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 !! 39 config CC_HAS_WARN_MAYBE_UNINITIALIZED
121 def_bool $(success,echo '__attribute__ !! 40 def_bool $(cc-option,-Wmaybe-uninitialized)
>> 41 help
>> 42 GCC >= 4.7 supports this option.
122 43
123 config PAHOLE_VERSION !! 44 config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
124 int !! 45 bool
125 default $(shell,$(srctree)/scripts/pah !! 46 depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
>> 47 default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9
>> 48 help
>> 49 GCC's -Wmaybe-uninitialized is not reliable by definition.
>> 50 Lots of false positive warnings are produced in some cases.
>> 51
>> 52 If this option is enabled, -Wno-maybe-uninitialzed is passed
>> 53 to the compiler to suppress maybe-uninitialized warnings.
126 54
127 config CONSTRUCTORS 55 config CONSTRUCTORS
128 bool 56 bool
>> 57 depends on !UML
129 58
130 config IRQ_WORK 59 config IRQ_WORK
131 def_bool y if SMP !! 60 bool
132 61
133 config BUILDTIME_TABLE_SORT !! 62 config BUILDTIME_EXTABLE_SORT
134 bool 63 bool
135 64
136 config THREAD_INFO_IN_TASK 65 config THREAD_INFO_IN_TASK
137 bool 66 bool
138 help 67 help
139 Select this to move thread_info off 68 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 69 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 70 except flags and fix any runtime bugs.
142 71
143 One subtle change that will be neede 72 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 73 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 74
146 menu "General setup" 75 menu "General setup"
147 76
148 config BROKEN 77 config BROKEN
149 bool 78 bool
150 79
151 config BROKEN_ON_SMP 80 config BROKEN_ON_SMP
152 bool 81 bool
153 depends on BROKEN || !SMP 82 depends on BROKEN || !SMP
154 default y 83 default y
155 84
156 config INIT_ENV_ARG_LIMIT 85 config INIT_ENV_ARG_LIMIT
157 int 86 int
158 default 32 if !UML 87 default 32 if !UML
159 default 128 if UML 88 default 128 if UML
160 help 89 help
161 Maximum of each of the number of arg 90 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 91 variables passed to init from the kernel command line.
163 92
164 config COMPILE_TEST 93 config COMPILE_TEST
165 bool "Compile also drivers which will 94 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM !! 95 depends on !UML
>> 96 default n
167 help 97 help
168 Some drivers can be compiled on a di 98 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 99 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 100 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 101 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 102 drivers to compile-test them.
173 103
174 If you are a developer and want to b 104 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 105 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 106 drivers to be distributed.
177 107
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 108 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 109 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L 110 depends on HEADERS_INSTALL && CC_CAN_LINK
198 help 111 help
199 Compile test headers exported to use 112 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 113 self-contained, i.e. compilable as standalone units.
201 114
202 If you are a developer or tester and 115 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 116 headers are self-contained, say Y here. Otherwise, choose N.
204 117
205 config LOCALVERSION 118 config LOCALVERSION
206 string "Local version - append to kern 119 string "Local version - append to kernel release"
207 help 120 help
208 Append an extra string to the end of 121 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 122 This will show up when you type uname, for example.
210 The string you set here will be appe 123 The string you set here will be appended after the contents of
211 any files with a filename matching l 124 any files with a filename matching localversion* in your
212 object and source tree, in that orde 125 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 126 be a maximum of 64 characters.
214 127
215 config LOCALVERSION_AUTO 128 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 129 bool "Automatically append version information to the version string"
217 default y 130 default y
218 depends on !COMPILE_TEST 131 depends on !COMPILE_TEST
219 help 132 help
220 This will try to automatically deter 133 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 134 release tree by looking for git tags that belong to the current
222 top of tree revision. 135 top of tree revision.
223 136
224 A string of the format -gxxxxxxxx wi 137 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 138 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 139 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 140 set in CONFIG_LOCALVERSION.
228 141
229 (The actual string used here is the !! 142 (The actual string used here is the first eight characters produced
230 by running the command: 143 by running the command:
231 144
232 $ git rev-parse --verify HEAD 145 $ git rev-parse --verify HEAD
233 146
234 which is done within the script "scr 147 which is done within the script "scripts/setlocalversion".)
235 148
236 config BUILD_SALT 149 config BUILD_SALT
237 string "Build ID Salt" 150 string "Build ID Salt"
238 default "" 151 default ""
239 help 152 help
240 The build ID is used to link binarie 153 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th 154 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi 155 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's 156 build is unique between builds. It's safe to leave the default.
244 157
245 config HAVE_KERNEL_GZIP 158 config HAVE_KERNEL_GZIP
246 bool 159 bool
247 160
248 config HAVE_KERNEL_BZIP2 161 config HAVE_KERNEL_BZIP2
249 bool 162 bool
250 163
251 config HAVE_KERNEL_LZMA 164 config HAVE_KERNEL_LZMA
252 bool 165 bool
253 166
254 config HAVE_KERNEL_XZ 167 config HAVE_KERNEL_XZ
255 bool 168 bool
256 169
257 config HAVE_KERNEL_LZO 170 config HAVE_KERNEL_LZO
258 bool 171 bool
259 172
260 config HAVE_KERNEL_LZ4 173 config HAVE_KERNEL_LZ4
261 bool 174 bool
262 175
263 config HAVE_KERNEL_ZSTD <<
264 bool <<
265 <<
266 config HAVE_KERNEL_UNCOMPRESSED 176 config HAVE_KERNEL_UNCOMPRESSED
267 bool 177 bool
268 178
269 choice 179 choice
270 prompt "Kernel compression mode" 180 prompt "Kernel compression mode"
271 default KERNEL_GZIP 181 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE !! 182 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 183 help
274 The linux kernel is a kind of self-e 184 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 185 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 186 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 187 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 188 Decompression speed is relevant at each boot.
279 189
280 If you have any problems with bzip2 190 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 191 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 192 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 193 supplied by Christian Ludwig)
284 194
285 High compression options are mostly 195 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 196 are low on disk space (embedded systems), but for whom ram
287 size matters less. 197 size matters less.
288 198
289 If in doubt, select 'gzip' 199 If in doubt, select 'gzip'
290 200
291 config KERNEL_GZIP 201 config KERNEL_GZIP
292 bool "Gzip" 202 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 203 depends on HAVE_KERNEL_GZIP
294 help 204 help
295 The old and tried gzip compression. 205 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 206 between compression ratio and decompression speed.
297 207
298 config KERNEL_BZIP2 208 config KERNEL_BZIP2
299 bool "Bzip2" 209 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 210 depends on HAVE_KERNEL_BZIP2
301 help 211 help
302 Its compression ratio and speed is i 212 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 213 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 214 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 215 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 216 will need at least 8MB RAM or more for booting.
307 217
308 config KERNEL_LZMA 218 config KERNEL_LZMA
309 bool "LZMA" 219 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 220 depends on HAVE_KERNEL_LZMA
311 help 221 help
312 This compression algorithm's ratio i 222 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 223 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 224 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 225
316 config KERNEL_XZ 226 config KERNEL_XZ
317 bool "XZ" 227 bool "XZ"
318 depends on HAVE_KERNEL_XZ 228 depends on HAVE_KERNEL_XZ
319 help 229 help
320 XZ uses the LZMA2 algorithm and inst 230 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 231 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 232 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 233 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 234 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 235 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 236
328 The speed is about the same as with 237 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 238 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 239 and LZO. Compression is slow.
331 240
332 config KERNEL_LZO 241 config KERNEL_LZO
333 bool "LZO" 242 bool "LZO"
334 depends on HAVE_KERNEL_LZO 243 depends on HAVE_KERNEL_LZO
335 help 244 help
336 Its compression ratio is the poorest 245 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 246 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 247 (both compression and decompression) is the fastest.
339 248
340 config KERNEL_LZ4 249 config KERNEL_LZ4
341 bool "LZ4" 250 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 251 depends on HAVE_KERNEL_LZ4
343 help 252 help
344 LZ4 is an LZ77-type compressor with 253 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 254 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 255 <https://code.google.com/p/lz4/>.
347 256
348 Its compression ratio is worse than 257 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 258 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 259 faster than LZO.
351 260
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 261 config KERNEL_UNCOMPRESSED
363 bool "None" 262 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 263 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 264 help
366 Produce uncompressed kernel image. T 265 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 266 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 267 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 268 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 269 and jump right at uncompressed kernel image.
371 270
372 endchoice 271 endchoice
373 272
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 273 config DEFAULT_HOSTNAME
385 string "Default hostname" 274 string "Default hostname"
386 default "(none)" 275 default "(none)"
387 help 276 help
388 This option determines the default s 277 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 278 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 279 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 280 system more usable with less configuration.
392 281
>> 282 #
>> 283 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 284 # add proper SWAP support to them, in which case this can be remove.
>> 285 #
>> 286 config ARCH_NO_SWAP
>> 287 bool
>> 288
>> 289 config SWAP
>> 290 bool "Support for paging of anonymous memory (swap)"
>> 291 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 292 default y
>> 293 help
>> 294 This option allows you to choose whether you want to have support
>> 295 for so called swap devices or swap files in your kernel that are
>> 296 used to provide more virtual memory than the actual RAM present
>> 297 in your computer. If unsure say Y.
>> 298
393 config SYSVIPC 299 config SYSVIPC
394 bool "System V IPC" 300 bool "System V IPC"
395 help !! 301 ---help---
396 Inter Process Communication is a sui 302 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 303 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 304 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 305 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 306 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 307 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 308 you'll need to say Y here.
403 309
404 You can find documentation about IPC 310 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 311 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 312 <http://www.tldp.org/guides.html>.
407 313
408 config SYSVIPC_SYSCTL 314 config SYSVIPC_SYSCTL
409 bool 315 bool
410 depends on SYSVIPC 316 depends on SYSVIPC
411 depends on SYSCTL 317 depends on SYSCTL
412 default y 318 default y
413 319
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 320 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 321 bool "POSIX Message Queues"
420 depends on NET 322 depends on NET
421 help !! 323 ---help---
422 POSIX variant of message queues is a 324 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 325 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 326 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 327 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 328 queues (functions mq_*) say Y here.
427 329
428 POSIX message queues are visible as 330 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 331 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 332 operations on message queues.
431 333
432 If unsure, say Y. 334 If unsure, say Y.
433 335
434 config POSIX_MQUEUE_SYSCTL 336 config POSIX_MQUEUE_SYSCTL
435 bool 337 bool
436 depends on POSIX_MQUEUE 338 depends on POSIX_MQUEUE
437 depends on SYSCTL 339 depends on SYSCTL
438 default y 340 default y
439 341
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 342 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 343 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 344 depends on MMU
455 default y 345 default y
456 help 346 help
457 Enabling this option adds the system 347 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 348 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 349 to directly read from or write to another process' address space.
460 See the man page for more details. 350 See the man page for more details.
461 351
462 config USELIB 352 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 353 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 354 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 355 help
466 This option enables the uselib sysca 356 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 357 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 358 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 359 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 360 running glibc can safely disable this.
471 361
472 config AUDIT 362 config AUDIT
473 bool "Auditing support" 363 bool "Auditing support"
474 depends on NET 364 depends on NET
475 help 365 help
476 Enable auditing infrastructure that 366 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 367 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 368 logging of avc messages output). System call auditing is included
479 on architectures which support it. 369 on architectures which support it.
480 370
481 config HAVE_ARCH_AUDITSYSCALL 371 config HAVE_ARCH_AUDITSYSCALL
482 bool 372 bool
483 373
484 config AUDITSYSCALL 374 config AUDITSYSCALL
485 def_bool y 375 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 376 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 377 select FSNOTIFY
488 378
489 source "kernel/irq/Kconfig" 379 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 380 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" <<
492 source "kernel/Kconfig.preempt" 381 source "kernel/Kconfig.preempt"
493 382
494 menu "CPU/Task time and stats accounting" 383 menu "CPU/Task time and stats accounting"
495 384
496 config VIRT_CPU_ACCOUNTING 385 config VIRT_CPU_ACCOUNTING
497 bool 386 bool
498 387
499 choice 388 choice
500 prompt "Cputime accounting" 389 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 390 default TICK_CPU_ACCOUNTING if !PPC64
>> 391 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 392
503 # Kind of a stub config for the pure tick base 393 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 394 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 395 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 396 depends on !S390 && !NO_HZ_FULL
507 help 397 help
508 This is the basic tick based cputime 398 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 399 statistics about user, system and idle time spent on per jiffies
510 granularity. 400 granularity.
511 401
512 If unsure, say Y. 402 If unsure, say Y.
513 403
514 config VIRT_CPU_ACCOUNTING_NATIVE 404 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 405 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 406 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 407 select VIRT_CPU_ACCOUNTING
518 help 408 help
519 Select this option to enable more ac 409 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 410 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 411 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 412 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 413 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 414 this also enables accounting of stolen time on logically-partitioned
525 systems. 415 systems.
526 416
527 config VIRT_CPU_ACCOUNTING_GEN 417 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 418 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 419 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 420 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 421 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 422 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 423 select CONTEXT_TRACKING
534 help 424 help
535 Select this option to enable task an 425 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 426 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 427 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 428 The accounting is thus performed at the expense of some significant
539 overhead. 429 overhead.
540 430
541 For now this is only useful if you a 431 For now this is only useful if you are working on the full
542 dynticks subsystem development. 432 dynticks subsystem development.
543 433
544 If unsure, say N. 434 If unsure, say N.
545 435
546 endchoice 436 endchoice
547 437
548 config IRQ_TIME_ACCOUNTING 438 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 439 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 440 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 441 help
552 Select this option to enable fine gr 442 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 443 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 444 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 445 small performance impact.
556 446
557 If in doubt, say N here. 447 If in doubt, say N here.
558 448
559 config HAVE_SCHED_AVG_IRQ 449 config HAVE_SCHED_AVG_IRQ
560 def_bool y 450 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 451 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 452 depends on SMP
563 453
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 454 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 455 bool "BSD Process Accounting"
585 depends on MULTIUSER 456 depends on MULTIUSER
586 help 457 help
587 If you say Y here, a user level prog 458 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 459 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 460 information to a file: whenever a process exits, information about
590 that process will be appended to the 461 that process will be appended to the file by the kernel. The
591 information includes things such as 462 information includes things such as creation time, owning user,
592 command name, memory usage, controll 463 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 464 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 465 up to the user level program to do useful things with this
595 information. This is generally a go 466 information. This is generally a good idea, so say Y.
596 467
597 config BSD_PROCESS_ACCT_V3 468 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 469 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 470 depends on BSD_PROCESS_ACCT
600 default n 471 default n
601 help 472 help
602 If you say Y here, the process accou 473 If you say Y here, the process accounting information is written
603 in a new file format that also logs 474 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 475 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 476 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 477 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 478 at <http://www.gnu.org/software/acct/>.
608 479
609 config TASKSTATS 480 config TASKSTATS
610 bool "Export task/process statistics t 481 bool "Export task/process statistics through netlink"
611 depends on NET 482 depends on NET
612 depends on MULTIUSER 483 depends on MULTIUSER
613 default n 484 default n
614 help 485 help
615 Export selected statistics for tasks 486 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 487 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 488 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 489 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 490 space on task exit.
620 491
621 Say N if unsure. 492 Say N if unsure.
622 493
623 config TASK_DELAY_ACCT 494 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 495 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 496 depends on TASKSTATS
626 select SCHED_INFO 497 select SCHED_INFO
627 help 498 help
628 Collect information on time spent by 499 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 500 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 501 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 502 relative to other tasks for cpu, io, rss limits etc.
632 503
633 Say N if unsure. 504 Say N if unsure.
634 505
635 config TASK_XACCT 506 config TASK_XACCT
636 bool "Enable extended accounting over 507 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 508 depends on TASKSTATS
638 help 509 help
639 Collect extended task accounting dat 510 Collect extended task accounting data and send the data
640 to userland for processing over the 511 to userland for processing over the taskstats interface.
641 512
642 Say N if unsure. 513 Say N if unsure.
643 514
644 config TASK_IO_ACCOUNTING 515 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 516 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 517 depends on TASK_XACCT
647 help 518 help
648 Collect information on the number of 519 Collect information on the number of bytes of storage I/O which this
649 task has caused. 520 task has caused.
650 521
651 Say N if unsure. 522 Say N if unsure.
652 523
653 config PSI 524 config PSI
654 bool "Pressure stall information track 525 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 526 help
657 Collect metrics that indicate how ov 527 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 528 and IO capacity are in the system.
659 529
660 If you say Y here, the kernel will c 530 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 531 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 532 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 533 delayed due to contention of the respective resource.
664 534
665 In kernels with cgroup support, cgro 535 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 536 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 537 which aggregate pressure stalls for the grouped tasks only.
668 538
669 For more details see Documentation/a 539 For more details see Documentation/accounting/psi.rst.
670 540
671 Say N if unsure. 541 Say N if unsure.
672 542
673 config PSI_DEFAULT_DISABLED 543 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 544 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 545 default n
676 depends on PSI 546 depends on PSI
677 help 547 help
678 If set, pressure stall information t 548 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 549 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 550 kernel commandline during boot.
681 551
682 This feature adds some code to the t 552 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 553 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 554 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 555 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 556 scheduler stress tests, such as hackbench.
687 557
688 If you are paranoid and not sure wha 558 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 559 used for, say Y.
690 560
691 Say N if unsure. 561 Say N if unsure.
692 562
693 endmenu # "CPU/Task time and stats accounting" 563 endmenu # "CPU/Task time and stats accounting"
694 564
695 config CPU_ISOLATION 565 config CPU_ISOLATION
696 bool "CPU isolation" 566 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 567 depends on SMP || COMPILE_TEST
698 default y 568 default y
699 help 569 help
700 Make sure that CPUs running critical 570 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 571 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 572 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 573 the "isolcpus=" boot parameter.
704 574
705 Say Y if unsure. 575 Say Y if unsure.
706 576
707 source "kernel/rcu/Kconfig" 577 source "kernel/rcu/Kconfig"
708 578
>> 579 config BUILD_BIN2C
>> 580 bool
>> 581 default n
>> 582
709 config IKCONFIG 583 config IKCONFIG
710 tristate "Kernel .config support" 584 tristate "Kernel .config support"
711 help !! 585 ---help---
712 This option enables the complete Lin 586 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 587 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 588 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 589 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 590 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 591 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 592 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 593 /proc/config.gz if enabled (below).
720 594
721 config IKCONFIG_PROC 595 config IKCONFIG_PROC
722 bool "Enable access to .config through 596 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 597 depends on IKCONFIG && PROC_FS
724 help !! 598 ---help---
725 This option enables access to the ke 599 This option enables access to the kernel configuration file
726 through /proc/config.gz. 600 through /proc/config.gz.
727 601
728 config IKHEADERS 602 config IKHEADERS
729 tristate "Enable kernel headers throug 603 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 604 depends on SYSFS
731 help 605 help
732 This option enables access to the in 606 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 607 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 608 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 609 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 610
737 config LOG_BUF_SHIFT 611 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 612 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 613 range 12 25
740 default 17 614 default 17
741 depends on PRINTK 615 depends on PRINTK
742 help 616 help
743 Select the minimal kernel log buffer 617 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 618 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 619 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 620 by "log_buf_len" boot parameter.
747 621
748 Examples: 622 Examples:
749 17 => 128 KB 623 17 => 128 KB
750 16 => 64 KB 624 16 => 64 KB
751 15 => 32 KB 625 15 => 32 KB
752 14 => 16 KB 626 14 => 16 KB
753 13 => 8 KB 627 13 => 8 KB
754 12 => 4 KB 628 12 => 4 KB
755 629
756 config LOG_CPU_MAX_BUF_SHIFT 630 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 631 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 632 depends on SMP
759 range 0 21 633 range 0 21
>> 634 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 635 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 636 depends on PRINTK
763 help 637 help
764 This option allows to increase the d 638 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 639 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 640 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 641 lines however it might be much more when problems are reported,
768 e.g. backtraces. 642 e.g. backtraces.
769 643
770 The increased size means that a new 644 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 645 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 646 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 647 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 648 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed !! 649 so that more than 64 CPUs are needed to trigger the allocation.
776 650
777 Also this option is ignored when "lo 651 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 652 used as it forces an exact (power of two) size of the ring buffer.
779 653
780 The number of possible CPUs is used 654 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 655 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 656 scenario while allowing a simple algorithm to be used from bootup.
783 657
784 Examples shift values and their mean 658 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 659 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 660 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 661 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 662 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 663 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 664 12 => 4 KB for each CPU
791 665
792 config PRINTK_INDEX !! 666 config PRINTK_SAFE_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 667 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 668 range 10 21
795 help !! 669 default 13
796 Add support for indexing of all prin !! 670 depends on PRINTK
797 at <debugfs>/printk/index/<module>. !! 671 help
798 !! 672 Select the size of an alternate printk per-CPU buffer where messages
799 This can be used as part of maintain !! 673 printed from usafe contexts are temporary stored. One example would
800 /dev/kmsg, as it permits auditing th !! 674 be NMI messages, another one - printk recursion. The messages are
801 kernel, allowing detection of cases !! 675 copied to the main log buffer in a safe context to avoid a deadlock.
802 changed or no longer present. !! 676 The value defines the size as a power of 2.
>> 677
>> 678 Those messages are rare and limited. The largest one is when
>> 679 a backtrace is printed. It usually fits into 4KB. Select
>> 680 8KB if you want to be on the safe side.
803 681
804 There is no additional runtime cost !! 682 Examples:
>> 683 17 => 128 KB for each CPU
>> 684 16 => 64 KB for each CPU
>> 685 15 => 32 KB for each CPU
>> 686 14 => 16 KB for each CPU
>> 687 13 => 8 KB for each CPU
>> 688 12 => 4 KB for each CPU
805 689
806 # 690 #
807 # Architectures with an unreliable sched_clock 691 # Architectures with an unreliable sched_clock() should select this:
808 # 692 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 693 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 694 bool
811 695
812 config GENERIC_SCHED_CLOCK 696 config GENERIC_SCHED_CLOCK
813 bool 697 bool
814 698
815 menu "Scheduler features" 699 menu "Scheduler features"
816 700
817 config UCLAMP_TASK 701 config UCLAMP_TASK
818 bool "Enable utilization clamping for 702 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 703 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 704 help
821 This feature enables the scheduler t 705 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 706 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 707
824 With this option, the user can speci 708 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 709 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 710 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 711 defines the minimum frequency it should use.
828 712
829 Both min and max utilization clamp v 713 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 714 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 715 enforce or grant any specific bandwidth for tasks.
832 716
833 If in doubt, say N. 717 If in doubt, say N.
834 718
835 config UCLAMP_BUCKETS_COUNT 719 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 720 int "Number of supported utilization clamp buckets"
837 range 5 20 721 range 5 20
838 default 5 722 default 5
839 depends on UCLAMP_TASK 723 depends on UCLAMP_TASK
840 help 724 help
841 Defines the number of clamp buckets 725 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 726 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 727 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 728 the precision of clamping aggregation and tracking at run-time.
845 729
846 For example, with the minimum config 730 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 731 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 732 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 733 effective value to 25%.
850 If a second 30% boosted task should 734 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 735 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 736 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 737 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 738 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 739 that bucket.
856 740
857 An additional boost/capping margin c 741 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 742 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 743 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 744 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 745 clamp buckets to trade off used memory for run-time tracking
862 precision. 746 precision.
863 747
864 If in doubt, use the default value. 748 If in doubt, use the default value.
865 749
866 endmenu 750 endmenu
867 751
868 # 752 #
869 # For architectures that want to enable the su 753 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 754 # balancing logic:
871 # 755 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 756 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 757 bool
874 758
875 # 759 #
876 # For architectures that prefer to flush all T 760 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 761 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 762 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 763 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 764 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 765 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 766 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 767 bool
884 768
885 config CC_HAS_INT128 769 config CC_HAS_INT128
886 def_bool !$(cc-option,$(m64-flag) -D__ 770 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
887 771
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 # 772 #
915 # For architectures that know their GCC __int1 773 # For architectures that know their GCC __int128 support is sound
916 # 774 #
917 config ARCH_SUPPORTS_INT128 775 config ARCH_SUPPORTS_INT128
918 bool 776 bool
919 777
920 # For architectures that (ab)use NUMA to repre 778 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 779 # all cpu-local but of different latencies, such as SuperH.
922 # 780 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 781 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 782 bool
925 783
926 config NUMA_BALANCING 784 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 785 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 786 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 787 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 788 depends on SMP && NUMA && MIGRATION
931 help 789 help
932 This option adds support for automat 790 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 791 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 792 it has references to the node the task is running on.
935 793
936 This system will be inactive on UMA 794 This system will be inactive on UMA systems.
937 795
938 config NUMA_BALANCING_DEFAULT_ENABLED 796 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 797 bool "Automatically enable NUMA aware memory/task placement"
940 default y 798 default y
941 depends on NUMA_BALANCING 799 depends on NUMA_BALANCING
942 help 800 help
943 If set, automatic NUMA balancing wil 801 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 802 machine.
945 803
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 804 menuconfig CGROUPS
950 bool "Control Group support" 805 bool "Control Group support"
951 select KERNFS 806 select KERNFS
952 help 807 help
953 This option adds support for groupin 808 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 809 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 810 controls or device isolation.
956 See 811 See
957 - Documentation/scheduler/sche 812 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 813 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 814 and resource control)
960 815
961 Say N if unsure. 816 Say N if unsure.
962 817
963 if CGROUPS 818 if CGROUPS
964 819
965 config PAGE_COUNTER 820 config PAGE_COUNTER
966 bool 821 bool
967 822
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 823 config MEMCG
979 bool "Memory controller" 824 bool "Memory controller"
980 select PAGE_COUNTER 825 select PAGE_COUNTER
981 select EVENTFD 826 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 827 help
984 Provides control over the memory foo 828 Provides control over the memory footprint of tasks in a cgroup.
985 829
986 config MEMCG_V1 !! 830 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 831 bool "Swap controller"
988 depends on MEMCG !! 832 depends on MEMCG && SWAP
989 default n <<
990 help 833 help
991 Legacy cgroup v1 memory controller w !! 834 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 835
1001 Say N if unsure. !! 836 config MEMCG_SWAP_ENABLED
>> 837 bool "Swap controller enabled by default"
>> 838 depends on MEMCG_SWAP
>> 839 default y
>> 840 help
>> 841 Memory Resource Controller Swap Extension comes with its price in
>> 842 a bigger memory consumption. General purpose distribution kernels
>> 843 which want to enable the feature but keep it disabled by default
>> 844 and let the user enable it by swapaccount=1 boot command line
>> 845 parameter should have this option unselected.
>> 846 For those who want to have the feature enabled by default should
>> 847 select this option (if, for some reason, they need to disable it
>> 848 then swapaccount=0 does the trick).
>> 849
>> 850 config MEMCG_KMEM
>> 851 bool
>> 852 depends on MEMCG && !SLOB
>> 853 default y
1002 854
1003 config BLK_CGROUP 855 config BLK_CGROUP
1004 bool "IO controller" 856 bool "IO controller"
1005 depends on BLOCK 857 depends on BLOCK
1006 default n 858 default n
1007 help !! 859 ---help---
1008 Generic block IO controller cgroup in 860 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 861 cgroup interface which should be used by various IO controlling
1010 policies. 862 policies.
1011 863
1012 Currently, CFQ IO scheduler uses it t 864 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 865 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 866 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 867 block layer to implement upper limit in IO rates on a device.
1016 868
1017 This option only enables generic Bloc 869 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 870 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 871 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl !! 872 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 873 CONFIG_BLK_DEV_THROTTLING=y.
1022 874
1023 See Documentation/admin-guide/cgroup- 875 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 876
1025 config CGROUP_WRITEBACK 877 config CGROUP_WRITEBACK
1026 bool 878 bool
1027 depends on MEMCG && BLK_CGROUP 879 depends on MEMCG && BLK_CGROUP
1028 default y 880 default y
1029 881
1030 menuconfig CGROUP_SCHED 882 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 883 bool "CPU controller"
1032 default n 884 default n
1033 help 885 help
1034 This feature lets CPU scheduler rec 886 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 887 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 888 tasks.
1037 889
1038 if CGROUP_SCHED 890 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 891 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 892 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 893 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 894 default CGROUP_SCHED
1047 895
1048 config CFS_BANDWIDTH 896 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 897 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 898 depends on FAIR_GROUP_SCHED
1051 default n 899 default n
1052 help 900 help
1053 This option allows users to define 901 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 902 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 903 set are considered to be unconstrained and will run with no
1056 restriction. 904 restriction.
1057 See Documentation/scheduler/sched-b 905 See Documentation/scheduler/sched-bwc.rst for more information.
1058 906
1059 config RT_GROUP_SCHED 907 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 908 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 909 depends on CGROUP_SCHED
1062 default n 910 default n
1063 help 911 help
1064 This feature lets you explicitly al 912 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 913 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 914 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 915 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 916 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 917
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 918 endif #CGROUP_SCHED
1077 919
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP 920 config UCLAMP_TASK_GROUP
1083 bool "Utilization clamping per group 921 bool "Utilization clamping per group of tasks"
1084 depends on CGROUP_SCHED 922 depends on CGROUP_SCHED
1085 depends on UCLAMP_TASK 923 depends on UCLAMP_TASK
1086 default n 924 default n
1087 help 925 help
1088 This feature enables the scheduler 926 This feature enables the scheduler to track the clamped utilization
1089 of each CPU based on RUNNABLE tasks 927 of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
1090 928
1091 When this option is enabled, the us 929 When this option is enabled, the user can specify a min and max
1092 CPU bandwidth which is allowed for 930 CPU bandwidth which is allowed for each single task in a group.
1093 The max bandwidth allows to clamp t 931 The max bandwidth allows to clamp the maximum frequency a task
1094 can use, while the min bandwidth al 932 can use, while the min bandwidth allows to define a minimum
1095 frequency a task will always use. 933 frequency a task will always use.
1096 934
1097 When task group based utilization c 935 When task group based utilization clamping is enabled, an eventually
1098 specified task-specific clamp value 936 specified task-specific clamp value is constrained by the cgroup
1099 specified clamp value. Both minimum 937 specified clamp value. Both minimum and maximum task clamping cannot
1100 be bigger than the corresponding cl 938 be bigger than the corresponding clamping defined at task group level.
1101 939
1102 If in doubt, say N. 940 If in doubt, say N.
1103 941
1104 config CGROUP_PIDS 942 config CGROUP_PIDS
1105 bool "PIDs controller" 943 bool "PIDs controller"
1106 help 944 help
1107 Provides enforcement of process num 945 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 946 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 947 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 948 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 949 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 950 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 951 PIDs controller is designed to stop this from happening.
1114 952
1115 It should be noted that organisatio 953 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 954 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 955 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 956 attach to a cgroup.
1119 957
1120 config CGROUP_RDMA 958 config CGROUP_RDMA
1121 bool "RDMA controller" 959 bool "RDMA controller"
1122 help 960 help
1123 Provides enforcement of RDMA resour 961 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 962 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 963 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 964 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 965 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 966 hierarchy is allowed even if can cross the hierarchy's limit.
1129 967
1130 config CGROUP_FREEZER 968 config CGROUP_FREEZER
1131 bool "Freezer controller" 969 bool "Freezer controller"
1132 help 970 help
1133 Provides a way to freeze and unfree 971 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 972 cgroup.
1135 973
1136 This option affects the ORIGINAL cg 974 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 975 controller includes important in-kernel memory consumers per default.
1138 976
1139 If you're using cgroup2, say N. 977 If you're using cgroup2, say N.
1140 978
1141 config CGROUP_HUGETLB 979 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 980 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 981 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 982 select PAGE_COUNTER
1145 default n 983 default n
1146 help 984 help
1147 Provides a cgroup controller for Hu 985 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 986 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 987 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 988 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 989 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 990 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 991 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 992 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 993 that we cannot use the controller with huge page less than 3 pages.
1156 994
1157 config CPUSETS 995 config CPUSETS
1158 bool "Cpuset controller" 996 bool "Cpuset controller"
1159 depends on SMP 997 depends on SMP
1160 help 998 help
1161 This option will let you create and 999 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 1000 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 1001 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 1002 This is primarily useful on large SMP or NUMA systems.
1165 1003
1166 Say N if unsure. 1004 Say N if unsure.
1167 1005
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 1006 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 1007 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 1008 depends on CPUSETS
1184 default y 1009 default y
1185 1010
1186 config CGROUP_DEVICE 1011 config CGROUP_DEVICE
1187 bool "Device controller" 1012 bool "Device controller"
1188 help 1013 help
1189 Provides a cgroup controller implem 1014 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1015 devices which a process in the cgroup can mknod or open.
1191 1016
1192 config CGROUP_CPUACCT 1017 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1018 bool "Simple CPU accounting controller"
1194 help 1019 help
1195 Provides a simple controller for mo 1020 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1021 total CPU consumed by the tasks in a cgroup.
1197 1022
1198 config CGROUP_PERF 1023 config CGROUP_PERF
1199 bool "Perf controller" 1024 bool "Perf controller"
1200 depends on PERF_EVENTS 1025 depends on PERF_EVENTS
1201 help 1026 help
1202 This option extends the perf per-cp 1027 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1028 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use !! 1029 designated cpu.
1205 so that it can monitor performance <<
1206 1030
1207 Say N if unsure. 1031 Say N if unsure.
1208 1032
1209 config CGROUP_BPF 1033 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1034 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1035 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1036 select SOCK_CGROUP_DATA
1213 help 1037 help
1214 Allow attaching eBPF programs to a 1038 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1039 syscall command BPF_PROG_ATTACH.
1216 1040
1217 In which context these programs are 1041 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1042 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1043 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1044 inet sockets.
1221 1045
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 1046 config CGROUP_DEBUG
1237 bool "Debug controller" 1047 bool "Debug controller"
1238 default n 1048 default n
1239 depends on DEBUG_KERNEL 1049 depends on DEBUG_KERNEL
1240 help 1050 help
1241 This option enables a simple contro 1051 This option enables a simple controller that exports
1242 debugging information about the cgr 1052 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1053 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1054 interfaces are not stable.
1245 1055
1246 Say N. 1056 Say N.
1247 1057
1248 config SOCK_CGROUP_DATA 1058 config SOCK_CGROUP_DATA
1249 bool 1059 bool
1250 default n 1060 default n
1251 1061
1252 endif # CGROUPS 1062 endif # CGROUPS
1253 1063
1254 menuconfig NAMESPACES 1064 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1065 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1066 depends on MULTIUSER
1257 default !EXPERT 1067 default !EXPERT
1258 help 1068 help
1259 Provides the way to make tasks work 1069 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1070 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1071 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1072 different namespaces.
1263 1073
1264 if NAMESPACES 1074 if NAMESPACES
1265 1075
1266 config UTS_NS 1076 config UTS_NS
1267 bool "UTS namespace" 1077 bool "UTS namespace"
1268 default y 1078 default y
1269 help 1079 help
1270 In this namespace tasks see differe 1080 In this namespace tasks see different info provided with the
1271 uname() system call 1081 uname() system call
1272 1082
1273 config TIME_NS <<
1274 bool "TIME namespace" <<
1275 depends on GENERIC_VDSO_TIME_NS <<
1276 default y <<
1277 help <<
1278 In this namespace boottime and mono <<
1279 The time will keep going with the s <<
1280 <<
1281 config IPC_NS 1083 config IPC_NS
1282 bool "IPC namespace" 1084 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1085 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1086 default y
1285 help 1087 help
1286 In this namespace tasks work with I 1088 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1089 different IPC objects in different namespaces.
1288 1090
1289 config USER_NS 1091 config USER_NS
1290 bool "User namespace" 1092 bool "User namespace"
1291 default n 1093 default n
1292 help 1094 help
1293 This allows containers, i.e. vserve 1095 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1096 to provide different user info for different servers.
1295 1097
1296 When user namespaces are enabled in 1098 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1099 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1100 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1101 of memory a memory unprivileged users can use.
1300 1102
1301 If unsure, say N. 1103 If unsure, say N.
1302 1104
1303 config PID_NS 1105 config PID_NS
1304 bool "PID Namespaces" 1106 bool "PID Namespaces"
1305 default y 1107 default y
1306 help 1108 help
1307 Support process id namespaces. Thi 1109 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1110 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1111 pid namespaces. This is a building block of containers.
1310 1112
1311 config NET_NS 1113 config NET_NS
1312 bool "Network namespace" 1114 bool "Network namespace"
1313 depends on NET 1115 depends on NET
1314 default y 1116 default y
1315 help 1117 help
1316 Allow user space to create what app 1118 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1119 of the network stack.
1318 1120
1319 endif # NAMESPACES 1121 endif # NAMESPACES
1320 1122
1321 config CHECKPOINT_RESTORE 1123 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1124 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1125 select PROC_CHILDREN
1325 select KCMP <<
1326 default n 1126 default n
1327 help 1127 help
1328 Enables additional kernel features 1128 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1129 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1130 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1131 entries.
1332 1132
1333 If unsure, say N here. 1133 If unsure, say N here.
1334 1134
1335 config SCHED_AUTOGROUP 1135 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1136 bool "Automatic process group scheduling"
1337 select CGROUPS 1137 select CGROUPS
1338 select CGROUP_SCHED 1138 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1139 select FAIR_GROUP_SCHED
1340 help 1140 help
1341 This option optimizes the scheduler 1141 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1142 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1143 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1144 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1145 upon task session.
1346 1146
>> 1147 config SYSFS_DEPRECATED
>> 1148 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1149 depends on SYSFS
>> 1150 default n
>> 1151 help
>> 1152 This option adds code that switches the layout of the "block" class
>> 1153 devices, to not show up in /sys/class/block/, but only in
>> 1154 /sys/block/.
>> 1155
>> 1156 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1157 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1158
>> 1159 This option allows new kernels to run on old distributions and tools,
>> 1160 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1161 major distributions and tools handle this just fine.
>> 1162
>> 1163 Recent distributions and userspace tools after 2009/2010 depend on
>> 1164 the existence of /sys/class/block/, and will not work with this
>> 1165 option enabled.
>> 1166
>> 1167 Only if you are using a new kernel on an old distribution, you might
>> 1168 need to say Y here.
>> 1169
>> 1170 config SYSFS_DEPRECATED_V2
>> 1171 bool "Enable deprecated sysfs features by default"
>> 1172 default n
>> 1173 depends on SYSFS
>> 1174 depends on SYSFS_DEPRECATED
>> 1175 help
>> 1176 Enable deprecated sysfs by default.
>> 1177
>> 1178 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1179 option.
>> 1180
>> 1181 Only if you are using a new kernel on an old distribution, you might
>> 1182 need to say Y here. Even then, odds are you would not need it
>> 1183 enabled, you can always pass the boot option if absolutely necessary.
>> 1184
1347 config RELAY 1185 config RELAY
1348 bool "Kernel->user space relay suppor 1186 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1187 select IRQ_WORK
1350 help 1188 help
1351 This option enables support for rel 1189 This option enables support for relay interface support in
1352 certain file systems (such as debug 1190 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1191 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1192 facilities to relay large amounts of data from kernel space to
1355 user space. 1193 user space.
1356 1194
1357 If unsure, say N. 1195 If unsure, say N.
1358 1196
1359 config BLK_DEV_INITRD 1197 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1198 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1199 help
1362 The initial RAM filesystem is a ram 1200 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1201 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1202 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1203 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1204 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1205
1368 If RAM disk support (BLK_DEV_RAM) i 1206 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1207 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1208 15 Kbytes (more on some other architectures) to the kernel size.
1371 1209
1372 If unsure say Y. 1210 If unsure say Y.
1373 1211
1374 if BLK_DEV_INITRD 1212 if BLK_DEV_INITRD
1375 1213
1376 source "usr/Kconfig" 1214 source "usr/Kconfig"
1377 1215
1378 endif 1216 endif
1379 1217
1380 config BOOT_CONFIG <<
1381 bool "Boot config support" <<
1382 select BLK_DEV_INITRD if !BOOT_CONFIG <<
1383 help <<
1384 Extra boot config allows system adm <<
1385 complemental extension of kernel cm <<
1386 The boot config file must be attach <<
1387 with checksum, size and magic word. <<
1388 See <file:Documentation/admin-guide <<
1389 <<
1390 If unsure, say Y. <<
1391 <<
1392 config BOOT_CONFIG_FORCE <<
1393 bool "Force unconditional bootconfig <<
1394 depends on BOOT_CONFIG <<
1395 default y if BOOT_CONFIG_EMBED <<
1396 help <<
1397 With this Kconfig option set, BOOT_ <<
1398 out even when the "bootconfig" kern <<
1399 In fact, with this Kconfig option s <<
1400 make the kernel ignore the BOOT_CON <<
1401 parameters. <<
1402 <<
1403 If unsure, say N. <<
1404 <<
1405 config BOOT_CONFIG_EMBED <<
1406 bool "Embed bootconfig file in the ke <<
1407 depends on BOOT_CONFIG <<
1408 help <<
1409 Embed a bootconfig file given by BO <<
1410 kernel. Usually, the bootconfig fil <<
1411 image. But if the system doesn't su <<
1412 help you by embedding a bootconfig <<
1413 <<
1414 If unsure, say N. <<
1415 <<
1416 config BOOT_CONFIG_EMBED_FILE <<
1417 string "Embedded bootconfig file path <<
1418 depends on BOOT_CONFIG_EMBED <<
1419 help <<
1420 Specify a bootconfig file which wil <<
1421 This bootconfig will be used if the <<
1422 bootconfig in the initrd. <<
1423 <<
1424 config INITRAMFS_PRESERVE_MTIME <<
1425 bool "Preserve cpio archive mtimes in <<
1426 default y <<
1427 help <<
1428 Each entry in an initramfs cpio arc <<
1429 enabled, extracted cpio items take <<
1430 setting deferred until after creati <<
1431 <<
1432 If unsure, say Y. <<
1433 <<
1434 choice 1218 choice
1435 prompt "Compiler optimization level" 1219 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1220 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1221
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1222 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" 1223 bool "Optimize for performance (-O2)"
1440 help 1224 help
1441 This is the default optimization le 1225 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1226 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1227 helpful compile-time warnings.
1444 1228
>> 1229 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
>> 1230 bool "Optimize more for performance (-O3)"
>> 1231 depends on ARC
>> 1232 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
>> 1233 help
>> 1234 Choosing this option will pass "-O3" to your compiler to optimize
>> 1235 the kernel yet more for performance.
>> 1236
1445 config CC_OPTIMIZE_FOR_SIZE 1237 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" 1238 bool "Optimize for size (-Os)"
>> 1239 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
1447 help 1240 help
1448 Choosing this option will pass "-Os 1241 Choosing this option will pass "-Os" to your compiler resulting
1449 in a smaller kernel. 1242 in a smaller kernel.
1450 1243
1451 endchoice 1244 endchoice
1452 1245
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1246 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1247 bool
1455 help 1248 help
1456 This requires that the arch annotat 1249 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1250 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1251 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1252 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1253 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1254 is used to distinguish them from label names / C identifiers.
1462 1255
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1256 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1257 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1258 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1259 depends on EXPERT
>> 1260 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1467 depends on $(cc-option,-ffunction-sec 1261 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1262 depends on $(ld-option,--gc-sections)
1469 help 1263 help
1470 Enable this if you want to do dead 1264 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1265 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1266 and linking with --gc-sections.
1473 1267
1474 This can reduce on disk and in-memo 1268 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1269 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1270 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1271 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1272 present. This option is not well tested yet, so use at your
1479 own risk. 1273 own risk.
1480 1274
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 1275 config SYSCTL
1494 bool 1276 bool
1495 1277
1496 config HAVE_UID16 1278 config HAVE_UID16
1497 bool 1279 bool
1498 1280
1499 config SYSCTL_EXCEPTION_TRACE 1281 config SYSCTL_EXCEPTION_TRACE
1500 bool 1282 bool
1501 help 1283 help
1502 Enable support for /proc/sys/debug/ 1284 Enable support for /proc/sys/debug/exception-trace.
1503 1285
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1286 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1287 bool
1506 help 1288 help
1507 Enable support for /proc/sys/kernel 1289 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1290 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1291 about unaligned access emulation going on under the hood.
1510 1292
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1293 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1294 bool
1513 help 1295 help
1514 Enable support for /proc/sys/kernel 1296 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1297 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1298 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1299 see arch/parisc/kernel/unaligned.c for reference
1518 1300
1519 config HAVE_PCSPKR_PLATFORM 1301 config HAVE_PCSPKR_PLATFORM
1520 bool 1302 bool
1521 1303
>> 1304 # interpreter that classic socket filters depend on
>> 1305 config BPF
>> 1306 bool
>> 1307
1522 menuconfig EXPERT 1308 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1309 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1310 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1311 select DEBUG_KERNEL
1526 help 1312 help
1527 This option allows certain base ker 1313 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is 1314 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " 1315 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh 1316 Only use this if you really know what you are doing.
1531 1317
1532 config UID16 1318 config UID16
1533 bool "Enable 16-bit UID system calls" 1319 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1320 depends on HAVE_UID16 && MULTIUSER
1535 default y 1321 default y
1536 help 1322 help
1537 This enables the legacy 16-bit UID 1323 This enables the legacy 16-bit UID syscall wrappers.
1538 1324
1539 config MULTIUSER 1325 config MULTIUSER
1540 bool "Multiple users, groups and capa 1326 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1327 default y
1542 help 1328 help
1543 This option enables support for non 1329 This option enables support for non-root users, groups and
1544 capabilities. 1330 capabilities.
1545 1331
1546 If you say N here, all processes wi 1332 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1333 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1334 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1335 setgid, and capset.
1550 1336
1551 If unsure, say Y here. 1337 If unsure, say Y here.
1552 1338
1553 config SGETMASK_SYSCALL 1339 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1340 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1341 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help !! 1342 ---help---
1557 sys_sgetmask and sys_ssetmask are o 1343 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1344 no longer supported in libc but still enabled by default in some
1559 architectures. 1345 architectures.
1560 1346
1561 If unsure, leave the default option 1347 If unsure, leave the default option here.
1562 1348
1563 config SYSFS_SYSCALL 1349 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1350 bool "Sysfs syscall support" if EXPERT
1565 default y 1351 default y
1566 help !! 1352 ---help---
1567 sys_sysfs is an obsolete system cal 1353 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1354 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1355 compatibility with some systems.
1570 1356
1571 If unsure say Y here. 1357 If unsure say Y here.
1572 1358
1573 config FHANDLE 1359 config FHANDLE
1574 bool "open by fhandle syscalls" if EX 1360 bool "open by fhandle syscalls" if EXPERT
1575 select EXPORTFS 1361 select EXPORTFS
1576 default y 1362 default y
1577 help 1363 help
1578 If you say Y here, a user level pro 1364 If you say Y here, a user level program will be able to map
1579 file names to handle and then later 1365 file names to handle and then later use the handle for
1580 different file system operations. T 1366 different file system operations. This is useful in implementing
1581 userspace file servers, which now t 1367 userspace file servers, which now track files using handles instead
1582 of names. The handle would remain t 1368 of names. The handle would remain the same even if file names
1583 get renamed. Enables open_by_handle 1369 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1584 syscalls. 1370 syscalls.
1585 1371
1586 config POSIX_TIMERS 1372 config POSIX_TIMERS
1587 bool "Posix Clocks & timers" if EXPER 1373 bool "Posix Clocks & timers" if EXPERT
1588 default y 1374 default y
1589 help 1375 help
1590 This includes native support for PO 1376 This includes native support for POSIX timers to the kernel.
1591 Some embedded systems have no use f 1377 Some embedded systems have no use for them and therefore they
1592 can be configured out to reduce the 1378 can be configured out to reduce the size of the kernel image.
1593 1379
1594 When this option is disabled, the f 1380 When this option is disabled, the following syscalls won't be
1595 available: timer_create, timer_gett 1381 available: timer_create, timer_gettime: timer_getoverrun,
1596 timer_settime, timer_delete, clock_ 1382 timer_settime, timer_delete, clock_adjtime, getitimer,
1597 setitimer, alarm. Furthermore, the 1383 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1598 clock_getres and clock_nanosleep sy 1384 clock_getres and clock_nanosleep syscalls will be limited to
1599 CLOCK_REALTIME, CLOCK_MONOTONIC and 1385 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1600 1386
1601 If unsure say y. 1387 If unsure say y.
1602 1388
1603 config PRINTK 1389 config PRINTK
1604 default y 1390 default y
1605 bool "Enable support for printk" if E 1391 bool "Enable support for printk" if EXPERT
1606 select IRQ_WORK 1392 select IRQ_WORK
1607 help 1393 help
1608 This option enables normal printk s 1394 This option enables normal printk support. Removing it
1609 eliminates most of the message stri 1395 eliminates most of the message strings from the kernel image
1610 and makes the kernel more or less s 1396 and makes the kernel more or less silent. As this makes it
1611 very difficult to diagnose system p 1397 very difficult to diagnose system problems, saying N here is
1612 strongly discouraged. 1398 strongly discouraged.
1613 1399
>> 1400 config PRINTK_NMI
>> 1401 def_bool y
>> 1402 depends on PRINTK
>> 1403 depends on HAVE_NMI
>> 1404
1614 config BUG 1405 config BUG
1615 bool "BUG() support" if EXPERT 1406 bool "BUG() support" if EXPERT
1616 default y 1407 default y
1617 help 1408 help
1618 Disabling this option eliminates su 1409 Disabling this option eliminates support for BUG and WARN, reducing
1619 the size of your kernel image and p 1410 the size of your kernel image and potentially quietly ignoring
1620 numerous fatal conditions. You shou 1411 numerous fatal conditions. You should only consider disabling this
1621 option for embedded systems with no 1412 option for embedded systems with no facilities for reporting errors.
1622 Just say Y. 1413 Just say Y.
1623 1414
1624 config ELF_CORE 1415 config ELF_CORE
1625 depends on COREDUMP 1416 depends on COREDUMP
1626 default y 1417 default y
1627 bool "Enable ELF core dumps" if EXPER 1418 bool "Enable ELF core dumps" if EXPERT
1628 help 1419 help
1629 Enable support for generating core 1420 Enable support for generating core dumps. Disabling saves about 4k.
1630 1421
1631 1422
1632 config PCSPKR_PLATFORM 1423 config PCSPKR_PLATFORM
1633 bool "Enable PC-Speaker support" if E 1424 bool "Enable PC-Speaker support" if EXPERT
1634 depends on HAVE_PCSPKR_PLATFORM 1425 depends on HAVE_PCSPKR_PLATFORM
1635 select I8253_LOCK 1426 select I8253_LOCK
1636 default y 1427 default y
1637 help 1428 help
1638 This option allows to disable the i 1429 This option allows to disable the internal PC-Speaker
1639 support, saving some memory. 1430 support, saving some memory.
1640 1431
1641 config BASE_SMALL !! 1432 config BASE_FULL
1642 bool "Enable smaller-sized data struc !! 1433 default y
>> 1434 bool "Enable full-sized data structures for core" if EXPERT
1643 help 1435 help
1644 Enabling this option reduces the si !! 1436 Disabling this option reduces the size of miscellaneous core
1645 kernel data structures. This saves 1437 kernel data structures. This saves memory on small machines,
1646 but may reduce performance. 1438 but may reduce performance.
1647 1439
1648 config FUTEX 1440 config FUTEX
1649 bool "Enable futex support" if EXPERT 1441 bool "Enable futex support" if EXPERT
1650 depends on !(SPARC32 && SMP) <<
1651 default y 1442 default y
1652 imply RT_MUTEXES 1443 imply RT_MUTEXES
1653 help 1444 help
1654 Disabling this option will cause th 1445 Disabling this option will cause the kernel to be built without
1655 support for "fast userspace mutexes 1446 support for "fast userspace mutexes". The resulting kernel may not
1656 run glibc-based applications correc 1447 run glibc-based applications correctly.
1657 1448
1658 config FUTEX_PI 1449 config FUTEX_PI
1659 bool 1450 bool
1660 depends on FUTEX && RT_MUTEXES 1451 depends on FUTEX && RT_MUTEXES
1661 default y 1452 default y
1662 1453
>> 1454 config HAVE_FUTEX_CMPXCHG
>> 1455 bool
>> 1456 depends on FUTEX
>> 1457 help
>> 1458 Architectures should select this if futex_atomic_cmpxchg_inatomic()
>> 1459 is implemented and always working. This removes a couple of runtime
>> 1460 checks.
>> 1461
1663 config EPOLL 1462 config EPOLL
1664 bool "Enable eventpoll support" if EX 1463 bool "Enable eventpoll support" if EXPERT
1665 default y 1464 default y
1666 help 1465 help
1667 Disabling this option will cause th 1466 Disabling this option will cause the kernel to be built without
1668 support for epoll family of system 1467 support for epoll family of system calls.
1669 1468
1670 config SIGNALFD 1469 config SIGNALFD
1671 bool "Enable signalfd() system call" 1470 bool "Enable signalfd() system call" if EXPERT
1672 default y 1471 default y
1673 help 1472 help
1674 Enable the signalfd() system call t 1473 Enable the signalfd() system call that allows to receive signals
1675 on a file descriptor. 1474 on a file descriptor.
1676 1475
1677 If unsure, say Y. 1476 If unsure, say Y.
1678 1477
1679 config TIMERFD 1478 config TIMERFD
1680 bool "Enable timerfd() system call" i 1479 bool "Enable timerfd() system call" if EXPERT
1681 default y 1480 default y
1682 help 1481 help
1683 Enable the timerfd() system call th 1482 Enable the timerfd() system call that allows to receive timer
1684 events on a file descriptor. 1483 events on a file descriptor.
1685 1484
1686 If unsure, say Y. 1485 If unsure, say Y.
1687 1486
1688 config EVENTFD 1487 config EVENTFD
1689 bool "Enable eventfd() system call" i 1488 bool "Enable eventfd() system call" if EXPERT
1690 default y 1489 default y
1691 help 1490 help
1692 Enable the eventfd() system call th 1491 Enable the eventfd() system call that allows to receive both
1693 kernel notification (ie. KAIO) or u 1492 kernel notification (ie. KAIO) or userspace notifications.
1694 1493
1695 If unsure, say Y. 1494 If unsure, say Y.
1696 1495
1697 config SHMEM 1496 config SHMEM
1698 bool "Use full shmem filesystem" if E 1497 bool "Use full shmem filesystem" if EXPERT
1699 default y 1498 default y
1700 depends on MMU 1499 depends on MMU
1701 help 1500 help
1702 The shmem is an internal filesystem 1501 The shmem is an internal filesystem used to manage shared memory.
1703 It is backed by swap and manages re 1502 It is backed by swap and manages resource limits. It is also exported
1704 to userspace as tmpfs if TMPFS is e 1503 to userspace as tmpfs if TMPFS is enabled. Disabling this
1705 option replaces shmem and tmpfs wit 1504 option replaces shmem and tmpfs with the much simpler ramfs code,
1706 which may be appropriate on small s 1505 which may be appropriate on small systems without swap.
1707 1506
1708 config AIO 1507 config AIO
1709 bool "Enable AIO support" if EXPERT 1508 bool "Enable AIO support" if EXPERT
1710 default y 1509 default y
1711 help 1510 help
1712 This option enables POSIX asynchron 1511 This option enables POSIX asynchronous I/O which may by used
1713 by some high performance threaded a 1512 by some high performance threaded applications. Disabling
1714 this option saves about 7k. 1513 this option saves about 7k.
1715 1514
1716 config IO_URING 1515 config IO_URING
1717 bool "Enable IO uring support" if EXP 1516 bool "Enable IO uring support" if EXPERT
>> 1517 select ANON_INODES
1718 select IO_WQ 1518 select IO_WQ
1719 default y 1519 default y
1720 help 1520 help
1721 This option enables support for the 1521 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1522 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1523 completion rings that are shared between the kernel and application.
1724 1524
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 1525 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1526 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1527 default y
1741 help 1528 help
1742 This option enables the madvise and 1529 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1530 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1531 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1532 applications use these syscalls, you can disable this option to save
1746 space. 1533 space.
1747 1534
1748 config MEMBARRIER 1535 config MEMBARRIER
1749 bool "Enable membarrier() system call 1536 bool "Enable membarrier() system call" if EXPERT
1750 default y 1537 default y
1751 help 1538 help
1752 Enable the membarrier() system call 1539 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1540 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1541 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1542 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1543 compiler barrier.
1757 1544
1758 If unsure, say Y. 1545 If unsure, say Y.
1759 1546
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 1547 config KALLSYMS
1811 bool "Load all symbols for debugging/ 1548 bool "Load all symbols for debugging/ksymoops" if EXPERT
1812 default y 1549 default y
1813 help 1550 help
1814 Say Y here to let the kernel print 1551 Say Y here to let the kernel print out symbolic crash information and
1815 symbolic stack backtraces. This inc 1552 symbolic stack backtraces. This increases the size of the kernel
1816 somewhat, as all symbols have to be 1553 somewhat, as all symbols have to be loaded into the kernel image.
1817 1554
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 1555 config KALLSYMS_ALL
1832 bool "Include all symbols in kallsyms 1556 bool "Include all symbols in kallsyms"
1833 depends on DEBUG_KERNEL && KALLSYMS 1557 depends on DEBUG_KERNEL && KALLSYMS
1834 help 1558 help
1835 Normally kallsyms only contains the 1559 Normally kallsyms only contains the symbols of functions for nicer
1836 OOPS messages and backtraces (i.e., 1560 OOPS messages and backtraces (i.e., symbols from the text and inittext
1837 sections). This is sufficient for m !! 1561 sections). This is sufficient for most cases. And only in very rare
1838 enable kernel live patching, or oth !! 1562 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1839 when a debugger is used) all symbol !! 1563 names of variables from the data sections, etc).
1840 variables from the data sections, e <<
1841 1564
1842 This option makes sure that all sym 1565 This option makes sure that all symbols are loaded into the kernel
1843 image (i.e., symbols from all secti 1566 image (i.e., symbols from all sections) in cost of increased kernel
1844 size (depending on the kernel confi 1567 size (depending on the kernel configuration, it may be 300KiB or
1845 something like this). 1568 something like this).
1846 1569
1847 Say N unless you really need all sy !! 1570 Say N unless you really need all symbols.
1848 1571
1849 config KALLSYMS_ABSOLUTE_PERCPU 1572 config KALLSYMS_ABSOLUTE_PERCPU
1850 bool 1573 bool
1851 depends on KALLSYMS 1574 depends on KALLSYMS
1852 default X86_64 && SMP 1575 default X86_64 && SMP
1853 1576
>> 1577 config KALLSYMS_BASE_RELATIVE
>> 1578 bool
>> 1579 depends on KALLSYMS
>> 1580 default !IA64
>> 1581 help
>> 1582 Instead of emitting them as absolute values in the native word size,
>> 1583 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1584 each containing a relative value in the range [base, base + U32_MAX]
>> 1585 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1586 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1587 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1588 address encountered in the image.
>> 1589
>> 1590 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1591 but more importantly, it results in entries whose values are build
>> 1592 time constants, and no relocation pass is required at runtime to fix
>> 1593 up the entries based on the runtime load address of the kernel.
>> 1594
1854 # end of the "standard kernel features (exper 1595 # end of the "standard kernel features (expert users)" menu
1855 1596
>> 1597 # syscall, maps, verifier
>> 1598 config BPF_SYSCALL
>> 1599 bool "Enable bpf() system call"
>> 1600 select BPF
>> 1601 select IRQ_WORK
>> 1602 default n
>> 1603 help
>> 1604 Enable the bpf() system call that allows to manipulate eBPF
>> 1605 programs and maps via file descriptors.
>> 1606
>> 1607 config BPF_JIT_ALWAYS_ON
>> 1608 bool "Permanently enable BPF JIT and remove BPF interpreter"
>> 1609 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
>> 1610 help
>> 1611 Enables BPF JIT and removes BPF interpreter to avoid
>> 1612 speculative execution of BPF instructions by the interpreter
>> 1613
>> 1614 config USERFAULTFD
>> 1615 bool "Enable userfaultfd() system call"
>> 1616 depends on MMU
>> 1617 help
>> 1618 Enable the userfaultfd() system call that allows to intercept and
>> 1619 handle page faults in userland.
>> 1620
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS 1621 config ARCH_HAS_MEMBARRIER_CALLBACKS
1857 bool 1622 bool
1858 1623
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE 1624 config ARCH_HAS_MEMBARRIER_SYNC_CORE
1860 bool 1625 bool
1861 1626
>> 1627 config RSEQ
>> 1628 bool "Enable rseq() system call" if EXPERT
>> 1629 default y
>> 1630 depends on HAVE_RSEQ
>> 1631 select MEMBARRIER
>> 1632 help
>> 1633 Enable the restartable sequences system call. It provides a
>> 1634 user-space cache for the current CPU number value, which
>> 1635 speeds up getting the current CPU number from user-space,
>> 1636 as well as an ABI to speed up user-space operations on
>> 1637 per-CPU data.
>> 1638
>> 1639 If unsure, say Y.
>> 1640
>> 1641 config DEBUG_RSEQ
>> 1642 default n
>> 1643 bool "Enabled debugging of rseq() system call" if EXPERT
>> 1644 depends on RSEQ && DEBUG_KERNEL
>> 1645 help
>> 1646 Enable extra debugging checks for the rseq system call.
>> 1647
>> 1648 If unsure, say N.
>> 1649
>> 1650 config EMBEDDED
>> 1651 bool "Embedded system"
>> 1652 option allnoconfig_y
>> 1653 select EXPERT
>> 1654 help
>> 1655 This option should be enabled if compiling the kernel for
>> 1656 an embedded system so certain expert options are available
>> 1657 for configuration.
>> 1658
1862 config HAVE_PERF_EVENTS 1659 config HAVE_PERF_EVENTS
1863 bool 1660 bool
1864 help 1661 help
1865 See tools/perf/design.txt for detai 1662 See tools/perf/design.txt for details.
1866 1663
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1664 config PERF_USE_VMALLOC
1872 bool 1665 bool
1873 help 1666 help
1874 See tools/perf/design.txt for detai 1667 See tools/perf/design.txt for details
1875 1668
>> 1669 config PC104
>> 1670 bool "PC/104 support" if EXPERT
>> 1671 help
>> 1672 Expose PC/104 form factor device drivers and options available for
>> 1673 selection and configuration. Enable this option if your target
>> 1674 machine has a PC/104 bus.
>> 1675
1876 menu "Kernel Performance Events And Counters" 1676 menu "Kernel Performance Events And Counters"
1877 1677
1878 config PERF_EVENTS 1678 config PERF_EVENTS
1879 bool "Kernel performance events and c 1679 bool "Kernel performance events and counters"
1880 default y if PROFILING 1680 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1681 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1682 select IRQ_WORK
>> 1683 select SRCU
1883 help 1684 help
1884 Enable kernel support for various p 1685 Enable kernel support for various performance events provided
1885 by software and hardware. 1686 by software and hardware.
1886 1687
1887 Software events are supported eithe 1688 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1689 use of generic tracepoints.
1889 1690
1890 Most modern CPUs support performanc 1691 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1692 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1693 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1694 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1695 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1696 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1697 used to profile the code that runs on that CPU.
1897 1698
1898 The Linux Performance Event subsyst 1699 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1700 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1701 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1702 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1703 capabilities on top of those.
1903 1704
1904 Say Y if unsure. 1705 Say Y if unsure.
1905 1706
1906 config DEBUG_PERF_USE_VMALLOC 1707 config DEBUG_PERF_USE_VMALLOC
1907 default n 1708 default n
1908 bool "Debug: use vmalloc to back perf 1709 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1710 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1711 select PERF_USE_VMALLOC
1911 help 1712 help
1912 Use vmalloc memory to back perf mma 1713 Use vmalloc memory to back perf mmap() buffers.
1913 1714
1914 Mostly useful for debugging the vma 1715 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. 1716 that don't require it.
1916 1717
1917 Say N if unsure. 1718 Say N if unsure.
1918 1719
1919 endmenu 1720 endmenu
1920 1721
>> 1722 config VM_EVENT_COUNTERS
>> 1723 default y
>> 1724 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1725 help
>> 1726 VM event counters are needed for event counts to be shown.
>> 1727 This option allows the disabling of the VM event counters
>> 1728 on EXPERT systems. /proc/vmstat will only show page counts
>> 1729 if VM event counters are disabled.
>> 1730
>> 1731 config SLUB_DEBUG
>> 1732 default y
>> 1733 bool "Enable SLUB debugging support" if EXPERT
>> 1734 depends on SLUB && SYSFS
>> 1735 help
>> 1736 SLUB has extensive debug support features. Disabling these can
>> 1737 result in significant savings in code size. This also disables
>> 1738 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1739 no support for cache validation etc.
>> 1740
>> 1741 config SLUB_MEMCG_SYSFS_ON
>> 1742 default n
>> 1743 bool "Enable memcg SLUB sysfs support by default" if EXPERT
>> 1744 depends on SLUB && SYSFS && MEMCG
>> 1745 help
>> 1746 SLUB creates a directory under /sys/kernel/slab for each
>> 1747 allocation cache to host info and debug files. If memory
>> 1748 cgroup is enabled, each cache can have per memory cgroup
>> 1749 caches. SLUB can create the same sysfs directories for these
>> 1750 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
>> 1751 to a very high number of debug files being created. This is
>> 1752 controlled by slub_memcg_sysfs boot parameter and this
>> 1753 config option determines the parameter's default value.
>> 1754
>> 1755 config COMPAT_BRK
>> 1756 bool "Disable heap randomization"
>> 1757 default y
>> 1758 help
>> 1759 Randomizing heap placement makes heap exploits harder, but it
>> 1760 also breaks ancient binaries (including anything libc5 based).
>> 1761 This option changes the bootup default to heap randomization
>> 1762 disabled, and can be overridden at runtime by setting
>> 1763 /proc/sys/kernel/randomize_va_space to 2.
>> 1764
>> 1765 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1766
>> 1767 choice
>> 1768 prompt "Choose SLAB allocator"
>> 1769 default SLUB
>> 1770 help
>> 1771 This option allows to select a slab allocator.
>> 1772
>> 1773 config SLAB
>> 1774 bool "SLAB"
>> 1775 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1776 help
>> 1777 The regular slab allocator that is established and known to work
>> 1778 well in all environments. It organizes cache hot objects in
>> 1779 per cpu and per node queues.
>> 1780
>> 1781 config SLUB
>> 1782 bool "SLUB (Unqueued Allocator)"
>> 1783 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1784 help
>> 1785 SLUB is a slab allocator that minimizes cache line usage
>> 1786 instead of managing queues of cached objects (SLAB approach).
>> 1787 Per cpu caching is realized using slabs of objects instead
>> 1788 of queues of objects. SLUB can use memory efficiently
>> 1789 and has enhanced diagnostics. SLUB is the default choice for
>> 1790 a slab allocator.
>> 1791
>> 1792 config SLOB
>> 1793 depends on EXPERT
>> 1794 bool "SLOB (Simple Allocator)"
>> 1795 help
>> 1796 SLOB replaces the stock allocator with a drastically simpler
>> 1797 allocator. SLOB is generally more space efficient but
>> 1798 does not perform as well on large systems.
>> 1799
>> 1800 endchoice
>> 1801
>> 1802 config SLAB_MERGE_DEFAULT
>> 1803 bool "Allow slab caches to be merged"
>> 1804 default y
>> 1805 help
>> 1806 For reduced kernel memory fragmentation, slab caches can be
>> 1807 merged when they share the same size and other characteristics.
>> 1808 This carries a risk of kernel heap overflows being able to
>> 1809 overwrite objects from merged caches (and more easily control
>> 1810 cache layout), which makes such heap attacks easier to exploit
>> 1811 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1812 can usually only damage objects in the same cache. To disable
>> 1813 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1814 command line.
>> 1815
>> 1816 config SLAB_FREELIST_RANDOM
>> 1817 default n
>> 1818 depends on SLAB || SLUB
>> 1819 bool "SLAB freelist randomization"
>> 1820 help
>> 1821 Randomizes the freelist order used on creating new pages. This
>> 1822 security feature reduces the predictability of the kernel slab
>> 1823 allocator against heap overflows.
>> 1824
>> 1825 config SLAB_FREELIST_HARDENED
>> 1826 bool "Harden slab freelist metadata"
>> 1827 depends on SLUB
>> 1828 help
>> 1829 Many kernel heap attacks try to target slab cache metadata and
>> 1830 other infrastructure. This options makes minor performance
>> 1831 sacrifices to harden the kernel slab allocator against common
>> 1832 freelist exploit methods.
>> 1833
>> 1834 config SHUFFLE_PAGE_ALLOCATOR
>> 1835 bool "Page allocator randomization"
>> 1836 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1837 help
>> 1838 Randomization of the page allocator improves the average
>> 1839 utilization of a direct-mapped memory-side-cache. See section
>> 1840 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1841 6.2a specification for an example of how a platform advertises
>> 1842 the presence of a memory-side-cache. There are also incidental
>> 1843 security benefits as it reduces the predictability of page
>> 1844 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1845 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1846 10th order of pages is selected based on cache utilization
>> 1847 benefits on x86.
>> 1848
>> 1849 While the randomization improves cache utilization it may
>> 1850 negatively impact workloads on platforms without a cache. For
>> 1851 this reason, by default, the randomization is enabled only
>> 1852 after runtime detection of a direct-mapped memory-side-cache.
>> 1853 Otherwise, the randomization may be force enabled with the
>> 1854 'page_alloc.shuffle' kernel command line parameter.
>> 1855
>> 1856 Say Y if unsure.
>> 1857
>> 1858 config SLUB_CPU_PARTIAL
>> 1859 default y
>> 1860 depends on SLUB && SMP
>> 1861 bool "SLUB per cpu partial cache"
>> 1862 help
>> 1863 Per cpu partial caches accelerate objects allocation and freeing
>> 1864 that is local to a processor at the price of more indeterminism
>> 1865 in the latency of the free. On overflow these caches will be cleared
>> 1866 which requires the taking of locks that may cause latency spikes.
>> 1867 Typically one would choose no for a realtime system.
>> 1868
>> 1869 config MMAP_ALLOW_UNINITIALIZED
>> 1870 bool "Allow mmapped anonymous memory to be uninitialized"
>> 1871 depends on EXPERT && !MMU
>> 1872 default n
>> 1873 help
>> 1874 Normally, and according to the Linux spec, anonymous memory obtained
>> 1875 from mmap() has its contents cleared before it is passed to
>> 1876 userspace. Enabling this config option allows you to request that
>> 1877 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 1878 providing a huge performance boost. If this option is not enabled,
>> 1879 then the flag will be ignored.
>> 1880
>> 1881 This is taken advantage of by uClibc's malloc(), and also by
>> 1882 ELF-FDPIC binfmt's brk and stack allocator.
>> 1883
>> 1884 Because of the obvious security issues, this option should only be
>> 1885 enabled on embedded devices where you control what is run in
>> 1886 userspace. Since that isn't generally a problem on no-MMU systems,
>> 1887 it is normally safe to say Y here.
>> 1888
>> 1889 See Documentation/nommu-mmap.txt for more information.
>> 1890
1921 config SYSTEM_DATA_VERIFICATION 1891 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1892 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1893 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1894 select KEYS
1925 select CRYPTO 1895 select CRYPTO
1926 select CRYPTO_RSA 1896 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1897 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1898 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1899 select ASN1
1930 select OID_REGISTRY 1900 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1901 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1902 select PKCS7_MESSAGE_PARSER
1933 help 1903 help
1934 Provide PKCS#7 message verification 1904 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1905 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1906 module verification, kexec image verification and firmware blob
1937 verification. 1907 verification.
1938 1908
1939 config PROFILING 1909 config PROFILING
1940 bool "Profiling support" 1910 bool "Profiling support"
1941 help 1911 help
1942 Say Y here to enable the extended p 1912 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 1913 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 1914
1986 # 1915 #
1987 # Place an empty function call at each tracep 1916 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1917 # dynamically changed for a probe function.
1989 # 1918 #
1990 config TRACEPOINTS 1919 config TRACEPOINTS
1991 bool 1920 bool
1992 1921
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1922 endmenu # General setup
1996 1923
1997 source "arch/Kconfig" 1924 source "arch/Kconfig"
1998 1925
1999 config RT_MUTEXES 1926 config RT_MUTEXES
2000 bool 1927 bool
2001 default y if PREEMPT_RT !! 1928
>> 1929 config BASE_SMALL
>> 1930 int
>> 1931 default 0 if BASE_FULL
>> 1932 default 1 if !BASE_FULL
2002 1933
2003 config MODULE_SIG_FORMAT 1934 config MODULE_SIG_FORMAT
2004 def_bool n 1935 def_bool n
2005 select SYSTEM_DATA_VERIFICATION 1936 select SYSTEM_DATA_VERIFICATION
2006 1937
2007 source "kernel/module/Kconfig" !! 1938 menuconfig MODULES
>> 1939 bool "Enable loadable module support"
>> 1940 option modules
>> 1941 help
>> 1942 Kernel modules are small pieces of compiled code which can
>> 1943 be inserted in the running kernel, rather than being
>> 1944 permanently built into the kernel. You use the "modprobe"
>> 1945 tool to add (and sometimes remove) them. If you say Y here,
>> 1946 many parts of the kernel can be built as modules (by
>> 1947 answering M instead of Y where indicated): this is most
>> 1948 useful for infrequently used options which are not required
>> 1949 for booting. For more information, see the man pages for
>> 1950 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1951
>> 1952 If you say Y here, you will need to run "make
>> 1953 modules_install" to put the modules under /lib/modules/
>> 1954 where modprobe can find them (you may need to be root to do
>> 1955 this).
>> 1956
>> 1957 If unsure, say Y.
>> 1958
>> 1959 if MODULES
>> 1960
>> 1961 config MODULE_FORCE_LOAD
>> 1962 bool "Forced module loading"
>> 1963 default n
>> 1964 help
>> 1965 Allow loading of modules without version information (ie. modprobe
>> 1966 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1967 is usually a really bad idea.
>> 1968
>> 1969 config MODULE_UNLOAD
>> 1970 bool "Module unloading"
>> 1971 help
>> 1972 Without this option you will not be able to unload any
>> 1973 modules (note that some modules may not be unloadable
>> 1974 anyway), which makes your kernel smaller, faster
>> 1975 and simpler. If unsure, say Y.
>> 1976
>> 1977 config MODULE_FORCE_UNLOAD
>> 1978 bool "Forced module unloading"
>> 1979 depends on MODULE_UNLOAD
>> 1980 help
>> 1981 This option allows you to force a module to unload, even if the
>> 1982 kernel believes it is unsafe: the kernel will remove the module
>> 1983 without waiting for anyone to stop using it (using the -f option to
>> 1984 rmmod). This is mainly for kernel developers and desperate users.
>> 1985 If unsure, say N.
>> 1986
>> 1987 config MODVERSIONS
>> 1988 bool "Module versioning support"
>> 1989 help
>> 1990 Usually, you have to use modules compiled with your kernel.
>> 1991 Saying Y here makes it sometimes possible to use modules
>> 1992 compiled for different kernels, by adding enough information
>> 1993 to the modules to (hopefully) spot any changes which would
>> 1994 make them incompatible with the kernel you are running. If
>> 1995 unsure, say N.
>> 1996
>> 1997 config ASM_MODVERSIONS
>> 1998 bool
>> 1999 default HAVE_ASM_MODVERSIONS && MODVERSIONS
>> 2000 help
>> 2001 This enables module versioning for exported symbols also from
>> 2002 assembly. This can be enabled only when the target architecture
>> 2003 supports it.
>> 2004
>> 2005 config MODULE_REL_CRCS
>> 2006 bool
>> 2007 depends on MODVERSIONS
>> 2008
>> 2009 config MODULE_SRCVERSION_ALL
>> 2010 bool "Source checksum for all modules"
>> 2011 help
>> 2012 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2013 field inserted into their modinfo section, which contains a
>> 2014 sum of the source files which made it. This helps maintainers
>> 2015 see exactly which source was used to build a module (since
>> 2016 others sometimes change the module source without updating
>> 2017 the version). With this option, such a "srcversion" field
>> 2018 will be created for all modules. If unsure, say N.
>> 2019
>> 2020 config MODULE_SIG
>> 2021 bool "Module signature verification"
>> 2022 select MODULE_SIG_FORMAT
>> 2023 help
>> 2024 Check modules for valid signatures upon load: the signature
>> 2025 is simply appended to the module. For more information see
>> 2026 <file:Documentation/admin-guide/module-signing.rst>.
>> 2027
>> 2028 Note that this option adds the OpenSSL development packages as a
>> 2029 kernel build dependency so that the signing tool can use its crypto
>> 2030 library.
>> 2031
>> 2032 You should enable this option if you wish to use either
>> 2033 CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
>> 2034 another LSM - otherwise unsigned modules will be loadable regardless
>> 2035 of the lockdown policy.
>> 2036
>> 2037 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2038 module DOES NOT get stripped after being signed. This includes the
>> 2039 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2040 inclusion into an initramfs that wants the module size reduced.
>> 2041
>> 2042 config MODULE_SIG_FORCE
>> 2043 bool "Require modules to be validly signed"
>> 2044 depends on MODULE_SIG
>> 2045 help
>> 2046 Reject unsigned modules or signed modules for which we don't have a
>> 2047 key. Without this, such modules will simply taint the kernel.
>> 2048
>> 2049 config MODULE_SIG_ALL
>> 2050 bool "Automatically sign all modules"
>> 2051 default y
>> 2052 depends on MODULE_SIG
>> 2053 help
>> 2054 Sign all modules during make modules_install. Without this option,
>> 2055 modules must be signed manually, using the scripts/sign-file tool.
>> 2056
>> 2057 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2058 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2059
>> 2060 choice
>> 2061 prompt "Which hash algorithm should modules be signed with?"
>> 2062 depends on MODULE_SIG
>> 2063 help
>> 2064 This determines which sort of hashing algorithm will be used during
>> 2065 signature generation. This algorithm _must_ be built into the kernel
>> 2066 directly so that signature verification can take place. It is not
>> 2067 possible to load a signed module containing the algorithm to check
>> 2068 the signature on that module.
>> 2069
>> 2070 config MODULE_SIG_SHA1
>> 2071 bool "Sign modules with SHA-1"
>> 2072 select CRYPTO_SHA1
>> 2073
>> 2074 config MODULE_SIG_SHA224
>> 2075 bool "Sign modules with SHA-224"
>> 2076 select CRYPTO_SHA256
>> 2077
>> 2078 config MODULE_SIG_SHA256
>> 2079 bool "Sign modules with SHA-256"
>> 2080 select CRYPTO_SHA256
>> 2081
>> 2082 config MODULE_SIG_SHA384
>> 2083 bool "Sign modules with SHA-384"
>> 2084 select CRYPTO_SHA512
>> 2085
>> 2086 config MODULE_SIG_SHA512
>> 2087 bool "Sign modules with SHA-512"
>> 2088 select CRYPTO_SHA512
>> 2089
>> 2090 endchoice
>> 2091
>> 2092 config MODULE_SIG_HASH
>> 2093 string
>> 2094 depends on MODULE_SIG
>> 2095 default "sha1" if MODULE_SIG_SHA1
>> 2096 default "sha224" if MODULE_SIG_SHA224
>> 2097 default "sha256" if MODULE_SIG_SHA256
>> 2098 default "sha384" if MODULE_SIG_SHA384
>> 2099 default "sha512" if MODULE_SIG_SHA512
>> 2100
>> 2101 config MODULE_COMPRESS
>> 2102 bool "Compress modules on installation"
>> 2103 help
>> 2104
>> 2105 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2106 xz depending on "Compression algorithm" below.
>> 2107
>> 2108 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2109
>> 2110 Out-of-tree kernel modules installed using Kbuild will also be
>> 2111 compressed upon installation.
>> 2112
>> 2113 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2114 to compress the whole initrd or initramfs instead.
>> 2115
>> 2116 Note: This is fully compatible with signed modules.
>> 2117
>> 2118 If in doubt, say N.
>> 2119
>> 2120 choice
>> 2121 prompt "Compression algorithm"
>> 2122 depends on MODULE_COMPRESS
>> 2123 default MODULE_COMPRESS_GZIP
>> 2124 help
>> 2125 This determines which sort of compression will be used during
>> 2126 'make modules_install'.
>> 2127
>> 2128 GZIP (default) and XZ are supported.
>> 2129
>> 2130 config MODULE_COMPRESS_GZIP
>> 2131 bool "GZIP"
>> 2132
>> 2133 config MODULE_COMPRESS_XZ
>> 2134 bool "XZ"
>> 2135
>> 2136 endchoice
>> 2137
>> 2138 config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
>> 2139 bool "Allow loading of modules with missing namespace imports"
>> 2140 help
>> 2141 Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
>> 2142 a namespace. A module that makes use of a symbol exported with such a
>> 2143 namespace is required to import the namespace via MODULE_IMPORT_NS().
>> 2144 There is no technical reason to enforce correct namespace imports,
>> 2145 but it creates consistency between symbols defining namespaces and
>> 2146 users importing namespaces they make use of. This option relaxes this
>> 2147 requirement and lifts the enforcement when loading a module.
>> 2148
>> 2149 If unsure, say N.
>> 2150
>> 2151 config UNUSED_SYMBOLS
>> 2152 bool "Enable unused/obsolete exported symbols"
>> 2153 default y if X86
>> 2154 help
>> 2155 Unused but exported symbols make the kernel needlessly bigger. For
>> 2156 that reason most of these unused exports will soon be removed. This
>> 2157 option is provided temporarily to provide a transition period in case
>> 2158 some external kernel module needs one of these symbols anyway. If you
>> 2159 encounter such a case in your module, consider if you are actually
>> 2160 using the right API. (rationale: since nobody in the kernel is using
>> 2161 this in a module, there is a pretty good chance it's actually the
>> 2162 wrong interface to use). If you really need the symbol, please send a
>> 2163 mail to the linux kernel mailing list mentioning the symbol and why
>> 2164 you really need it, and what the merge plan to the mainline kernel for
>> 2165 your module is.
>> 2166
>> 2167 config TRIM_UNUSED_KSYMS
>> 2168 bool "Trim unused exported kernel symbols"
>> 2169 depends on !UNUSED_SYMBOLS
>> 2170 help
>> 2171 The kernel and some modules make many symbols available for
>> 2172 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2173 on the set of modules being selected in your kernel configuration,
>> 2174 many of those exported symbols might never be used.
>> 2175
>> 2176 This option allows for unused exported symbols to be dropped from
>> 2177 the build. In turn, this provides the compiler more opportunities
>> 2178 (especially when using LTO) for optimizing the code and reducing
>> 2179 binary size. This might have some security advantages as well.
>> 2180
>> 2181 If unsure, or if you need to build out-of-tree modules, say N.
>> 2182
>> 2183 endif # MODULES
>> 2184
>> 2185 config MODULES_TREE_LOOKUP
>> 2186 def_bool y
>> 2187 depends on PERF_EVENTS || TRACING
2008 2188
2009 config INIT_ALL_POSSIBLE 2189 config INIT_ALL_POSSIBLE
2010 bool 2190 bool
2011 help 2191 help
2012 Back when each arch used to define 2192 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2193 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2194 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2195 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2196 and have several arch maintainers pursuing me down dark alleys.
2017 2197
2018 source "block/Kconfig" 2198 source "block/Kconfig"
2019 2199
2020 config PREEMPT_NOTIFIERS 2200 config PREEMPT_NOTIFIERS
2021 bool 2201 bool
2022 2202
2023 config PADATA 2203 config PADATA
2024 depends on SMP 2204 depends on SMP
2025 bool 2205 bool
2026 2206
2027 config ASN1 2207 config ASN1
2028 tristate 2208 tristate
2029 help 2209 help
2030 Build a simple ASN.1 grammar compil 2210 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2211 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2212 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2213 functions to call on what tags.
2034 2214
2035 source "kernel/Kconfig.locks" 2215 source "kernel/Kconfig.locks"
2036 <<
2037 config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE <<
2038 bool <<
2039 <<
2040 config ARCH_HAS_PREPARE_SYNC_CORE_CMD <<
2041 bool <<
2042 2216
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2217 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2218 bool
2045 2219
2046 # It may be useful for an architecture to ove 2220 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2221 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2222 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2223 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2224 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2225 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2226 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2227 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2228 def_bool n
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