMP
154 default y 122 default y
155 123
156 config INIT_ENV_ARG_LIMIT 124 config INIT_ENV_ARG_LIMIT
157 int 125 int
158 default 32 if !UML 126 default 32 if !UML
159 default 128 if UML 127 default 128 if UML
160 help 128 help
161 Maximum of each of the number of arg 129 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 130 variables passed to init from the kernel command line.
163 131
164 config COMPILE_TEST 132 config COMPILE_TEST
165 bool "Compile also drivers which will 133 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 134 depends on HAS_IOMEM
167 help 135 help
168 Some drivers can be compiled on a di 136 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 137 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 138 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 139 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 140 drivers to compile-test them.
173 141
174 If you are a developer and want to b 142 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 143 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 144 drivers to be distributed.
177 145
178 config WERROR <<
179 bool "Compile the kernel with warnings <<
180 default COMPILE_TEST <<
181 help <<
182 A kernel build should not cause any <<
183 enables the '-Werror' (for C) and '- <<
184 to enforce that rule by default. Cer <<
185 such as the linker may be upgraded t <<
186 well. <<
187 <<
188 However, if you have a new (or very <<
189 and unusual warnings, or you have so <<
190 you may need to disable this config <<
191 successfully build the kernel. <<
192 <<
193 If in doubt, say Y. <<
194 <<
195 config UAPI_HEADER_TEST 146 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 147 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 148 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 149 help
199 Compile test headers exported to use 150 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 151 self-contained, i.e. compilable as standalone units.
201 152
202 If you are a developer or tester and 153 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 154 headers are self-contained, say Y here. Otherwise, choose N.
204 155
205 config LOCALVERSION 156 config LOCALVERSION
206 string "Local version - append to kern 157 string "Local version - append to kernel release"
207 help 158 help
208 Append an extra string to the end of 159 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 160 This will show up when you type uname, for example.
210 The string you set here will be appe 161 The string you set here will be appended after the contents of
211 any files with a filename matching l 162 any files with a filename matching localversion* in your
212 object and source tree, in that orde 163 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 164 be a maximum of 64 characters.
214 165
215 config LOCALVERSION_AUTO 166 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 167 bool "Automatically append version information to the version string"
217 default y 168 default y
218 depends on !COMPILE_TEST 169 depends on !COMPILE_TEST
219 help 170 help
220 This will try to automatically deter 171 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 172 release tree by looking for git tags that belong to the current
222 top of tree revision. 173 top of tree revision.
223 174
224 A string of the format -gxxxxxxxx wi 175 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 176 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 177 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 178 set in CONFIG_LOCALVERSION.
228 179
229 (The actual string used here is the !! 180 (The actual string used here is the first eight characters produced
230 by running the command: 181 by running the command:
231 182
232 $ git rev-parse --verify HEAD 183 $ git rev-parse --verify HEAD
233 184
234 which is done within the script "scr 185 which is done within the script "scripts/setlocalversion".)
235 186
236 config BUILD_SALT 187 config BUILD_SALT
237 string "Build ID Salt" 188 string "Build ID Salt"
238 default "" 189 default ""
239 help 190 help
240 The build ID is used to link binarie 191 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 192 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 193 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 194 build is unique between builds. It's safe to leave the default.
244 195
245 config HAVE_KERNEL_GZIP 196 config HAVE_KERNEL_GZIP
246 bool 197 bool
247 198
248 config HAVE_KERNEL_BZIP2 199 config HAVE_KERNEL_BZIP2
249 bool 200 bool
250 201
251 config HAVE_KERNEL_LZMA 202 config HAVE_KERNEL_LZMA
252 bool 203 bool
253 204
254 config HAVE_KERNEL_XZ 205 config HAVE_KERNEL_XZ
255 bool 206 bool
256 207
257 config HAVE_KERNEL_LZO 208 config HAVE_KERNEL_LZO
258 bool 209 bool
259 210
260 config HAVE_KERNEL_LZ4 211 config HAVE_KERNEL_LZ4
261 bool 212 bool
262 213
263 config HAVE_KERNEL_ZSTD 214 config HAVE_KERNEL_ZSTD
264 bool 215 bool
265 216
266 config HAVE_KERNEL_UNCOMPRESSED 217 config HAVE_KERNEL_UNCOMPRESSED
267 bool 218 bool
268 219
269 choice 220 choice
270 prompt "Kernel compression mode" 221 prompt "Kernel compression mode"
271 default KERNEL_GZIP 222 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE 223 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 224 help
274 The linux kernel is a kind of self-e 225 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 226 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 227 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 228 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 229 Decompression speed is relevant at each boot.
279 230
280 If you have any problems with bzip2 231 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 232 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 233 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 234 supplied by Christian Ludwig)
284 235
285 High compression options are mostly 236 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 237 are low on disk space (embedded systems), but for whom ram
287 size matters less. 238 size matters less.
288 239
289 If in doubt, select 'gzip' 240 If in doubt, select 'gzip'
290 241
291 config KERNEL_GZIP 242 config KERNEL_GZIP
292 bool "Gzip" 243 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 244 depends on HAVE_KERNEL_GZIP
294 help 245 help
295 The old and tried gzip compression. 246 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 247 between compression ratio and decompression speed.
297 248
298 config KERNEL_BZIP2 249 config KERNEL_BZIP2
299 bool "Bzip2" 250 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 251 depends on HAVE_KERNEL_BZIP2
301 help 252 help
302 Its compression ratio and speed is i 253 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 254 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 255 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 256 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 257 will need at least 8MB RAM or more for booting.
307 258
308 config KERNEL_LZMA 259 config KERNEL_LZMA
309 bool "LZMA" 260 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 261 depends on HAVE_KERNEL_LZMA
311 help 262 help
312 This compression algorithm's ratio i 263 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 264 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 265 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 266
316 config KERNEL_XZ 267 config KERNEL_XZ
317 bool "XZ" 268 bool "XZ"
318 depends on HAVE_KERNEL_XZ 269 depends on HAVE_KERNEL_XZ
319 help 270 help
320 XZ uses the LZMA2 algorithm and inst 271 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 272 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 273 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 274 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 275 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 276 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 277
328 The speed is about the same as with 278 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 279 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 280 and LZO. Compression is slow.
331 281
332 config KERNEL_LZO 282 config KERNEL_LZO
333 bool "LZO" 283 bool "LZO"
334 depends on HAVE_KERNEL_LZO 284 depends on HAVE_KERNEL_LZO
335 help 285 help
336 Its compression ratio is the poorest 286 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 287 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 288 (both compression and decompression) is the fastest.
339 289
340 config KERNEL_LZ4 290 config KERNEL_LZ4
341 bool "LZ4" 291 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 292 depends on HAVE_KERNEL_LZ4
343 help 293 help
344 LZ4 is an LZ77-type compressor with 294 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 295 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 296 <https://code.google.com/p/lz4/>.
347 297
348 Its compression ratio is worse than 298 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 299 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 300 faster than LZO.
351 301
352 config KERNEL_ZSTD 302 config KERNEL_ZSTD
353 bool "ZSTD" 303 bool "ZSTD"
354 depends on HAVE_KERNEL_ZSTD 304 depends on HAVE_KERNEL_ZSTD
355 help 305 help
356 ZSTD is a compression algorithm targ 306 ZSTD is a compression algorithm targeting intermediate compression
357 with fast decompression speed. It wi 307 with fast decompression speed. It will compress better than GZIP and
358 decompress around the same speed as 308 decompress around the same speed as LZO, but slower than LZ4. You
359 will need at least 192 KB RAM or mor 309 will need at least 192 KB RAM or more for booting. The zstd command
360 line tool is required for compressio 310 line tool is required for compression.
361 311
362 config KERNEL_UNCOMPRESSED 312 config KERNEL_UNCOMPRESSED
363 bool "None" 313 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 314 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 315 help
366 Produce uncompressed kernel image. T 316 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 317 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 318 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 319 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 320 and jump right at uncompressed kernel image.
371 321
372 endchoice 322 endchoice
373 323
374 config DEFAULT_INIT 324 config DEFAULT_INIT
375 string "Default init path" 325 string "Default init path"
376 default "" 326 default ""
377 help 327 help
378 This option determines the default i 328 This option determines the default init for the system if no init=
379 option is passed on the kernel comma 329 option is passed on the kernel command line. If the requested path is
380 not present, we will still then move 330 not present, we will still then move on to attempting further
381 locations (e.g. /sbin/init, etc). If 331 locations (e.g. /sbin/init, etc). If this is empty, we will just use
382 the fallback list when init= is not 332 the fallback list when init= is not passed.
383 333
384 config DEFAULT_HOSTNAME 334 config DEFAULT_HOSTNAME
385 string "Default hostname" 335 string "Default hostname"
386 default "(none)" 336 default "(none)"
387 help 337 help
388 This option determines the default s 338 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 339 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 340 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 341 system more usable with less configuration.
392 342
>> 343 #
>> 344 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 345 # add proper SWAP support to them, in which case this can be remove.
>> 346 #
>> 347 config ARCH_NO_SWAP
>> 348 bool
>> 349
>> 350 config SWAP
>> 351 bool "Support for paging of anonymous memory (swap)"
>> 352 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 353 default y
>> 354 help
>> 355 This option allows you to choose whether you want to have support
>> 356 for so called swap devices or swap files in your kernel that are
>> 357 used to provide more virtual memory than the actual RAM present
>> 358 in your computer. If unsure say Y.
>> 359
393 config SYSVIPC 360 config SYSVIPC
394 bool "System V IPC" 361 bool "System V IPC"
395 help 362 help
396 Inter Process Communication is a sui 363 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 364 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 365 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 366 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 367 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 368 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 369 you'll need to say Y here.
403 370
404 You can find documentation about IPC 371 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 372 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 373 <http://www.tldp.org/guides.html>.
407 374
408 config SYSVIPC_SYSCTL 375 config SYSVIPC_SYSCTL
409 bool 376 bool
410 depends on SYSVIPC 377 depends on SYSVIPC
411 depends on SYSCTL 378 depends on SYSCTL
412 default y 379 default y
413 380
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 381 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 382 bool "POSIX Message Queues"
420 depends on NET 383 depends on NET
421 help 384 help
422 POSIX variant of message queues is a 385 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 386 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 387 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 388 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 389 queues (functions mq_*) say Y here.
427 390
428 POSIX message queues are visible as 391 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 392 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 393 operations on message queues.
431 394
432 If unsure, say Y. 395 If unsure, say Y.
433 396
434 config POSIX_MQUEUE_SYSCTL 397 config POSIX_MQUEUE_SYSCTL
435 bool 398 bool
436 depends on POSIX_MQUEUE 399 depends on POSIX_MQUEUE
437 depends on SYSCTL 400 depends on SYSCTL
438 default y 401 default y
439 402
440 config WATCH_QUEUE 403 config WATCH_QUEUE
441 bool "General notification queue" 404 bool "General notification queue"
442 default n 405 default n
443 help 406 help
444 407
445 This is a general notification queue 408 This is a general notification queue for the kernel to pass events to
446 userspace by splicing them into pipe 409 userspace by splicing them into pipes. It can be used in conjunction
447 with watches for key/keyring change 410 with watches for key/keyring change notifications and device
448 notifications. 411 notifications.
449 412
450 See Documentation/core-api/watch_que !! 413 See Documentation/watch_queue.rst
451 414
452 config CROSS_MEMORY_ATTACH 415 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 416 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 417 depends on MMU
455 default y 418 default y
456 help 419 help
457 Enabling this option adds the system 420 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 421 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 422 to directly read from or write to another process' address space.
460 See the man page for more details. 423 See the man page for more details.
461 424
462 config USELIB 425 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 426 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 427 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 428 help
466 This option enables the uselib sysca 429 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 430 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 431 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 432 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 433 running glibc can safely disable this.
471 434
472 config AUDIT 435 config AUDIT
473 bool "Auditing support" 436 bool "Auditing support"
474 depends on NET 437 depends on NET
475 help 438 help
476 Enable auditing infrastructure that 439 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 440 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 441 logging of avc messages output). System call auditing is included
479 on architectures which support it. 442 on architectures which support it.
480 443
481 config HAVE_ARCH_AUDITSYSCALL 444 config HAVE_ARCH_AUDITSYSCALL
482 bool 445 bool
483 446
484 config AUDITSYSCALL 447 config AUDITSYSCALL
485 def_bool y 448 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 449 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 450 select FSNOTIFY
488 451
489 source "kernel/irq/Kconfig" 452 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 453 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" <<
492 source "kernel/Kconfig.preempt" 454 source "kernel/Kconfig.preempt"
493 455
494 menu "CPU/Task time and stats accounting" 456 menu "CPU/Task time and stats accounting"
495 457
496 config VIRT_CPU_ACCOUNTING 458 config VIRT_CPU_ACCOUNTING
497 bool 459 bool
498 460
499 choice 461 choice
500 prompt "Cputime accounting" 462 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 463 default TICK_CPU_ACCOUNTING if !PPC64
>> 464 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 465
503 # Kind of a stub config for the pure tick base 466 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 467 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 468 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 469 depends on !S390 && !NO_HZ_FULL
507 help 470 help
508 This is the basic tick based cputime 471 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 472 statistics about user, system and idle time spent on per jiffies
510 granularity. 473 granularity.
511 474
512 If unsure, say Y. 475 If unsure, say Y.
513 476
514 config VIRT_CPU_ACCOUNTING_NATIVE 477 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 478 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 479 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 480 select VIRT_CPU_ACCOUNTING
518 help 481 help
519 Select this option to enable more ac 482 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 483 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 484 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 485 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 486 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 487 this also enables accounting of stolen time on logically-partitioned
525 systems. 488 systems.
526 489
527 config VIRT_CPU_ACCOUNTING_GEN 490 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 491 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 492 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 493 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 494 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 495 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 496 select CONTEXT_TRACKING
534 help 497 help
535 Select this option to enable task an 498 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 499 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 500 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 501 The accounting is thus performed at the expense of some significant
539 overhead. 502 overhead.
540 503
541 For now this is only useful if you a 504 For now this is only useful if you are working on the full
542 dynticks subsystem development. 505 dynticks subsystem development.
543 506
544 If unsure, say N. 507 If unsure, say N.
545 508
546 endchoice 509 endchoice
547 510
548 config IRQ_TIME_ACCOUNTING 511 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 512 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 513 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 514 help
552 Select this option to enable fine gr 515 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 516 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 517 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 518 small performance impact.
556 519
557 If in doubt, say N here. 520 If in doubt, say N here.
558 521
559 config HAVE_SCHED_AVG_IRQ 522 config HAVE_SCHED_AVG_IRQ
560 def_bool y 523 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 524 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 525 depends on SMP
563 526
564 config SCHED_HW_PRESSURE !! 527 config SCHED_THERMAL_PRESSURE
565 bool 528 bool
566 default y if ARM && ARM_CPU_TOPOLOGY 529 default y if ARM && ARM_CPU_TOPOLOGY
567 default y if ARM64 530 default y if ARM64
568 depends on SMP 531 depends on SMP
569 depends on CPU_FREQ_THERMAL 532 depends on CPU_FREQ_THERMAL
570 help 533 help
571 Select this option to enable HW pres !! 534 Select this option to enable thermal pressure accounting in the
572 scheduler. HW pressure is the value !! 535 scheduler. Thermal pressure is the value conveyed to the scheduler
573 that reflects the reduction in CPU c 536 that reflects the reduction in CPU compute capacity resulted from
574 HW throttling. HW throttling occurs !! 537 thermal throttling. Thermal throttling occurs when the performance of
575 a CPU is capped due to high operatin !! 538 a CPU is capped due to high operating temperatures.
576 539
577 If selected, the scheduler will be a 540 If selected, the scheduler will be able to balance tasks accordingly,
578 i.e. put less load on throttled CPUs 541 i.e. put less load on throttled CPUs than on non/less throttled ones.
579 542
580 This requires the architecture to im 543 This requires the architecture to implement
581 arch_update_hw_pressure() and arch_s !! 544 arch_set_thermal_pressure() and arch_get_thermal_pressure().
582 545
583 config BSD_PROCESS_ACCT 546 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 547 bool "BSD Process Accounting"
585 depends on MULTIUSER 548 depends on MULTIUSER
586 help 549 help
587 If you say Y here, a user level prog 550 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 551 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 552 information to a file: whenever a process exits, information about
590 that process will be appended to the 553 that process will be appended to the file by the kernel. The
591 information includes things such as 554 information includes things such as creation time, owning user,
592 command name, memory usage, controll 555 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 556 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 557 up to the user level program to do useful things with this
595 information. This is generally a go 558 information. This is generally a good idea, so say Y.
596 559
597 config BSD_PROCESS_ACCT_V3 560 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 561 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 562 depends on BSD_PROCESS_ACCT
600 default n 563 default n
601 help 564 help
602 If you say Y here, the process accou 565 If you say Y here, the process accounting information is written
603 in a new file format that also logs 566 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 567 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 568 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 569 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 570 at <http://www.gnu.org/software/acct/>.
608 571
609 config TASKSTATS 572 config TASKSTATS
610 bool "Export task/process statistics t 573 bool "Export task/process statistics through netlink"
611 depends on NET 574 depends on NET
612 depends on MULTIUSER 575 depends on MULTIUSER
613 default n 576 default n
614 help 577 help
615 Export selected statistics for tasks 578 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 579 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 580 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 581 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 582 space on task exit.
620 583
621 Say N if unsure. 584 Say N if unsure.
622 585
623 config TASK_DELAY_ACCT 586 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 587 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 588 depends on TASKSTATS
626 select SCHED_INFO 589 select SCHED_INFO
627 help 590 help
628 Collect information on time spent by 591 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 592 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 593 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 594 relative to other tasks for cpu, io, rss limits etc.
632 595
633 Say N if unsure. 596 Say N if unsure.
634 597
635 config TASK_XACCT 598 config TASK_XACCT
636 bool "Enable extended accounting over 599 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 600 depends on TASKSTATS
638 help 601 help
639 Collect extended task accounting dat 602 Collect extended task accounting data and send the data
640 to userland for processing over the 603 to userland for processing over the taskstats interface.
641 604
642 Say N if unsure. 605 Say N if unsure.
643 606
644 config TASK_IO_ACCOUNTING 607 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 608 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 609 depends on TASK_XACCT
647 help 610 help
648 Collect information on the number of 611 Collect information on the number of bytes of storage I/O which this
649 task has caused. 612 task has caused.
650 613
651 Say N if unsure. 614 Say N if unsure.
652 615
653 config PSI 616 config PSI
654 bool "Pressure stall information track 617 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 618 help
657 Collect metrics that indicate how ov 619 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 620 and IO capacity are in the system.
659 621
660 If you say Y here, the kernel will c 622 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 623 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 624 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 625 delayed due to contention of the respective resource.
664 626
665 In kernels with cgroup support, cgro 627 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 628 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 629 which aggregate pressure stalls for the grouped tasks only.
668 630
669 For more details see Documentation/a 631 For more details see Documentation/accounting/psi.rst.
670 632
671 Say N if unsure. 633 Say N if unsure.
672 634
673 config PSI_DEFAULT_DISABLED 635 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 636 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 637 default n
676 depends on PSI 638 depends on PSI
677 help 639 help
678 If set, pressure stall information t 640 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 641 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 642 kernel commandline during boot.
681 643
682 This feature adds some code to the t 644 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 645 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 646 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 647 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 648 scheduler stress tests, such as hackbench.
687 649
688 If you are paranoid and not sure wha 650 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 651 used for, say Y.
690 652
691 Say N if unsure. 653 Say N if unsure.
692 654
693 endmenu # "CPU/Task time and stats accounting" 655 endmenu # "CPU/Task time and stats accounting"
694 656
695 config CPU_ISOLATION 657 config CPU_ISOLATION
696 bool "CPU isolation" 658 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 659 depends on SMP || COMPILE_TEST
698 default y 660 default y
699 help 661 help
700 Make sure that CPUs running critical 662 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 663 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 664 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 665 the "isolcpus=" boot parameter.
704 666
705 Say Y if unsure. 667 Say Y if unsure.
706 668
707 source "kernel/rcu/Kconfig" 669 source "kernel/rcu/Kconfig"
708 670
>> 671 config BUILD_BIN2C
>> 672 bool
>> 673 default n
>> 674
709 config IKCONFIG 675 config IKCONFIG
710 tristate "Kernel .config support" 676 tristate "Kernel .config support"
711 help 677 help
712 This option enables the complete Lin 678 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 679 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 680 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 681 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 682 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 683 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 684 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 685 /proc/config.gz if enabled (below).
720 686
721 config IKCONFIG_PROC 687 config IKCONFIG_PROC
722 bool "Enable access to .config through 688 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 689 depends on IKCONFIG && PROC_FS
724 help 690 help
725 This option enables access to the ke 691 This option enables access to the kernel configuration file
726 through /proc/config.gz. 692 through /proc/config.gz.
727 693
728 config IKHEADERS 694 config IKHEADERS
729 tristate "Enable kernel headers throug 695 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 696 depends on SYSFS
731 help 697 help
732 This option enables access to the in 698 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 699 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 700 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 701 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 702
737 config LOG_BUF_SHIFT 703 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 704 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 !! 705 range 12 25 if !H8300
>> 706 range 12 19 if H8300
740 default 17 707 default 17
741 depends on PRINTK 708 depends on PRINTK
742 help 709 help
743 Select the minimal kernel log buffer 710 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 711 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 712 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 713 by "log_buf_len" boot parameter.
747 714
748 Examples: 715 Examples:
749 17 => 128 KB 716 17 => 128 KB
750 16 => 64 KB 717 16 => 64 KB
751 15 => 32 KB 718 15 => 32 KB
752 14 => 16 KB 719 14 => 16 KB
753 13 => 8 KB 720 13 => 8 KB
754 12 => 4 KB 721 12 => 4 KB
755 722
756 config LOG_CPU_MAX_BUF_SHIFT 723 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 724 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 725 depends on SMP
759 range 0 21 726 range 0 21
>> 727 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 728 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 729 depends on PRINTK
763 help 730 help
764 This option allows to increase the d 731 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 732 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 733 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 734 lines however it might be much more when problems are reported,
768 e.g. backtraces. 735 e.g. backtraces.
769 736
770 The increased size means that a new 737 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 738 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 739 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 740 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 741 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed 742 so that more than 16 CPUs are needed to trigger the allocation.
776 743
777 Also this option is ignored when "lo 744 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 745 used as it forces an exact (power of two) size of the ring buffer.
779 746
780 The number of possible CPUs is used 747 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 748 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 749 scenario while allowing a simple algorithm to be used from bootup.
783 750
784 Examples shift values and their mean 751 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 752 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 753 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 754 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 755 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 756 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 757 12 => 4 KB for each CPU
791 758
792 config PRINTK_INDEX !! 759 config PRINTK_SAFE_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 760 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 761 range 10 21
795 help !! 762 default 13
796 Add support for indexing of all prin !! 763 depends on PRINTK
797 at <debugfs>/printk/index/<module>. !! 764 help
798 !! 765 Select the size of an alternate printk per-CPU buffer where messages
799 This can be used as part of maintain !! 766 printed from usafe contexts are temporary stored. One example would
800 /dev/kmsg, as it permits auditing th !! 767 be NMI messages, another one - printk recursion. The messages are
801 kernel, allowing detection of cases !! 768 copied to the main log buffer in a safe context to avoid a deadlock.
802 changed or no longer present. !! 769 The value defines the size as a power of 2.
>> 770
>> 771 Those messages are rare and limited. The largest one is when
>> 772 a backtrace is printed. It usually fits into 4KB. Select
>> 773 8KB if you want to be on the safe side.
803 774
804 There is no additional runtime cost !! 775 Examples:
>> 776 17 => 128 KB for each CPU
>> 777 16 => 64 KB for each CPU
>> 778 15 => 32 KB for each CPU
>> 779 14 => 16 KB for each CPU
>> 780 13 => 8 KB for each CPU
>> 781 12 => 4 KB for each CPU
805 782
806 # 783 #
807 # Architectures with an unreliable sched_clock 784 # Architectures with an unreliable sched_clock() should select this:
808 # 785 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 786 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 787 bool
811 788
812 config GENERIC_SCHED_CLOCK 789 config GENERIC_SCHED_CLOCK
813 bool 790 bool
814 791
815 menu "Scheduler features" 792 menu "Scheduler features"
816 793
817 config UCLAMP_TASK 794 config UCLAMP_TASK
818 bool "Enable utilization clamping for 795 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 796 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 797 help
821 This feature enables the scheduler t 798 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 799 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 800
824 With this option, the user can speci 801 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 802 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 803 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 804 defines the minimum frequency it should use.
828 805
829 Both min and max utilization clamp v 806 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 807 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 808 enforce or grant any specific bandwidth for tasks.
832 809
833 If in doubt, say N. 810 If in doubt, say N.
834 811
835 config UCLAMP_BUCKETS_COUNT 812 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 813 int "Number of supported utilization clamp buckets"
837 range 5 20 814 range 5 20
838 default 5 815 default 5
839 depends on UCLAMP_TASK 816 depends on UCLAMP_TASK
840 help 817 help
841 Defines the number of clamp buckets 818 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 819 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 820 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 821 the precision of clamping aggregation and tracking at run-time.
845 822
846 For example, with the minimum config 823 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 824 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 825 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 826 effective value to 25%.
850 If a second 30% boosted task should 827 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 828 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 829 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 830 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 831 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 832 that bucket.
856 833
857 An additional boost/capping margin c 834 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 835 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 836 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 837 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 838 clamp buckets to trade off used memory for run-time tracking
862 precision. 839 precision.
863 840
864 If in doubt, use the default value. 841 If in doubt, use the default value.
865 842
866 endmenu 843 endmenu
867 844
868 # 845 #
869 # For architectures that want to enable the su 846 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 847 # balancing logic:
871 # 848 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 849 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 850 bool
874 851
875 # 852 #
876 # For architectures that prefer to flush all T 853 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 854 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 855 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 856 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 857 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 858 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 859 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 860 bool
884 861
885 config CC_HAS_INT128 862 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 863 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 864
888 config CC_IMPLICIT_FALLTHROUGH <<
889 string <<
890 default "-Wimplicit-fallthrough=5" if <<
891 default "-Wimplicit-fallthrough" if CC <<
892 <<
893 # Currently, disable gcc-10+ array-bounds glob <<
894 # It's still broken in gcc-13, so no upper bou <<
895 config GCC10_NO_ARRAY_BOUNDS <<
896 def_bool y <<
897 <<
898 config CC_NO_ARRAY_BOUNDS <<
899 bool <<
900 default y if CC_IS_GCC && GCC_VERSION <<
901 <<
902 # Currently, disable -Wstringop-overflow for G <<
903 config GCC_NO_STRINGOP_OVERFLOW <<
904 def_bool y <<
905 <<
906 config CC_NO_STRINGOP_OVERFLOW <<
907 bool <<
908 default y if CC_IS_GCC && GCC_NO_STRIN <<
909 <<
910 config CC_STRINGOP_OVERFLOW <<
911 bool <<
912 default y if CC_IS_GCC && !CC_NO_STRIN <<
913 <<
914 # 865 #
915 # For architectures that know their GCC __int1 866 # For architectures that know their GCC __int128 support is sound
916 # 867 #
917 config ARCH_SUPPORTS_INT128 868 config ARCH_SUPPORTS_INT128
918 bool 869 bool
919 870
920 # For architectures that (ab)use NUMA to repre 871 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 872 # all cpu-local but of different latencies, such as SuperH.
922 # 873 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 874 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 875 bool
925 876
926 config NUMA_BALANCING 877 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 878 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 879 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 880 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 881 depends on SMP && NUMA && MIGRATION
931 help 882 help
932 This option adds support for automat 883 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 884 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 885 it has references to the node the task is running on.
935 886
936 This system will be inactive on UMA 887 This system will be inactive on UMA systems.
937 888
938 config NUMA_BALANCING_DEFAULT_ENABLED 889 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 890 bool "Automatically enable NUMA aware memory/task placement"
940 default y 891 default y
941 depends on NUMA_BALANCING 892 depends on NUMA_BALANCING
942 help 893 help
943 If set, automatic NUMA balancing wil 894 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 895 machine.
945 896
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 897 menuconfig CGROUPS
950 bool "Control Group support" 898 bool "Control Group support"
951 select KERNFS 899 select KERNFS
952 help 900 help
953 This option adds support for groupin 901 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 902 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 903 controls or device isolation.
956 See 904 See
957 - Documentation/scheduler/sche 905 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 906 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 907 and resource control)
960 908
961 Say N if unsure. 909 Say N if unsure.
962 910
963 if CGROUPS 911 if CGROUPS
964 912
965 config PAGE_COUNTER 913 config PAGE_COUNTER
966 bool 914 bool
967 915
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 916 config MEMCG
979 bool "Memory controller" 917 bool "Memory controller"
980 select PAGE_COUNTER 918 select PAGE_COUNTER
981 select EVENTFD 919 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 920 help
984 Provides control over the memory foo 921 Provides control over the memory footprint of tasks in a cgroup.
985 922
986 config MEMCG_V1 !! 923 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 924 bool
988 depends on MEMCG !! 925 depends on MEMCG && SWAP
989 default n !! 926 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 927
1001 Say N if unsure. !! 928 config MEMCG_KMEM
>> 929 bool
>> 930 depends on MEMCG && !SLOB
>> 931 default y
1002 932
1003 config BLK_CGROUP 933 config BLK_CGROUP
1004 bool "IO controller" 934 bool "IO controller"
1005 depends on BLOCK 935 depends on BLOCK
1006 default n 936 default n
1007 help 937 help
1008 Generic block IO controller cgroup in 938 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 939 cgroup interface which should be used by various IO controlling
1010 policies. 940 policies.
1011 941
1012 Currently, CFQ IO scheduler uses it t 942 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 943 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 944 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 945 block layer to implement upper limit in IO rates on a device.
1016 946
1017 This option only enables generic Bloc 947 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 948 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 949 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl 950 CONFIG_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 951 CONFIG_BLK_DEV_THROTTLING=y.
1022 952
1023 See Documentation/admin-guide/cgroup- 953 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 954
1025 config CGROUP_WRITEBACK 955 config CGROUP_WRITEBACK
1026 bool 956 bool
1027 depends on MEMCG && BLK_CGROUP 957 depends on MEMCG && BLK_CGROUP
1028 default y 958 default y
1029 959
1030 menuconfig CGROUP_SCHED 960 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 961 bool "CPU controller"
1032 default n 962 default n
1033 help 963 help
1034 This feature lets CPU scheduler rec 964 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 965 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 966 tasks.
1037 967
1038 if CGROUP_SCHED 968 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 969 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 970 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 971 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 972 default CGROUP_SCHED
1047 973
1048 config CFS_BANDWIDTH 974 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 975 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 976 depends on FAIR_GROUP_SCHED
1051 default n 977 default n
1052 help 978 help
1053 This option allows users to define 979 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 980 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 981 set are considered to be unconstrained and will run with no
1056 restriction. 982 restriction.
1057 See Documentation/scheduler/sched-b 983 See Documentation/scheduler/sched-bwc.rst for more information.
1058 984
1059 config RT_GROUP_SCHED 985 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 986 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 987 depends on CGROUP_SCHED
1062 default n 988 default n
1063 help 989 help
1064 This feature lets you explicitly al 990 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 991 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 992 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 993 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 994 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 995
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 996 endif #CGROUP_SCHED
1077 997
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 998 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 999 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 1000 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 1001 depends on UCLAMP_TASK
1086 default n 1002 default n
1087 help 1003 help
1088 This feature enables the scheduler 1004 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 1005 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 1006
1091 When this option is enabled, the us 1007 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 1008 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 1009 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 1010 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 1011 frequency a task will always use.
1096 1012
1097 When task group based utilization c 1013 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 1014 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 1015 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 1016 be bigger than the corresponding clamping defined at task group level.
1101 1017
1102 If in doubt, say N. 1018 If in doubt, say N.
1103 1019
1104 config CGROUP_PIDS 1020 config CGROUP_PIDS
1105 bool "PIDs controller" 1021 bool "PIDs controller"
1106 help 1022 help
1107 Provides enforcement of process num 1023 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 1024 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 1025 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 1026 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 1027 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 1028 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 1029 PIDs controller is designed to stop this from happening.
1114 1030
1115 It should be noted that organisatio 1031 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 1032 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 1033 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 1034 attach to a cgroup.
1119 1035
1120 config CGROUP_RDMA 1036 config CGROUP_RDMA
1121 bool "RDMA controller" 1037 bool "RDMA controller"
1122 help 1038 help
1123 Provides enforcement of RDMA resour 1039 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 1040 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 1041 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 1042 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 1043 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 1044 hierarchy is allowed even if can cross the hierarchy's limit.
1129 1045
1130 config CGROUP_FREEZER 1046 config CGROUP_FREEZER
1131 bool "Freezer controller" 1047 bool "Freezer controller"
1132 help 1048 help
1133 Provides a way to freeze and unfree 1049 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 1050 cgroup.
1135 1051
1136 This option affects the ORIGINAL cg 1052 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 1053 controller includes important in-kernel memory consumers per default.
1138 1054
1139 If you're using cgroup2, say N. 1055 If you're using cgroup2, say N.
1140 1056
1141 config CGROUP_HUGETLB 1057 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 1058 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 1059 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 1060 select PAGE_COUNTER
1145 default n 1061 default n
1146 help 1062 help
1147 Provides a cgroup controller for Hu 1063 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 1064 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 1065 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 1066 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 1067 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 1068 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 1069 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 1070 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 1071 that we cannot use the controller with huge page less than 3 pages.
1156 1072
1157 config CPUSETS 1073 config CPUSETS
1158 bool "Cpuset controller" 1074 bool "Cpuset controller"
1159 depends on SMP 1075 depends on SMP
1160 help 1076 help
1161 This option will let you create and 1077 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1078 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1079 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1080 This is primarily useful on large SMP or NUMA systems.
1165 1081
1166 Say N if unsure. 1082 Say N if unsure.
1167 1083
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 1084 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1085 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1086 depends on CPUSETS
1184 default y 1087 default y
1185 1088
1186 config CGROUP_DEVICE 1089 config CGROUP_DEVICE
1187 bool "Device controller" 1090 bool "Device controller"
1188 help 1091 help
1189 Provides a cgroup controller implem 1092 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1093 devices which a process in the cgroup can mknod or open.
1191 1094
1192 config CGROUP_CPUACCT 1095 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1096 bool "Simple CPU accounting controller"
1194 help 1097 help
1195 Provides a simple controller for mo 1098 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1099 total CPU consumed by the tasks in a cgroup.
1197 1100
1198 config CGROUP_PERF 1101 config CGROUP_PERF
1199 bool "Perf controller" 1102 bool "Perf controller"
1200 depends on PERF_EVENTS 1103 depends on PERF_EVENTS
1201 help 1104 help
1202 This option extends the perf per-cp 1105 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1106 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use 1107 designated cpu. Or this can be used to have cgroup ID in samples
1205 so that it can monitor performance 1108 so that it can monitor performance events among cgroups.
1206 1109
1207 Say N if unsure. 1110 Say N if unsure.
1208 1111
1209 config CGROUP_BPF 1112 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1113 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1114 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1115 select SOCK_CGROUP_DATA
1213 help 1116 help
1214 Allow attaching eBPF programs to a 1117 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1118 syscall command BPF_PROG_ATTACH.
1216 1119
1217 In which context these programs are 1120 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1121 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1122 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1123 inet sockets.
1221 1124
1222 config CGROUP_MISC <<
1223 bool "Misc resource controller" <<
1224 default n <<
1225 help <<
1226 Provides a controller for miscellan <<
1227 <<
1228 Miscellaneous scalar resources are <<
1229 which cannot be abstracted like the <<
1230 tracks and limits the miscellaneous <<
1231 attached to a cgroup hierarchy. <<
1232 <<
1233 For more information, please check <<
1234 /Documentation/admin-guide/cgroup-v <<
1235 <<
1236 config CGROUP_DEBUG 1125 config CGROUP_DEBUG
1237 bool "Debug controller" 1126 bool "Debug controller"
1238 default n 1127 default n
1239 depends on DEBUG_KERNEL 1128 depends on DEBUG_KERNEL
1240 help 1129 help
1241 This option enables a simple contro 1130 This option enables a simple controller that exports
1242 debugging information about the cgr 1131 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1132 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1133 interfaces are not stable.
1245 1134
1246 Say N. 1135 Say N.
1247 1136
1248 config SOCK_CGROUP_DATA 1137 config SOCK_CGROUP_DATA
1249 bool 1138 bool
1250 default n 1139 default n
1251 1140
1252 endif # CGROUPS 1141 endif # CGROUPS
1253 1142
1254 menuconfig NAMESPACES 1143 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1144 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1145 depends on MULTIUSER
1257 default !EXPERT 1146 default !EXPERT
1258 help 1147 help
1259 Provides the way to make tasks work 1148 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1149 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1150 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1151 different namespaces.
1263 1152
1264 if NAMESPACES 1153 if NAMESPACES
1265 1154
1266 config UTS_NS 1155 config UTS_NS
1267 bool "UTS namespace" 1156 bool "UTS namespace"
1268 default y 1157 default y
1269 help 1158 help
1270 In this namespace tasks see differe 1159 In this namespace tasks see different info provided with the
1271 uname() system call 1160 uname() system call
1272 1161
1273 config TIME_NS 1162 config TIME_NS
1274 bool "TIME namespace" 1163 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1164 depends on GENERIC_VDSO_TIME_NS
1276 default y 1165 default y
1277 help 1166 help
1278 In this namespace boottime and mono 1167 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1168 The time will keep going with the same pace.
1280 1169
1281 config IPC_NS 1170 config IPC_NS
1282 bool "IPC namespace" 1171 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1172 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1173 default y
1285 help 1174 help
1286 In this namespace tasks work with I 1175 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1176 different IPC objects in different namespaces.
1288 1177
1289 config USER_NS 1178 config USER_NS
1290 bool "User namespace" 1179 bool "User namespace"
1291 default n 1180 default n
1292 help 1181 help
1293 This allows containers, i.e. vserve 1182 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1183 to provide different user info for different servers.
1295 1184
1296 When user namespaces are enabled in 1185 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1186 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1187 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1188 of memory a memory unprivileged users can use.
1300 1189
1301 If unsure, say N. 1190 If unsure, say N.
1302 1191
1303 config PID_NS 1192 config PID_NS
1304 bool "PID Namespaces" 1193 bool "PID Namespaces"
1305 default y 1194 default y
1306 help 1195 help
1307 Support process id namespaces. Thi 1196 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1197 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1198 pid namespaces. This is a building block of containers.
1310 1199
1311 config NET_NS 1200 config NET_NS
1312 bool "Network namespace" 1201 bool "Network namespace"
1313 depends on NET 1202 depends on NET
1314 default y 1203 default y
1315 help 1204 help
1316 Allow user space to create what app 1205 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1206 of the network stack.
1318 1207
1319 endif # NAMESPACES 1208 endif # NAMESPACES
1320 1209
1321 config CHECKPOINT_RESTORE 1210 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1211 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1212 select PROC_CHILDREN
1325 select KCMP 1213 select KCMP
1326 default n 1214 default n
1327 help 1215 help
1328 Enables additional kernel features 1216 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1217 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1218 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1219 entries.
1332 1220
1333 If unsure, say N here. 1221 If unsure, say N here.
1334 1222
1335 config SCHED_AUTOGROUP 1223 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1224 bool "Automatic process group scheduling"
1337 select CGROUPS 1225 select CGROUPS
1338 select CGROUP_SCHED 1226 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1227 select FAIR_GROUP_SCHED
1340 help 1228 help
1341 This option optimizes the scheduler 1229 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1230 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1231 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1232 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1233 upon task session.
1346 1234
>> 1235 config SYSFS_DEPRECATED
>> 1236 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1237 depends on SYSFS
>> 1238 default n
>> 1239 help
>> 1240 This option adds code that switches the layout of the "block" class
>> 1241 devices, to not show up in /sys/class/block/, but only in
>> 1242 /sys/block/.
>> 1243
>> 1244 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1245 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1246
>> 1247 This option allows new kernels to run on old distributions and tools,
>> 1248 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1249 major distributions and tools handle this just fine.
>> 1250
>> 1251 Recent distributions and userspace tools after 2009/2010 depend on
>> 1252 the existence of /sys/class/block/, and will not work with this
>> 1253 option enabled.
>> 1254
>> 1255 Only if you are using a new kernel on an old distribution, you might
>> 1256 need to say Y here.
>> 1257
>> 1258 config SYSFS_DEPRECATED_V2
>> 1259 bool "Enable deprecated sysfs features by default"
>> 1260 default n
>> 1261 depends on SYSFS
>> 1262 depends on SYSFS_DEPRECATED
>> 1263 help
>> 1264 Enable deprecated sysfs by default.
>> 1265
>> 1266 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1267 option.
>> 1268
>> 1269 Only if you are using a new kernel on an old distribution, you might
>> 1270 need to say Y here. Even then, odds are you would not need it
>> 1271 enabled, you can always pass the boot option if absolutely necessary.
>> 1272
1347 config RELAY 1273 config RELAY
1348 bool "Kernel->user space relay suppor 1274 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1275 select IRQ_WORK
1350 help 1276 help
1351 This option enables support for rel 1277 This option enables support for relay interface support in
1352 certain file systems (such as debug 1278 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1279 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1280 facilities to relay large amounts of data from kernel space to
1355 user space. 1281 user space.
1356 1282
1357 If unsure, say N. 1283 If unsure, say N.
1358 1284
1359 config BLK_DEV_INITRD 1285 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1286 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1287 help
1362 The initial RAM filesystem is a ram 1288 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1289 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1290 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1291 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1292 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1293
1368 If RAM disk support (BLK_DEV_RAM) i 1294 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1295 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1296 15 Kbytes (more on some other architectures) to the kernel size.
1371 1297
1372 If unsure say Y. 1298 If unsure say Y.
1373 1299
1374 if BLK_DEV_INITRD 1300 if BLK_DEV_INITRD
1375 1301
1376 source "usr/Kconfig" 1302 source "usr/Kconfig"
1377 1303
1378 endif 1304 endif
1379 1305
1380 config BOOT_CONFIG 1306 config BOOT_CONFIG
1381 bool "Boot config support" 1307 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG !! 1308 select BLK_DEV_INITRD
1383 help 1309 help
1384 Extra boot config allows system adm 1310 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1311 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1312 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1313 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1314 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1315
1390 If unsure, say Y. 1316 If unsure, say Y.
1391 1317
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 1318 choice
1435 prompt "Compiler optimization level" 1319 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1320 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1321
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1322 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1323 bool "Optimize for performance (-O2)"
1440 help 1324 help
1441 This is the default optimization le 1325 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1326 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1327 helpful compile-time warnings.
1444 1328
>> 1329 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1330 bool "Optimize more for performance (-O3)"
>> 1331 depends on ARC
>> 1332 help
>> 1333 Choosing this option will pass "-O3" to your compiler to optimize
>> 1334 the kernel yet more for performance.
>> 1335
1445 config CC_OPTIMIZE_FOR_SIZE 1336 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1337 bool "Optimize for size (-Os)"
1447 help 1338 help
1448 Choosing this option will pass "-Os 1339 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1340 in a smaller kernel.
1450 1341
1451 endchoice 1342 endchoice
1452 1343
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1344 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1345 bool
1455 help 1346 help
1456 This requires that the arch annotat 1347 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1348 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1349 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1350 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1351 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1352 is used to distinguish them from label names / C identifiers.
1462 1353
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1354 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1355 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1356 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1357 depends on EXPERT
1467 depends on $(cc-option,-ffunction-sec 1358 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1359 depends on $(ld-option,--gc-sections)
1469 help 1360 help
1470 Enable this if you want to do dead 1361 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1362 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1363 and linking with --gc-sections.
1473 1364
1474 This can reduce on disk and in-memo 1365 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1366 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1367 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1368 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1369 present. This option is not well tested yet, so use at your
1479 own risk. 1370 own risk.
1480 1371
1481 config LD_ORPHAN_WARN 1372 config LD_ORPHAN_WARN
1482 def_bool y 1373 def_bool y
1483 depends on ARCH_WANT_LD_ORPHAN_WARN 1374 depends on ARCH_WANT_LD_ORPHAN_WARN
>> 1375 depends on !LD_IS_LLD || LLD_VERSION >= 110000
1484 depends on $(ld-option,--orphan-handl 1376 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 1377
1493 config SYSCTL 1378 config SYSCTL
1494 bool 1379 bool
1495 1380
1496 config HAVE_UID16 1381 config HAVE_UID16
1497 bool 1382 bool
1498 1383
1499 config SYSCTL_EXCEPTION_TRACE 1384 config SYSCTL_EXCEPTION_TRACE
1500 bool 1385 bool
1501 help 1386 help
1502 Enable support for /proc/sys/debug/ 1387 Enable support for /proc/sys/debug/exception-trace.
1503 1388
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1389 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1390 bool
1506 help 1391 help
1507 Enable support for /proc/sys/kernel 1392 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1393 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1394 about unaligned access emulation going on under the hood.
1510 1395
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1396 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1397 bool
1513 help 1398 help
1514 Enable support for /proc/sys/kernel 1399 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1400 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1401 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1402 see arch/parisc/kernel/unaligned.c for reference
1518 1403
1519 config HAVE_PCSPKR_PLATFORM 1404 config HAVE_PCSPKR_PLATFORM
1520 bool 1405 bool
1521 1406
>> 1407 # interpreter that classic socket filters depend on
>> 1408 config BPF
>> 1409 bool
>> 1410
1522 menuconfig EXPERT 1411 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1412 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1413 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1414 select DEBUG_KERNEL
1526 help 1415 help
1527 This option allows certain base ker 1416 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1417 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1418 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1419 Only use this if you really know what you are doing.
1531 1420
1532 config UID16 1421 config UID16
1533 bool "Enable 16-bit UID system calls" 1422 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1423 depends on HAVE_UID16 && MULTIUSER
1535 default y 1424 default y
1536 help 1425 help
1537 This enables the legacy 16-bit UID 1426 This enables the legacy 16-bit UID syscall wrappers.
1538 1427
1539 config MULTIUSER 1428 config MULTIUSER
1540 bool "Multiple users, groups and capa 1429 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1430 default y
1542 help 1431 help
1543 This option enables support for non 1432 This option enables support for non-root users, groups and
1544 capabilities. 1433 capabilities.
1545 1434
1546 If you say N here, all processes wi 1435 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1436 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1437 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1438 setgid, and capset.
1550 1439
1551 If unsure, say Y here. 1440 If unsure, say Y here.
1552 1441
1553 config SGETMASK_SYSCALL 1442 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1443 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1444 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help 1445 help
1557 sys_sgetmask and sys_ssetmask are o 1446 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1447 no longer supported in libc but still enabled by default in some
1559 architectures. 1448 architectures.
1560 1449
1561 If unsure, leave the default option 1450 If unsure, leave the default option here.
1562 1451
1563 config SYSFS_SYSCALL 1452 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1453 bool "Sysfs syscall support" if EXPERT
1565 default y 1454 default y
1566 help 1455 help
1567 sys_sysfs is an obsolete system cal 1456 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1457 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1458 compatibility with some systems.
1570 1459
1571 If unsure say Y here. 1460 If unsure say Y here.
1572 1461
1573 config FHANDLE 1462 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1463 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1464 select EXPORTFS
1576 default y 1465 default y
1577 help 1466 help
1578 If you say Y here, a user level pro 1467 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1468 file names to handle and then later use the handle for
1580 different file system operations. T 1469 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1470 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1471 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1472 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1473 syscalls.
1585 1474
1586 config POSIX_TIMERS 1475 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1476 bool "Posix Clocks & timers" if EXPERT
1588 default y 1477 default y
1589 help 1478 help
1590 This includes native support for PO 1479 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1480 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1481 can be configured out to reduce the size of the kernel image.
1593 1482
1594 When this option is disabled, the f 1483 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1484 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1485 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1486 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1487 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1488 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1489
1601 If unsure say y. 1490 If unsure say y.
1602 1491
1603 config PRINTK 1492 config PRINTK
1604 default y 1493 default y
1605 bool "Enable support for printk" if E 1494 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1495 select IRQ_WORK
1607 help 1496 help
1608 This option enables normal printk s 1497 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1498 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1499 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1500 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1501 strongly discouraged.
1613 1502
>> 1503 config PRINTK_NMI
>> 1504 def_bool y
>> 1505 depends on PRINTK
>> 1506 depends on HAVE_NMI
>> 1507
1614 config BUG 1508 config BUG
1615 bool "BUG() support" if EXPERT 1509 bool "BUG() support" if EXPERT
1616 default y 1510 default y
1617 help 1511 help
1618 Disabling this option eliminates su 1512 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1513 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1514 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1515 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1516 Just say Y.
1623 1517
1624 config ELF_CORE 1518 config ELF_CORE
1625 depends on COREDUMP 1519 depends on COREDUMP
1626 default y 1520 default y
1627 bool "Enable ELF core dumps" if EXPER 1521 bool "Enable ELF core dumps" if EXPERT
1628 help 1522 help
1629 Enable support for generating core 1523 Enable support for generating core dumps. Disabling saves about 4k.
1630 1524
1631 1525
1632 config PCSPKR_PLATFORM 1526 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1527 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1528 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1529 select I8253_LOCK
1636 default y 1530 default y
1637 help 1531 help
1638 This option allows to disable the i 1532 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1533 support, saving some memory.
1640 1534
1641 config BASE_SMALL !! 1535 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1536 default y
>> 1537 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1538 help
1644 Enabling this option reduces the si !! 1539 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1540 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1541 but may reduce performance.
1647 1542
1648 config FUTEX 1543 config FUTEX
1649 bool "Enable futex support" if EXPERT 1544 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1545 default y
1652 imply RT_MUTEXES 1546 imply RT_MUTEXES
1653 help 1547 help
1654 Disabling this option will cause th 1548 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1549 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1550 run glibc-based applications correctly.
1657 1551
1658 config FUTEX_PI 1552 config FUTEX_PI
1659 bool 1553 bool
1660 depends on FUTEX && RT_MUTEXES 1554 depends on FUTEX && RT_MUTEXES
1661 default y 1555 default y
1662 1556
>> 1557 config HAVE_FUTEX_CMPXCHG
>> 1558 bool
>> 1559 depends on FUTEX
>> 1560 help
>> 1561 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1562 is implemented and always working. This removes a couple of runtime
>> 1563 checks.
>> 1564
1663 config EPOLL 1565 config EPOLL
1664 bool "Enable eventpoll support" if EX 1566 bool "Enable eventpoll support" if EXPERT
1665 default y 1567 default y
1666 help 1568 help
1667 Disabling this option will cause th 1569 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1570 support for epoll family of system calls.
1669 1571
1670 config SIGNALFD 1572 config SIGNALFD
1671 bool "Enable signalfd() system call" 1573 bool "Enable signalfd() system call" if EXPERT
1672 default y 1574 default y
1673 help 1575 help
1674 Enable the signalfd() system call t 1576 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1577 on a file descriptor.
1676 1578
1677 If unsure, say Y. 1579 If unsure, say Y.
1678 1580
1679 config TIMERFD 1581 config TIMERFD
1680 bool "Enable timerfd() system call" i 1582 bool "Enable timerfd() system call" if EXPERT
1681 default y 1583 default y
1682 help 1584 help
1683 Enable the timerfd() system call th 1585 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1586 events on a file descriptor.
1685 1587
1686 If unsure, say Y. 1588 If unsure, say Y.
1687 1589
1688 config EVENTFD 1590 config EVENTFD
1689 bool "Enable eventfd() system call" i 1591 bool "Enable eventfd() system call" if EXPERT
1690 default y 1592 default y
1691 help 1593 help
1692 Enable the eventfd() system call th 1594 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1595 kernel notification (ie. KAIO) or userspace notifications.
1694 1596
1695 If unsure, say Y. 1597 If unsure, say Y.
1696 1598
1697 config SHMEM 1599 config SHMEM
1698 bool "Use full shmem filesystem" if E 1600 bool "Use full shmem filesystem" if EXPERT
1699 default y 1601 default y
1700 depends on MMU 1602 depends on MMU
1701 help 1603 help
1702 The shmem is an internal filesystem 1604 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1605 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1606 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1607 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1608 which may be appropriate on small systems without swap.
1707 1609
1708 config AIO 1610 config AIO
1709 bool "Enable AIO support" if EXPERT 1611 bool "Enable AIO support" if EXPERT
1710 default y 1612 default y
1711 help 1613 help
1712 This option enables POSIX asynchron 1614 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1615 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1616 this option saves about 7k.
1715 1617
1716 config IO_URING 1618 config IO_URING
1717 bool "Enable IO uring support" if EXP 1619 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ 1620 select IO_WQ
1719 default y 1621 default y
1720 help 1622 help
1721 This option enables support for the 1623 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1624 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1625 completion rings that are shared between the kernel and application.
1724 1626
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 1627 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1628 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1629 default y
1741 help 1630 help
1742 This option enables the madvise and 1631 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1632 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1633 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1634 applications use these syscalls, you can disable this option to save
1746 space. 1635 space.
1747 1636
>> 1637 config HAVE_ARCH_USERFAULTFD_WP
>> 1638 bool
>> 1639 help
>> 1640 Arch has userfaultfd write protection support
>> 1641
1748 config MEMBARRIER 1642 config MEMBARRIER
1749 bool "Enable membarrier() system call 1643 bool "Enable membarrier() system call" if EXPERT
1750 default y 1644 default y
1751 help 1645 help
1752 Enable the membarrier() system call 1646 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1647 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1648 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1649 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1650 compiler barrier.
1757 1651
1758 If unsure, say Y. 1652 If unsure, say Y.
1759 1653
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 1654 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1655 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1656 default y
1813 help 1657 help
1814 Say Y here to let the kernel print 1658 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1659 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1660 somewhat, as all symbols have to be loaded into the kernel image.
1817 1661
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 1662 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1663 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1664 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1665 help
1835 Normally kallsyms only contains the 1666 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1667 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m !! 1668 sections). This is sufficient for most cases. And only in very rare
1838 enable kernel live patching, or oth !! 1669 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1839 when a debugger is used) all symbol !! 1670 names of variables from the data sections, etc).
1840 variables from the data sections, e <<
1841 1671
1842 This option makes sure that all sym 1672 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1673 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1674 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1675 something like this).
1846 1676
1847 Say N unless you really need all sy !! 1677 Say N unless you really need all symbols.
1848 1678
1849 config KALLSYMS_ABSOLUTE_PERCPU 1679 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1680 bool
1851 depends on KALLSYMS 1681 depends on KALLSYMS
1852 default X86_64 && SMP 1682 default X86_64 && SMP
1853 1683
>> 1684 config KALLSYMS_BASE_RELATIVE
>> 1685 bool
>> 1686 depends on KALLSYMS
>> 1687 default !IA64
>> 1688 help
>> 1689 Instead of emitting them as absolute values in the native word size,
>> 1690 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1691 each containing a relative value in the range [base, base + U32_MAX]
>> 1692 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1693 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1694 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1695 address encountered in the image.
>> 1696
>> 1697 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1698 but more importantly, it results in entries whose values are build
>> 1699 time constants, and no relocation pass is required at runtime to fix
>> 1700 up the entries based on the runtime load address of the kernel.
>> 1701
1854 # end of the "standard kernel features (exper 1702 # end of the "standard kernel features (expert users)" menu
1855 1703
>> 1704 # syscall, maps, verifier
>> 1705
>> 1706 config BPF_LSM
>> 1707 bool "LSM Instrumentation with BPF"
>> 1708 depends on BPF_EVENTS
>> 1709 depends on BPF_SYSCALL
>> 1710 depends on SECURITY
>> 1711 depends on BPF_JIT
>> 1712 help
>> 1713 Enables instrumentation of the security hooks with eBPF programs for
>> 1714 implementing dynamic MAC and Audit Policies.
>> 1715
>> 1716 If you are unsure how to answer this question, answer N.
>> 1717
>> 1718 config BPF_SYSCALL
>> 1719 bool "Enable bpf() system call"
>> 1720 select BPF
>> 1721 select IRQ_WORK
>> 1722 select TASKS_TRACE_RCU
>> 1723 default n
>> 1724 help
>> 1725 Enable the bpf() system call that allows to manipulate eBPF
>> 1726 programs and maps via file descriptors.
>> 1727
>> 1728 config ARCH_WANT_DEFAULT_BPF_JIT
>> 1729 bool
>> 1730
>> 1731 config BPF_JIT_ALWAYS_ON
>> 1732 bool "Permanently enable BPF JIT and remove BPF interpreter"
>> 1733 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
>> 1734 help
>> 1735 Enables BPF JIT and removes BPF interpreter to avoid
>> 1736 speculative execution of BPF instructions by the interpreter
>> 1737
>> 1738 config BPF_JIT_DEFAULT_ON
>> 1739 def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
>> 1740 depends on HAVE_EBPF_JIT && BPF_JIT
>> 1741
>> 1742 config BPF_UNPRIV_DEFAULT_OFF
>> 1743 bool "Disable unprivileged BPF by default"
>> 1744 depends on BPF_SYSCALL
>> 1745 help
>> 1746 Disables unprivileged BPF by default by setting the corresponding
>> 1747 /proc/sys/kernel/unprivileged_bpf_disabled knob to 2. An admin can
>> 1748 still reenable it by setting it to 0 later on, or permanently
>> 1749 disable it by setting it to 1 (from which no other transition to
>> 1750 0 is possible anymore).
>> 1751
>> 1752 source "kernel/bpf/preload/Kconfig"
>> 1753
>> 1754 config USERFAULTFD
>> 1755 bool "Enable userfaultfd() system call"
>> 1756 depends on MMU
>> 1757 help
>> 1758 Enable the userfaultfd() system call that allows to intercept and
>> 1759 handle page faults in userland.
>> 1760
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1761 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1762 bool
1858 1763
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1764 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1765 bool
1861 1766
>> 1767 config KCMP
>> 1768 bool "Enable kcmp() system call" if EXPERT
>> 1769 help
>> 1770 Enable the kernel resource comparison system call. It provides
>> 1771 user-space with the ability to compare two processes to see if they
>> 1772 share a common resource, such as a file descriptor or even virtual
>> 1773 memory space.
>> 1774
>> 1775 If unsure, say N.
>> 1776
>> 1777 config RSEQ
>> 1778 bool "Enable rseq() system call" if EXPERT
>> 1779 default y
>> 1780 depends on HAVE_RSEQ
>> 1781 select MEMBARRIER
>> 1782 help
>> 1783 Enable the restartable sequences system call. It provides a
>> 1784 user-space cache for the current CPU number value, which
>> 1785 speeds up getting the current CPU number from user-space,
>> 1786 as well as an ABI to speed up user-space operations on
>> 1787 per-CPU data.
>> 1788
>> 1789 If unsure, say Y.
>> 1790
>> 1791 config DEBUG_RSEQ
>> 1792 default n
>> 1793 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1794 depends on RSEQ && DEBUG_KERNEL
>> 1795 help
>> 1796 Enable extra debugging checks for the rseq system call.
>> 1797
>> 1798 If unsure, say N.
>> 1799
>> 1800 config EMBEDDED
>> 1801 bool "Embedded system"
>> 1802 option allnoconfig_y
>> 1803 select EXPERT
>> 1804 help
>> 1805 This option should be enabled if compiling the kernel for
>> 1806 an embedded system so certain expert options are available
>> 1807 for configuration.
>> 1808
1862 config HAVE_PERF_EVENTS 1809 config HAVE_PERF_EVENTS
1863 bool 1810 bool
1864 help 1811 help
1865 See tools/perf/design.txt for detai 1812 See tools/perf/design.txt for details.
1866 1813
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1814 config PERF_USE_VMALLOC
1872 bool 1815 bool
1873 help 1816 help
1874 See tools/perf/design.txt for detai 1817 See tools/perf/design.txt for details
1875 1818
>> 1819 config PC104
>> 1820 bool "PC/104 support" if EXPERT
>> 1821 help
>> 1822 Expose PC/104 form factor device drivers and options available for
>> 1823 selection and configuration. Enable this option if your target
>> 1824 machine has a PC/104 bus.
>> 1825
1876 menu "Kernel Performance Events And Counters" 1826 menu "Kernel Performance Events And Counters"
1877 1827
1878 config PERF_EVENTS 1828 config PERF_EVENTS
1879 bool "Kernel performance events and c 1829 bool "Kernel performance events and counters"
1880 default y if PROFILING 1830 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1831 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1832 select IRQ_WORK
>> 1833 select SRCU
1883 help 1834 help
1884 Enable kernel support for various p 1835 Enable kernel support for various performance events provided
1885 by software and hardware. 1836 by software and hardware.
1886 1837
1887 Software events are supported eithe 1838 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1839 use of generic tracepoints.
1889 1840
1890 Most modern CPUs support performanc 1841 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1842 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1843 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1844 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1845 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1846 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1847 used to profile the code that runs on that CPU.
1897 1848
1898 The Linux Performance Event subsyst 1849 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1850 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1851 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1852 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1853 capabilities on top of those.
1903 1854
1904 Say Y if unsure. 1855 Say Y if unsure.
1905 1856
1906 config DEBUG_PERF_USE_VMALLOC 1857 config DEBUG_PERF_USE_VMALLOC
1907 default n 1858 default n
1908 bool "Debug: use vmalloc to back perf 1859 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1860 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1861 select PERF_USE_VMALLOC
1911 help 1862 help
1912 Use vmalloc memory to back perf mma 1863 Use vmalloc memory to back perf mmap() buffers.
1913 1864
1914 Mostly useful for debugging the vma 1865 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1866 that don't require it.
1916 1867
1917 Say N if unsure. 1868 Say N if unsure.
1918 1869
1919 endmenu 1870 endmenu
1920 1871
>> 1872 config VM_EVENT_COUNTERS
>> 1873 default y
>> 1874 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1875 help
>> 1876 VM event counters are needed for event counts to be shown.
>> 1877 This option allows the disabling of the VM event counters
>> 1878 on EXPERT systems. /proc/vmstat will only show page counts
>> 1879 if VM event counters are disabled.
>> 1880
>> 1881 config SLUB_DEBUG
>> 1882 default y
>> 1883 bool "Enable SLUB debugging support" if EXPERT
>> 1884 depends on SLUB && SYSFS
>> 1885 help
>> 1886 SLUB has extensive debug support features. Disabling these can
>> 1887 result in significant savings in code size. This also disables
>> 1888 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1889 no support for cache validation etc.
>> 1890
>> 1891 config SLUB_MEMCG_SYSFS_ON
>> 1892 default n
>> 1893 bool "Enable memcg SLUB sysfs support by default" if EXPERT
>> 1894 depends on SLUB && SYSFS && MEMCG
>> 1895 help
>> 1896 SLUB creates a directory under /sys/kernel/slab for each
>> 1897 allocation cache to host info and debug files. If memory
>> 1898 cgroup is enabled, each cache can have per memory cgroup
>> 1899 caches. SLUB can create the same sysfs directories for these
>> 1900 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
>> 1901 to a very high number of debug files being created. This is
>> 1902 controlled by slub_memcg_sysfs boot parameter and this
>> 1903 config option determines the parameter's default value.
>> 1904
>> 1905 config COMPAT_BRK
>> 1906 bool "Disable heap randomization"
>> 1907 default y
>> 1908 help
>> 1909 Randomizing heap placement makes heap exploits harder, but it
>> 1910 also breaks ancient binaries (including anything libc5 based).
>> 1911 This option changes the bootup default to heap randomization
>> 1912 disabled, and can be overridden at runtime by setting
>> 1913 /proc/sys/kernel/randomize_va_space to 2.
>> 1914
>> 1915 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1916
>> 1917 choice
>> 1918 prompt "Choose SLAB allocator"
>> 1919 default SLUB
>> 1920 help
>> 1921 This option allows to select a slab allocator.
>> 1922
>> 1923 config SLAB
>> 1924 bool "SLAB"
>> 1925 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1926 help
>> 1927 The regular slab allocator that is established and known to work
>> 1928 well in all environments. It organizes cache hot objects in
>> 1929 per cpu and per node queues.
>> 1930
>> 1931 config SLUB
>> 1932 bool "SLUB (Unqueued Allocator)"
>> 1933 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1934 help
>> 1935 SLUB is a slab allocator that minimizes cache line usage
>> 1936 instead of managing queues of cached objects (SLAB approach).
>> 1937 Per cpu caching is realized using slabs of objects instead
>> 1938 of queues of objects. SLUB can use memory efficiently
>> 1939 and has enhanced diagnostics. SLUB is the default choice for
>> 1940 a slab allocator.
>> 1941
>> 1942 config SLOB
>> 1943 depends on EXPERT
>> 1944 bool "SLOB (Simple Allocator)"
>> 1945 help
>> 1946 SLOB replaces the stock allocator with a drastically simpler
>> 1947 allocator. SLOB is generally more space efficient but
>> 1948 does not perform as well on large systems.
>> 1949
>> 1950 endchoice
>> 1951
>> 1952 config SLAB_MERGE_DEFAULT
>> 1953 bool "Allow slab caches to be merged"
>> 1954 default y
>> 1955 help
>> 1956 For reduced kernel memory fragmentation, slab caches can be
>> 1957 merged when they share the same size and other characteristics.
>> 1958 This carries a risk of kernel heap overflows being able to
>> 1959 overwrite objects from merged caches (and more easily control
>> 1960 cache layout), which makes such heap attacks easier to exploit
>> 1961 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1962 can usually only damage objects in the same cache. To disable
>> 1963 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1964 command line.
>> 1965
>> 1966 config SLAB_FREELIST_RANDOM
>> 1967 bool "Randomize slab freelist"
>> 1968 depends on SLAB || SLUB
>> 1969 help
>> 1970 Randomizes the freelist order used on creating new pages. This
>> 1971 security feature reduces the predictability of the kernel slab
>> 1972 allocator against heap overflows.
>> 1973
>> 1974 config SLAB_FREELIST_HARDENED
>> 1975 bool "Harden slab freelist metadata"
>> 1976 depends on SLAB || SLUB
>> 1977 help
>> 1978 Many kernel heap attacks try to target slab cache metadata and
>> 1979 other infrastructure. This options makes minor performance
>> 1980 sacrifices to harden the kernel slab allocator against common
>> 1981 freelist exploit methods. Some slab implementations have more
>> 1982 sanity-checking than others. This option is most effective with
>> 1983 CONFIG_SLUB.
>> 1984
>> 1985 config SHUFFLE_PAGE_ALLOCATOR
>> 1986 bool "Page allocator randomization"
>> 1987 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1988 help
>> 1989 Randomization of the page allocator improves the average
>> 1990 utilization of a direct-mapped memory-side-cache. See section
>> 1991 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1992 6.2a specification for an example of how a platform advertises
>> 1993 the presence of a memory-side-cache. There are also incidental
>> 1994 security benefits as it reduces the predictability of page
>> 1995 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1996 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1997 10th order of pages is selected based on cache utilization
>> 1998 benefits on x86.
>> 1999
>> 2000 While the randomization improves cache utilization it may
>> 2001 negatively impact workloads on platforms without a cache. For
>> 2002 this reason, by default, the randomization is enabled only
>> 2003 after runtime detection of a direct-mapped memory-side-cache.
>> 2004 Otherwise, the randomization may be force enabled with the
>> 2005 'page_alloc.shuffle' kernel command line parameter.
>> 2006
>> 2007 Say Y if unsure.
>> 2008
>> 2009 config SLUB_CPU_PARTIAL
>> 2010 default y
>> 2011 depends on SLUB && SMP
>> 2012 bool "SLUB per cpu partial cache"
>> 2013 help
>> 2014 Per cpu partial caches accelerate objects allocation and freeing
>> 2015 that is local to a processor at the price of more indeterminism
>> 2016 in the latency of the free. On overflow these caches will be cleared
>> 2017 which requires the taking of locks that may cause latency spikes.
>> 2018 Typically one would choose no for a realtime system.
>> 2019
>> 2020 config MMAP_ALLOW_UNINITIALIZED
>> 2021 bool "Allow mmapped anonymous memory to be uninitialized"
>> 2022 depends on EXPERT && !MMU
>> 2023 default n
>> 2024 help
>> 2025 Normally, and according to the Linux spec, anonymous memory obtained
>> 2026 from mmap() has its contents cleared before it is passed to
>> 2027 userspace. Enabling this config option allows you to request that
>> 2028 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 2029 providing a huge performance boost. If this option is not enabled,
>> 2030 then the flag will be ignored.
>> 2031
>> 2032 This is taken advantage of by uClibc's malloc(), and also by
>> 2033 ELF-FDPIC binfmt's brk and stack allocator.
>> 2034
>> 2035 Because of the obvious security issues, this option should only be
>> 2036 enabled on embedded devices where you control what is run in
>> 2037 userspace. Since that isn't generally a problem on no-MMU systems,
>> 2038 it is normally safe to say Y here.
>> 2039
>> 2040 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
>> 2041
1921 config SYSTEM_DATA_VERIFICATION 2042 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 2043 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 2044 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 2045 select KEYS
1925 select CRYPTO 2046 select CRYPTO
1926 select CRYPTO_RSA 2047 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 2048 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 2049 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 2050 select ASN1
1930 select OID_REGISTRY 2051 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 2052 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 2053 select PKCS7_MESSAGE_PARSER
1933 help 2054 help
1934 Provide PKCS#7 message verification 2055 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 2056 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 2057 module verification, kexec image verification and firmware blob
1937 verification. 2058 verification.
1938 2059
1939 config PROFILING 2060 config PROFILING
1940 bool "Profiling support" 2061 bool "Profiling support"
1941 help 2062 help
1942 Say Y here to enable the extended p 2063 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 2064 by profilers such as OProfile.
1944 <<
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 2065
1986 # 2066 #
1987 # Place an empty function call at each tracep 2067 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 2068 # dynamically changed for a probe function.
1989 # 2069 #
1990 config TRACEPOINTS 2070 config TRACEPOINTS
1991 bool 2071 bool
1992 2072
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 2073 endmenu # General setup
1996 2074
1997 source "arch/Kconfig" 2075 source "arch/Kconfig"
1998 2076
1999 config RT_MUTEXES 2077 config RT_MUTEXES
2000 bool 2078 bool
2001 default y if PREEMPT_RT !! 2079
>> 2080 config BASE_SMALL
>> 2081 int
>> 2082 default 0 if BASE_FULL
>> 2083 default 1 if !BASE_FULL
2002 2084
2003 config MODULE_SIG_FORMAT 2085 config MODULE_SIG_FORMAT
2004 def_bool n 2086 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 2087 select SYSTEM_DATA_VERIFICATION
2006 2088
2007 source "kernel/module/Kconfig" !! 2089 menuconfig MODULES
>> 2090 bool "Enable loadable module support"
>> 2091 option modules
>> 2092 help
>> 2093 Kernel modules are small pieces of compiled code which can
>> 2094 be inserted in the running kernel, rather than being
>> 2095 permanently built into the kernel. You use the "modprobe"
>> 2096 tool to add (and sometimes remove) them. If you say Y here,
>> 2097 many parts of the kernel can be built as modules (by
>> 2098 answering M instead of Y where indicated): this is most
>> 2099 useful for infrequently used options which are not required
>> 2100 for booting. For more information, see the man pages for
>> 2101 modprobe, lsmod, modinfo, insmod and rmmod.
>> 2102
>> 2103 If you say Y here, you will need to run "make
>> 2104 modules_install" to put the modules under /lib/modules/
>> 2105 where modprobe can find them (you may need to be root to do
>> 2106 this).
>> 2107
>> 2108 If unsure, say Y.
>> 2109
>> 2110 if MODULES
>> 2111
>> 2112 config MODULE_FORCE_LOAD
>> 2113 bool "Forced module loading"
>> 2114 default n
>> 2115 help
>> 2116 Allow loading of modules without version information (ie. modprobe
>> 2117 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 2118 is usually a really bad idea.
>> 2119
>> 2120 config MODULE_UNLOAD
>> 2121 bool "Module unloading"
>> 2122 help
>> 2123 Without this option you will not be able to unload any
>> 2124 modules (note that some modules may not be unloadable
>> 2125 anyway), which makes your kernel smaller, faster
>> 2126 and simpler. If unsure, say Y.
>> 2127
>> 2128 config MODULE_FORCE_UNLOAD
>> 2129 bool "Forced module unloading"
>> 2130 depends on MODULE_UNLOAD
>> 2131 help
>> 2132 This option allows you to force a module to unload, even if the
>> 2133 kernel believes it is unsafe: the kernel will remove the module
>> 2134 without waiting for anyone to stop using it (using the -f option to
>> 2135 rmmod). This is mainly for kernel developers and desperate users.
>> 2136 If unsure, say N.
>> 2137
>> 2138 config MODVERSIONS
>> 2139 bool "Module versioning support"
>> 2140 help
>> 2141 Usually, you have to use modules compiled with your kernel.
>> 2142 Saying Y here makes it sometimes possible to use modules
>> 2143 compiled for different kernels, by adding enough information
>> 2144 to the modules to (hopefully) spot any changes which would
>> 2145 make them incompatible with the kernel you are running. If
>> 2146 unsure, say N.
>> 2147
>> 2148 config ASM_MODVERSIONS
>> 2149 bool
>> 2150 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 2151 help
>> 2152 This enables module versioning for exported symbols also from
>> 2153 assembly. This can be enabled only when the target architecture
>> 2154 supports it.
>> 2155
>> 2156 config MODULE_REL_CRCS
>> 2157 bool
>> 2158 depends on MODVERSIONS
>> 2159
>> 2160 config MODULE_SRCVERSION_ALL
>> 2161 bool "Source checksum for all modules"
>> 2162 help
>> 2163 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2164 field inserted into their modinfo section, which contains a
>> 2165 sum of the source files which made it. This helps maintainers
>> 2166 see exactly which source was used to build a module (since
>> 2167 others sometimes change the module source without updating
>> 2168 the version). With this option, such a "srcversion" field
>> 2169 will be created for all modules. If unsure, say N.
>> 2170
>> 2171 config MODULE_SIG
>> 2172 bool "Module signature verification"
>> 2173 select MODULE_SIG_FORMAT
>> 2174 help
>> 2175 Check modules for valid signatures upon load: the signature
>> 2176 is simply appended to the module. For more information see
>> 2177 <file:Documentation/admin-guide/module-signing.rst>.
>> 2178
>> 2179 Note that this option adds the OpenSSL development packages as a
>> 2180 kernel build dependency so that the signing tool can use its crypto
>> 2181 library.
>> 2182
>> 2183 You should enable this option if you wish to use either
>> 2184 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2185 another LSM - otherwise unsigned modules will be loadable regardless
>> 2186 of the lockdown policy.
>> 2187
>> 2188 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2189 module DOES NOT get stripped after being signed. This includes the
>> 2190 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2191 inclusion into an initramfs that wants the module size reduced.
>> 2192
>> 2193 config MODULE_SIG_FORCE
>> 2194 bool "Require modules to be validly signed"
>> 2195 depends on MODULE_SIG
>> 2196 help
>> 2197 Reject unsigned modules or signed modules for which we don't have a
>> 2198 key. Without this, such modules will simply taint the kernel.
>> 2199
>> 2200 config MODULE_SIG_ALL
>> 2201 bool "Automatically sign all modules"
>> 2202 default y
>> 2203 depends on MODULE_SIG
>> 2204 help
>> 2205 Sign all modules during make modules_install. Without this option,
>> 2206 modules must be signed manually, using the scripts/sign-file tool.
>> 2207
>> 2208 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2209 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2210
>> 2211 choice
>> 2212 prompt "Which hash algorithm should modules be signed with?"
>> 2213 depends on MODULE_SIG
>> 2214 help
>> 2215 This determines which sort of hashing algorithm will be used during
>> 2216 signature generation. This algorithm _must_ be built into the kernel
>> 2217 directly so that signature verification can take place. It is not
>> 2218 possible to load a signed module containing the algorithm to check
>> 2219 the signature on that module.
>> 2220
>> 2221 config MODULE_SIG_SHA1
>> 2222 bool "Sign modules with SHA-1"
>> 2223 select CRYPTO_SHA1
>> 2224
>> 2225 config MODULE_SIG_SHA224
>> 2226 bool "Sign modules with SHA-224"
>> 2227 select CRYPTO_SHA256
>> 2228
>> 2229 config MODULE_SIG_SHA256
>> 2230 bool "Sign modules with SHA-256"
>> 2231 select CRYPTO_SHA256
>> 2232
>> 2233 config MODULE_SIG_SHA384
>> 2234 bool "Sign modules with SHA-384"
>> 2235 select CRYPTO_SHA512
>> 2236
>> 2237 config MODULE_SIG_SHA512
>> 2238 bool "Sign modules with SHA-512"
>> 2239 select CRYPTO_SHA512
>> 2240
>> 2241 endchoice
>> 2242
>> 2243 config MODULE_SIG_HASH
>> 2244 string
>> 2245 depends on MODULE_SIG
>> 2246 default "sha1" if MODULE_SIG_SHA1
>> 2247 default "sha224" if MODULE_SIG_SHA224
>> 2248 default "sha256" if MODULE_SIG_SHA256
>> 2249 default "sha384" if MODULE_SIG_SHA384
>> 2250 default "sha512" if MODULE_SIG_SHA512
>> 2251
>> 2252 config MODULE_COMPRESS
>> 2253 bool "Compress modules on installation"
>> 2254 help
>> 2255
>> 2256 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2257 xz depending on "Compression algorithm" below.
>> 2258
>> 2259 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2260
>> 2261 Out-of-tree kernel modules installed using Kbuild will also be
>> 2262 compressed upon installation.
>> 2263
>> 2264 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2265 to compress the whole initrd or initramfs instead.
>> 2266
>> 2267 Note: This is fully compatible with signed modules.
>> 2268
>> 2269 If in doubt, say N.
>> 2270
>> 2271 choice
>> 2272 prompt "Compression algorithm"
>> 2273 depends on MODULE_COMPRESS
>> 2274 default MODULE_COMPRESS_GZIP
>> 2275 help
>> 2276 This determines which sort of compression will be used during
>> 2277 'make modules_install'.
>> 2278
>> 2279 GZIP (default) and XZ are supported.
>> 2280
>> 2281 config MODULE_COMPRESS_GZIP
>> 2282 bool "GZIP"
>> 2283
>> 2284 config MODULE_COMPRESS_XZ
>> 2285 bool "XZ"
>> 2286
>> 2287 endchoice
>> 2288
>> 2289 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2290 bool "Allow loading of modules with missing namespace imports"
>> 2291 help
>> 2292 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2293 a namespace. A module that makes use of a symbol exported with such a
>> 2294 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2295 There is no technical reason to enforce correct namespace imports,
>> 2296 but it creates consistency between symbols defining namespaces and
>> 2297 users importing namespaces they make use of. This option relaxes this
>> 2298 requirement and lifts the enforcement when loading a module.
>> 2299
>> 2300 If unsure, say N.
>> 2301
>> 2302 config UNUSED_SYMBOLS
>> 2303 bool "Enable unused/obsolete exported symbols"
>> 2304 default y if X86
>> 2305 help
>> 2306 Unused but exported symbols make the kernel needlessly bigger. For
>> 2307 that reason most of these unused exports will soon be removed. This
>> 2308 option is provided temporarily to provide a transition period in case
>> 2309 some external kernel module needs one of these symbols anyway. If you
>> 2310 encounter such a case in your module, consider if you are actually
>> 2311 using the right API. (rationale: since nobody in the kernel is using
>> 2312 this in a module, there is a pretty good chance it's actually the
>> 2313 wrong interface to use). If you really need the symbol, please send a
>> 2314 mail to the linux kernel mailing list mentioning the symbol and why
>> 2315 you really need it, and what the merge plan to the mainline kernel for
>> 2316 your module is.
>> 2317
>> 2318 config TRIM_UNUSED_KSYMS
>> 2319 bool "Trim unused exported kernel symbols"
>> 2320 depends on !UNUSED_SYMBOLS
>> 2321 help
>> 2322 The kernel and some modules make many symbols available for
>> 2323 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2324 on the set of modules being selected in your kernel configuration,
>> 2325 many of those exported symbols might never be used.
>> 2326
>> 2327 This option allows for unused exported symbols to be dropped from
>> 2328 the build. In turn, this provides the compiler more opportunities
>> 2329 (especially when using LTO) for optimizing the code and reducing
>> 2330 binary size. This might have some security advantages as well.
>> 2331
>> 2332 If unsure, or if you need to build out-of-tree modules, say N.
>> 2333
>> 2334 config UNUSED_KSYMS_WHITELIST
>> 2335 string "Whitelist of symbols to keep in ksymtab"
>> 2336 depends on TRIM_UNUSED_KSYMS
>> 2337 help
>> 2338 By default, all unused exported symbols will be un-exported from the
>> 2339 build when TRIM_UNUSED_KSYMS is selected.
>> 2340
>> 2341 UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
>> 2342 exported at all times, even in absence of in-tree users. The value to
>> 2343 set here is the path to a text file containing the list of symbols,
>> 2344 one per line. The path can be absolute, or relative to the kernel
>> 2345 source tree.
>> 2346
>> 2347 endif # MODULES
>> 2348
>> 2349 config MODULES_TREE_LOOKUP
>> 2350 def_bool y
>> 2351 depends on PERF_EVENTS || TRACING
2008 2352
2009 config INIT_ALL_POSSIBLE 2353 config INIT_ALL_POSSIBLE
2010 bool 2354 bool
2011 help 2355 help
2012 Back when each arch used to define 2356 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2357 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2358 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2359 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2360 and have several arch maintainers pursuing me down dark alleys.
2017 2361
2018 source "block/Kconfig" 2362 source "block/Kconfig"
2019 2363
2020 config PREEMPT_NOTIFIERS 2364 config PREEMPT_NOTIFIERS
2021 bool 2365 bool
2022 2366
2023 config PADATA 2367 config PADATA
2024 depends on SMP 2368 depends on SMP
2025 bool 2369 bool
2026 2370
2027 config ASN1 2371 config ASN1
2028 tristate 2372 tristate
2029 help 2373 help
2030 Build a simple ASN.1 grammar compil 2374 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2375 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2376 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2377 functions to call on what tags.
2034 2378
2035 source "kernel/Kconfig.locks" 2379 source "kernel/Kconfig.locks"
2036 2380
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2381 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2382 bool
2042 2383
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2384 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2385 bool
2045 2386
2046 # It may be useful for an architecture to ove 2387 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2388 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2389 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2390 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2391 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2392 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2393 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2394 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2395 def_bool n
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