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