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