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 22
30 config CLANG_VERSION 23 config CLANG_VERSION
31 int 24 int
32 default $(cc-version) if CC_IS_CLANG !! 25 default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
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 <<
55 config LD_IS_LLD <<
56 def_bool $(success,test "$(ld-name)" = <<
57 <<
58 config LLD_VERSION <<
59 int <<
60 default $(ld-version) if LD_IS_LLD <<
61 default 0 <<
62 <<
63 config RUSTC_VERSION <<
64 int <<
65 default $(rustc-version) <<
66 help <<
67 It does not depend on `RUST` since t <<
68 in a `depends on`. <<
69 <<
70 config RUST_IS_AVAILABLE <<
71 def_bool $(success,$(srctree)/scripts/ <<
72 help <<
73 This shows whether a suitable Rust t <<
74 <<
75 Please see Documentation/rust/quick- <<
76 to satisfy the build requirements of <<
77 <<
78 In particular, the Makefile target ' <<
79 why the Rust toolchain is not being <<
80 <<
81 config RUSTC_LLVM_VERSION <<
82 int <<
83 default $(rustc-llvm-version) <<
84 26
85 config CC_CAN_LINK 27 config CC_CAN_LINK
86 bool !! 28 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 <<
104 config CC_HAS_ASM_GOTO_OUTPUT <<
105 def_bool y <<
106 depends on !GCC_ASM_GOTO_OUTPUT_BROKEN <<
107 depends on $(success,echo 'int foo(int <<
108 29
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT !! 30 config CC_HAS_ASM_GOTO
110 depends on CC_HAS_ASM_GOTO_OUTPUT !! 31 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
111 # Detect buggy gcc and clang, fixed in <<
112 def_bool $(success,echo 'int foo(int * <<
113 32
114 config TOOLS_SUPPORT_RELR 33 config TOOLS_SUPPORT_RELR
115 def_bool $(success,env "CC=$(CC)" "LD= 34 def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
116 35
117 config CC_HAS_ASM_INLINE 36 config CC_HAS_ASM_INLINE
118 def_bool $(success,echo 'void foo(void 37 def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
119 38
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 39 config CONSTRUCTORS
128 bool 40 bool
>> 41 depends on !UML
129 42
130 config IRQ_WORK 43 config IRQ_WORK
131 def_bool y if SMP !! 44 bool
132 45
133 config BUILDTIME_TABLE_SORT 46 config BUILDTIME_TABLE_SORT
134 bool 47 bool
135 48
136 config THREAD_INFO_IN_TASK 49 config THREAD_INFO_IN_TASK
137 bool 50 bool
138 help 51 help
139 Select this to move thread_info off 52 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 53 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 54 except flags and fix any runtime bugs.
142 55
143 One subtle change that will be neede 56 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 57 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 58
146 menu "General setup" 59 menu "General setup"
147 60
148 config BROKEN 61 config BROKEN
149 bool 62 bool
150 63
151 config BROKEN_ON_SMP 64 config BROKEN_ON_SMP
152 bool 65 bool
153 depends on BROKEN || !SMP 66 depends on BROKEN || !SMP
154 default y 67 default y
155 68
156 config INIT_ENV_ARG_LIMIT 69 config INIT_ENV_ARG_LIMIT
157 int 70 int
158 default 32 if !UML 71 default 32 if !UML
159 default 128 if UML 72 default 128 if UML
160 help 73 help
161 Maximum of each of the number of arg 74 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 75 variables passed to init from the kernel command line.
163 76
164 config COMPILE_TEST 77 config COMPILE_TEST
165 bool "Compile also drivers which will 78 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM !! 79 depends on !UML
>> 80 default n
167 help 81 help
168 Some drivers can be compiled on a di 82 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 83 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 84 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 85 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 86 drivers to compile-test them.
173 87
174 If you are a developer and want to b 88 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 89 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 90 drivers to be distributed.
177 91
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 92 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 93 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 94 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 95 help
199 Compile test headers exported to use 96 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 97 self-contained, i.e. compilable as standalone units.
201 98
202 If you are a developer or tester and 99 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 100 headers are self-contained, say Y here. Otherwise, choose N.
204 101
205 config LOCALVERSION 102 config LOCALVERSION
206 string "Local version - append to kern 103 string "Local version - append to kernel release"
207 help 104 help
208 Append an extra string to the end of 105 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 106 This will show up when you type uname, for example.
210 The string you set here will be appe 107 The string you set here will be appended after the contents of
211 any files with a filename matching l 108 any files with a filename matching localversion* in your
212 object and source tree, in that orde 109 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 110 be a maximum of 64 characters.
214 111
215 config LOCALVERSION_AUTO 112 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 113 bool "Automatically append version information to the version string"
217 default y 114 default y
218 depends on !COMPILE_TEST 115 depends on !COMPILE_TEST
219 help 116 help
220 This will try to automatically deter 117 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 118 release tree by looking for git tags that belong to the current
222 top of tree revision. 119 top of tree revision.
223 120
224 A string of the format -gxxxxxxxx wi 121 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 122 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 123 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 124 set in CONFIG_LOCALVERSION.
228 125
229 (The actual string used here is the !! 126 (The actual string used here is the first eight characters produced
230 by running the command: 127 by running the command:
231 128
232 $ git rev-parse --verify HEAD 129 $ git rev-parse --verify HEAD
233 130
234 which is done within the script "scr 131 which is done within the script "scripts/setlocalversion".)
235 132
236 config BUILD_SALT 133 config BUILD_SALT
237 string "Build ID Salt" 134 string "Build ID Salt"
238 default "" 135 default ""
239 help 136 help
240 The build ID is used to link binarie 137 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 138 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 139 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 140 build is unique between builds. It's safe to leave the default.
244 141
245 config HAVE_KERNEL_GZIP 142 config HAVE_KERNEL_GZIP
246 bool 143 bool
247 144
248 config HAVE_KERNEL_BZIP2 145 config HAVE_KERNEL_BZIP2
249 bool 146 bool
250 147
251 config HAVE_KERNEL_LZMA 148 config HAVE_KERNEL_LZMA
252 bool 149 bool
253 150
254 config HAVE_KERNEL_XZ 151 config HAVE_KERNEL_XZ
255 bool 152 bool
256 153
257 config HAVE_KERNEL_LZO 154 config HAVE_KERNEL_LZO
258 bool 155 bool
259 156
260 config HAVE_KERNEL_LZ4 157 config HAVE_KERNEL_LZ4
261 bool 158 bool
262 159
263 config HAVE_KERNEL_ZSTD <<
264 bool <<
265 <<
266 config HAVE_KERNEL_UNCOMPRESSED 160 config HAVE_KERNEL_UNCOMPRESSED
267 bool 161 bool
268 162
269 choice 163 choice
270 prompt "Kernel compression mode" 164 prompt "Kernel compression mode"
271 default KERNEL_GZIP 165 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE !! 166 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 167 help
274 The linux kernel is a kind of self-e 168 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 169 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 170 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 171 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 172 Decompression speed is relevant at each boot.
279 173
280 If you have any problems with bzip2 174 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 175 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 176 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 177 supplied by Christian Ludwig)
284 178
285 High compression options are mostly 179 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 180 are low on disk space (embedded systems), but for whom ram
287 size matters less. 181 size matters less.
288 182
289 If in doubt, select 'gzip' 183 If in doubt, select 'gzip'
290 184
291 config KERNEL_GZIP 185 config KERNEL_GZIP
292 bool "Gzip" 186 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 187 depends on HAVE_KERNEL_GZIP
294 help 188 help
295 The old and tried gzip compression. 189 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 190 between compression ratio and decompression speed.
297 191
298 config KERNEL_BZIP2 192 config KERNEL_BZIP2
299 bool "Bzip2" 193 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 194 depends on HAVE_KERNEL_BZIP2
301 help 195 help
302 Its compression ratio and speed is i 196 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 197 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 198 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 199 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 200 will need at least 8MB RAM or more for booting.
307 201
308 config KERNEL_LZMA 202 config KERNEL_LZMA
309 bool "LZMA" 203 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 204 depends on HAVE_KERNEL_LZMA
311 help 205 help
312 This compression algorithm's ratio i 206 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 207 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 208 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 209
316 config KERNEL_XZ 210 config KERNEL_XZ
317 bool "XZ" 211 bool "XZ"
318 depends on HAVE_KERNEL_XZ 212 depends on HAVE_KERNEL_XZ
319 help 213 help
320 XZ uses the LZMA2 algorithm and inst 214 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 215 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 216 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 217 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 218 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 219 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 220
328 The speed is about the same as with 221 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 222 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 223 and LZO. Compression is slow.
331 224
332 config KERNEL_LZO 225 config KERNEL_LZO
333 bool "LZO" 226 bool "LZO"
334 depends on HAVE_KERNEL_LZO 227 depends on HAVE_KERNEL_LZO
335 help 228 help
336 Its compression ratio is the poorest 229 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 230 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 231 (both compression and decompression) is the fastest.
339 232
340 config KERNEL_LZ4 233 config KERNEL_LZ4
341 bool "LZ4" 234 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 235 depends on HAVE_KERNEL_LZ4
343 help 236 help
344 LZ4 is an LZ77-type compressor with 237 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 238 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 239 <https://code.google.com/p/lz4/>.
347 240
348 Its compression ratio is worse than 241 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 242 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 243 faster than LZO.
351 244
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 245 config KERNEL_UNCOMPRESSED
363 bool "None" 246 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 247 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 248 help
366 Produce uncompressed kernel image. T 249 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 250 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 251 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 252 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 253 and jump right at uncompressed kernel image.
371 254
372 endchoice 255 endchoice
373 256
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 257 config DEFAULT_HOSTNAME
385 string "Default hostname" 258 string "Default hostname"
386 default "(none)" 259 default "(none)"
387 help 260 help
388 This option determines the default s 261 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 262 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 263 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 264 system more usable with less configuration.
392 265
>> 266 #
>> 267 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 268 # add proper SWAP support to them, in which case this can be remove.
>> 269 #
>> 270 config ARCH_NO_SWAP
>> 271 bool
>> 272
>> 273 config SWAP
>> 274 bool "Support for paging of anonymous memory (swap)"
>> 275 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 276 default y
>> 277 help
>> 278 This option allows you to choose whether you want to have support
>> 279 for so called swap devices or swap files in your kernel that are
>> 280 used to provide more virtual memory than the actual RAM present
>> 281 in your computer. If unsure say Y.
>> 282
393 config SYSVIPC 283 config SYSVIPC
394 bool "System V IPC" 284 bool "System V IPC"
395 help !! 285 ---help---
396 Inter Process Communication is a sui 286 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 287 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 288 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 289 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 290 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 291 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 292 you'll need to say Y here.
403 293
404 You can find documentation about IPC 294 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 295 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 296 <http://www.tldp.org/guides.html>.
407 297
408 config SYSVIPC_SYSCTL 298 config SYSVIPC_SYSCTL
409 bool 299 bool
410 depends on SYSVIPC 300 depends on SYSVIPC
411 depends on SYSCTL 301 depends on SYSCTL
412 default y 302 default y
413 303
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 304 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 305 bool "POSIX Message Queues"
420 depends on NET 306 depends on NET
421 help !! 307 ---help---
422 POSIX variant of message queues is a 308 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 309 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 310 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 311 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 312 queues (functions mq_*) say Y here.
427 313
428 POSIX message queues are visible as 314 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 315 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 316 operations on message queues.
431 317
432 If unsure, say Y. 318 If unsure, say Y.
433 319
434 config POSIX_MQUEUE_SYSCTL 320 config POSIX_MQUEUE_SYSCTL
435 bool 321 bool
436 depends on POSIX_MQUEUE 322 depends on POSIX_MQUEUE
437 depends on SYSCTL 323 depends on SYSCTL
438 default y 324 default y
439 325
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 326 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 327 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 328 depends on MMU
455 default y 329 default y
456 help 330 help
457 Enabling this option adds the system 331 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 332 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 333 to directly read from or write to another process' address space.
460 See the man page for more details. 334 See the man page for more details.
461 335
462 config USELIB 336 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 337 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 338 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 339 help
466 This option enables the uselib sysca 340 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 341 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 342 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 343 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 344 running glibc can safely disable this.
471 345
472 config AUDIT 346 config AUDIT
473 bool "Auditing support" 347 bool "Auditing support"
474 depends on NET 348 depends on NET
475 help 349 help
476 Enable auditing infrastructure that 350 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 351 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 352 logging of avc messages output). System call auditing is included
479 on architectures which support it. 353 on architectures which support it.
480 354
481 config HAVE_ARCH_AUDITSYSCALL 355 config HAVE_ARCH_AUDITSYSCALL
482 bool 356 bool
483 357
484 config AUDITSYSCALL 358 config AUDITSYSCALL
485 def_bool y 359 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 360 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 361 select FSNOTIFY
488 362
489 source "kernel/irq/Kconfig" 363 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 364 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" <<
492 source "kernel/Kconfig.preempt" 365 source "kernel/Kconfig.preempt"
493 366
494 menu "CPU/Task time and stats accounting" 367 menu "CPU/Task time and stats accounting"
495 368
496 config VIRT_CPU_ACCOUNTING 369 config VIRT_CPU_ACCOUNTING
497 bool 370 bool
498 371
499 choice 372 choice
500 prompt "Cputime accounting" 373 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 374 default TICK_CPU_ACCOUNTING if !PPC64
>> 375 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 376
503 # Kind of a stub config for the pure tick base 377 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 378 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 379 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 380 depends on !S390 && !NO_HZ_FULL
507 help 381 help
508 This is the basic tick based cputime 382 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 383 statistics about user, system and idle time spent on per jiffies
510 granularity. 384 granularity.
511 385
512 If unsure, say Y. 386 If unsure, say Y.
513 387
514 config VIRT_CPU_ACCOUNTING_NATIVE 388 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 389 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 390 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 391 select VIRT_CPU_ACCOUNTING
518 help 392 help
519 Select this option to enable more ac 393 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 394 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 395 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 396 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 397 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 398 this also enables accounting of stolen time on logically-partitioned
525 systems. 399 systems.
526 400
527 config VIRT_CPU_ACCOUNTING_GEN 401 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 402 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 403 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 404 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 405 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 406 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 407 select CONTEXT_TRACKING
534 help 408 help
535 Select this option to enable task an 409 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 410 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 411 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 412 The accounting is thus performed at the expense of some significant
539 overhead. 413 overhead.
540 414
541 For now this is only useful if you a 415 For now this is only useful if you are working on the full
542 dynticks subsystem development. 416 dynticks subsystem development.
543 417
544 If unsure, say N. 418 If unsure, say N.
545 419
546 endchoice 420 endchoice
547 421
548 config IRQ_TIME_ACCOUNTING 422 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 423 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 424 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 425 help
552 Select this option to enable fine gr 426 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 427 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 428 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 429 small performance impact.
556 430
557 If in doubt, say N here. 431 If in doubt, say N here.
558 432
559 config HAVE_SCHED_AVG_IRQ 433 config HAVE_SCHED_AVG_IRQ
560 def_bool y 434 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 435 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 436 depends on SMP
563 437
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 438 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 439 bool "BSD Process Accounting"
585 depends on MULTIUSER 440 depends on MULTIUSER
586 help 441 help
587 If you say Y here, a user level prog 442 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 443 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 444 information to a file: whenever a process exits, information about
590 that process will be appended to the 445 that process will be appended to the file by the kernel. The
591 information includes things such as 446 information includes things such as creation time, owning user,
592 command name, memory usage, controll 447 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 448 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 449 up to the user level program to do useful things with this
595 information. This is generally a go 450 information. This is generally a good idea, so say Y.
596 451
597 config BSD_PROCESS_ACCT_V3 452 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 453 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 454 depends on BSD_PROCESS_ACCT
600 default n 455 default n
601 help 456 help
602 If you say Y here, the process accou 457 If you say Y here, the process accounting information is written
603 in a new file format that also logs 458 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 459 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 460 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 461 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 462 at <http://www.gnu.org/software/acct/>.
608 463
609 config TASKSTATS 464 config TASKSTATS
610 bool "Export task/process statistics t 465 bool "Export task/process statistics through netlink"
611 depends on NET 466 depends on NET
612 depends on MULTIUSER 467 depends on MULTIUSER
613 default n 468 default n
614 help 469 help
615 Export selected statistics for tasks 470 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 471 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 472 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 473 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 474 space on task exit.
620 475
621 Say N if unsure. 476 Say N if unsure.
622 477
623 config TASK_DELAY_ACCT 478 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 479 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 480 depends on TASKSTATS
626 select SCHED_INFO 481 select SCHED_INFO
627 help 482 help
628 Collect information on time spent by 483 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 484 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 485 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 486 relative to other tasks for cpu, io, rss limits etc.
632 487
633 Say N if unsure. 488 Say N if unsure.
634 489
635 config TASK_XACCT 490 config TASK_XACCT
636 bool "Enable extended accounting over 491 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 492 depends on TASKSTATS
638 help 493 help
639 Collect extended task accounting dat 494 Collect extended task accounting data and send the data
640 to userland for processing over the 495 to userland for processing over the taskstats interface.
641 496
642 Say N if unsure. 497 Say N if unsure.
643 498
644 config TASK_IO_ACCOUNTING 499 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 500 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 501 depends on TASK_XACCT
647 help 502 help
648 Collect information on the number of 503 Collect information on the number of bytes of storage I/O which this
649 task has caused. 504 task has caused.
650 505
651 Say N if unsure. 506 Say N if unsure.
652 507
653 config PSI 508 config PSI
654 bool "Pressure stall information track 509 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 510 help
657 Collect metrics that indicate how ov 511 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 512 and IO capacity are in the system.
659 513
660 If you say Y here, the kernel will c 514 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 515 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 516 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 517 delayed due to contention of the respective resource.
664 518
665 In kernels with cgroup support, cgro 519 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 520 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 521 which aggregate pressure stalls for the grouped tasks only.
668 522
669 For more details see Documentation/a 523 For more details see Documentation/accounting/psi.rst.
670 524
671 Say N if unsure. 525 Say N if unsure.
672 526
673 config PSI_DEFAULT_DISABLED 527 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 528 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 529 default n
676 depends on PSI 530 depends on PSI
677 help 531 help
678 If set, pressure stall information t 532 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 533 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 534 kernel commandline during boot.
681 535
682 This feature adds some code to the t 536 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 537 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 538 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 539 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 540 scheduler stress tests, such as hackbench.
687 541
688 If you are paranoid and not sure wha 542 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 543 used for, say Y.
690 544
691 Say N if unsure. 545 Say N if unsure.
692 546
693 endmenu # "CPU/Task time and stats accounting" 547 endmenu # "CPU/Task time and stats accounting"
694 548
695 config CPU_ISOLATION 549 config CPU_ISOLATION
696 bool "CPU isolation" 550 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 551 depends on SMP || COMPILE_TEST
698 default y 552 default y
699 help 553 help
700 Make sure that CPUs running critical 554 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 555 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 556 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 557 the "isolcpus=" boot parameter.
704 558
705 Say Y if unsure. 559 Say Y if unsure.
706 560
707 source "kernel/rcu/Kconfig" 561 source "kernel/rcu/Kconfig"
708 562
>> 563 config BUILD_BIN2C
>> 564 bool
>> 565 default n
>> 566
709 config IKCONFIG 567 config IKCONFIG
710 tristate "Kernel .config support" 568 tristate "Kernel .config support"
711 help !! 569 ---help---
712 This option enables the complete Lin 570 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 571 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 572 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 573 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 574 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 575 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 576 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 577 /proc/config.gz if enabled (below).
720 578
721 config IKCONFIG_PROC 579 config IKCONFIG_PROC
722 bool "Enable access to .config through 580 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 581 depends on IKCONFIG && PROC_FS
724 help !! 582 ---help---
725 This option enables access to the ke 583 This option enables access to the kernel configuration file
726 through /proc/config.gz. 584 through /proc/config.gz.
727 585
728 config IKHEADERS 586 config IKHEADERS
729 tristate "Enable kernel headers throug 587 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 588 depends on SYSFS
731 help 589 help
732 This option enables access to the in 590 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 591 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 592 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 593 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 594
737 config LOG_BUF_SHIFT 595 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 596 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 597 range 12 25
740 default 17 598 default 17
741 depends on PRINTK 599 depends on PRINTK
742 help 600 help
743 Select the minimal kernel log buffer 601 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 602 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 603 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 604 by "log_buf_len" boot parameter.
747 605
748 Examples: 606 Examples:
749 17 => 128 KB 607 17 => 128 KB
750 16 => 64 KB 608 16 => 64 KB
751 15 => 32 KB 609 15 => 32 KB
752 14 => 16 KB 610 14 => 16 KB
753 13 => 8 KB 611 13 => 8 KB
754 12 => 4 KB 612 12 => 4 KB
755 613
756 config LOG_CPU_MAX_BUF_SHIFT 614 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 615 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 616 depends on SMP
759 range 0 21 617 range 0 21
>> 618 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 619 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 620 depends on PRINTK
763 help 621 help
764 This option allows to increase the d 622 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 623 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 624 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 625 lines however it might be much more when problems are reported,
768 e.g. backtraces. 626 e.g. backtraces.
769 627
770 The increased size means that a new 628 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 629 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 630 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 631 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 632 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed !! 633 so that more than 64 CPUs are needed to trigger the allocation.
776 634
777 Also this option is ignored when "lo 635 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 636 used as it forces an exact (power of two) size of the ring buffer.
779 637
780 The number of possible CPUs is used 638 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 639 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 640 scenario while allowing a simple algorithm to be used from bootup.
783 641
784 Examples shift values and their mean 642 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 643 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 644 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 645 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 646 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 647 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 648 12 => 4 KB for each CPU
791 649
792 config PRINTK_INDEX !! 650 config PRINTK_SAFE_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 651 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 652 range 10 21
795 help !! 653 default 13
796 Add support for indexing of all prin !! 654 depends on PRINTK
797 at <debugfs>/printk/index/<module>. !! 655 help
798 !! 656 Select the size of an alternate printk per-CPU buffer where messages
799 This can be used as part of maintain !! 657 printed from usafe contexts are temporary stored. One example would
800 /dev/kmsg, as it permits auditing th !! 658 be NMI messages, another one - printk recursion. The messages are
801 kernel, allowing detection of cases !! 659 copied to the main log buffer in a safe context to avoid a deadlock.
802 changed or no longer present. !! 660 The value defines the size as a power of 2.
>> 661
>> 662 Those messages are rare and limited. The largest one is when
>> 663 a backtrace is printed. It usually fits into 4KB. Select
>> 664 8KB if you want to be on the safe side.
803 665
804 There is no additional runtime cost !! 666 Examples:
>> 667 17 => 128 KB for each CPU
>> 668 16 => 64 KB for each CPU
>> 669 15 => 32 KB for each CPU
>> 670 14 => 16 KB for each CPU
>> 671 13 => 8 KB for each CPU
>> 672 12 => 4 KB for each CPU
805 673
806 # 674 #
807 # Architectures with an unreliable sched_clock 675 # Architectures with an unreliable sched_clock() should select this:
808 # 676 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 677 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 678 bool
811 679
812 config GENERIC_SCHED_CLOCK 680 config GENERIC_SCHED_CLOCK
813 bool 681 bool
814 682
815 menu "Scheduler features" 683 menu "Scheduler features"
816 684
817 config UCLAMP_TASK 685 config UCLAMP_TASK
818 bool "Enable utilization clamping for 686 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 687 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 688 help
821 This feature enables the scheduler t 689 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 690 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 691
824 With this option, the user can speci 692 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 693 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 694 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 695 defines the minimum frequency it should use.
828 696
829 Both min and max utilization clamp v 697 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 698 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 699 enforce or grant any specific bandwidth for tasks.
832 700
833 If in doubt, say N. 701 If in doubt, say N.
834 702
835 config UCLAMP_BUCKETS_COUNT 703 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 704 int "Number of supported utilization clamp buckets"
837 range 5 20 705 range 5 20
838 default 5 706 default 5
839 depends on UCLAMP_TASK 707 depends on UCLAMP_TASK
840 help 708 help
841 Defines the number of clamp buckets 709 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 710 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 711 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 712 the precision of clamping aggregation and tracking at run-time.
845 713
846 For example, with the minimum config 714 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 715 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 716 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 717 effective value to 25%.
850 If a second 30% boosted task should 718 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 719 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 720 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 721 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 722 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 723 that bucket.
856 724
857 An additional boost/capping margin c 725 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 726 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 727 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 728 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 729 clamp buckets to trade off used memory for run-time tracking
862 precision. 730 precision.
863 731
864 If in doubt, use the default value. 732 If in doubt, use the default value.
865 733
866 endmenu 734 endmenu
867 735
868 # 736 #
869 # For architectures that want to enable the su 737 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 738 # balancing logic:
871 # 739 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 740 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 741 bool
874 742
875 # 743 #
876 # For architectures that prefer to flush all T 744 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 745 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 746 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 747 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 748 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 749 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 750 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 751 bool
884 752
885 config CC_HAS_INT128 753 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 754 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 755
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 # 756 #
915 # For architectures that know their GCC __int1 757 # For architectures that know their GCC __int128 support is sound
916 # 758 #
917 config ARCH_SUPPORTS_INT128 759 config ARCH_SUPPORTS_INT128
918 bool 760 bool
919 761
920 # For architectures that (ab)use NUMA to repre 762 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 763 # all cpu-local but of different latencies, such as SuperH.
922 # 764 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 765 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 766 bool
925 767
926 config NUMA_BALANCING 768 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 769 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 770 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 771 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 772 depends on SMP && NUMA && MIGRATION
931 help 773 help
932 This option adds support for automat 774 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 775 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 776 it has references to the node the task is running on.
935 777
936 This system will be inactive on UMA 778 This system will be inactive on UMA systems.
937 779
938 config NUMA_BALANCING_DEFAULT_ENABLED 780 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 781 bool "Automatically enable NUMA aware memory/task placement"
940 default y 782 default y
941 depends on NUMA_BALANCING 783 depends on NUMA_BALANCING
942 help 784 help
943 If set, automatic NUMA balancing wil 785 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 786 machine.
945 787
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 788 menuconfig CGROUPS
950 bool "Control Group support" 789 bool "Control Group support"
951 select KERNFS 790 select KERNFS
952 help 791 help
953 This option adds support for groupin 792 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 793 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 794 controls or device isolation.
956 See 795 See
957 - Documentation/scheduler/sche 796 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 797 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 798 and resource control)
960 799
961 Say N if unsure. 800 Say N if unsure.
962 801
963 if CGROUPS 802 if CGROUPS
964 803
965 config PAGE_COUNTER 804 config PAGE_COUNTER
966 bool 805 bool
967 806
968 config CGROUP_FAVOR_DYNMODS <<
969 bool "Favor dynamic modification laten <<
970 help <<
971 This option enables the "favordynmod <<
972 which reduces the latencies of dynam <<
973 as task migrations and controller on <<
974 hot path operations such as forks an <<
975 <<
976 Say N if unsure. <<
977 <<
978 config MEMCG 807 config MEMCG
979 bool "Memory controller" 808 bool "Memory controller"
980 select PAGE_COUNTER 809 select PAGE_COUNTER
981 select EVENTFD 810 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 811 help
984 Provides control over the memory foo 812 Provides control over the memory footprint of tasks in a cgroup.
985 813
986 config MEMCG_V1 !! 814 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 815 bool "Swap controller"
988 depends on MEMCG !! 816 depends on MEMCG && SWAP
989 default n <<
990 help 817 help
991 Legacy cgroup v1 memory controller w !! 818 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 819
1001 Say N if unsure. !! 820 config MEMCG_SWAP_ENABLED
>> 821 bool "Swap controller enabled by default"
>> 822 depends on MEMCG_SWAP
>> 823 default y
>> 824 help
>> 825 Memory Resource Controller Swap Extension comes with its price in
>> 826 a bigger memory consumption. General purpose distribution kernels
>> 827 which want to enable the feature but keep it disabled by default
>> 828 and let the user enable it by swapaccount=1 boot command line
>> 829 parameter should have this option unselected.
>> 830 For those who want to have the feature enabled by default should
>> 831 select this option (if, for some reason, they need to disable it
>> 832 then swapaccount=0 does the trick).
>> 833
>> 834 config MEMCG_KMEM
>> 835 bool
>> 836 depends on MEMCG && !SLOB
>> 837 default y
1002 838
1003 config BLK_CGROUP 839 config BLK_CGROUP
1004 bool "IO controller" 840 bool "IO controller"
1005 depends on BLOCK 841 depends on BLOCK
1006 default n 842 default n
1007 help !! 843 ---help---
1008 Generic block IO controller cgroup in 844 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 845 cgroup interface which should be used by various IO controlling
1010 policies. 846 policies.
1011 847
1012 Currently, CFQ IO scheduler uses it t 848 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 849 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 850 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 851 block layer to implement upper limit in IO rates on a device.
1016 852
1017 This option only enables generic Bloc 853 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 854 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 855 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl !! 856 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 857 CONFIG_BLK_DEV_THROTTLING=y.
1022 858
1023 See Documentation/admin-guide/cgroup- 859 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 860
1025 config CGROUP_WRITEBACK 861 config CGROUP_WRITEBACK
1026 bool 862 bool
1027 depends on MEMCG && BLK_CGROUP 863 depends on MEMCG && BLK_CGROUP
1028 default y 864 default y
1029 865
1030 menuconfig CGROUP_SCHED 866 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 867 bool "CPU controller"
1032 default n 868 default n
1033 help 869 help
1034 This feature lets CPU scheduler rec 870 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 871 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 872 tasks.
1037 873
1038 if CGROUP_SCHED 874 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 875 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 876 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 877 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 878 default CGROUP_SCHED
1047 879
1048 config CFS_BANDWIDTH 880 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 881 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 882 depends on FAIR_GROUP_SCHED
1051 default n 883 default n
1052 help 884 help
1053 This option allows users to define 885 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 886 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 887 set are considered to be unconstrained and will run with no
1056 restriction. 888 restriction.
1057 See Documentation/scheduler/sched-b 889 See Documentation/scheduler/sched-bwc.rst for more information.
1058 890
1059 config RT_GROUP_SCHED 891 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 892 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 893 depends on CGROUP_SCHED
1062 default n 894 default n
1063 help 895 help
1064 This feature lets you explicitly al 896 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 897 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 898 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 899 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 900 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 901
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 902 endif #CGROUP_SCHED
1077 903
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 904 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 905 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 906 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 907 depends on UCLAMP_TASK
1086 default n 908 default n
1087 help 909 help
1088 This feature enables the scheduler 910 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 911 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 912
1091 When this option is enabled, the us 913 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 914 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 915 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 916 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 917 frequency a task will always use.
1096 918
1097 When task group based utilization c 919 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 920 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 921 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 922 be bigger than the corresponding clamping defined at task group level.
1101 923
1102 If in doubt, say N. 924 If in doubt, say N.
1103 925
1104 config CGROUP_PIDS 926 config CGROUP_PIDS
1105 bool "PIDs controller" 927 bool "PIDs controller"
1106 help 928 help
1107 Provides enforcement of process num 929 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 930 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 931 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 932 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 933 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 934 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 935 PIDs controller is designed to stop this from happening.
1114 936
1115 It should be noted that organisatio 937 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 938 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 939 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 940 attach to a cgroup.
1119 941
1120 config CGROUP_RDMA 942 config CGROUP_RDMA
1121 bool "RDMA controller" 943 bool "RDMA controller"
1122 help 944 help
1123 Provides enforcement of RDMA resour 945 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 946 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 947 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 948 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 949 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 950 hierarchy is allowed even if can cross the hierarchy's limit.
1129 951
1130 config CGROUP_FREEZER 952 config CGROUP_FREEZER
1131 bool "Freezer controller" 953 bool "Freezer controller"
1132 help 954 help
1133 Provides a way to freeze and unfree 955 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 956 cgroup.
1135 957
1136 This option affects the ORIGINAL cg 958 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 959 controller includes important in-kernel memory consumers per default.
1138 960
1139 If you're using cgroup2, say N. 961 If you're using cgroup2, say N.
1140 962
1141 config CGROUP_HUGETLB 963 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 964 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 965 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 966 select PAGE_COUNTER
1145 default n 967 default n
1146 help 968 help
1147 Provides a cgroup controller for Hu 969 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 970 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 971 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 972 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 973 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 974 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 975 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 976 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 977 that we cannot use the controller with huge page less than 3 pages.
1156 978
1157 config CPUSETS 979 config CPUSETS
1158 bool "Cpuset controller" 980 bool "Cpuset controller"
1159 depends on SMP 981 depends on SMP
1160 help 982 help
1161 This option will let you create and 983 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 984 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 985 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 986 This is primarily useful on large SMP or NUMA systems.
1165 987
1166 Say N if unsure. 988 Say N if unsure.
1167 989
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 990 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 991 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 992 depends on CPUSETS
1184 default y 993 default y
1185 994
1186 config CGROUP_DEVICE 995 config CGROUP_DEVICE
1187 bool "Device controller" 996 bool "Device controller"
1188 help 997 help
1189 Provides a cgroup controller implem 998 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 999 devices which a process in the cgroup can mknod or open.
1191 1000
1192 config CGROUP_CPUACCT 1001 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1002 bool "Simple CPU accounting controller"
1194 help 1003 help
1195 Provides a simple controller for mo 1004 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1005 total CPU consumed by the tasks in a cgroup.
1197 1006
1198 config CGROUP_PERF 1007 config CGROUP_PERF
1199 bool "Perf controller" 1008 bool "Perf controller"
1200 depends on PERF_EVENTS 1009 depends on PERF_EVENTS
1201 help 1010 help
1202 This option extends the perf per-cp 1011 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1012 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use !! 1013 designated cpu.
1205 so that it can monitor performance <<
1206 1014
1207 Say N if unsure. 1015 Say N if unsure.
1208 1016
1209 config CGROUP_BPF 1017 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1018 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1019 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1020 select SOCK_CGROUP_DATA
1213 help 1021 help
1214 Allow attaching eBPF programs to a 1022 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1023 syscall command BPF_PROG_ATTACH.
1216 1024
1217 In which context these programs are 1025 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1026 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1027 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1028 inet sockets.
1221 1029
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 1030 config CGROUP_DEBUG
1237 bool "Debug controller" 1031 bool "Debug controller"
1238 default n 1032 default n
1239 depends on DEBUG_KERNEL 1033 depends on DEBUG_KERNEL
1240 help 1034 help
1241 This option enables a simple contro 1035 This option enables a simple controller that exports
1242 debugging information about the cgr 1036 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1037 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1038 interfaces are not stable.
1245 1039
1246 Say N. 1040 Say N.
1247 1041
1248 config SOCK_CGROUP_DATA 1042 config SOCK_CGROUP_DATA
1249 bool 1043 bool
1250 default n 1044 default n
1251 1045
1252 endif # CGROUPS 1046 endif # CGROUPS
1253 1047
1254 menuconfig NAMESPACES 1048 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1049 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1050 depends on MULTIUSER
1257 default !EXPERT 1051 default !EXPERT
1258 help 1052 help
1259 Provides the way to make tasks work 1053 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1054 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1055 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1056 different namespaces.
1263 1057
1264 if NAMESPACES 1058 if NAMESPACES
1265 1059
1266 config UTS_NS 1060 config UTS_NS
1267 bool "UTS namespace" 1061 bool "UTS namespace"
1268 default y 1062 default y
1269 help 1063 help
1270 In this namespace tasks see differe 1064 In this namespace tasks see different info provided with the
1271 uname() system call 1065 uname() system call
1272 1066
1273 config TIME_NS 1067 config TIME_NS
1274 bool "TIME namespace" 1068 bool "TIME namespace"
1275 depends on GENERIC_VDSO_TIME_NS 1069 depends on GENERIC_VDSO_TIME_NS
1276 default y 1070 default y
1277 help 1071 help
1278 In this namespace boottime and mono 1072 In this namespace boottime and monotonic clocks can be set.
1279 The time will keep going with the s 1073 The time will keep going with the same pace.
1280 1074
1281 config IPC_NS 1075 config IPC_NS
1282 bool "IPC namespace" 1076 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1077 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1078 default y
1285 help 1079 help
1286 In this namespace tasks work with I 1080 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1081 different IPC objects in different namespaces.
1288 1082
1289 config USER_NS 1083 config USER_NS
1290 bool "User namespace" 1084 bool "User namespace"
1291 default n 1085 default n
1292 help 1086 help
1293 This allows containers, i.e. vserve 1087 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1088 to provide different user info for different servers.
1295 1089
1296 When user namespaces are enabled in 1090 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1091 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1092 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1093 of memory a memory unprivileged users can use.
1300 1094
1301 If unsure, say N. 1095 If unsure, say N.
1302 1096
1303 config PID_NS 1097 config PID_NS
1304 bool "PID Namespaces" 1098 bool "PID Namespaces"
1305 default y 1099 default y
1306 help 1100 help
1307 Support process id namespaces. Thi 1101 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1102 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1103 pid namespaces. This is a building block of containers.
1310 1104
1311 config NET_NS 1105 config NET_NS
1312 bool "Network namespace" 1106 bool "Network namespace"
1313 depends on NET 1107 depends on NET
1314 default y 1108 default y
1315 help 1109 help
1316 Allow user space to create what app 1110 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1111 of the network stack.
1318 1112
1319 endif # NAMESPACES 1113 endif # NAMESPACES
1320 1114
1321 config CHECKPOINT_RESTORE 1115 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1116 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1117 select PROC_CHILDREN
1325 select KCMP <<
1326 default n 1118 default n
1327 help 1119 help
1328 Enables additional kernel features 1120 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1121 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1122 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1123 entries.
1332 1124
1333 If unsure, say N here. 1125 If unsure, say N here.
1334 1126
1335 config SCHED_AUTOGROUP 1127 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1128 bool "Automatic process group scheduling"
1337 select CGROUPS 1129 select CGROUPS
1338 select CGROUP_SCHED 1130 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1131 select FAIR_GROUP_SCHED
1340 help 1132 help
1341 This option optimizes the scheduler 1133 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1134 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1135 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1136 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1137 upon task session.
1346 1138
>> 1139 config SYSFS_DEPRECATED
>> 1140 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1141 depends on SYSFS
>> 1142 default n
>> 1143 help
>> 1144 This option adds code that switches the layout of the "block" class
>> 1145 devices, to not show up in /sys/class/block/, but only in
>> 1146 /sys/block/.
>> 1147
>> 1148 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1149 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1150
>> 1151 This option allows new kernels to run on old distributions and tools,
>> 1152 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1153 major distributions and tools handle this just fine.
>> 1154
>> 1155 Recent distributions and userspace tools after 2009/2010 depend on
>> 1156 the existence of /sys/class/block/, and will not work with this
>> 1157 option enabled.
>> 1158
>> 1159 Only if you are using a new kernel on an old distribution, you might
>> 1160 need to say Y here.
>> 1161
>> 1162 config SYSFS_DEPRECATED_V2
>> 1163 bool "Enable deprecated sysfs features by default"
>> 1164 default n
>> 1165 depends on SYSFS
>> 1166 depends on SYSFS_DEPRECATED
>> 1167 help
>> 1168 Enable deprecated sysfs by default.
>> 1169
>> 1170 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1171 option.
>> 1172
>> 1173 Only if you are using a new kernel on an old distribution, you might
>> 1174 need to say Y here. Even then, odds are you would not need it
>> 1175 enabled, you can always pass the boot option if absolutely necessary.
>> 1176
1347 config RELAY 1177 config RELAY
1348 bool "Kernel->user space relay suppor 1178 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1179 select IRQ_WORK
1350 help 1180 help
1351 This option enables support for rel 1181 This option enables support for relay interface support in
1352 certain file systems (such as debug 1182 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1183 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1184 facilities to relay large amounts of data from kernel space to
1355 user space. 1185 user space.
1356 1186
1357 If unsure, say N. 1187 If unsure, say N.
1358 1188
1359 config BLK_DEV_INITRD 1189 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1190 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1191 help
1362 The initial RAM filesystem is a ram 1192 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1193 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1194 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1195 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1196 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1197
1368 If RAM disk support (BLK_DEV_RAM) i 1198 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1199 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1200 15 Kbytes (more on some other architectures) to the kernel size.
1371 1201
1372 If unsure say Y. 1202 If unsure say Y.
1373 1203
1374 if BLK_DEV_INITRD 1204 if BLK_DEV_INITRD
1375 1205
1376 source "usr/Kconfig" 1206 source "usr/Kconfig"
1377 1207
1378 endif 1208 endif
1379 1209
1380 config BOOT_CONFIG 1210 config BOOT_CONFIG
1381 bool "Boot config support" 1211 bool "Boot config support"
1382 select BLK_DEV_INITRD if !BOOT_CONFIG !! 1212 select BLK_DEV_INITRD
1383 help 1213 help
1384 Extra boot config allows system adm 1214 Extra boot config allows system admin to pass a config file as
1385 complemental extension of kernel cm 1215 complemental extension of kernel cmdline when booting.
1386 The boot config file must be attach 1216 The boot config file must be attached at the end of initramfs
1387 with checksum, size and magic word. 1217 with checksum, size and magic word.
1388 See <file:Documentation/admin-guide 1218 See <file:Documentation/admin-guide/bootconfig.rst> for details.
1389 1219
1390 If unsure, say Y. 1220 If unsure, say Y.
1391 1221
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 1222 choice
1435 prompt "Compiler optimization level" 1223 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1224 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1225
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1226 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1227 bool "Optimize for performance (-O2)"
1440 help 1228 help
1441 This is the default optimization le 1229 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1230 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1231 helpful compile-time warnings.
1444 1232
>> 1233 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1234 bool "Optimize more for performance (-O3)"
>> 1235 depends on ARC
>> 1236 help
>> 1237 Choosing this option will pass "-O3" to your compiler to optimize
>> 1238 the kernel yet more for performance.
>> 1239
1445 config CC_OPTIMIZE_FOR_SIZE 1240 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1241 bool "Optimize for size (-Os)"
1447 help 1242 help
1448 Choosing this option will pass "-Os 1243 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1244 in a smaller kernel.
1450 1245
1451 endchoice 1246 endchoice
1452 1247
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1248 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1249 bool
1455 help 1250 help
1456 This requires that the arch annotat 1251 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1252 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1253 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1254 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1255 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1256 is used to distinguish them from label names / C identifiers.
1462 1257
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1258 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1259 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1260 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1261 depends on EXPERT
>> 1262 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1467 depends on $(cc-option,-ffunction-sec 1263 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1264 depends on $(ld-option,--gc-sections)
1469 help 1265 help
1470 Enable this if you want to do dead 1266 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1267 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1268 and linking with --gc-sections.
1473 1269
1474 This can reduce on disk and in-memo 1270 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1271 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1272 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1273 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1274 present. This option is not well tested yet, so use at your
1479 own risk. 1275 own risk.
1480 1276
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 1277 config SYSCTL
1494 bool 1278 bool
1495 1279
1496 config HAVE_UID16 1280 config HAVE_UID16
1497 bool 1281 bool
1498 1282
1499 config SYSCTL_EXCEPTION_TRACE 1283 config SYSCTL_EXCEPTION_TRACE
1500 bool 1284 bool
1501 help 1285 help
1502 Enable support for /proc/sys/debug/ 1286 Enable support for /proc/sys/debug/exception-trace.
1503 1287
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1288 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1289 bool
1506 help 1290 help
1507 Enable support for /proc/sys/kernel 1291 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1292 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1293 about unaligned access emulation going on under the hood.
1510 1294
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1295 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1296 bool
1513 help 1297 help
1514 Enable support for /proc/sys/kernel 1298 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1299 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1300 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1301 see arch/parisc/kernel/unaligned.c for reference
1518 1302
1519 config HAVE_PCSPKR_PLATFORM 1303 config HAVE_PCSPKR_PLATFORM
1520 bool 1304 bool
1521 1305
>> 1306 # interpreter that classic socket filters depend on
>> 1307 config BPF
>> 1308 bool
>> 1309
1522 menuconfig EXPERT 1310 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1311 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1312 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1313 select DEBUG_KERNEL
1526 help 1314 help
1527 This option allows certain base ker 1315 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1316 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1317 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1318 Only use this if you really know what you are doing.
1531 1319
1532 config UID16 1320 config UID16
1533 bool "Enable 16-bit UID system calls" 1321 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1322 depends on HAVE_UID16 && MULTIUSER
1535 default y 1323 default y
1536 help 1324 help
1537 This enables the legacy 16-bit UID 1325 This enables the legacy 16-bit UID syscall wrappers.
1538 1326
1539 config MULTIUSER 1327 config MULTIUSER
1540 bool "Multiple users, groups and capa 1328 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1329 default y
1542 help 1330 help
1543 This option enables support for non 1331 This option enables support for non-root users, groups and
1544 capabilities. 1332 capabilities.
1545 1333
1546 If you say N here, all processes wi 1334 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1335 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1336 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1337 setgid, and capset.
1550 1338
1551 If unsure, say Y here. 1339 If unsure, say Y here.
1552 1340
1553 config SGETMASK_SYSCALL 1341 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1342 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1343 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help !! 1344 ---help---
1557 sys_sgetmask and sys_ssetmask are o 1345 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1346 no longer supported in libc but still enabled by default in some
1559 architectures. 1347 architectures.
1560 1348
1561 If unsure, leave the default option 1349 If unsure, leave the default option here.
1562 1350
1563 config SYSFS_SYSCALL 1351 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1352 bool "Sysfs syscall support" if EXPERT
1565 default y 1353 default y
1566 help !! 1354 ---help---
1567 sys_sysfs is an obsolete system cal 1355 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1356 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1357 compatibility with some systems.
1570 1358
1571 If unsure say Y here. 1359 If unsure say Y here.
1572 1360
1573 config FHANDLE 1361 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1362 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1363 select EXPORTFS
1576 default y 1364 default y
1577 help 1365 help
1578 If you say Y here, a user level pro 1366 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1367 file names to handle and then later use the handle for
1580 different file system operations. T 1368 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1369 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1370 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1371 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1372 syscalls.
1585 1373
1586 config POSIX_TIMERS 1374 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1375 bool "Posix Clocks & timers" if EXPERT
1588 default y 1376 default y
1589 help 1377 help
1590 This includes native support for PO 1378 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1379 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1380 can be configured out to reduce the size of the kernel image.
1593 1381
1594 When this option is disabled, the f 1382 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1383 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1384 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1385 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1386 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1387 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1388
1601 If unsure say y. 1389 If unsure say y.
1602 1390
1603 config PRINTK 1391 config PRINTK
1604 default y 1392 default y
1605 bool "Enable support for printk" if E 1393 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1394 select IRQ_WORK
1607 help 1395 help
1608 This option enables normal printk s 1396 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1397 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1398 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1399 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1400 strongly discouraged.
1613 1401
>> 1402 config PRINTK_NMI
>> 1403 def_bool y
>> 1404 depends on PRINTK
>> 1405 depends on HAVE_NMI
>> 1406
1614 config BUG 1407 config BUG
1615 bool "BUG() support" if EXPERT 1408 bool "BUG() support" if EXPERT
1616 default y 1409 default y
1617 help 1410 help
1618 Disabling this option eliminates su 1411 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1412 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1413 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1414 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1415 Just say Y.
1623 1416
1624 config ELF_CORE 1417 config ELF_CORE
1625 depends on COREDUMP 1418 depends on COREDUMP
1626 default y 1419 default y
1627 bool "Enable ELF core dumps" if EXPER 1420 bool "Enable ELF core dumps" if EXPERT
1628 help 1421 help
1629 Enable support for generating core 1422 Enable support for generating core dumps. Disabling saves about 4k.
1630 1423
1631 1424
1632 config PCSPKR_PLATFORM 1425 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1426 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1427 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1428 select I8253_LOCK
1636 default y 1429 default y
1637 help 1430 help
1638 This option allows to disable the i 1431 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1432 support, saving some memory.
1640 1433
1641 config BASE_SMALL !! 1434 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1435 default y
>> 1436 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1437 help
1644 Enabling this option reduces the si !! 1438 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1439 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1440 but may reduce performance.
1647 1441
1648 config FUTEX 1442 config FUTEX
1649 bool "Enable futex support" if EXPERT 1443 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1444 default y
1652 imply RT_MUTEXES 1445 imply RT_MUTEXES
1653 help 1446 help
1654 Disabling this option will cause th 1447 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1448 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1449 run glibc-based applications correctly.
1657 1450
1658 config FUTEX_PI 1451 config FUTEX_PI
1659 bool 1452 bool
1660 depends on FUTEX && RT_MUTEXES 1453 depends on FUTEX && RT_MUTEXES
1661 default y 1454 default y
1662 1455
>> 1456 config HAVE_FUTEX_CMPXCHG
>> 1457 bool
>> 1458 depends on FUTEX
>> 1459 help
>> 1460 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1461 is implemented and always working. This removes a couple of runtime
>> 1462 checks.
>> 1463
1663 config EPOLL 1464 config EPOLL
1664 bool "Enable eventpoll support" if EX 1465 bool "Enable eventpoll support" if EXPERT
1665 default y 1466 default y
1666 help 1467 help
1667 Disabling this option will cause th 1468 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1469 support for epoll family of system calls.
1669 1470
1670 config SIGNALFD 1471 config SIGNALFD
1671 bool "Enable signalfd() system call" 1472 bool "Enable signalfd() system call" if EXPERT
1672 default y 1473 default y
1673 help 1474 help
1674 Enable the signalfd() system call t 1475 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1476 on a file descriptor.
1676 1477
1677 If unsure, say Y. 1478 If unsure, say Y.
1678 1479
1679 config TIMERFD 1480 config TIMERFD
1680 bool "Enable timerfd() system call" i 1481 bool "Enable timerfd() system call" if EXPERT
1681 default y 1482 default y
1682 help 1483 help
1683 Enable the timerfd() system call th 1484 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1485 events on a file descriptor.
1685 1486
1686 If unsure, say Y. 1487 If unsure, say Y.
1687 1488
1688 config EVENTFD 1489 config EVENTFD
1689 bool "Enable eventfd() system call" i 1490 bool "Enable eventfd() system call" if EXPERT
1690 default y 1491 default y
1691 help 1492 help
1692 Enable the eventfd() system call th 1493 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1494 kernel notification (ie. KAIO) or userspace notifications.
1694 1495
1695 If unsure, say Y. 1496 If unsure, say Y.
1696 1497
1697 config SHMEM 1498 config SHMEM
1698 bool "Use full shmem filesystem" if E 1499 bool "Use full shmem filesystem" if EXPERT
1699 default y 1500 default y
1700 depends on MMU 1501 depends on MMU
1701 help 1502 help
1702 The shmem is an internal filesystem 1503 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1504 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1505 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1506 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1507 which may be appropriate on small systems without swap.
1707 1508
1708 config AIO 1509 config AIO
1709 bool "Enable AIO support" if EXPERT 1510 bool "Enable AIO support" if EXPERT
1710 default y 1511 default y
1711 help 1512 help
1712 This option enables POSIX asynchron 1513 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1514 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1515 this option saves about 7k.
1715 1516
1716 config IO_URING 1517 config IO_URING
1717 bool "Enable IO uring support" if EXP 1518 bool "Enable IO uring support" if EXPERT
>> 1519 select ANON_INODES
1718 select IO_WQ 1520 select IO_WQ
1719 default y 1521 default y
1720 help 1522 help
1721 This option enables support for the 1523 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1524 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1525 completion rings that are shared between the kernel and application.
1724 1526
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 1527 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1528 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1529 default y
1741 help 1530 help
1742 This option enables the madvise and 1531 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1532 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1533 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1534 applications use these syscalls, you can disable this option to save
1746 space. 1535 space.
1747 1536
1748 config MEMBARRIER 1537 config MEMBARRIER
1749 bool "Enable membarrier() system call 1538 bool "Enable membarrier() system call" if EXPERT
1750 default y 1539 default y
1751 help 1540 help
1752 Enable the membarrier() system call 1541 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1542 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1543 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1544 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1545 compiler barrier.
1757 1546
1758 If unsure, say Y. 1547 If unsure, say Y.
1759 1548
1760 config KCMP <<
1761 bool "Enable kcmp() system call" if E <<
1762 help <<
1763 Enable the kernel resource comparis <<
1764 user-space with the ability to comp <<
1765 share a common resource, such as a <<
1766 memory space. <<
1767 <<
1768 If unsure, say N. <<
1769 <<
1770 config RSEQ <<
1771 bool "Enable rseq() system call" if E <<
1772 default y <<
1773 depends on HAVE_RSEQ <<
1774 select MEMBARRIER <<
1775 help <<
1776 Enable the restartable sequences sy <<
1777 user-space cache for the current CP <<
1778 speeds up getting the current CPU n <<
1779 as well as an ABI to speed up user- <<
1780 per-CPU data. <<
1781 <<
1782 If unsure, say Y. <<
1783 <<
1784 config DEBUG_RSEQ <<
1785 default n <<
1786 bool "Enable debugging of rseq() syst <<
1787 depends on RSEQ && DEBUG_KERNEL <<
1788 help <<
1789 Enable extra debugging checks for t <<
1790 <<
1791 If unsure, say N. <<
1792 <<
1793 config CACHESTAT_SYSCALL <<
1794 bool "Enable cachestat() system call" <<
1795 default y <<
1796 help <<
1797 Enable the cachestat system call, w <<
1798 statistics of a file (number of cac <<
1799 pages marked for writeback, (recent <<
1800 <<
1801 If unsure say Y here. <<
1802 <<
1803 config PC104 <<
1804 bool "PC/104 support" if EXPERT <<
1805 help <<
1806 Expose PC/104 form factor device dr <<
1807 selection and configuration. Enable <<
1808 machine has a PC/104 bus. <<
1809 <<
1810 config KALLSYMS 1549 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1550 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1551 default y
1813 help 1552 help
1814 Say Y here to let the kernel print 1553 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1554 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1555 somewhat, as all symbols have to be loaded into the kernel image.
1817 1556
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 1557 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1558 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1559 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1560 help
1835 Normally kallsyms only contains the 1561 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1562 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m !! 1563 sections). This is sufficient for most cases. And only in very rare
1838 enable kernel live patching, or oth !! 1564 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1839 when a debugger is used) all symbol !! 1565 names of variables from the data sections, etc).
1840 variables from the data sections, e <<
1841 1566
1842 This option makes sure that all sym 1567 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1568 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1569 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1570 something like this).
1846 1571
1847 Say N unless you really need all sy !! 1572 Say N unless you really need all symbols.
1848 1573
1849 config KALLSYMS_ABSOLUTE_PERCPU 1574 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1575 bool
1851 depends on KALLSYMS 1576 depends on KALLSYMS
1852 default X86_64 && SMP 1577 default X86_64 && SMP
1853 1578
>> 1579 config KALLSYMS_BASE_RELATIVE
>> 1580 bool
>> 1581 depends on KALLSYMS
>> 1582 default !IA64
>> 1583 help
>> 1584 Instead of emitting them as absolute values in the native word size,
>> 1585 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1586 each containing a relative value in the range [base, base + U32_MAX]
>> 1587 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1588 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1589 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1590 address encountered in the image.
>> 1591
>> 1592 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1593 but more importantly, it results in entries whose values are build
>> 1594 time constants, and no relocation pass is required at runtime to fix
>> 1595 up the entries based on the runtime load address of the kernel.
>> 1596
1854 # end of the "standard kernel features (exper 1597 # end of the "standard kernel features (expert users)" menu
1855 1598
>> 1599 # syscall, maps, verifier
>> 1600 config BPF_SYSCALL
>> 1601 bool "Enable bpf() system call"
>> 1602 select BPF
>> 1603 select IRQ_WORK
>> 1604 default n
>> 1605 help
>> 1606 Enable the bpf() system call that allows to manipulate eBPF
>> 1607 programs and maps via file descriptors.
>> 1608
>> 1609 config ARCH_WANT_DEFAULT_BPF_JIT
>> 1610 bool
>> 1611
>> 1612 config BPF_JIT_ALWAYS_ON
>> 1613 bool "Permanently enable BPF JIT and remove BPF interpreter"
>> 1614 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
>> 1615 help
>> 1616 Enables BPF JIT and removes BPF interpreter to avoid
>> 1617 speculative execution of BPF instructions by the interpreter
>> 1618
>> 1619 config BPF_JIT_DEFAULT_ON
>> 1620 def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
>> 1621 depends on HAVE_EBPF_JIT && BPF_JIT
>> 1622
>> 1623 config USERFAULTFD
>> 1624 bool "Enable userfaultfd() system call"
>> 1625 depends on MMU
>> 1626 help
>> 1627 Enable the userfaultfd() system call that allows to intercept and
>> 1628 handle page faults in userland.
>> 1629
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1630 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1631 bool
1858 1632
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1633 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1634 bool
1861 1635
>> 1636 config RSEQ
>> 1637 bool "Enable rseq() system call" if EXPERT
>> 1638 default y
>> 1639 depends on HAVE_RSEQ
>> 1640 select MEMBARRIER
>> 1641 help
>> 1642 Enable the restartable sequences system call. It provides a
>> 1643 user-space cache for the current CPU number value, which
>> 1644 speeds up getting the current CPU number from user-space,
>> 1645 as well as an ABI to speed up user-space operations on
>> 1646 per-CPU data.
>> 1647
>> 1648 If unsure, say Y.
>> 1649
>> 1650 config DEBUG_RSEQ
>> 1651 default n
>> 1652 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1653 depends on RSEQ && DEBUG_KERNEL
>> 1654 help
>> 1655 Enable extra debugging checks for the rseq system call.
>> 1656
>> 1657 If unsure, say N.
>> 1658
>> 1659 config EMBEDDED
>> 1660 bool "Embedded system"
>> 1661 option allnoconfig_y
>> 1662 select EXPERT
>> 1663 help
>> 1664 This option should be enabled if compiling the kernel for
>> 1665 an embedded system so certain expert options are available
>> 1666 for configuration.
>> 1667
1862 config HAVE_PERF_EVENTS 1668 config HAVE_PERF_EVENTS
1863 bool 1669 bool
1864 help 1670 help
1865 See tools/perf/design.txt for detai 1671 See tools/perf/design.txt for details.
1866 1672
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1673 config PERF_USE_VMALLOC
1872 bool 1674 bool
1873 help 1675 help
1874 See tools/perf/design.txt for detai 1676 See tools/perf/design.txt for details
1875 1677
>> 1678 config PC104
>> 1679 bool "PC/104 support" if EXPERT
>> 1680 help
>> 1681 Expose PC/104 form factor device drivers and options available for
>> 1682 selection and configuration. Enable this option if your target
>> 1683 machine has a PC/104 bus.
>> 1684
1876 menu "Kernel Performance Events And Counters" 1685 menu "Kernel Performance Events And Counters"
1877 1686
1878 config PERF_EVENTS 1687 config PERF_EVENTS
1879 bool "Kernel performance events and c 1688 bool "Kernel performance events and counters"
1880 default y if PROFILING 1689 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1690 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1691 select IRQ_WORK
>> 1692 select SRCU
1883 help 1693 help
1884 Enable kernel support for various p 1694 Enable kernel support for various performance events provided
1885 by software and hardware. 1695 by software and hardware.
1886 1696
1887 Software events are supported eithe 1697 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1698 use of generic tracepoints.
1889 1699
1890 Most modern CPUs support performanc 1700 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1701 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1702 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1703 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1704 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1705 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1706 used to profile the code that runs on that CPU.
1897 1707
1898 The Linux Performance Event subsyst 1708 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1709 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1710 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1711 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1712 capabilities on top of those.
1903 1713
1904 Say Y if unsure. 1714 Say Y if unsure.
1905 1715
1906 config DEBUG_PERF_USE_VMALLOC 1716 config DEBUG_PERF_USE_VMALLOC
1907 default n 1717 default n
1908 bool "Debug: use vmalloc to back perf 1718 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1719 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1720 select PERF_USE_VMALLOC
1911 help 1721 help
1912 Use vmalloc memory to back perf mma 1722 Use vmalloc memory to back perf mmap() buffers.
1913 1723
1914 Mostly useful for debugging the vma 1724 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1725 that don't require it.
1916 1726
1917 Say N if unsure. 1727 Say N if unsure.
1918 1728
1919 endmenu 1729 endmenu
1920 1730
>> 1731 config VM_EVENT_COUNTERS
>> 1732 default y
>> 1733 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1734 help
>> 1735 VM event counters are needed for event counts to be shown.
>> 1736 This option allows the disabling of the VM event counters
>> 1737 on EXPERT systems. /proc/vmstat will only show page counts
>> 1738 if VM event counters are disabled.
>> 1739
>> 1740 config SLUB_DEBUG
>> 1741 default y
>> 1742 bool "Enable SLUB debugging support" if EXPERT
>> 1743 depends on SLUB && SYSFS
>> 1744 help
>> 1745 SLUB has extensive debug support features. Disabling these can
>> 1746 result in significant savings in code size. This also disables
>> 1747 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1748 no support for cache validation etc.
>> 1749
>> 1750 config SLUB_MEMCG_SYSFS_ON
>> 1751 default n
>> 1752 bool "Enable memcg SLUB sysfs support by default" if EXPERT
>> 1753 depends on SLUB && SYSFS && MEMCG
>> 1754 help
>> 1755 SLUB creates a directory under /sys/kernel/slab for each
>> 1756 allocation cache to host info and debug files. If memory
>> 1757 cgroup is enabled, each cache can have per memory cgroup
>> 1758 caches. SLUB can create the same sysfs directories for these
>> 1759 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
>> 1760 to a very high number of debug files being created. This is
>> 1761 controlled by slub_memcg_sysfs boot parameter and this
>> 1762 config option determines the parameter's default value.
>> 1763
>> 1764 config COMPAT_BRK
>> 1765 bool "Disable heap randomization"
>> 1766 default y
>> 1767 help
>> 1768 Randomizing heap placement makes heap exploits harder, but it
>> 1769 also breaks ancient binaries (including anything libc5 based).
>> 1770 This option changes the bootup default to heap randomization
>> 1771 disabled, and can be overridden at runtime by setting
>> 1772 /proc/sys/kernel/randomize_va_space to 2.
>> 1773
>> 1774 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1775
>> 1776 choice
>> 1777 prompt "Choose SLAB allocator"
>> 1778 default SLUB
>> 1779 help
>> 1780 This option allows to select a slab allocator.
>> 1781
>> 1782 config SLAB
>> 1783 bool "SLAB"
>> 1784 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1785 help
>> 1786 The regular slab allocator that is established and known to work
>> 1787 well in all environments. It organizes cache hot objects in
>> 1788 per cpu and per node queues.
>> 1789
>> 1790 config SLUB
>> 1791 bool "SLUB (Unqueued Allocator)"
>> 1792 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1793 help
>> 1794 SLUB is a slab allocator that minimizes cache line usage
>> 1795 instead of managing queues of cached objects (SLAB approach).
>> 1796 Per cpu caching is realized using slabs of objects instead
>> 1797 of queues of objects. SLUB can use memory efficiently
>> 1798 and has enhanced diagnostics. SLUB is the default choice for
>> 1799 a slab allocator.
>> 1800
>> 1801 config SLOB
>> 1802 depends on EXPERT
>> 1803 bool "SLOB (Simple Allocator)"
>> 1804 help
>> 1805 SLOB replaces the stock allocator with a drastically simpler
>> 1806 allocator. SLOB is generally more space efficient but
>> 1807 does not perform as well on large systems.
>> 1808
>> 1809 endchoice
>> 1810
>> 1811 config SLAB_MERGE_DEFAULT
>> 1812 bool "Allow slab caches to be merged"
>> 1813 default y
>> 1814 help
>> 1815 For reduced kernel memory fragmentation, slab caches can be
>> 1816 merged when they share the same size and other characteristics.
>> 1817 This carries a risk of kernel heap overflows being able to
>> 1818 overwrite objects from merged caches (and more easily control
>> 1819 cache layout), which makes such heap attacks easier to exploit
>> 1820 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1821 can usually only damage objects in the same cache. To disable
>> 1822 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1823 command line.
>> 1824
>> 1825 config SLAB_FREELIST_RANDOM
>> 1826 default n
>> 1827 depends on SLAB || SLUB
>> 1828 bool "SLAB freelist randomization"
>> 1829 help
>> 1830 Randomizes the freelist order used on creating new pages. This
>> 1831 security feature reduces the predictability of the kernel slab
>> 1832 allocator against heap overflows.
>> 1833
>> 1834 config SLAB_FREELIST_HARDENED
>> 1835 bool "Harden slab freelist metadata"
>> 1836 depends on SLUB
>> 1837 help
>> 1838 Many kernel heap attacks try to target slab cache metadata and
>> 1839 other infrastructure. This options makes minor performance
>> 1840 sacrifices to harden the kernel slab allocator against common
>> 1841 freelist exploit methods.
>> 1842
>> 1843 config SHUFFLE_PAGE_ALLOCATOR
>> 1844 bool "Page allocator randomization"
>> 1845 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1846 help
>> 1847 Randomization of the page allocator improves the average
>> 1848 utilization of a direct-mapped memory-side-cache. See section
>> 1849 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1850 6.2a specification for an example of how a platform advertises
>> 1851 the presence of a memory-side-cache. There are also incidental
>> 1852 security benefits as it reduces the predictability of page
>> 1853 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1854 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1855 10th order of pages is selected based on cache utilization
>> 1856 benefits on x86.
>> 1857
>> 1858 While the randomization improves cache utilization it may
>> 1859 negatively impact workloads on platforms without a cache. For
>> 1860 this reason, by default, the randomization is enabled only
>> 1861 after runtime detection of a direct-mapped memory-side-cache.
>> 1862 Otherwise, the randomization may be force enabled with the
>> 1863 'page_alloc.shuffle' kernel command line parameter.
>> 1864
>> 1865 Say Y if unsure.
>> 1866
>> 1867 config SLUB_CPU_PARTIAL
>> 1868 default y
>> 1869 depends on SLUB && SMP
>> 1870 bool "SLUB per cpu partial cache"
>> 1871 help
>> 1872 Per cpu partial caches accelerate objects allocation and freeing
>> 1873 that is local to a processor at the price of more indeterminism
>> 1874 in the latency of the free. On overflow these caches will be cleared
>> 1875 which requires the taking of locks that may cause latency spikes.
>> 1876 Typically one would choose no for a realtime system.
>> 1877
>> 1878 config MMAP_ALLOW_UNINITIALIZED
>> 1879 bool "Allow mmapped anonymous memory to be uninitialized"
>> 1880 depends on EXPERT && !MMU
>> 1881 default n
>> 1882 help
>> 1883 Normally, and according to the Linux spec, anonymous memory obtained
>> 1884 from mmap() has its contents cleared before it is passed to
>> 1885 userspace. Enabling this config option allows you to request that
>> 1886 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 1887 providing a huge performance boost. If this option is not enabled,
>> 1888 then the flag will be ignored.
>> 1889
>> 1890 This is taken advantage of by uClibc's malloc(), and also by
>> 1891 ELF-FDPIC binfmt's brk and stack allocator.
>> 1892
>> 1893 Because of the obvious security issues, this option should only be
>> 1894 enabled on embedded devices where you control what is run in
>> 1895 userspace. Since that isn't generally a problem on no-MMU systems,
>> 1896 it is normally safe to say Y here.
>> 1897
>> 1898 See Documentation/nommu-mmap.txt for more information.
>> 1899
1921 config SYSTEM_DATA_VERIFICATION 1900 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1901 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1902 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1903 select KEYS
1925 select CRYPTO 1904 select CRYPTO
1926 select CRYPTO_RSA 1905 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1906 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1907 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1908 select ASN1
1930 select OID_REGISTRY 1909 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1910 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1911 select PKCS7_MESSAGE_PARSER
1933 help 1912 help
1934 Provide PKCS#7 message verification 1913 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1914 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1915 module verification, kexec image verification and firmware blob
1937 verification. 1916 verification.
1938 1917
1939 config PROFILING 1918 config PROFILING
1940 bool "Profiling support" 1919 bool "Profiling support"
1941 help 1920 help
1942 Say Y here to enable the extended p 1921 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 1922 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 1923
1986 # 1924 #
1987 # Place an empty function call at each tracep 1925 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1926 # dynamically changed for a probe function.
1989 # 1927 #
1990 config TRACEPOINTS 1928 config TRACEPOINTS
1991 bool 1929 bool
1992 1930
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1931 endmenu # General setup
1996 1932
1997 source "arch/Kconfig" 1933 source "arch/Kconfig"
1998 1934
1999 config RT_MUTEXES 1935 config RT_MUTEXES
2000 bool 1936 bool
2001 default y if PREEMPT_RT !! 1937
>> 1938 config BASE_SMALL
>> 1939 int
>> 1940 default 0 if BASE_FULL
>> 1941 default 1 if !BASE_FULL
2002 1942
2003 config MODULE_SIG_FORMAT 1943 config MODULE_SIG_FORMAT
2004 def_bool n 1944 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 1945 select SYSTEM_DATA_VERIFICATION
2006 1946
2007 source "kernel/module/Kconfig" !! 1947 menuconfig MODULES
>> 1948 bool "Enable loadable module support"
>> 1949 option modules
>> 1950 help
>> 1951 Kernel modules are small pieces of compiled code which can
>> 1952 be inserted in the running kernel, rather than being
>> 1953 permanently built into the kernel. You use the "modprobe"
>> 1954 tool to add (and sometimes remove) them. If you say Y here,
>> 1955 many parts of the kernel can be built as modules (by
>> 1956 answering M instead of Y where indicated): this is most
>> 1957 useful for infrequently used options which are not required
>> 1958 for booting. For more information, see the man pages for
>> 1959 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1960
>> 1961 If you say Y here, you will need to run "make
>> 1962 modules_install" to put the modules under /lib/modules/
>> 1963 where modprobe can find them (you may need to be root to do
>> 1964 this).
>> 1965
>> 1966 If unsure, say Y.
>> 1967
>> 1968 if MODULES
>> 1969
>> 1970 config MODULE_FORCE_LOAD
>> 1971 bool "Forced module loading"
>> 1972 default n
>> 1973 help
>> 1974 Allow loading of modules without version information (ie. modprobe
>> 1975 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1976 is usually a really bad idea.
>> 1977
>> 1978 config MODULE_UNLOAD
>> 1979 bool "Module unloading"
>> 1980 help
>> 1981 Without this option you will not be able to unload any
>> 1982 modules (note that some modules may not be unloadable
>> 1983 anyway), which makes your kernel smaller, faster
>> 1984 and simpler. If unsure, say Y.
>> 1985
>> 1986 config MODULE_FORCE_UNLOAD
>> 1987 bool "Forced module unloading"
>> 1988 depends on MODULE_UNLOAD
>> 1989 help
>> 1990 This option allows you to force a module to unload, even if the
>> 1991 kernel believes it is unsafe: the kernel will remove the module
>> 1992 without waiting for anyone to stop using it (using the -f option to
>> 1993 rmmod). This is mainly for kernel developers and desperate users.
>> 1994 If unsure, say N.
>> 1995
>> 1996 config MODVERSIONS
>> 1997 bool "Module versioning support"
>> 1998 help
>> 1999 Usually, you have to use modules compiled with your kernel.
>> 2000 Saying Y here makes it sometimes possible to use modules
>> 2001 compiled for different kernels, by adding enough information
>> 2002 to the modules to (hopefully) spot any changes which would
>> 2003 make them incompatible with the kernel you are running. If
>> 2004 unsure, say N.
>> 2005
>> 2006 config ASM_MODVERSIONS
>> 2007 bool
>> 2008 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 2009 help
>> 2010 This enables module versioning for exported symbols also from
>> 2011 assembly. This can be enabled only when the target architecture
>> 2012 supports it.
>> 2013
>> 2014 config MODULE_REL_CRCS
>> 2015 bool
>> 2016 depends on MODVERSIONS
>> 2017
>> 2018 config MODULE_SRCVERSION_ALL
>> 2019 bool "Source checksum for all modules"
>> 2020 help
>> 2021 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2022 field inserted into their modinfo section, which contains a
>> 2023 sum of the source files which made it. This helps maintainers
>> 2024 see exactly which source was used to build a module (since
>> 2025 others sometimes change the module source without updating
>> 2026 the version). With this option, such a "srcversion" field
>> 2027 will be created for all modules. If unsure, say N.
>> 2028
>> 2029 config MODULE_SIG
>> 2030 bool "Module signature verification"
>> 2031 select MODULE_SIG_FORMAT
>> 2032 help
>> 2033 Check modules for valid signatures upon load: the signature
>> 2034 is simply appended to the module. For more information see
>> 2035 <file:Documentation/admin-guide/module-signing.rst>.
>> 2036
>> 2037 Note that this option adds the OpenSSL development packages as a
>> 2038 kernel build dependency so that the signing tool can use its crypto
>> 2039 library.
>> 2040
>> 2041 You should enable this option if you wish to use either
>> 2042 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2043 another LSM - otherwise unsigned modules will be loadable regardless
>> 2044 of the lockdown policy.
>> 2045
>> 2046 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2047 module DOES NOT get stripped after being signed. This includes the
>> 2048 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2049 inclusion into an initramfs that wants the module size reduced.
>> 2050
>> 2051 config MODULE_SIG_FORCE
>> 2052 bool "Require modules to be validly signed"
>> 2053 depends on MODULE_SIG
>> 2054 help
>> 2055 Reject unsigned modules or signed modules for which we don't have a
>> 2056 key. Without this, such modules will simply taint the kernel.
>> 2057
>> 2058 config MODULE_SIG_ALL
>> 2059 bool "Automatically sign all modules"
>> 2060 default y
>> 2061 depends on MODULE_SIG
>> 2062 help
>> 2063 Sign all modules during make modules_install. Without this option,
>> 2064 modules must be signed manually, using the scripts/sign-file tool.
>> 2065
>> 2066 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2067 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2068
>> 2069 choice
>> 2070 prompt "Which hash algorithm should modules be signed with?"
>> 2071 depends on MODULE_SIG
>> 2072 help
>> 2073 This determines which sort of hashing algorithm will be used during
>> 2074 signature generation. This algorithm _must_ be built into the kernel
>> 2075 directly so that signature verification can take place. It is not
>> 2076 possible to load a signed module containing the algorithm to check
>> 2077 the signature on that module.
>> 2078
>> 2079 config MODULE_SIG_SHA1
>> 2080 bool "Sign modules with SHA-1"
>> 2081 select CRYPTO_SHA1
>> 2082
>> 2083 config MODULE_SIG_SHA224
>> 2084 bool "Sign modules with SHA-224"
>> 2085 select CRYPTO_SHA256
>> 2086
>> 2087 config MODULE_SIG_SHA256
>> 2088 bool "Sign modules with SHA-256"
>> 2089 select CRYPTO_SHA256
>> 2090
>> 2091 config MODULE_SIG_SHA384
>> 2092 bool "Sign modules with SHA-384"
>> 2093 select CRYPTO_SHA512
>> 2094
>> 2095 config MODULE_SIG_SHA512
>> 2096 bool "Sign modules with SHA-512"
>> 2097 select CRYPTO_SHA512
>> 2098
>> 2099 endchoice
>> 2100
>> 2101 config MODULE_SIG_HASH
>> 2102 string
>> 2103 depends on MODULE_SIG
>> 2104 default "sha1" if MODULE_SIG_SHA1
>> 2105 default "sha224" if MODULE_SIG_SHA224
>> 2106 default "sha256" if MODULE_SIG_SHA256
>> 2107 default "sha384" if MODULE_SIG_SHA384
>> 2108 default "sha512" if MODULE_SIG_SHA512
>> 2109
>> 2110 config MODULE_COMPRESS
>> 2111 bool "Compress modules on installation"
>> 2112 help
>> 2113
>> 2114 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2115 xz depending on "Compression algorithm" below.
>> 2116
>> 2117 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2118
>> 2119 Out-of-tree kernel modules installed using Kbuild will also be
>> 2120 compressed upon installation.
>> 2121
>> 2122 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2123 to compress the whole initrd or initramfs instead.
>> 2124
>> 2125 Note: This is fully compatible with signed modules.
>> 2126
>> 2127 If in doubt, say N.
>> 2128
>> 2129 choice
>> 2130 prompt "Compression algorithm"
>> 2131 depends on MODULE_COMPRESS
>> 2132 default MODULE_COMPRESS_GZIP
>> 2133 help
>> 2134 This determines which sort of compression will be used during
>> 2135 'make modules_install'.
>> 2136
>> 2137 GZIP (default) and XZ are supported.
>> 2138
>> 2139 config MODULE_COMPRESS_GZIP
>> 2140 bool "GZIP"
>> 2141
>> 2142 config MODULE_COMPRESS_XZ
>> 2143 bool "XZ"
>> 2144
>> 2145 endchoice
>> 2146
>> 2147 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2148 bool "Allow loading of modules with missing namespace imports"
>> 2149 help
>> 2150 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2151 a namespace. A module that makes use of a symbol exported with such a
>> 2152 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2153 There is no technical reason to enforce correct namespace imports,
>> 2154 but it creates consistency between symbols defining namespaces and
>> 2155 users importing namespaces they make use of. This option relaxes this
>> 2156 requirement and lifts the enforcement when loading a module.
>> 2157
>> 2158 If unsure, say N.
>> 2159
>> 2160 config UNUSED_SYMBOLS
>> 2161 bool "Enable unused/obsolete exported symbols"
>> 2162 default y if X86
>> 2163 help
>> 2164 Unused but exported symbols make the kernel needlessly bigger. For
>> 2165 that reason most of these unused exports will soon be removed. This
>> 2166 option is provided temporarily to provide a transition period in case
>> 2167 some external kernel module needs one of these symbols anyway. If you
>> 2168 encounter such a case in your module, consider if you are actually
>> 2169 using the right API. (rationale: since nobody in the kernel is using
>> 2170 this in a module, there is a pretty good chance it's actually the
>> 2171 wrong interface to use). If you really need the symbol, please send a
>> 2172 mail to the linux kernel mailing list mentioning the symbol and why
>> 2173 you really need it, and what the merge plan to the mainline kernel for
>> 2174 your module is.
>> 2175
>> 2176 config TRIM_UNUSED_KSYMS
>> 2177 bool "Trim unused exported kernel symbols"
>> 2178 depends on !UNUSED_SYMBOLS
>> 2179 help
>> 2180 The kernel and some modules make many symbols available for
>> 2181 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2182 on the set of modules being selected in your kernel configuration,
>> 2183 many of those exported symbols might never be used.
>> 2184
>> 2185 This option allows for unused exported symbols to be dropped from
>> 2186 the build. In turn, this provides the compiler more opportunities
>> 2187 (especially when using LTO) for optimizing the code and reducing
>> 2188 binary size. This might have some security advantages as well.
>> 2189
>> 2190 If unsure, or if you need to build out-of-tree modules, say N.
>> 2191
>> 2192 endif # MODULES
>> 2193
>> 2194 config MODULES_TREE_LOOKUP
>> 2195 def_bool y
>> 2196 depends on PERF_EVENTS || TRACING
2008 2197
2009 config INIT_ALL_POSSIBLE 2198 config INIT_ALL_POSSIBLE
2010 bool 2199 bool
2011 help 2200 help
2012 Back when each arch used to define 2201 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2202 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2203 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2204 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2205 and have several arch maintainers pursuing me down dark alleys.
2017 2206
2018 source "block/Kconfig" 2207 source "block/Kconfig"
2019 2208
2020 config PREEMPT_NOTIFIERS 2209 config PREEMPT_NOTIFIERS
2021 bool 2210 bool
2022 2211
2023 config PADATA 2212 config PADATA
2024 depends on SMP 2213 depends on SMP
2025 bool 2214 bool
2026 2215
2027 config ASN1 2216 config ASN1
2028 tristate 2217 tristate
2029 help 2218 help
2030 Build a simple ASN.1 grammar compil 2219 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2220 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2221 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2222 functions to call on what tags.
2034 2223
2035 source "kernel/Kconfig.locks" 2224 source "kernel/Kconfig.locks"
2036 2225
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE 2226 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool 2227 bool
2042 2228
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2229 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2230 bool
2045 2231
2046 # It may be useful for an architecture to ove 2232 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2233 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2234 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2235 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2236 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2237 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2238 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2239 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2240 def_bool n
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