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