1 # SPDX-License-Identifier: GPL-2.0-only 1 # SPDX-License-Identifier: GPL-2.0-only
2 config CC_VERSION_TEXT !! 2 config DEFCONFIG_LIST
3 string 3 string
4 default "$(CC_VERSION_TEXT)" !! 4 depends on !UML
5 help !! 5 option defconfig_list
6 This is used in unclear ways: !! 6 default "/lib/modules/$(shell,uname -r)/.config"
7 !! 7 default "/etc/kernel-config"
8 - Re-run Kconfig when the compiler i !! 8 default "/boot/config-$(shell,uname -r)"
9 The 'default' property references !! 9 default ARCH_DEFCONFIG
10 CC_VERSION_TEXT so it is recorded !! 10 default "arch/$(ARCH)/defconfig"
11 When the compiler is updated, Kcon <<
12 <<
13 - Ensure full rebuild when the compi <<
14 include/linux/compiler-version.h c <<
15 line so fixdep adds include/config <<
16 auto-generated dependency. When th <<
17 will touch it and then every file <<
18 11
19 config CC_IS_GCC 12 config CC_IS_GCC
20 def_bool $(success,test "$(cc-name)" = !! 13 def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
21 14
22 config GCC_VERSION 15 config GCC_VERSION
23 int 16 int
24 default $(cc-version) if CC_IS_GCC !! 17 default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
25 default 0 18 default 0
26 19
27 config CC_IS_CLANG 20 config CC_IS_CLANG
28 def_bool $(success,test "$(cc-name)" = !! 21 def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
29 <<
30 config CLANG_VERSION <<
31 int <<
32 default $(cc-version) if CC_IS_CLANG <<
33 default 0 <<
34 <<
35 config AS_IS_GNU <<
36 def_bool $(success,test "$(as-name)" = <<
37 <<
38 config AS_IS_LLVM <<
39 def_bool $(success,test "$(as-name)" = <<
40 <<
41 config AS_VERSION <<
42 int <<
43 # Use clang version if this is the int <<
44 default CLANG_VERSION if AS_IS_LLVM <<
45 default $(as-version) <<
46 <<
47 config LD_IS_BFD <<
48 def_bool $(success,test "$(ld-name)" = <<
49 <<
50 config LD_VERSION <<
51 int <<
52 default $(ld-version) if LD_IS_BFD <<
53 default 0 <<
54 22
55 config LD_IS_LLD 23 config LD_IS_LLD
56 def_bool $(success,test "$(ld-name)" = !! 24 def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
57 <<
58 config LLD_VERSION <<
59 int <<
60 default $(ld-version) if LD_IS_LLD <<
61 default 0 <<
62 <<
63 config RUSTC_VERSION <<
64 int <<
65 default $(rustc-version) <<
66 help <<
67 It does not depend on `RUST` since t <<
68 in a `depends on`. <<
69 <<
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 25
81 config RUSTC_LLVM_VERSION !! 26 config CLANG_VERSION
82 int 27 int
83 default $(rustc-llvm-version) !! 28 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
84 29
85 config CC_CAN_LINK 30 config CC_CAN_LINK
86 bool !! 31 def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC))
87 default $(success,$(srctree)/scripts/c <<
88 default $(success,$(srctree)/scripts/c <<
89 <<
90 config CC_CAN_LINK_STATIC <<
91 bool <<
92 default $(success,$(srctree)/scripts/c <<
93 default $(success,$(srctree)/scripts/c <<
94 <<
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5 <<
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id <<
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 32
104 config CC_HAS_ASM_GOTO_OUTPUT !! 33 config CC_HAS_ASM_GOTO
105 def_bool y !! 34 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN <<
107 depends on $(success,echo 'int foo(int <<
108 35
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT 36 config CC_HAS_ASM_GOTO_TIED_OUTPUT
110 depends on CC_HAS_ASM_GOTO_OUTPUT 37 depends on CC_HAS_ASM_GOTO_OUTPUT
111 # Detect buggy gcc and clang, fixed in 38 # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
112 def_bool $(success,echo 'int foo(int * 39 def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
113 40
>> 41 config CC_HAS_ASM_GOTO_OUTPUT
>> 42 depends on CC_HAS_ASM_GOTO
>> 43 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)
>> 44
114 config TOOLS_SUPPORT_RELR 45 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 46 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 47
117 config CC_HAS_ASM_INLINE 48 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 49 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 50
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 51 config CONSTRUCTORS
128 bool 52 bool
>> 53 depends on !UML
129 54
130 config IRQ_WORK 55 config IRQ_WORK
131 def_bool y if SMP !! 56 bool
132 57
133 config BUILDTIME_TABLE_SORT !! 58 config BUILDTIME_EXTABLE_SORT
134 bool 59 bool
135 60
136 config THREAD_INFO_IN_TASK 61 config THREAD_INFO_IN_TASK
137 bool 62 bool
138 help 63 help
139 Select this to move thread_info off 64 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 65 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 66 except flags and fix any runtime bugs.
142 67
143 One subtle change that will be neede 68 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 69 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 70
146 menu "General setup" 71 menu "General setup"
147 72
148 config BROKEN 73 config BROKEN
149 bool 74 bool
150 75
151 config BROKEN_ON_SMP 76 config BROKEN_ON_SMP
152 bool 77 bool
153 depends on BROKEN || !SMP 78 depends on BROKEN || !SMP
154 default y 79 default y
155 80
156 config INIT_ENV_ARG_LIMIT 81 config INIT_ENV_ARG_LIMIT
157 int 82 int
158 default 32 if !UML 83 default 32 if !UML
159 default 128 if UML 84 default 128 if UML
160 help 85 help
161 Maximum of each of the number of arg 86 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 87 variables passed to init from the kernel command line.
163 88
164 config COMPILE_TEST 89 config COMPILE_TEST
165 bool "Compile also drivers which will 90 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM 91 depends on HAS_IOMEM
167 help 92 help
168 Some drivers can be compiled on a di 93 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 94 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 95 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 96 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 97 drivers to compile-test them.
173 98
174 If you are a developer and want to b 99 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 100 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 101 drivers to be distributed.
177 102
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 103 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 104 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 105 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 106 help
199 Compile test headers exported to use 107 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 108 self-contained, i.e. compilable as standalone units.
201 109
202 If you are a developer or tester and 110 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 111 headers are self-contained, say Y here. Otherwise, choose N.
204 112
205 config LOCALVERSION 113 config LOCALVERSION
206 string "Local version - append to kern 114 string "Local version - append to kernel release"
207 help 115 help
208 Append an extra string to the end of 116 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 117 This will show up when you type uname, for example.
210 The string you set here will be appe 118 The string you set here will be appended after the contents of
211 any files with a filename matching l 119 any files with a filename matching localversion* in your
212 object and source tree, in that orde 120 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 121 be a maximum of 64 characters.
214 122
215 config LOCALVERSION_AUTO 123 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 124 bool "Automatically append version information to the version string"
217 default y 125 default y
218 depends on !COMPILE_TEST 126 depends on !COMPILE_TEST
219 help 127 help
220 This will try to automatically deter 128 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 129 release tree by looking for git tags that belong to the current
222 top of tree revision. 130 top of tree revision.
223 131
224 A string of the format -gxxxxxxxx wi 132 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 133 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 134 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 135 set in CONFIG_LOCALVERSION.
228 136
229 (The actual string used here is the !! 137 (The actual string used here is the first eight characters produced
230 by running the command: 138 by running the command:
231 139
232 $ git rev-parse --verify HEAD 140 $ git rev-parse --verify HEAD
233 141
234 which is done within the script "scr 142 which is done within the script "scripts/setlocalversion".)
235 143
236 config BUILD_SALT 144 config BUILD_SALT
237 string "Build ID Salt" !! 145 string "Build ID Salt"
238 default "" !! 146 default ""
239 help !! 147 help
240 The build ID is used to link binarie !! 148 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th !! 149 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi !! 150 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's !! 151 build is unique between builds. It's safe to leave the default.
244 152
245 config HAVE_KERNEL_GZIP 153 config HAVE_KERNEL_GZIP
246 bool 154 bool
247 155
248 config HAVE_KERNEL_BZIP2 156 config HAVE_KERNEL_BZIP2
249 bool 157 bool
250 158
251 config HAVE_KERNEL_LZMA 159 config HAVE_KERNEL_LZMA
252 bool 160 bool
253 161
254 config HAVE_KERNEL_XZ 162 config HAVE_KERNEL_XZ
255 bool 163 bool
256 164
257 config HAVE_KERNEL_LZO 165 config HAVE_KERNEL_LZO
258 bool 166 bool
259 167
260 config HAVE_KERNEL_LZ4 168 config HAVE_KERNEL_LZ4
261 bool 169 bool
262 170
263 config HAVE_KERNEL_ZSTD <<
264 bool <<
265 <<
266 config HAVE_KERNEL_UNCOMPRESSED 171 config HAVE_KERNEL_UNCOMPRESSED
267 bool 172 bool
268 173
269 choice 174 choice
270 prompt "Kernel compression mode" 175 prompt "Kernel compression mode"
271 default KERNEL_GZIP 176 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE !! 177 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
273 help 178 help
274 The linux kernel is a kind of self-e 179 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 180 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 181 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 182 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 183 Decompression speed is relevant at each boot.
279 184
280 If you have any problems with bzip2 185 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 186 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 187 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 188 supplied by Christian Ludwig)
284 189
285 High compression options are mostly 190 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 191 are low on disk space (embedded systems), but for whom ram
287 size matters less. 192 size matters less.
288 193
289 If in doubt, select 'gzip' 194 If in doubt, select 'gzip'
290 195
291 config KERNEL_GZIP 196 config KERNEL_GZIP
292 bool "Gzip" 197 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 198 depends on HAVE_KERNEL_GZIP
294 help 199 help
295 The old and tried gzip compression. 200 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 201 between compression ratio and decompression speed.
297 202
298 config KERNEL_BZIP2 203 config KERNEL_BZIP2
299 bool "Bzip2" 204 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 205 depends on HAVE_KERNEL_BZIP2
301 help 206 help
302 Its compression ratio and speed is i 207 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 208 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 209 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 210 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 211 will need at least 8MB RAM or more for booting.
307 212
308 config KERNEL_LZMA 213 config KERNEL_LZMA
309 bool "LZMA" 214 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 215 depends on HAVE_KERNEL_LZMA
311 help 216 help
312 This compression algorithm's ratio i 217 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 218 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 219 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 220
316 config KERNEL_XZ 221 config KERNEL_XZ
317 bool "XZ" 222 bool "XZ"
318 depends on HAVE_KERNEL_XZ 223 depends on HAVE_KERNEL_XZ
319 help 224 help
320 XZ uses the LZMA2 algorithm and inst 225 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 226 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 227 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 228 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 229 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 230 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 231
328 The speed is about the same as with 232 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 233 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 234 and LZO. Compression is slow.
331 235
332 config KERNEL_LZO 236 config KERNEL_LZO
333 bool "LZO" 237 bool "LZO"
334 depends on HAVE_KERNEL_LZO 238 depends on HAVE_KERNEL_LZO
335 help 239 help
336 Its compression ratio is the poorest 240 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 241 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 242 (both compression and decompression) is the fastest.
339 243
340 config KERNEL_LZ4 244 config KERNEL_LZ4
341 bool "LZ4" 245 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 246 depends on HAVE_KERNEL_LZ4
343 help 247 help
344 LZ4 is an LZ77-type compressor with 248 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 249 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 250 <https://code.google.com/p/lz4/>.
347 251
348 Its compression ratio is worse than 252 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 253 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 254 faster than LZO.
351 255
352 config KERNEL_ZSTD <<
353 bool "ZSTD" <<
354 depends on HAVE_KERNEL_ZSTD <<
355 help <<
356 ZSTD is a compression algorithm targ <<
357 with fast decompression speed. It wi <<
358 decompress around the same speed as <<
359 will need at least 192 KB RAM or mor <<
360 line tool is required for compressio <<
361 <<
362 config KERNEL_UNCOMPRESSED 256 config KERNEL_UNCOMPRESSED
363 bool "None" 257 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 258 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 259 help
366 Produce uncompressed kernel image. T 260 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 261 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 262 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 263 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 264 and jump right at uncompressed kernel image.
371 265
372 endchoice 266 endchoice
373 267
374 config DEFAULT_INIT <<
375 string "Default init path" <<
376 default "" <<
377 help <<
378 This option determines the default i <<
379 option is passed on the kernel comma <<
380 not present, we will still then move <<
381 locations (e.g. /sbin/init, etc). If <<
382 the fallback list when init= is not <<
383 <<
384 config DEFAULT_HOSTNAME 268 config DEFAULT_HOSTNAME
385 string "Default hostname" 269 string "Default hostname"
386 default "(none)" 270 default "(none)"
387 help 271 help
388 This option determines the default s 272 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 273 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 274 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 275 system more usable with less configuration.
392 276
>> 277 #
>> 278 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 279 # add proper SWAP support to them, in which case this can be remove.
>> 280 #
>> 281 config ARCH_NO_SWAP
>> 282 bool
>> 283
>> 284 config SWAP
>> 285 bool "Support for paging of anonymous memory (swap)"
>> 286 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 287 default y
>> 288 help
>> 289 This option allows you to choose whether you want to have support
>> 290 for so called swap devices or swap files in your kernel that are
>> 291 used to provide more virtual memory than the actual RAM present
>> 292 in your computer. If unsure say Y.
>> 293
393 config SYSVIPC 294 config SYSVIPC
394 bool "System V IPC" 295 bool "System V IPC"
395 help !! 296 ---help---
396 Inter Process Communication is a sui 297 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 298 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 299 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 300 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 301 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 302 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 303 you'll need to say Y here.
403 304
404 You can find documentation about IPC 305 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 306 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 307 <http://www.tldp.org/guides.html>.
407 308
408 config SYSVIPC_SYSCTL 309 config SYSVIPC_SYSCTL
409 bool 310 bool
410 depends on SYSVIPC 311 depends on SYSVIPC
411 depends on SYSCTL 312 depends on SYSCTL
412 default y 313 default y
413 314
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 315 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 316 bool "POSIX Message Queues"
420 depends on NET 317 depends on NET
421 help !! 318 ---help---
422 POSIX variant of message queues is a 319 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 320 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 321 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 322 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 323 queues (functions mq_*) say Y here.
427 324
428 POSIX message queues are visible as 325 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 326 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 327 operations on message queues.
431 328
432 If unsure, say Y. 329 If unsure, say Y.
433 330
434 config POSIX_MQUEUE_SYSCTL 331 config POSIX_MQUEUE_SYSCTL
435 bool 332 bool
436 depends on POSIX_MQUEUE 333 depends on POSIX_MQUEUE
437 depends on SYSCTL 334 depends on SYSCTL
438 default y 335 default y
439 336
440 config WATCH_QUEUE <<
441 bool "General notification queue" <<
442 default n <<
443 help <<
444 <<
445 This is a general notification queue <<
446 userspace by splicing them into pipe <<
447 with watches for key/keyring change <<
448 notifications. <<
449 <<
450 See Documentation/core-api/watch_que <<
451 <<
452 config CROSS_MEMORY_ATTACH 337 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 338 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 339 depends on MMU
455 default y 340 default y
456 help 341 help
457 Enabling this option adds the system 342 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 343 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 344 to directly read from or write to another process' address space.
460 See the man page for more details. 345 See the man page for more details.
461 346
462 config USELIB 347 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 348 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 349 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 350 help
466 This option enables the uselib sysca 351 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 352 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 353 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 354 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 355 running glibc can safely disable this.
471 356
472 config AUDIT 357 config AUDIT
473 bool "Auditing support" 358 bool "Auditing support"
474 depends on NET 359 depends on NET
475 help 360 help
476 Enable auditing infrastructure that 361 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 362 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 363 logging of avc messages output). System call auditing is included
479 on architectures which support it. 364 on architectures which support it.
480 365
481 config HAVE_ARCH_AUDITSYSCALL 366 config HAVE_ARCH_AUDITSYSCALL
482 bool 367 bool
483 368
484 config AUDITSYSCALL 369 config AUDITSYSCALL
485 def_bool y 370 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 371 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 372 select FSNOTIFY
488 373
489 source "kernel/irq/Kconfig" 374 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 375 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" <<
492 source "kernel/Kconfig.preempt" 376 source "kernel/Kconfig.preempt"
493 377
494 menu "CPU/Task time and stats accounting" 378 menu "CPU/Task time and stats accounting"
495 379
496 config VIRT_CPU_ACCOUNTING 380 config VIRT_CPU_ACCOUNTING
497 bool 381 bool
498 382
499 choice 383 choice
500 prompt "Cputime accounting" 384 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 385 default TICK_CPU_ACCOUNTING if !PPC64
>> 386 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 387
503 # Kind of a stub config for the pure tick base 388 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 389 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 390 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 391 depends on !S390 && !NO_HZ_FULL
507 help 392 help
508 This is the basic tick based cputime 393 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 394 statistics about user, system and idle time spent on per jiffies
510 granularity. 395 granularity.
511 396
512 If unsure, say Y. 397 If unsure, say Y.
513 398
514 config VIRT_CPU_ACCOUNTING_NATIVE 399 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 400 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 401 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 402 select VIRT_CPU_ACCOUNTING
518 help 403 help
519 Select this option to enable more ac 404 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 405 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 406 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 407 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 408 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 409 this also enables accounting of stolen time on logically-partitioned
525 systems. 410 systems.
526 411
527 config VIRT_CPU_ACCOUNTING_GEN 412 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 413 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 414 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 415 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 416 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 417 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 418 select CONTEXT_TRACKING
534 help 419 help
535 Select this option to enable task an 420 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 421 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 422 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 423 The accounting is thus performed at the expense of some significant
539 overhead. 424 overhead.
540 425
541 For now this is only useful if you a 426 For now this is only useful if you are working on the full
542 dynticks subsystem development. 427 dynticks subsystem development.
543 428
544 If unsure, say N. 429 If unsure, say N.
545 430
546 endchoice 431 endchoice
547 432
548 config IRQ_TIME_ACCOUNTING 433 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 434 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 435 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 436 help
552 Select this option to enable fine gr 437 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 438 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 439 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 440 small performance impact.
556 441
557 If in doubt, say N here. 442 If in doubt, say N here.
558 443
559 config HAVE_SCHED_AVG_IRQ 444 config HAVE_SCHED_AVG_IRQ
560 def_bool y 445 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 446 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 447 depends on SMP
563 448
564 config SCHED_HW_PRESSURE <<
565 bool <<
566 default y if ARM && ARM_CPU_TOPOLOGY <<
567 default y if ARM64 <<
568 depends on SMP <<
569 depends on CPU_FREQ_THERMAL <<
570 help <<
571 Select this option to enable HW pres <<
572 scheduler. HW pressure is the value <<
573 that reflects the reduction in CPU c <<
574 HW throttling. HW throttling occurs <<
575 a CPU is capped due to high operatin <<
576 <<
577 If selected, the scheduler will be a <<
578 i.e. put less load on throttled CPUs <<
579 <<
580 This requires the architecture to im <<
581 arch_update_hw_pressure() and arch_s <<
582 <<
583 config BSD_PROCESS_ACCT 449 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 450 bool "BSD Process Accounting"
585 depends on MULTIUSER 451 depends on MULTIUSER
586 help 452 help
587 If you say Y here, a user level prog 453 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 454 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 455 information to a file: whenever a process exits, information about
590 that process will be appended to the 456 that process will be appended to the file by the kernel. The
591 information includes things such as 457 information includes things such as creation time, owning user,
592 command name, memory usage, controll 458 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 459 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 460 up to the user level program to do useful things with this
595 information. This is generally a go 461 information. This is generally a good idea, so say Y.
596 462
597 config BSD_PROCESS_ACCT_V3 463 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 464 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 465 depends on BSD_PROCESS_ACCT
600 default n 466 default n
601 help 467 help
602 If you say Y here, the process accou 468 If you say Y here, the process accounting information is written
603 in a new file format that also logs 469 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 470 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 471 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 472 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 473 at <http://www.gnu.org/software/acct/>.
608 474
609 config TASKSTATS 475 config TASKSTATS
610 bool "Export task/process statistics t 476 bool "Export task/process statistics through netlink"
611 depends on NET 477 depends on NET
612 depends on MULTIUSER 478 depends on MULTIUSER
613 default n 479 default n
614 help 480 help
615 Export selected statistics for tasks 481 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 482 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 483 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 484 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 485 space on task exit.
620 486
621 Say N if unsure. 487 Say N if unsure.
622 488
623 config TASK_DELAY_ACCT 489 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 490 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 491 depends on TASKSTATS
626 select SCHED_INFO 492 select SCHED_INFO
627 help 493 help
628 Collect information on time spent by 494 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 495 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 496 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 497 relative to other tasks for cpu, io, rss limits etc.
632 498
633 Say N if unsure. 499 Say N if unsure.
634 500
635 config TASK_XACCT 501 config TASK_XACCT
636 bool "Enable extended accounting over 502 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 503 depends on TASKSTATS
638 help 504 help
639 Collect extended task accounting dat 505 Collect extended task accounting data and send the data
640 to userland for processing over the 506 to userland for processing over the taskstats interface.
641 507
642 Say N if unsure. 508 Say N if unsure.
643 509
644 config TASK_IO_ACCOUNTING 510 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 511 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 512 depends on TASK_XACCT
647 help 513 help
648 Collect information on the number of 514 Collect information on the number of bytes of storage I/O which this
649 task has caused. 515 task has caused.
650 516
651 Say N if unsure. 517 Say N if unsure.
652 518
653 config PSI 519 config PSI
654 bool "Pressure stall information track 520 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 521 help
657 Collect metrics that indicate how ov 522 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 523 and IO capacity are in the system.
659 524
660 If you say Y here, the kernel will c 525 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 526 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 527 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 528 delayed due to contention of the respective resource.
664 529
665 In kernels with cgroup support, cgro 530 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 531 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 532 which aggregate pressure stalls for the grouped tasks only.
668 533
669 For more details see Documentation/a 534 For more details see Documentation/accounting/psi.rst.
670 535
671 Say N if unsure. 536 Say N if unsure.
672 537
673 config PSI_DEFAULT_DISABLED 538 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 539 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 540 default n
676 depends on PSI 541 depends on PSI
677 help 542 help
678 If set, pressure stall information t 543 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 544 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 545 kernel commandline during boot.
681 546
682 This feature adds some code to the t 547 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 548 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 549 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 550 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 551 scheduler stress tests, such as hackbench.
687 552
688 If you are paranoid and not sure wha 553 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 554 used for, say Y.
690 555
691 Say N if unsure. 556 Say N if unsure.
692 557
693 endmenu # "CPU/Task time and stats accounting" 558 endmenu # "CPU/Task time and stats accounting"
694 559
695 config CPU_ISOLATION 560 config CPU_ISOLATION
696 bool "CPU isolation" 561 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 562 depends on SMP || COMPILE_TEST
698 default y 563 default y
699 help 564 help
700 Make sure that CPUs running critical 565 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 566 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 567 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 568 the "isolcpus=" boot parameter.
704 569
705 Say Y if unsure. 570 Say Y if unsure.
706 571
707 source "kernel/rcu/Kconfig" 572 source "kernel/rcu/Kconfig"
708 573
>> 574 config BUILD_BIN2C
>> 575 bool
>> 576 default n
>> 577
709 config IKCONFIG 578 config IKCONFIG
710 tristate "Kernel .config support" 579 tristate "Kernel .config support"
711 help !! 580 ---help---
712 This option enables the complete Lin 581 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 582 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 583 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 584 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 585 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 586 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 587 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 588 /proc/config.gz if enabled (below).
720 589
721 config IKCONFIG_PROC 590 config IKCONFIG_PROC
722 bool "Enable access to .config through 591 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 592 depends on IKCONFIG && PROC_FS
724 help !! 593 ---help---
725 This option enables access to the ke 594 This option enables access to the kernel configuration file
726 through /proc/config.gz. 595 through /proc/config.gz.
727 596
728 config IKHEADERS 597 config IKHEADERS
729 tristate "Enable kernel headers throug 598 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 599 depends on SYSFS
731 help 600 help
732 This option enables access to the in 601 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 602 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 603 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 604 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 605
737 config LOG_BUF_SHIFT 606 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 607 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 !! 608 range 12 25 if !H8300
>> 609 range 12 19 if H8300
740 default 17 610 default 17
741 depends on PRINTK 611 depends on PRINTK
742 help 612 help
743 Select the minimal kernel log buffer 613 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 614 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 615 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 616 by "log_buf_len" boot parameter.
747 617
748 Examples: 618 Examples:
749 17 => 128 KB 619 17 => 128 KB
750 16 => 64 KB 620 16 => 64 KB
751 15 => 32 KB 621 15 => 32 KB
752 14 => 16 KB 622 14 => 16 KB
753 13 => 8 KB 623 13 => 8 KB
754 12 => 4 KB 624 12 => 4 KB
755 625
756 config LOG_CPU_MAX_BUF_SHIFT 626 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 627 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 628 depends on SMP
759 range 0 21 629 range 0 21
>> 630 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 631 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 632 depends on PRINTK
763 help 633 help
764 This option allows to increase the d 634 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 635 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 636 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 637 lines however it might be much more when problems are reported,
768 e.g. backtraces. 638 e.g. backtraces.
769 639
770 The increased size means that a new 640 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 641 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 642 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 643 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 644 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed !! 645 so that more than 64 CPUs are needed to trigger the allocation.
776 646
777 Also this option is ignored when "lo 647 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 648 used as it forces an exact (power of two) size of the ring buffer.
779 649
780 The number of possible CPUs is used 650 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 651 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 652 scenario while allowing a simple algorithm to be used from bootup.
783 653
784 Examples shift values and their mean 654 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 655 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 656 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 657 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 658 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 659 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 660 12 => 4 KB for each CPU
791 661
792 config PRINTK_INDEX !! 662 config PRINTK_SAFE_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 663 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 664 range 10 21
795 help !! 665 default 13
796 Add support for indexing of all prin !! 666 depends on PRINTK
797 at <debugfs>/printk/index/<module>. !! 667 help
798 !! 668 Select the size of an alternate printk per-CPU buffer where messages
799 This can be used as part of maintain !! 669 printed from usafe contexts are temporary stored. One example would
800 /dev/kmsg, as it permits auditing th !! 670 be NMI messages, another one - printk recursion. The messages are
801 kernel, allowing detection of cases !! 671 copied to the main log buffer in a safe context to avoid a deadlock.
802 changed or no longer present. !! 672 The value defines the size as a power of 2.
>> 673
>> 674 Those messages are rare and limited. The largest one is when
>> 675 a backtrace is printed. It usually fits into 4KB. Select
>> 676 8KB if you want to be on the safe side.
803 677
804 There is no additional runtime cost !! 678 Examples:
>> 679 17 => 128 KB for each CPU
>> 680 16 => 64 KB for each CPU
>> 681 15 => 32 KB for each CPU
>> 682 14 => 16 KB for each CPU
>> 683 13 => 8 KB for each CPU
>> 684 12 => 4 KB for each CPU
805 685
806 # 686 #
807 # Architectures with an unreliable sched_clock 687 # Architectures with an unreliable sched_clock() should select this:
808 # 688 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 689 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 690 bool
811 691
812 config GENERIC_SCHED_CLOCK 692 config GENERIC_SCHED_CLOCK
813 bool 693 bool
814 694
815 menu "Scheduler features" 695 menu "Scheduler features"
816 696
817 config UCLAMP_TASK 697 config UCLAMP_TASK
818 bool "Enable utilization clamping for 698 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 699 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 700 help
821 This feature enables the scheduler t 701 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 702 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 703
824 With this option, the user can speci 704 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 705 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 706 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 707 defines the minimum frequency it should use.
828 708
829 Both min and max utilization clamp v 709 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 710 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 711 enforce or grant any specific bandwidth for tasks.
832 712
833 If in doubt, say N. 713 If in doubt, say N.
834 714
835 config UCLAMP_BUCKETS_COUNT 715 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 716 int "Number of supported utilization clamp buckets"
837 range 5 20 717 range 5 20
838 default 5 718 default 5
839 depends on UCLAMP_TASK 719 depends on UCLAMP_TASK
840 help 720 help
841 Defines the number of clamp buckets 721 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 722 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 723 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 724 the precision of clamping aggregation and tracking at run-time.
845 725
846 For example, with the minimum config 726 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 727 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 728 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 729 effective value to 25%.
850 If a second 30% boosted task should 730 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 731 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 732 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 733 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 734 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 735 that bucket.
856 736
857 An additional boost/capping margin c 737 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 738 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 739 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 740 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 741 clamp buckets to trade off used memory for run-time tracking
862 precision. 742 precision.
863 743
864 If in doubt, use the default value. 744 If in doubt, use the default value.
865 745
866 endmenu 746 endmenu
867 747
868 # 748 #
869 # For architectures that want to enable the su 749 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 750 # balancing logic:
871 # 751 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 752 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 753 bool
874 754
875 # 755 #
876 # For architectures that prefer to flush all T 756 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 757 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 758 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 759 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 760 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 761 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 762 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 763 bool
884 764
885 config CC_HAS_INT128 <<
886 def_bool !$(cc-option,$(m64-flag) -D__ <<
887 <<
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 # 765 #
915 # For architectures that know their GCC __int1 766 # For architectures that know their GCC __int128 support is sound
916 # 767 #
917 config ARCH_SUPPORTS_INT128 768 config ARCH_SUPPORTS_INT128
918 bool 769 bool
919 770
920 # For architectures that (ab)use NUMA to repre 771 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 772 # all cpu-local but of different latencies, such as SuperH.
922 # 773 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 774 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 775 bool
925 776
926 config NUMA_BALANCING 777 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 778 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 779 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 780 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 781 depends on SMP && NUMA && MIGRATION
931 help 782 help
932 This option adds support for automat 783 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 784 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 785 it has references to the node the task is running on.
935 786
936 This system will be inactive on UMA 787 This system will be inactive on UMA systems.
937 788
938 config NUMA_BALANCING_DEFAULT_ENABLED 789 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 790 bool "Automatically enable NUMA aware memory/task placement"
940 default y 791 default y
941 depends on NUMA_BALANCING 792 depends on NUMA_BALANCING
942 help 793 help
943 If set, automatic NUMA balancing wil 794 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 795 machine.
945 796
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 797 menuconfig CGROUPS
950 bool "Control Group support" 798 bool "Control Group support"
951 select KERNFS 799 select KERNFS
952 help 800 help
953 This option adds support for groupin 801 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 802 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 803 controls or device isolation.
956 See 804 See
957 - Documentation/scheduler/sche 805 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 806 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 807 and resource control)
960 808
961 Say N if unsure. 809 Say N if unsure.
962 810
963 if CGROUPS 811 if CGROUPS
964 812
965 config PAGE_COUNTER 813 config PAGE_COUNTER
966 bool !! 814 bool
967 <<
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. <<
977 815
978 config MEMCG 816 config MEMCG
979 bool "Memory controller" 817 bool "Memory controller"
980 select PAGE_COUNTER 818 select PAGE_COUNTER
981 select EVENTFD 819 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 820 help
984 Provides control over the memory foo 821 Provides control over the memory footprint of tasks in a cgroup.
985 822
986 config MEMCG_V1 !! 823 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 824 bool "Swap controller"
988 depends on MEMCG !! 825 depends on MEMCG && SWAP
989 default n <<
990 help 826 help
991 Legacy cgroup v1 memory controller w !! 827 Provides control over the swap space consumed by tasks in a cgroup.
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 828
1001 Say N if unsure. !! 829 config MEMCG_SWAP_ENABLED
>> 830 bool "Swap controller enabled by default"
>> 831 depends on MEMCG_SWAP
>> 832 default y
>> 833 help
>> 834 Memory Resource Controller Swap Extension comes with its price in
>> 835 a bigger memory consumption. General purpose distribution kernels
>> 836 which want to enable the feature but keep it disabled by default
>> 837 and let the user enable it by swapaccount=1 boot command line
>> 838 parameter should have this option unselected.
>> 839 For those who want to have the feature enabled by default should
>> 840 select this option (if, for some reason, they need to disable it
>> 841 then swapaccount=0 does the trick).
>> 842
>> 843 config MEMCG_KMEM
>> 844 bool
>> 845 depends on MEMCG && !SLOB
>> 846 default y
1002 847
1003 config BLK_CGROUP 848 config BLK_CGROUP
1004 bool "IO controller" 849 bool "IO controller"
1005 depends on BLOCK 850 depends on BLOCK
1006 default n 851 default n
1007 help !! 852 ---help---
1008 Generic block IO controller cgroup in 853 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 854 cgroup interface which should be used by various IO controlling
1010 policies. 855 policies.
1011 856
1012 Currently, CFQ IO scheduler uses it t 857 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 858 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 859 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 860 block layer to implement upper limit in IO rates on a device.
1016 861
1017 This option only enables generic Bloc 862 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 863 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 864 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl !! 865 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 866 CONFIG_BLK_DEV_THROTTLING=y.
1022 867
1023 See Documentation/admin-guide/cgroup- 868 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 869
1025 config CGROUP_WRITEBACK 870 config CGROUP_WRITEBACK
1026 bool 871 bool
1027 depends on MEMCG && BLK_CGROUP 872 depends on MEMCG && BLK_CGROUP
1028 default y 873 default y
1029 874
1030 menuconfig CGROUP_SCHED 875 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 876 bool "CPU controller"
1032 default n 877 default n
1033 help 878 help
1034 This feature lets CPU scheduler rec 879 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 880 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 881 tasks.
1037 882
1038 if CGROUP_SCHED 883 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 884 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 885 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 886 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 887 default CGROUP_SCHED
1047 888
1048 config CFS_BANDWIDTH 889 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 890 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 891 depends on FAIR_GROUP_SCHED
1051 default n 892 default n
1052 help 893 help
1053 This option allows users to define 894 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 895 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 896 set are considered to be unconstrained and will run with no
1056 restriction. 897 restriction.
1057 See Documentation/scheduler/sched-b 898 See Documentation/scheduler/sched-bwc.rst for more information.
1058 899
1059 config RT_GROUP_SCHED 900 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 901 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 902 depends on CGROUP_SCHED
1062 default n 903 default n
1063 help 904 help
1064 This feature lets you explicitly al 905 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 906 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 907 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 908 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 909 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 910
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 911 endif #CGROUP_SCHED
1077 912
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 913 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 914 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 915 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 916 depends on UCLAMP_TASK
1086 default n 917 default n
1087 help 918 help
1088 This feature enables the scheduler 919 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 920 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 921
1091 When this option is enabled, the us 922 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 923 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 924 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 925 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 926 frequency a task will always use.
1096 927
1097 When task group based utilization c 928 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 929 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 930 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 931 be bigger than the corresponding clamping defined at task group level.
1101 932
1102 If in doubt, say N. 933 If in doubt, say N.
1103 934
1104 config CGROUP_PIDS 935 config CGROUP_PIDS
1105 bool "PIDs controller" 936 bool "PIDs controller"
1106 help 937 help
1107 Provides enforcement of process num 938 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 939 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 940 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 941 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 942 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 943 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 944 PIDs controller is designed to stop this from happening.
1114 945
1115 It should be noted that organisatio 946 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 947 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 948 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 949 attach to a cgroup.
1119 950
1120 config CGROUP_RDMA 951 config CGROUP_RDMA
1121 bool "RDMA controller" 952 bool "RDMA controller"
1122 help 953 help
1123 Provides enforcement of RDMA resour 954 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 955 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 956 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 957 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 958 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 959 hierarchy is allowed even if can cross the hierarchy's limit.
1129 960
1130 config CGROUP_FREEZER 961 config CGROUP_FREEZER
1131 bool "Freezer controller" 962 bool "Freezer controller"
1132 help 963 help
1133 Provides a way to freeze and unfree 964 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 965 cgroup.
1135 966
1136 This option affects the ORIGINAL cg 967 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 968 controller includes important in-kernel memory consumers per default.
1138 969
1139 If you're using cgroup2, say N. 970 If you're using cgroup2, say N.
1140 971
1141 config CGROUP_HUGETLB 972 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 973 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 974 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 975 select PAGE_COUNTER
1145 default n 976 default n
1146 help 977 help
1147 Provides a cgroup controller for Hu 978 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 979 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 980 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 981 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 982 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 983 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 984 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 985 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 986 that we cannot use the controller with huge page less than 3 pages.
1156 987
1157 config CPUSETS 988 config CPUSETS
1158 bool "Cpuset controller" 989 bool "Cpuset controller"
1159 depends on SMP 990 depends on SMP
1160 help 991 help
1161 This option will let you create and 992 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 993 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 994 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 995 This is primarily useful on large SMP or NUMA systems.
1165 996
1166 Say N if unsure. 997 Say N if unsure.
1167 998
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 999 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1000 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1001 depends on CPUSETS
1184 default y 1002 default y
1185 1003
1186 config CGROUP_DEVICE 1004 config CGROUP_DEVICE
1187 bool "Device controller" 1005 bool "Device controller"
1188 help 1006 help
1189 Provides a cgroup controller implem 1007 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1008 devices which a process in the cgroup can mknod or open.
1191 1009
1192 config CGROUP_CPUACCT 1010 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1011 bool "Simple CPU accounting controller"
1194 help 1012 help
1195 Provides a simple controller for mo 1013 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1014 total CPU consumed by the tasks in a cgroup.
1197 1015
1198 config CGROUP_PERF 1016 config CGROUP_PERF
1199 bool "Perf controller" 1017 bool "Perf controller"
1200 depends on PERF_EVENTS 1018 depends on PERF_EVENTS
1201 help 1019 help
1202 This option extends the perf per-cp 1020 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1021 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use !! 1022 designated cpu.
1205 so that it can monitor performance <<
1206 1023
1207 Say N if unsure. 1024 Say N if unsure.
1208 1025
1209 config CGROUP_BPF 1026 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1027 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1028 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1029 select SOCK_CGROUP_DATA
1213 help 1030 help
1214 Allow attaching eBPF programs to a 1031 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1032 syscall command BPF_PROG_ATTACH.
1216 1033
1217 In which context these programs are 1034 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1035 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1036 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1037 inet sockets.
1221 1038
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 1039 config CGROUP_DEBUG
1237 bool "Debug controller" 1040 bool "Debug controller"
1238 default n 1041 default n
1239 depends on DEBUG_KERNEL 1042 depends on DEBUG_KERNEL
1240 help 1043 help
1241 This option enables a simple contro 1044 This option enables a simple controller that exports
1242 debugging information about the cgr 1045 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1046 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1047 interfaces are not stable.
1245 1048
1246 Say N. 1049 Say N.
1247 1050
1248 config SOCK_CGROUP_DATA 1051 config SOCK_CGROUP_DATA
1249 bool 1052 bool
1250 default n 1053 default n
1251 1054
1252 endif # CGROUPS 1055 endif # CGROUPS
1253 1056
1254 menuconfig NAMESPACES 1057 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1058 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1059 depends on MULTIUSER
1257 default !EXPERT 1060 default !EXPERT
1258 help 1061 help
1259 Provides the way to make tasks work 1062 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1063 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1064 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1065 different namespaces.
1263 1066
1264 if NAMESPACES 1067 if NAMESPACES
1265 1068
1266 config UTS_NS 1069 config UTS_NS
1267 bool "UTS namespace" 1070 bool "UTS namespace"
1268 default y 1071 default y
1269 help 1072 help
1270 In this namespace tasks see differe 1073 In this namespace tasks see different info provided with the
1271 uname() system call 1074 uname() system call
1272 1075
1273 config TIME_NS <<
1274 bool "TIME namespace" <<
1275 depends on GENERIC_VDSO_TIME_NS <<
1276 default y <<
1277 help <<
1278 In this namespace boottime and mono <<
1279 The time will keep going with the s <<
1280 <<
1281 config IPC_NS 1076 config IPC_NS
1282 bool "IPC namespace" 1077 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1078 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1079 default y
1285 help 1080 help
1286 In this namespace tasks work with I 1081 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1082 different IPC objects in different namespaces.
1288 1083
1289 config USER_NS 1084 config USER_NS
1290 bool "User namespace" 1085 bool "User namespace"
1291 default n 1086 default n
1292 help 1087 help
1293 This allows containers, i.e. vserve 1088 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1089 to provide different user info for different servers.
1295 1090
1296 When user namespaces are enabled in 1091 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1092 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1093 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1094 of memory a memory unprivileged users can use.
1300 1095
1301 If unsure, say N. 1096 If unsure, say N.
1302 1097
1303 config PID_NS 1098 config PID_NS
1304 bool "PID Namespaces" 1099 bool "PID Namespaces"
1305 default y 1100 default y
1306 help 1101 help
1307 Support process id namespaces. Thi 1102 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1103 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1104 pid namespaces. This is a building block of containers.
1310 1105
1311 config NET_NS 1106 config NET_NS
1312 bool "Network namespace" 1107 bool "Network namespace"
1313 depends on NET 1108 depends on NET
1314 default y 1109 default y
1315 help 1110 help
1316 Allow user space to create what app 1111 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1112 of the network stack.
1318 1113
1319 endif # NAMESPACES 1114 endif # NAMESPACES
1320 1115
1321 config CHECKPOINT_RESTORE 1116 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1117 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1118 select PROC_CHILDREN
1325 select KCMP <<
1326 default n 1119 default n
1327 help 1120 help
1328 Enables additional kernel features 1121 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1122 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1123 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1124 entries.
1332 1125
1333 If unsure, say N here. 1126 If unsure, say N here.
1334 1127
1335 config SCHED_AUTOGROUP 1128 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1129 bool "Automatic process group scheduling"
1337 select CGROUPS 1130 select CGROUPS
1338 select CGROUP_SCHED 1131 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1132 select FAIR_GROUP_SCHED
1340 help 1133 help
1341 This option optimizes the scheduler 1134 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1135 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1136 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1137 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1138 upon task session.
1346 1139
>> 1140 config SYSFS_DEPRECATED
>> 1141 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1142 depends on SYSFS
>> 1143 default n
>> 1144 help
>> 1145 This option adds code that switches the layout of the "block" class
>> 1146 devices, to not show up in /sys/class/block/, but only in
>> 1147 /sys/block/.
>> 1148
>> 1149 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1150 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1151
>> 1152 This option allows new kernels to run on old distributions and tools,
>> 1153 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1154 major distributions and tools handle this just fine.
>> 1155
>> 1156 Recent distributions and userspace tools after 2009/2010 depend on
>> 1157 the existence of /sys/class/block/, and will not work with this
>> 1158 option enabled.
>> 1159
>> 1160 Only if you are using a new kernel on an old distribution, you might
>> 1161 need to say Y here.
>> 1162
>> 1163 config SYSFS_DEPRECATED_V2
>> 1164 bool "Enable deprecated sysfs features by default"
>> 1165 default n
>> 1166 depends on SYSFS
>> 1167 depends on SYSFS_DEPRECATED
>> 1168 help
>> 1169 Enable deprecated sysfs by default.
>> 1170
>> 1171 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1172 option.
>> 1173
>> 1174 Only if you are using a new kernel on an old distribution, you might
>> 1175 need to say Y here. Even then, odds are you would not need it
>> 1176 enabled, you can always pass the boot option if absolutely necessary.
>> 1177
1347 config RELAY 1178 config RELAY
1348 bool "Kernel->user space relay suppor 1179 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1180 select IRQ_WORK
1350 help 1181 help
1351 This option enables support for rel 1182 This option enables support for relay interface support in
1352 certain file systems (such as debug 1183 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1184 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1185 facilities to relay large amounts of data from kernel space to
1355 user space. 1186 user space.
1356 1187
1357 If unsure, say N. 1188 If unsure, say N.
1358 1189
1359 config BLK_DEV_INITRD 1190 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1191 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1192 help
1362 The initial RAM filesystem is a ram 1193 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1194 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1195 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1196 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1197 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1198
1368 If RAM disk support (BLK_DEV_RAM) i 1199 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1200 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1201 15 Kbytes (more on some other architectures) to the kernel size.
1371 1202
1372 If unsure say Y. 1203 If unsure say Y.
1373 1204
1374 if BLK_DEV_INITRD 1205 if BLK_DEV_INITRD
1375 1206
1376 source "usr/Kconfig" 1207 source "usr/Kconfig"
1377 1208
1378 endif 1209 endif
1379 1210
1380 config BOOT_CONFIG <<
1381 bool "Boot config support" <<
1382 select BLK_DEV_INITRD if !BOOT_CONFIG <<
1383 help <<
1384 Extra boot config allows system adm <<
1385 complemental extension of kernel cm <<
1386 The boot config file must be attach <<
1387 with checksum, size and magic word. <<
1388 See <file:Documentation/admin-guide <<
1389 <<
1390 If unsure, say Y. <<
1391 <<
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 1211 choice
1435 prompt "Compiler optimization level" 1212 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1213 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1214
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1215 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1216 bool "Optimize for performance (-O2)"
1440 help 1217 help
1441 This is the default optimization le 1218 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1219 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1220 helpful compile-time warnings.
1444 1221
>> 1222 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1223 bool "Optimize more for performance (-O3)"
>> 1224 depends on ARC
>> 1225 help
>> 1226 Choosing this option will pass "-O3" to your compiler to optimize
>> 1227 the kernel yet more for performance.
>> 1228
1445 config CC_OPTIMIZE_FOR_SIZE 1229 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1230 bool "Optimize for size (-Os)"
1447 help 1231 help
1448 Choosing this option will pass "-Os 1232 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1233 in a smaller kernel.
1450 1234
1451 endchoice 1235 endchoice
1452 1236
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1237 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1238 bool
1455 help 1239 help
1456 This requires that the arch annotat 1240 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1241 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1242 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1243 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1244 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1245 is used to distinguish them from label names / C identifiers.
1462 1246
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1247 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1248 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1249 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1250 depends on EXPERT
>> 1251 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1467 depends on $(cc-option,-ffunction-sec 1252 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1253 depends on $(ld-option,--gc-sections)
1469 help 1254 help
1470 Enable this if you want to do dead 1255 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1256 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1257 and linking with --gc-sections.
1473 1258
1474 This can reduce on disk and in-memo 1259 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1260 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1261 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1262 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1263 present. This option is not well tested yet, so use at your
1479 own risk. 1264 own risk.
1480 1265
1481 config LD_ORPHAN_WARN <<
1482 def_bool y <<
1483 depends on ARCH_WANT_LD_ORPHAN_WARN <<
1484 depends on $(ld-option,--orphan-handl <<
1485 depends on $(ld-option,--orphan-handl <<
1486 <<
1487 config LD_ORPHAN_WARN_LEVEL <<
1488 string <<
1489 depends on LD_ORPHAN_WARN <<
1490 default "error" if WERROR <<
1491 default "warn" <<
1492 <<
1493 config SYSCTL 1266 config SYSCTL
1494 bool 1267 bool
1495 1268
1496 config HAVE_UID16 1269 config HAVE_UID16
1497 bool 1270 bool
1498 1271
1499 config SYSCTL_EXCEPTION_TRACE 1272 config SYSCTL_EXCEPTION_TRACE
1500 bool 1273 bool
1501 help 1274 help
1502 Enable support for /proc/sys/debug/ 1275 Enable support for /proc/sys/debug/exception-trace.
1503 1276
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1277 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1278 bool
1506 help 1279 help
1507 Enable support for /proc/sys/kernel 1280 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1281 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1282 about unaligned access emulation going on under the hood.
1510 1283
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1284 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1285 bool
1513 help 1286 help
1514 Enable support for /proc/sys/kernel 1287 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1288 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1289 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1290 see arch/parisc/kernel/unaligned.c for reference
1518 1291
1519 config HAVE_PCSPKR_PLATFORM 1292 config HAVE_PCSPKR_PLATFORM
1520 bool 1293 bool
1521 1294
>> 1295 # interpreter that classic socket filters depend on
>> 1296 config BPF
>> 1297 bool
>> 1298
1522 menuconfig EXPERT 1299 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1300 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1301 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1302 select DEBUG_KERNEL
1526 help 1303 help
1527 This option allows certain base ker 1304 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is !! 1305 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " !! 1306 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh !! 1307 Only use this if you really know what you are doing.
1531 1308
1532 config UID16 1309 config UID16
1533 bool "Enable 16-bit UID system calls" 1310 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1311 depends on HAVE_UID16 && MULTIUSER
1535 default y 1312 default y
1536 help 1313 help
1537 This enables the legacy 16-bit UID 1314 This enables the legacy 16-bit UID syscall wrappers.
1538 1315
1539 config MULTIUSER 1316 config MULTIUSER
1540 bool "Multiple users, groups and capa 1317 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1318 default y
1542 help 1319 help
1543 This option enables support for non 1320 This option enables support for non-root users, groups and
1544 capabilities. 1321 capabilities.
1545 1322
1546 If you say N here, all processes wi 1323 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1324 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1325 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1326 setgid, and capset.
1550 1327
1551 If unsure, say Y here. 1328 If unsure, say Y here.
1552 1329
1553 config SGETMASK_SYSCALL 1330 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1331 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1332 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help !! 1333 ---help---
1557 sys_sgetmask and sys_ssetmask are o 1334 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1335 no longer supported in libc but still enabled by default in some
1559 architectures. 1336 architectures.
1560 1337
1561 If unsure, leave the default option 1338 If unsure, leave the default option here.
1562 1339
1563 config SYSFS_SYSCALL 1340 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1341 bool "Sysfs syscall support" if EXPERT
1565 default y 1342 default y
1566 help !! 1343 ---help---
1567 sys_sysfs is an obsolete system cal 1344 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1345 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1346 compatibility with some systems.
1570 1347
1571 If unsure say Y here. 1348 If unsure say Y here.
1572 1349
>> 1350 config SYSCTL_SYSCALL
>> 1351 bool "Sysctl syscall support" if EXPERT
>> 1352 depends on PROC_SYSCTL
>> 1353 default n
>> 1354 select SYSCTL
>> 1355 ---help---
>> 1356 sys_sysctl uses binary paths that have been found challenging
>> 1357 to properly maintain and use. The interface in /proc/sys
>> 1358 using paths with ascii names is now the primary path to this
>> 1359 information.
>> 1360
>> 1361 Almost nothing using the binary sysctl interface so if you are
>> 1362 trying to save some space it is probably safe to disable this,
>> 1363 making your kernel marginally smaller.
>> 1364
>> 1365 If unsure say N here.
>> 1366
1573 config FHANDLE 1367 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1368 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1369 select EXPORTFS
1576 default y 1370 default y
1577 help 1371 help
1578 If you say Y here, a user level pro 1372 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1373 file names to handle and then later use the handle for
1580 different file system operations. T 1374 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1375 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1376 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1377 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1378 syscalls.
1585 1379
1586 config POSIX_TIMERS 1380 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1381 bool "Posix Clocks & timers" if EXPERT
1588 default y 1382 default y
1589 help 1383 help
1590 This includes native support for PO 1384 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1385 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1386 can be configured out to reduce the size of the kernel image.
1593 1387
1594 When this option is disabled, the f 1388 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1389 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1390 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1391 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1392 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1393 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1394
1601 If unsure say y. 1395 If unsure say y.
1602 1396
1603 config PRINTK 1397 config PRINTK
1604 default y 1398 default y
1605 bool "Enable support for printk" if E 1399 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1400 select IRQ_WORK
1607 help 1401 help
1608 This option enables normal printk s 1402 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1403 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1404 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1405 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1406 strongly discouraged.
1613 1407
>> 1408 config PRINTK_NMI
>> 1409 def_bool y
>> 1410 depends on PRINTK
>> 1411 depends on HAVE_NMI
>> 1412
1614 config BUG 1413 config BUG
1615 bool "BUG() support" if EXPERT 1414 bool "BUG() support" if EXPERT
1616 default y 1415 default y
1617 help 1416 help
1618 Disabling this option eliminates su !! 1417 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p !! 1418 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou !! 1419 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no !! 1420 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. !! 1421 Just say Y.
1623 1422
1624 config ELF_CORE 1423 config ELF_CORE
1625 depends on COREDUMP 1424 depends on COREDUMP
1626 default y 1425 default y
1627 bool "Enable ELF core dumps" if EXPER 1426 bool "Enable ELF core dumps" if EXPERT
1628 help 1427 help
1629 Enable support for generating core 1428 Enable support for generating core dumps. Disabling saves about 4k.
1630 1429
1631 1430
1632 config PCSPKR_PLATFORM 1431 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1432 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1433 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1434 select I8253_LOCK
1636 default y 1435 default y
1637 help 1436 help
1638 This option allows to disable the i !! 1437 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. !! 1438 support, saving some memory.
1640 1439
1641 config BASE_SMALL !! 1440 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1441 default y
>> 1442 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1443 help
1644 Enabling this option reduces the si !! 1444 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1445 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1446 but may reduce performance.
1647 1447
1648 config FUTEX 1448 config FUTEX
1649 bool "Enable futex support" if EXPERT 1449 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1450 default y
1652 imply RT_MUTEXES 1451 imply RT_MUTEXES
1653 help 1452 help
1654 Disabling this option will cause th 1453 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1454 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1455 run glibc-based applications correctly.
1657 1456
1658 config FUTEX_PI 1457 config FUTEX_PI
1659 bool 1458 bool
1660 depends on FUTEX && RT_MUTEXES 1459 depends on FUTEX && RT_MUTEXES
1661 default y 1460 default y
1662 1461
>> 1462 config HAVE_FUTEX_CMPXCHG
>> 1463 bool
>> 1464 depends on FUTEX
>> 1465 help
>> 1466 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1467 is implemented and always working. This removes a couple of runtime
>> 1468 checks.
>> 1469
1663 config EPOLL 1470 config EPOLL
1664 bool "Enable eventpoll support" if EX 1471 bool "Enable eventpoll support" if EXPERT
1665 default y 1472 default y
1666 help 1473 help
1667 Disabling this option will cause th 1474 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1475 support for epoll family of system calls.
1669 1476
1670 config SIGNALFD 1477 config SIGNALFD
1671 bool "Enable signalfd() system call" 1478 bool "Enable signalfd() system call" if EXPERT
1672 default y 1479 default y
1673 help 1480 help
1674 Enable the signalfd() system call t 1481 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1482 on a file descriptor.
1676 1483
1677 If unsure, say Y. 1484 If unsure, say Y.
1678 1485
1679 config TIMERFD 1486 config TIMERFD
1680 bool "Enable timerfd() system call" i 1487 bool "Enable timerfd() system call" if EXPERT
1681 default y 1488 default y
1682 help 1489 help
1683 Enable the timerfd() system call th 1490 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1491 events on a file descriptor.
1685 1492
1686 If unsure, say Y. 1493 If unsure, say Y.
1687 1494
1688 config EVENTFD 1495 config EVENTFD
1689 bool "Enable eventfd() system call" i 1496 bool "Enable eventfd() system call" if EXPERT
1690 default y 1497 default y
1691 help 1498 help
1692 Enable the eventfd() system call th 1499 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1500 kernel notification (ie. KAIO) or userspace notifications.
1694 1501
1695 If unsure, say Y. 1502 If unsure, say Y.
1696 1503
1697 config SHMEM 1504 config SHMEM
1698 bool "Use full shmem filesystem" if E 1505 bool "Use full shmem filesystem" if EXPERT
1699 default y 1506 default y
1700 depends on MMU 1507 depends on MMU
1701 help 1508 help
1702 The shmem is an internal filesystem 1509 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1510 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1511 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1512 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1513 which may be appropriate on small systems without swap.
1707 1514
1708 config AIO 1515 config AIO
1709 bool "Enable AIO support" if EXPERT 1516 bool "Enable AIO support" if EXPERT
1710 default y 1517 default y
1711 help 1518 help
1712 This option enables POSIX asynchron 1519 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1520 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1521 this option saves about 7k.
1715 1522
1716 config IO_URING 1523 config IO_URING
1717 bool "Enable IO uring support" if EXP 1524 bool "Enable IO uring support" if EXPERT
1718 select IO_WQ !! 1525 select ANON_INODES
1719 default y 1526 default y
1720 help 1527 help
1721 This option enables support for the 1528 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1529 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1530 completion rings that are shared between the kernel and application.
1724 1531
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 1532 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1533 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1534 default y
1741 help 1535 help
1742 This option enables the madvise and 1536 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1537 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1538 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1539 applications use these syscalls, you can disable this option to save
1746 space. 1540 space.
1747 1541
1748 config MEMBARRIER 1542 config MEMBARRIER
1749 bool "Enable membarrier() system call 1543 bool "Enable membarrier() system call" if EXPERT
1750 default y 1544 default y
1751 help 1545 help
1752 Enable the membarrier() system call 1546 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1547 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1548 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1549 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1550 compiler barrier.
1757 1551
1758 If unsure, say Y. 1552 If unsure, say Y.
1759 1553
1760 config KCMP !! 1554 config KALLSYMS
1761 bool "Enable kcmp() system call" if E !! 1555 bool "Load all symbols for debugging/ksymoops" if EXPERT
>> 1556 default y
>> 1557 help
>> 1558 Say Y here to let the kernel print out symbolic crash information and
>> 1559 symbolic stack backtraces. This increases the size of the kernel
>> 1560 somewhat, as all symbols have to be loaded into the kernel image.
>> 1561
>> 1562 config KALLSYMS_ALL
>> 1563 bool "Include all symbols in kallsyms"
>> 1564 depends on DEBUG_KERNEL && KALLSYMS
1762 help 1565 help
1763 Enable the kernel resource comparis !! 1566 Normally kallsyms only contains the symbols of functions for nicer
1764 user-space with the ability to comp !! 1567 OOPS messages and backtraces (i.e., symbols from the text and inittext
1765 share a common resource, such as a !! 1568 sections). This is sufficient for most cases. And only in very rare
1766 memory space. !! 1569 cases (e.g., when a debugger is used) all symbols are required (e.g.,
>> 1570 names of variables from the data sections, etc).
>> 1571
>> 1572 This option makes sure that all symbols are loaded into the kernel
>> 1573 image (i.e., symbols from all sections) in cost of increased kernel
>> 1574 size (depending on the kernel configuration, it may be 300KiB or
>> 1575 something like this).
1767 1576
1768 If unsure, say N. !! 1577 Say N unless you really need all symbols.
>> 1578
>> 1579 config KALLSYMS_ABSOLUTE_PERCPU
>> 1580 bool
>> 1581 depends on KALLSYMS
>> 1582 default X86_64 && SMP
>> 1583
>> 1584 config KALLSYMS_BASE_RELATIVE
>> 1585 bool
>> 1586 depends on KALLSYMS
>> 1587 default !IA64
>> 1588 help
>> 1589 Instead of emitting them as absolute values in the native word size,
>> 1590 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1591 each containing a relative value in the range [base, base + U32_MAX]
>> 1592 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1593 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1594 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1595 address encountered in the image.
>> 1596
>> 1597 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1598 but more importantly, it results in entries whose values are build
>> 1599 time constants, and no relocation pass is required at runtime to fix
>> 1600 up the entries based on the runtime load address of the kernel.
>> 1601
>> 1602 # end of the "standard kernel features (expert users)" menu
>> 1603
>> 1604 # syscall, maps, verifier
>> 1605 config BPF_SYSCALL
>> 1606 bool "Enable bpf() system call"
>> 1607 select BPF
>> 1608 select IRQ_WORK
>> 1609 default n
>> 1610 help
>> 1611 Enable the bpf() system call that allows to manipulate eBPF
>> 1612 programs and maps via file descriptors.
>> 1613
>> 1614 config BPF_JIT_ALWAYS_ON
>> 1615 bool "Permanently enable BPF JIT and remove BPF interpreter"
>> 1616 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
>> 1617 help
>> 1618 Enables BPF JIT and removes BPF interpreter to avoid
>> 1619 speculative execution of BPF instructions by the interpreter
>> 1620
>> 1621 config BPF_UNPRIV_DEFAULT_OFF
>> 1622 bool "Disable unprivileged BPF by default"
>> 1623 depends on BPF_SYSCALL
>> 1624 help
>> 1625 Disables unprivileged BPF by default by setting the corresponding
>> 1626 /proc/sys/kernel/unprivileged_bpf_disabled knob to 2. An admin can
>> 1627 still reenable it by setting it to 0 later on, or permanently
>> 1628 disable it by setting it to 1 (from which no other transition to
>> 1629 0 is possible anymore).
>> 1630
>> 1631 config USERFAULTFD
>> 1632 bool "Enable userfaultfd() system call"
>> 1633 depends on MMU
>> 1634 help
>> 1635 Enable the userfaultfd() system call that allows to intercept and
>> 1636 handle page faults in userland.
>> 1637
>> 1638 config ARCH_HAS_MEMBARRIER_CALLBACKS
>> 1639 bool
>> 1640
>> 1641 config ARCH_HAS_MEMBARRIER_SYNC_CORE
>> 1642 bool
1769 1643
1770 config RSEQ 1644 config RSEQ
1771 bool "Enable rseq() system call" if E 1645 bool "Enable rseq() system call" if EXPERT
1772 default y 1646 default y
1773 depends on HAVE_RSEQ 1647 depends on HAVE_RSEQ
1774 select MEMBARRIER 1648 select MEMBARRIER
1775 help 1649 help
1776 Enable the restartable sequences sy 1650 Enable the restartable sequences system call. It provides a
1777 user-space cache for the current CP 1651 user-space cache for the current CPU number value, which
1778 speeds up getting the current CPU n 1652 speeds up getting the current CPU number from user-space,
1779 as well as an ABI to speed up user- 1653 as well as an ABI to speed up user-space operations on
1780 per-CPU data. 1654 per-CPU data.
1781 1655
1782 If unsure, say Y. 1656 If unsure, say Y.
1783 1657
1784 config DEBUG_RSEQ 1658 config DEBUG_RSEQ
1785 default n 1659 default n
1786 bool "Enable debugging of rseq() syst !! 1660 bool "Enabled debugging of rseq() system call" if EXPERT
1787 depends on RSEQ && DEBUG_KERNEL 1661 depends on RSEQ && DEBUG_KERNEL
1788 help 1662 help
1789 Enable extra debugging checks for t 1663 Enable extra debugging checks for the rseq system call.
1790 1664
1791 If unsure, say N. 1665 If unsure, say N.
1792 1666
1793 config CACHESTAT_SYSCALL !! 1667 config EMBEDDED
1794 bool "Enable cachestat() system call" !! 1668 bool "Embedded system"
1795 default y !! 1669 option allnoconfig_y
1796 help !! 1670 select EXPERT
1797 Enable the cachestat system call, w !! 1671 help
1798 statistics of a file (number of cac !! 1672 This option should be enabled if compiling the kernel for
1799 pages marked for writeback, (recent !! 1673 an embedded system so certain expert options are available
1800 !! 1674 for configuration.
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 <<
1811 bool "Load all symbols for debugging/ <<
1812 default y <<
1813 help <<
1814 Say Y here to let the kernel print <<
1815 symbolic stack backtraces. This inc <<
1816 somewhat, as all symbols have to be <<
1817 <<
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 <<
1832 bool "Include all symbols in kallsyms <<
1833 depends on DEBUG_KERNEL && KALLSYMS <<
1834 help <<
1835 Normally kallsyms only contains the <<
1836 OOPS messages and backtraces (i.e., <<
1837 sections). This is sufficient for m <<
1838 enable kernel live patching, or oth <<
1839 when a debugger is used) all symbol <<
1840 variables from the data sections, e <<
1841 <<
1842 This option makes sure that all sym <<
1843 image (i.e., symbols from all secti <<
1844 size (depending on the kernel confi <<
1845 something like this). <<
1846 <<
1847 Say N unless you really need all sy <<
1848 <<
1849 config KALLSYMS_ABSOLUTE_PERCPU <<
1850 bool <<
1851 depends on KALLSYMS <<
1852 default X86_64 && SMP <<
1853 <<
1854 # end of the "standard kernel features (exper <<
1855 <<
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS <<
1857 bool <<
1858 <<
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE <<
1860 bool <<
1861 1675
1862 config HAVE_PERF_EVENTS 1676 config HAVE_PERF_EVENTS
1863 bool 1677 bool
1864 help 1678 help
1865 See tools/perf/design.txt for detai 1679 See tools/perf/design.txt for details.
1866 1680
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1681 config PERF_USE_VMALLOC
1872 bool 1682 bool
1873 help 1683 help
1874 See tools/perf/design.txt for detai 1684 See tools/perf/design.txt for details
1875 1685
>> 1686 config PC104
>> 1687 bool "PC/104 support" if EXPERT
>> 1688 help
>> 1689 Expose PC/104 form factor device drivers and options available for
>> 1690 selection and configuration. Enable this option if your target
>> 1691 machine has a PC/104 bus.
>> 1692
1876 menu "Kernel Performance Events And Counters" 1693 menu "Kernel Performance Events And Counters"
1877 1694
1878 config PERF_EVENTS 1695 config PERF_EVENTS
1879 bool "Kernel performance events and c 1696 bool "Kernel performance events and counters"
1880 default y if PROFILING 1697 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1698 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1699 select IRQ_WORK
>> 1700 select SRCU
1883 help 1701 help
1884 Enable kernel support for various p 1702 Enable kernel support for various performance events provided
1885 by software and hardware. 1703 by software and hardware.
1886 1704
1887 Software events are supported eithe 1705 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1706 use of generic tracepoints.
1889 1707
1890 Most modern CPUs support performanc 1708 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1709 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1710 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1711 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1712 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1713 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1714 used to profile the code that runs on that CPU.
1897 1715
1898 The Linux Performance Event subsyst 1716 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1717 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1718 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1719 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1720 capabilities on top of those.
1903 1721
1904 Say Y if unsure. 1722 Say Y if unsure.
1905 1723
1906 config DEBUG_PERF_USE_VMALLOC 1724 config DEBUG_PERF_USE_VMALLOC
1907 default n 1725 default n
1908 bool "Debug: use vmalloc to back perf 1726 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1727 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1728 select PERF_USE_VMALLOC
1911 help 1729 help
1912 Use vmalloc memory to back perf mma !! 1730 Use vmalloc memory to back perf mmap() buffers.
1913 1731
1914 Mostly useful for debugging the vma !! 1732 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. !! 1733 that don't require it.
1916 1734
1917 Say N if unsure. !! 1735 Say N if unsure.
1918 1736
1919 endmenu 1737 endmenu
1920 1738
>> 1739 config VM_EVENT_COUNTERS
>> 1740 default y
>> 1741 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1742 help
>> 1743 VM event counters are needed for event counts to be shown.
>> 1744 This option allows the disabling of the VM event counters
>> 1745 on EXPERT systems. /proc/vmstat will only show page counts
>> 1746 if VM event counters are disabled.
>> 1747
>> 1748 config SLUB_DEBUG
>> 1749 default y
>> 1750 bool "Enable SLUB debugging support" if EXPERT
>> 1751 depends on SLUB && SYSFS
>> 1752 help
>> 1753 SLUB has extensive debug support features. Disabling these can
>> 1754 result in significant savings in code size. This also disables
>> 1755 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1756 no support for cache validation etc.
>> 1757
>> 1758 config SLUB_MEMCG_SYSFS_ON
>> 1759 default n
>> 1760 bool "Enable memcg SLUB sysfs support by default" if EXPERT
>> 1761 depends on SLUB && SYSFS && MEMCG
>> 1762 help
>> 1763 SLUB creates a directory under /sys/kernel/slab for each
>> 1764 allocation cache to host info and debug files. If memory
>> 1765 cgroup is enabled, each cache can have per memory cgroup
>> 1766 caches. SLUB can create the same sysfs directories for these
>> 1767 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
>> 1768 to a very high number of debug files being created. This is
>> 1769 controlled by slub_memcg_sysfs boot parameter and this
>> 1770 config option determines the parameter's default value.
>> 1771
>> 1772 config COMPAT_BRK
>> 1773 bool "Disable heap randomization"
>> 1774 default y
>> 1775 help
>> 1776 Randomizing heap placement makes heap exploits harder, but it
>> 1777 also breaks ancient binaries (including anything libc5 based).
>> 1778 This option changes the bootup default to heap randomization
>> 1779 disabled, and can be overridden at runtime by setting
>> 1780 /proc/sys/kernel/randomize_va_space to 2.
>> 1781
>> 1782 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1783
>> 1784 choice
>> 1785 prompt "Choose SLAB allocator"
>> 1786 default SLUB
>> 1787 help
>> 1788 This option allows to select a slab allocator.
>> 1789
>> 1790 config SLAB
>> 1791 bool "SLAB"
>> 1792 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1793 help
>> 1794 The regular slab allocator that is established and known to work
>> 1795 well in all environments. It organizes cache hot objects in
>> 1796 per cpu and per node queues.
>> 1797
>> 1798 config SLUB
>> 1799 bool "SLUB (Unqueued Allocator)"
>> 1800 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1801 help
>> 1802 SLUB is a slab allocator that minimizes cache line usage
>> 1803 instead of managing queues of cached objects (SLAB approach).
>> 1804 Per cpu caching is realized using slabs of objects instead
>> 1805 of queues of objects. SLUB can use memory efficiently
>> 1806 and has enhanced diagnostics. SLUB is the default choice for
>> 1807 a slab allocator.
>> 1808
>> 1809 config SLOB
>> 1810 depends on EXPERT
>> 1811 bool "SLOB (Simple Allocator)"
>> 1812 help
>> 1813 SLOB replaces the stock allocator with a drastically simpler
>> 1814 allocator. SLOB is generally more space efficient but
>> 1815 does not perform as well on large systems.
>> 1816
>> 1817 endchoice
>> 1818
>> 1819 config SLAB_MERGE_DEFAULT
>> 1820 bool "Allow slab caches to be merged"
>> 1821 default y
>> 1822 help
>> 1823 For reduced kernel memory fragmentation, slab caches can be
>> 1824 merged when they share the same size and other characteristics.
>> 1825 This carries a risk of kernel heap overflows being able to
>> 1826 overwrite objects from merged caches (and more easily control
>> 1827 cache layout), which makes such heap attacks easier to exploit
>> 1828 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1829 can usually only damage objects in the same cache. To disable
>> 1830 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1831 command line.
>> 1832
>> 1833 config SLAB_FREELIST_RANDOM
>> 1834 default n
>> 1835 depends on SLAB || SLUB
>> 1836 bool "SLAB freelist randomization"
>> 1837 help
>> 1838 Randomizes the freelist order used on creating new pages. This
>> 1839 security feature reduces the predictability of the kernel slab
>> 1840 allocator against heap overflows.
>> 1841
>> 1842 config SLAB_FREELIST_HARDENED
>> 1843 bool "Harden slab freelist metadata"
>> 1844 depends on SLUB
>> 1845 help
>> 1846 Many kernel heap attacks try to target slab cache metadata and
>> 1847 other infrastructure. This options makes minor performance
>> 1848 sacrifices to harden the kernel slab allocator against common
>> 1849 freelist exploit methods.
>> 1850
>> 1851 config SHUFFLE_PAGE_ALLOCATOR
>> 1852 bool "Page allocator randomization"
>> 1853 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1854 help
>> 1855 Randomization of the page allocator improves the average
>> 1856 utilization of a direct-mapped memory-side-cache. See section
>> 1857 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1858 6.2a specification for an example of how a platform advertises
>> 1859 the presence of a memory-side-cache. There are also incidental
>> 1860 security benefits as it reduces the predictability of page
>> 1861 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1862 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1863 10th order of pages is selected based on cache utilization
>> 1864 benefits on x86.
>> 1865
>> 1866 While the randomization improves cache utilization it may
>> 1867 negatively impact workloads on platforms without a cache. For
>> 1868 this reason, by default, the randomization is enabled only
>> 1869 after runtime detection of a direct-mapped memory-side-cache.
>> 1870 Otherwise, the randomization may be force enabled with the
>> 1871 'page_alloc.shuffle' kernel command line parameter.
>> 1872
>> 1873 Say Y if unsure.
>> 1874
>> 1875 config SLUB_CPU_PARTIAL
>> 1876 default y
>> 1877 depends on SLUB && SMP
>> 1878 bool "SLUB per cpu partial cache"
>> 1879 help
>> 1880 Per cpu partial caches accelerate objects allocation and freeing
>> 1881 that is local to a processor at the price of more indeterminism
>> 1882 in the latency of the free. On overflow these caches will be cleared
>> 1883 which requires the taking of locks that may cause latency spikes.
>> 1884 Typically one would choose no for a realtime system.
>> 1885
>> 1886 config MMAP_ALLOW_UNINITIALIZED
>> 1887 bool "Allow mmapped anonymous memory to be uninitialized"
>> 1888 depends on EXPERT && !MMU
>> 1889 default n
>> 1890 help
>> 1891 Normally, and according to the Linux spec, anonymous memory obtained
>> 1892 from mmap() has its contents cleared before it is passed to
>> 1893 userspace. Enabling this config option allows you to request that
>> 1894 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 1895 providing a huge performance boost. If this option is not enabled,
>> 1896 then the flag will be ignored.
>> 1897
>> 1898 This is taken advantage of by uClibc's malloc(), and also by
>> 1899 ELF-FDPIC binfmt's brk and stack allocator.
>> 1900
>> 1901 Because of the obvious security issues, this option should only be
>> 1902 enabled on embedded devices where you control what is run in
>> 1903 userspace. Since that isn't generally a problem on no-MMU systems,
>> 1904 it is normally safe to say Y here.
>> 1905
>> 1906 See Documentation/nommu-mmap.txt for more information.
>> 1907
1921 config SYSTEM_DATA_VERIFICATION 1908 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1909 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1910 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1911 select KEYS
1925 select CRYPTO 1912 select CRYPTO
1926 select CRYPTO_RSA 1913 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1914 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1915 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1916 select ASN1
1930 select OID_REGISTRY 1917 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1918 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1919 select PKCS7_MESSAGE_PARSER
1933 help 1920 help
1934 Provide PKCS#7 message verification 1921 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1922 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1923 module verification, kexec image verification and firmware blob
1937 verification. 1924 verification.
1938 1925
1939 config PROFILING 1926 config PROFILING
1940 bool "Profiling support" 1927 bool "Profiling support"
1941 help 1928 help
1942 Say Y here to enable the extended p 1929 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 1930 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 1931
1986 # 1932 #
1987 # Place an empty function call at each tracep 1933 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1934 # dynamically changed for a probe function.
1989 # 1935 #
1990 config TRACEPOINTS 1936 config TRACEPOINTS
1991 bool 1937 bool
1992 1938
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1939 endmenu # General setup
1996 1940
1997 source "arch/Kconfig" 1941 source "arch/Kconfig"
1998 1942
1999 config RT_MUTEXES 1943 config RT_MUTEXES
2000 bool 1944 bool
2001 default y if PREEMPT_RT !! 1945
>> 1946 config BASE_SMALL
>> 1947 int
>> 1948 default 0 if BASE_FULL
>> 1949 default 1 if !BASE_FULL
2002 1950
2003 config MODULE_SIG_FORMAT 1951 config MODULE_SIG_FORMAT
2004 def_bool n 1952 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 1953 select SYSTEM_DATA_VERIFICATION
2006 1954
2007 source "kernel/module/Kconfig" !! 1955 menuconfig MODULES
>> 1956 bool "Enable loadable module support"
>> 1957 option modules
>> 1958 help
>> 1959 Kernel modules are small pieces of compiled code which can
>> 1960 be inserted in the running kernel, rather than being
>> 1961 permanently built into the kernel. You use the "modprobe"
>> 1962 tool to add (and sometimes remove) them. If you say Y here,
>> 1963 many parts of the kernel can be built as modules (by
>> 1964 answering M instead of Y where indicated): this is most
>> 1965 useful for infrequently used options which are not required
>> 1966 for booting. For more information, see the man pages for
>> 1967 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1968
>> 1969 If you say Y here, you will need to run "make
>> 1970 modules_install" to put the modules under /lib/modules/
>> 1971 where modprobe can find them (you may need to be root to do
>> 1972 this).
>> 1973
>> 1974 If unsure, say Y.
>> 1975
>> 1976 if MODULES
>> 1977
>> 1978 config MODULE_FORCE_LOAD
>> 1979 bool "Forced module loading"
>> 1980 default n
>> 1981 help
>> 1982 Allow loading of modules without version information (ie. modprobe
>> 1983 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1984 is usually a really bad idea.
>> 1985
>> 1986 config MODULE_UNLOAD
>> 1987 bool "Module unloading"
>> 1988 help
>> 1989 Without this option you will not be able to unload any
>> 1990 modules (note that some modules may not be unloadable
>> 1991 anyway), which makes your kernel smaller, faster
>> 1992 and simpler. If unsure, say Y.
>> 1993
>> 1994 config MODULE_FORCE_UNLOAD
>> 1995 bool "Forced module unloading"
>> 1996 depends on MODULE_UNLOAD
>> 1997 help
>> 1998 This option allows you to force a module to unload, even if the
>> 1999 kernel believes it is unsafe: the kernel will remove the module
>> 2000 without waiting for anyone to stop using it (using the -f option to
>> 2001 rmmod). This is mainly for kernel developers and desperate users.
>> 2002 If unsure, say N.
>> 2003
>> 2004 config MODVERSIONS
>> 2005 bool "Module versioning support"
>> 2006 help
>> 2007 Usually, you have to use modules compiled with your kernel.
>> 2008 Saying Y here makes it sometimes possible to use modules
>> 2009 compiled for different kernels, by adding enough information
>> 2010 to the modules to (hopefully) spot any changes which would
>> 2011 make them incompatible with the kernel you are running. If
>> 2012 unsure, say N.
>> 2013
>> 2014 config ASM_MODVERSIONS
>> 2015 bool
>> 2016 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 2017 help
>> 2018 This enables module versioning for exported symbols also from
>> 2019 assembly. This can be enabled only when the target architecture
>> 2020 supports it.
>> 2021
>> 2022 config MODULE_REL_CRCS
>> 2023 bool
>> 2024 depends on MODVERSIONS
>> 2025
>> 2026 config MODULE_SRCVERSION_ALL
>> 2027 bool "Source checksum for all modules"
>> 2028 help
>> 2029 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2030 field inserted into their modinfo section, which contains a
>> 2031 sum of the source files which made it. This helps maintainers
>> 2032 see exactly which source was used to build a module (since
>> 2033 others sometimes change the module source without updating
>> 2034 the version). With this option, such a "srcversion" field
>> 2035 will be created for all modules. If unsure, say N.
>> 2036
>> 2037 config MODULE_SIG
>> 2038 bool "Module signature verification"
>> 2039 select MODULE_SIG_FORMAT
>> 2040 help
>> 2041 Check modules for valid signatures upon load: the signature
>> 2042 is simply appended to the module. For more information see
>> 2043 <file:Documentation/admin-guide/module-signing.rst>.
>> 2044
>> 2045 Note that this option adds the OpenSSL development packages as a
>> 2046 kernel build dependency so that the signing tool can use its crypto
>> 2047 library.
>> 2048
>> 2049 You should enable this option if you wish to use either
>> 2050 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2051 another LSM - otherwise unsigned modules will be loadable regardless
>> 2052 of the lockdown policy.
>> 2053
>> 2054 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2055 module DOES NOT get stripped after being signed. This includes the
>> 2056 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2057 inclusion into an initramfs that wants the module size reduced.
>> 2058
>> 2059 config MODULE_SIG_FORCE
>> 2060 bool "Require modules to be validly signed"
>> 2061 depends on MODULE_SIG
>> 2062 help
>> 2063 Reject unsigned modules or signed modules for which we don't have a
>> 2064 key. Without this, such modules will simply taint the kernel.
>> 2065
>> 2066 config MODULE_SIG_ALL
>> 2067 bool "Automatically sign all modules"
>> 2068 default y
>> 2069 depends on MODULE_SIG
>> 2070 help
>> 2071 Sign all modules during make modules_install. Without this option,
>> 2072 modules must be signed manually, using the scripts/sign-file tool.
>> 2073
>> 2074 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2075 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2076
>> 2077 choice
>> 2078 prompt "Which hash algorithm should modules be signed with?"
>> 2079 depends on MODULE_SIG
>> 2080 help
>> 2081 This determines which sort of hashing algorithm will be used during
>> 2082 signature generation. This algorithm _must_ be built into the kernel
>> 2083 directly so that signature verification can take place. It is not
>> 2084 possible to load a signed module containing the algorithm to check
>> 2085 the signature on that module.
>> 2086
>> 2087 config MODULE_SIG_SHA1
>> 2088 bool "Sign modules with SHA-1"
>> 2089 select CRYPTO_SHA1
>> 2090
>> 2091 config MODULE_SIG_SHA224
>> 2092 bool "Sign modules with SHA-224"
>> 2093 select CRYPTO_SHA256
>> 2094
>> 2095 config MODULE_SIG_SHA256
>> 2096 bool "Sign modules with SHA-256"
>> 2097 select CRYPTO_SHA256
>> 2098
>> 2099 config MODULE_SIG_SHA384
>> 2100 bool "Sign modules with SHA-384"
>> 2101 select CRYPTO_SHA512
>> 2102
>> 2103 config MODULE_SIG_SHA512
>> 2104 bool "Sign modules with SHA-512"
>> 2105 select CRYPTO_SHA512
>> 2106
>> 2107 endchoice
>> 2108
>> 2109 config MODULE_SIG_HASH
>> 2110 string
>> 2111 depends on MODULE_SIG
>> 2112 default "sha1" if MODULE_SIG_SHA1
>> 2113 default "sha224" if MODULE_SIG_SHA224
>> 2114 default "sha256" if MODULE_SIG_SHA256
>> 2115 default "sha384" if MODULE_SIG_SHA384
>> 2116 default "sha512" if MODULE_SIG_SHA512
>> 2117
>> 2118 config MODULE_COMPRESS
>> 2119 bool "Compress modules on installation"
>> 2120 help
>> 2121
>> 2122 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2123 xz depending on "Compression algorithm" below.
>> 2124
>> 2125 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2126
>> 2127 Out-of-tree kernel modules installed using Kbuild will also be
>> 2128 compressed upon installation.
>> 2129
>> 2130 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2131 to compress the whole initrd or initramfs instead.
>> 2132
>> 2133 Note: This is fully compatible with signed modules.
>> 2134
>> 2135 If in doubt, say N.
>> 2136
>> 2137 choice
>> 2138 prompt "Compression algorithm"
>> 2139 depends on MODULE_COMPRESS
>> 2140 default MODULE_COMPRESS_GZIP
>> 2141 help
>> 2142 This determines which sort of compression will be used during
>> 2143 'make modules_install'.
>> 2144
>> 2145 GZIP (default) and XZ are supported.
>> 2146
>> 2147 config MODULE_COMPRESS_GZIP
>> 2148 bool "GZIP"
>> 2149
>> 2150 config MODULE_COMPRESS_XZ
>> 2151 bool "XZ"
>> 2152
>> 2153 endchoice
>> 2154
>> 2155 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2156 bool "Allow loading of modules with missing namespace imports"
>> 2157 help
>> 2158 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2159 a namespace. A module that makes use of a symbol exported with such a
>> 2160 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2161 There is no technical reason to enforce correct namespace imports,
>> 2162 but it creates consistency between symbols defining namespaces and
>> 2163 users importing namespaces they make use of. This option relaxes this
>> 2164 requirement and lifts the enforcement when loading a module.
>> 2165
>> 2166 If unsure, say N.
>> 2167
>> 2168 config UNUSED_SYMBOLS
>> 2169 bool "Enable unused/obsolete exported symbols"
>> 2170 default y if X86
>> 2171 help
>> 2172 Unused but exported symbols make the kernel needlessly bigger. For
>> 2173 that reason most of these unused exports will soon be removed. This
>> 2174 option is provided temporarily to provide a transition period in case
>> 2175 some external kernel module needs one of these symbols anyway. If you
>> 2176 encounter such a case in your module, consider if you are actually
>> 2177 using the right API. (rationale: since nobody in the kernel is using
>> 2178 this in a module, there is a pretty good chance it's actually the
>> 2179 wrong interface to use). If you really need the symbol, please send a
>> 2180 mail to the linux kernel mailing list mentioning the symbol and why
>> 2181 you really need it, and what the merge plan to the mainline kernel for
>> 2182 your module is.
>> 2183
>> 2184 config TRIM_UNUSED_KSYMS
>> 2185 bool "Trim unused exported kernel symbols"
>> 2186 depends on !UNUSED_SYMBOLS
>> 2187 help
>> 2188 The kernel and some modules make many symbols available for
>> 2189 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2190 on the set of modules being selected in your kernel configuration,
>> 2191 many of those exported symbols might never be used.
>> 2192
>> 2193 This option allows for unused exported symbols to be dropped from
>> 2194 the build. In turn, this provides the compiler more opportunities
>> 2195 (especially when using LTO) for optimizing the code and reducing
>> 2196 binary size. This might have some security advantages as well.
>> 2197
>> 2198 If unsure, or if you need to build out-of-tree modules, say N.
>> 2199
>> 2200 endif # MODULES
>> 2201
>> 2202 config MODULES_TREE_LOOKUP
>> 2203 def_bool y
>> 2204 depends on PERF_EVENTS || TRACING
2008 2205
2009 config INIT_ALL_POSSIBLE 2206 config INIT_ALL_POSSIBLE
2010 bool 2207 bool
2011 help 2208 help
2012 Back when each arch used to define 2209 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2210 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2211 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2212 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2213 and have several arch maintainers pursuing me down dark alleys.
2017 2214
2018 source "block/Kconfig" 2215 source "block/Kconfig"
2019 2216
2020 config PREEMPT_NOTIFIERS 2217 config PREEMPT_NOTIFIERS
2021 bool 2218 bool
2022 2219
2023 config PADATA 2220 config PADATA
2024 depends on SMP 2221 depends on SMP
2025 bool 2222 bool
2026 2223
2027 config ASN1 2224 config ASN1
2028 tristate 2225 tristate
2029 help 2226 help
2030 Build a simple ASN.1 grammar compil 2227 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2228 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2229 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2230 functions to call on what tags.
2034 2231
2035 source "kernel/Kconfig.locks" 2232 source "kernel/Kconfig.locks"
2036 <<
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE <<
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool <<
2042 2233
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2234 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2235 bool
2045 2236
2046 # It may be useful for an architecture to ove 2237 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2238 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2239 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2240 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2241 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2242 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2243 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2244 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2245 def_bool n
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