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 26
58 config LLD_VERSION !! 27 config CC_CAN_LINK
59 int !! 28 def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC))
60 default $(ld-version) if LD_IS_LLD <<
61 default 0 <<
62 29
63 config RUSTC_VERSION !! 30 config CC_HAS_ASM_GOTO
64 int !! 31 def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
65 default $(rustc-version) <<
66 help <<
67 It does not depend on `RUST` since t <<
68 in a `depends on`. <<
69 32
70 config RUST_IS_AVAILABLE !! 33 config CC_HAS_WARN_MAYBE_UNINITIALIZED
71 def_bool $(success,$(srctree)/scripts/ !! 34 def_bool $(cc-option,-Wmaybe-uninitialized)
72 help 35 help
73 This shows whether a suitable Rust t !! 36 GCC >= 4.7 supports this option.
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 <<
85 config CC_CAN_LINK <<
86 bool <<
87 default $(success,$(srctree)/scripts/c <<
88 default $(success,$(srctree)/scripts/c <<
89 37
90 config CC_CAN_LINK_STATIC !! 38 config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
91 bool 39 bool
92 default $(success,$(srctree)/scripts/c !! 40 depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
93 default $(success,$(srctree)/scripts/c !! 41 default CC_IS_GCC && GCC_VERSION < 40900 # unreliable for GCC < 4.9
94 !! 42 help
95 # Fixed in GCC 14, 13.3, 12.4 and 11.5 !! 43 GCC's -Wmaybe-uninitialized is not reliable by definition.
96 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id !! 44 Lots of false positive warnings are produced in some cases.
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 <<
109 config CC_HAS_ASM_GOTO_TIED_OUTPUT <<
110 depends on CC_HAS_ASM_GOTO_OUTPUT <<
111 # Detect buggy gcc and clang, fixed in <<
112 def_bool $(success,echo 'int foo(int * <<
113 <<
114 config TOOLS_SUPPORT_RELR <<
115 def_bool $(success,env "CC=$(CC)" "LD= <<
116 <<
117 config CC_HAS_ASM_INLINE <<
118 def_bool $(success,echo 'void foo(void <<
119 <<
120 config CC_HAS_NO_PROFILE_FN_ATTR <<
121 def_bool $(success,echo '__attribute__ <<
122 45
123 config PAHOLE_VERSION !! 46 If this option is enabled, -Wno-maybe-uninitialzed is passed
124 int !! 47 to the compiler to suppress maybe-uninitialized warnings.
125 default $(shell,$(srctree)/scripts/pah <<
126 48
127 config CONSTRUCTORS 49 config CONSTRUCTORS
128 bool 50 bool
>> 51 depends on !UML
129 52
130 config IRQ_WORK 53 config IRQ_WORK
131 def_bool y if SMP !! 54 bool
132 55
133 config BUILDTIME_TABLE_SORT !! 56 config BUILDTIME_EXTABLE_SORT
134 bool 57 bool
135 58
136 config THREAD_INFO_IN_TASK 59 config THREAD_INFO_IN_TASK
137 bool 60 bool
138 help 61 help
139 Select this to move thread_info off 62 Select this to move thread_info off the stack into task_struct. To
140 make this work, an arch will need to 63 make this work, an arch will need to remove all thread_info fields
141 except flags and fix any runtime bug 64 except flags and fix any runtime bugs.
142 65
143 One subtle change that will be neede 66 One subtle change that will be needed is to use try_get_task_stack()
144 and put_task_stack() in save_thread_ 67 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
145 68
146 menu "General setup" 69 menu "General setup"
147 70
148 config BROKEN 71 config BROKEN
149 bool 72 bool
150 73
151 config BROKEN_ON_SMP 74 config BROKEN_ON_SMP
152 bool 75 bool
153 depends on BROKEN || !SMP 76 depends on BROKEN || !SMP
154 default y 77 default y
155 78
156 config INIT_ENV_ARG_LIMIT 79 config INIT_ENV_ARG_LIMIT
157 int 80 int
158 default 32 if !UML 81 default 32 if !UML
159 default 128 if UML 82 default 128 if UML
160 help 83 help
161 Maximum of each of the number of arg 84 Maximum of each of the number of arguments and environment
162 variables passed to init from the ke 85 variables passed to init from the kernel command line.
163 86
164 config COMPILE_TEST 87 config COMPILE_TEST
165 bool "Compile also drivers which will 88 bool "Compile also drivers which will not load"
166 depends on HAS_IOMEM !! 89 depends on !UML
>> 90 default n
167 help 91 help
168 Some drivers can be compiled on a di 92 Some drivers can be compiled on a different platform than they are
169 intended to be run on. Despite they 93 intended to be run on. Despite they cannot be loaded there (or even
170 when they load they cannot be used d 94 when they load they cannot be used due to missing HW support),
171 developers still, opposing to distri 95 developers still, opposing to distributors, might want to build such
172 drivers to compile-test them. 96 drivers to compile-test them.
173 97
174 If you are a developer and want to b 98 If you are a developer and want to build everything available, say Y
175 here. If you are a user/distributor, 99 here. If you are a user/distributor, say N here to exclude useless
176 drivers to be distributed. 100 drivers to be distributed.
177 101
178 config WERROR !! 102 config HEADER_TEST
179 bool "Compile the kernel with warnings !! 103 bool "Compile test headers that should be standalone compilable"
180 default COMPILE_TEST !! 104 help
181 help !! 105 Compile test headers listed in header-test-y target to ensure they are
182 A kernel build should not cause any !! 106 self-contained, i.e. compilable as standalone units.
183 enables the '-Werror' (for C) and '- !! 107
184 to enforce that rule by default. Cer !! 108 If you are a developer or tester and want to ensure the requested
185 such as the linker may be upgraded t !! 109 headers are self-contained, say Y here. Otherwise, choose N.
186 well. !! 110
187 !! 111 config KERNEL_HEADER_TEST
188 However, if you have a new (or very !! 112 bool "Compile test kernel headers"
189 and unusual warnings, or you have so !! 113 depends on HEADER_TEST
190 you may need to disable this config !! 114 help
191 successfully build the kernel. !! 115 Headers in include/ are used to build external moduls.
>> 116 Compile test them to ensure they are self-contained, i.e.
>> 117 compilable as standalone units.
192 118
193 If in doubt, say Y. !! 119 If you are a developer or tester and want to ensure the headers
>> 120 in include/ are self-contained, say Y here. Otherwise, choose N.
194 121
195 config UAPI_HEADER_TEST 122 config UAPI_HEADER_TEST
196 bool "Compile test UAPI headers" 123 bool "Compile test UAPI headers"
197 depends on HEADERS_INSTALL && CC_CAN_L !! 124 depends on HEADER_TEST && HEADERS_INSTALL && CC_CAN_LINK
198 help 125 help
199 Compile test headers exported to use 126 Compile test headers exported to user-space to ensure they are
200 self-contained, i.e. compilable as s 127 self-contained, i.e. compilable as standalone units.
201 128
202 If you are a developer or tester and 129 If you are a developer or tester and want to ensure the exported
203 headers are self-contained, say Y he 130 headers are self-contained, say Y here. Otherwise, choose N.
204 131
205 config LOCALVERSION 132 config LOCALVERSION
206 string "Local version - append to kern 133 string "Local version - append to kernel release"
207 help 134 help
208 Append an extra string to the end of 135 Append an extra string to the end of your kernel version.
209 This will show up when you type unam 136 This will show up when you type uname, for example.
210 The string you set here will be appe 137 The string you set here will be appended after the contents of
211 any files with a filename matching l 138 any files with a filename matching localversion* in your
212 object and source tree, in that orde 139 object and source tree, in that order. Your total string can
213 be a maximum of 64 characters. 140 be a maximum of 64 characters.
214 141
215 config LOCALVERSION_AUTO 142 config LOCALVERSION_AUTO
216 bool "Automatically append version inf 143 bool "Automatically append version information to the version string"
217 default y 144 default y
218 depends on !COMPILE_TEST 145 depends on !COMPILE_TEST
219 help 146 help
220 This will try to automatically deter 147 This will try to automatically determine if the current tree is a
221 release tree by looking for git tags 148 release tree by looking for git tags that belong to the current
222 top of tree revision. 149 top of tree revision.
223 150
224 A string of the format -gxxxxxxxx wi 151 A string of the format -gxxxxxxxx will be added to the localversion
225 if a git-based tree is found. The s 152 if a git-based tree is found. The string generated by this will be
226 appended after any matching localver 153 appended after any matching localversion* files, and after the value
227 set in CONFIG_LOCALVERSION. 154 set in CONFIG_LOCALVERSION.
228 155
229 (The actual string used here is the !! 156 (The actual string used here is the first eight characters produced
230 by running the command: 157 by running the command:
231 158
232 $ git rev-parse --verify HEAD 159 $ git rev-parse --verify HEAD
233 160
234 which is done within the script "scr 161 which is done within the script "scripts/setlocalversion".)
235 162
236 config BUILD_SALT 163 config BUILD_SALT
237 string "Build ID Salt" !! 164 string "Build ID Salt"
238 default "" !! 165 default ""
239 help !! 166 help
240 The build ID is used to link binarie !! 167 The build ID is used to link binaries and their debug info. Setting
241 this option will use the value in th !! 168 this option will use the value in the calculation of the build id.
242 This is mostly useful for distributi !! 169 This is mostly useful for distributions which want to ensure the
243 build is unique between builds. It's !! 170 build is unique between builds. It's safe to leave the default.
244 171
245 config HAVE_KERNEL_GZIP 172 config HAVE_KERNEL_GZIP
246 bool 173 bool
247 174
248 config HAVE_KERNEL_BZIP2 175 config HAVE_KERNEL_BZIP2
249 bool 176 bool
250 177
251 config HAVE_KERNEL_LZMA 178 config HAVE_KERNEL_LZMA
252 bool 179 bool
253 180
254 config HAVE_KERNEL_XZ 181 config HAVE_KERNEL_XZ
255 bool 182 bool
256 183
257 config HAVE_KERNEL_LZO 184 config HAVE_KERNEL_LZO
258 bool 185 bool
259 186
260 config HAVE_KERNEL_LZ4 187 config HAVE_KERNEL_LZ4
261 bool 188 bool
262 189
263 config HAVE_KERNEL_ZSTD <<
264 bool <<
265 <<
266 config HAVE_KERNEL_UNCOMPRESSED 190 config HAVE_KERNEL_UNCOMPRESSED
267 bool 191 bool
268 192
269 choice 193 choice
270 prompt "Kernel compression mode" 194 prompt "Kernel compression mode"
271 default KERNEL_GZIP 195 default KERNEL_GZIP
272 depends on HAVE_KERNEL_GZIP || HAVE_KE !! 196 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 197 help
274 The linux kernel is a kind of self-e 198 The linux kernel is a kind of self-extracting executable.
275 Several compression algorithms are a 199 Several compression algorithms are available, which differ
276 in efficiency, compression and decom 200 in efficiency, compression and decompression speed.
277 Compression speed is only relevant w 201 Compression speed is only relevant when building a kernel.
278 Decompression speed is relevant at e 202 Decompression speed is relevant at each boot.
279 203
280 If you have any problems with bzip2 204 If you have any problems with bzip2 or lzma compressed
281 kernels, mail me (Alain Knaff) <alain 205 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
282 version of this functionality (bzip2 206 version of this functionality (bzip2 only), for 2.4, was
283 supplied by Christian Ludwig) 207 supplied by Christian Ludwig)
284 208
285 High compression options are mostly 209 High compression options are mostly useful for users, who
286 are low on disk space (embedded syst 210 are low on disk space (embedded systems), but for whom ram
287 size matters less. 211 size matters less.
288 212
289 If in doubt, select 'gzip' 213 If in doubt, select 'gzip'
290 214
291 config KERNEL_GZIP 215 config KERNEL_GZIP
292 bool "Gzip" 216 bool "Gzip"
293 depends on HAVE_KERNEL_GZIP 217 depends on HAVE_KERNEL_GZIP
294 help 218 help
295 The old and tried gzip compression. 219 The old and tried gzip compression. It provides a good balance
296 between compression ratio and decomp 220 between compression ratio and decompression speed.
297 221
298 config KERNEL_BZIP2 222 config KERNEL_BZIP2
299 bool "Bzip2" 223 bool "Bzip2"
300 depends on HAVE_KERNEL_BZIP2 224 depends on HAVE_KERNEL_BZIP2
301 help 225 help
302 Its compression ratio and speed is i 226 Its compression ratio and speed is intermediate.
303 Decompression speed is slowest among 227 Decompression speed is slowest among the choices. The kernel
304 size is about 10% smaller with bzip2 228 size is about 10% smaller with bzip2, in comparison to gzip.
305 Bzip2 uses a large amount of memory. 229 Bzip2 uses a large amount of memory. For modern kernels you
306 will need at least 8MB RAM or more f 230 will need at least 8MB RAM or more for booting.
307 231
308 config KERNEL_LZMA 232 config KERNEL_LZMA
309 bool "LZMA" 233 bool "LZMA"
310 depends on HAVE_KERNEL_LZMA 234 depends on HAVE_KERNEL_LZMA
311 help 235 help
312 This compression algorithm's ratio i 236 This compression algorithm's ratio is best. Decompression speed
313 is between gzip and bzip2. Compress 237 is between gzip and bzip2. Compression is slowest.
314 The kernel size is about 33% smaller 238 The kernel size is about 33% smaller with LZMA in comparison to gzip.
315 239
316 config KERNEL_XZ 240 config KERNEL_XZ
317 bool "XZ" 241 bool "XZ"
318 depends on HAVE_KERNEL_XZ 242 depends on HAVE_KERNEL_XZ
319 help 243 help
320 XZ uses the LZMA2 algorithm and inst 244 XZ uses the LZMA2 algorithm and instruction set specific
321 BCJ filters which can improve compre 245 BCJ filters which can improve compression ratio of executable
322 code. The size of the kernel is abou 246 code. The size of the kernel is about 30% smaller with XZ in
323 comparison to gzip. On architectures 247 comparison to gzip. On architectures for which there is a BCJ
324 filter (i386, x86_64, ARM, ARM64, RI !! 248 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
325 and SPARC), XZ will create a few per !! 249 will create a few percent smaller kernel than plain LZMA.
326 plain LZMA. <<
327 250
328 The speed is about the same as with 251 The speed is about the same as with LZMA: The decompression
329 speed of XZ is better than that of b 252 speed of XZ is better than that of bzip2 but worse than gzip
330 and LZO. Compression is slow. 253 and LZO. Compression is slow.
331 254
332 config KERNEL_LZO 255 config KERNEL_LZO
333 bool "LZO" 256 bool "LZO"
334 depends on HAVE_KERNEL_LZO 257 depends on HAVE_KERNEL_LZO
335 help 258 help
336 Its compression ratio is the poorest 259 Its compression ratio is the poorest among the choices. The kernel
337 size is about 10% bigger than gzip; 260 size is about 10% bigger than gzip; however its speed
338 (both compression and decompression) 261 (both compression and decompression) is the fastest.
339 262
340 config KERNEL_LZ4 263 config KERNEL_LZ4
341 bool "LZ4" 264 bool "LZ4"
342 depends on HAVE_KERNEL_LZ4 265 depends on HAVE_KERNEL_LZ4
343 help 266 help
344 LZ4 is an LZ77-type compressor with 267 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
345 A preliminary version of LZ4 de/comp 268 A preliminary version of LZ4 de/compression tool is available at
346 <https://code.google.com/p/lz4/>. 269 <https://code.google.com/p/lz4/>.
347 270
348 Its compression ratio is worse than 271 Its compression ratio is worse than LZO. The size of the kernel
349 is about 8% bigger than LZO. But the 272 is about 8% bigger than LZO. But the decompression speed is
350 faster than LZO. 273 faster than LZO.
351 274
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 275 config KERNEL_UNCOMPRESSED
363 bool "None" 276 bool "None"
364 depends on HAVE_KERNEL_UNCOMPRESSED 277 depends on HAVE_KERNEL_UNCOMPRESSED
365 help 278 help
366 Produce uncompressed kernel image. T 279 Produce uncompressed kernel image. This option is usually not what
367 you want. It is useful for debugging 280 you want. It is useful for debugging the kernel in slow simulation
368 environments, where decompressing an 281 environments, where decompressing and moving the kernel is awfully
369 slow. This option allows early boot 282 slow. This option allows early boot code to skip the decompressor
370 and jump right at uncompressed kerne 283 and jump right at uncompressed kernel image.
371 284
372 endchoice 285 endchoice
373 286
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 287 config DEFAULT_HOSTNAME
385 string "Default hostname" 288 string "Default hostname"
386 default "(none)" 289 default "(none)"
387 help 290 help
388 This option determines the default s 291 This option determines the default system hostname before userspace
389 calls sethostname(2). The kernel tra 292 calls sethostname(2). The kernel traditionally uses "(none)" here,
390 but you may wish to use a different 293 but you may wish to use a different default here to make a minimal
391 system more usable with less configu 294 system more usable with less configuration.
392 295
>> 296 #
>> 297 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
>> 298 # add proper SWAP support to them, in which case this can be remove.
>> 299 #
>> 300 config ARCH_NO_SWAP
>> 301 bool
>> 302
>> 303 config SWAP
>> 304 bool "Support for paging of anonymous memory (swap)"
>> 305 depends on MMU && BLOCK && !ARCH_NO_SWAP
>> 306 default y
>> 307 help
>> 308 This option allows you to choose whether you want to have support
>> 309 for so called swap devices or swap files in your kernel that are
>> 310 used to provide more virtual memory than the actual RAM present
>> 311 in your computer. If unsure say Y.
>> 312
393 config SYSVIPC 313 config SYSVIPC
394 bool "System V IPC" 314 bool "System V IPC"
395 help !! 315 ---help---
396 Inter Process Communication is a sui 316 Inter Process Communication is a suite of library functions and
397 system calls which let processes (ru 317 system calls which let processes (running programs) synchronize and
398 exchange information. It is generall 318 exchange information. It is generally considered to be a good thing,
399 and some programs won't run unless y 319 and some programs won't run unless you say Y here. In particular, if
400 you want to run the DOS emulator dos 320 you want to run the DOS emulator dosemu under Linux (read the
401 DOSEMU-HOWTO, available from <http:/ 321 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
402 you'll need to say Y here. 322 you'll need to say Y here.
403 323
404 You can find documentation about IPC 324 You can find documentation about IPC with "info ipc" and also in
405 section 6.4 of the Linux Programmer' 325 section 6.4 of the Linux Programmer's Guide, available from
406 <http://www.tldp.org/guides.html>. 326 <http://www.tldp.org/guides.html>.
407 327
408 config SYSVIPC_SYSCTL 328 config SYSVIPC_SYSCTL
409 bool 329 bool
410 depends on SYSVIPC 330 depends on SYSVIPC
411 depends on SYSCTL 331 depends on SYSCTL
412 default y 332 default y
413 333
414 config SYSVIPC_COMPAT <<
415 def_bool y <<
416 depends on COMPAT && SYSVIPC <<
417 <<
418 config POSIX_MQUEUE 334 config POSIX_MQUEUE
419 bool "POSIX Message Queues" 335 bool "POSIX Message Queues"
420 depends on NET 336 depends on NET
421 help !! 337 ---help---
422 POSIX variant of message queues is a 338 POSIX variant of message queues is a part of IPC. In POSIX message
423 queues every message has a priority 339 queues every message has a priority which decides about succession
424 of receiving it by a process. If you 340 of receiving it by a process. If you want to compile and run
425 programs written e.g. for Solaris wi 341 programs written e.g. for Solaris with use of its POSIX message
426 queues (functions mq_*) say Y here. 342 queues (functions mq_*) say Y here.
427 343
428 POSIX message queues are visible as 344 POSIX message queues are visible as a filesystem called 'mqueue'
429 and can be mounted somewhere if you 345 and can be mounted somewhere if you want to do filesystem
430 operations on message queues. 346 operations on message queues.
431 347
432 If unsure, say Y. 348 If unsure, say Y.
433 349
434 config POSIX_MQUEUE_SYSCTL 350 config POSIX_MQUEUE_SYSCTL
435 bool 351 bool
436 depends on POSIX_MQUEUE 352 depends on POSIX_MQUEUE
437 depends on SYSCTL 353 depends on SYSCTL
438 default y 354 default y
439 355
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 356 config CROSS_MEMORY_ATTACH
453 bool "Enable process_vm_readv/writev s 357 bool "Enable process_vm_readv/writev syscalls"
454 depends on MMU 358 depends on MMU
455 default y 359 default y
456 help 360 help
457 Enabling this option adds the system 361 Enabling this option adds the system calls process_vm_readv and
458 process_vm_writev which allow a proc 362 process_vm_writev which allow a process with the correct privileges
459 to directly read from or write to an 363 to directly read from or write to another process' address space.
460 See the man page for more details. 364 See the man page for more details.
461 365
462 config USELIB 366 config USELIB
463 bool "uselib syscall (for libc5 and ea !! 367 bool "uselib syscall"
464 default ALPHA || M68K || SPARC !! 368 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
465 help 369 help
466 This option enables the uselib sysca 370 This option enables the uselib syscall, a system call used in the
467 dynamic linker from libc5 and earlie 371 dynamic linker from libc5 and earlier. glibc does not use this
468 system call. If you intend to run p 372 system call. If you intend to run programs built on libc5 or
469 earlier, you may need to enable this 373 earlier, you may need to enable this syscall. Current systems
470 running glibc can safely disable thi 374 running glibc can safely disable this.
471 375
472 config AUDIT 376 config AUDIT
473 bool "Auditing support" 377 bool "Auditing support"
474 depends on NET 378 depends on NET
475 help 379 help
476 Enable auditing infrastructure that 380 Enable auditing infrastructure that can be used with another
477 kernel subsystem, such as SELinux (w 381 kernel subsystem, such as SELinux (which requires this for
478 logging of avc messages output). Sy 382 logging of avc messages output). System call auditing is included
479 on architectures which support it. 383 on architectures which support it.
480 384
481 config HAVE_ARCH_AUDITSYSCALL 385 config HAVE_ARCH_AUDITSYSCALL
482 bool 386 bool
483 387
484 config AUDITSYSCALL 388 config AUDITSYSCALL
485 def_bool y 389 def_bool y
486 depends on AUDIT && HAVE_ARCH_AUDITSYS 390 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
487 select FSNOTIFY 391 select FSNOTIFY
488 392
489 source "kernel/irq/Kconfig" 393 source "kernel/irq/Kconfig"
490 source "kernel/time/Kconfig" 394 source "kernel/time/Kconfig"
491 source "kernel/bpf/Kconfig" <<
492 source "kernel/Kconfig.preempt" 395 source "kernel/Kconfig.preempt"
493 396
494 menu "CPU/Task time and stats accounting" 397 menu "CPU/Task time and stats accounting"
495 398
496 config VIRT_CPU_ACCOUNTING 399 config VIRT_CPU_ACCOUNTING
497 bool 400 bool
498 401
499 choice 402 choice
500 prompt "Cputime accounting" 403 prompt "Cputime accounting"
501 default TICK_CPU_ACCOUNTING !! 404 default TICK_CPU_ACCOUNTING if !PPC64
>> 405 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
502 406
503 # Kind of a stub config for the pure tick base 407 # Kind of a stub config for the pure tick based cputime accounting
504 config TICK_CPU_ACCOUNTING 408 config TICK_CPU_ACCOUNTING
505 bool "Simple tick based cputime accoun 409 bool "Simple tick based cputime accounting"
506 depends on !S390 && !NO_HZ_FULL 410 depends on !S390 && !NO_HZ_FULL
507 help 411 help
508 This is the basic tick based cputime 412 This is the basic tick based cputime accounting that maintains
509 statistics about user, system and id 413 statistics about user, system and idle time spent on per jiffies
510 granularity. 414 granularity.
511 415
512 If unsure, say Y. 416 If unsure, say Y.
513 417
514 config VIRT_CPU_ACCOUNTING_NATIVE 418 config VIRT_CPU_ACCOUNTING_NATIVE
515 bool "Deterministic task and CPU time 419 bool "Deterministic task and CPU time accounting"
516 depends on HAVE_VIRT_CPU_ACCOUNTING && 420 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
517 select VIRT_CPU_ACCOUNTING 421 select VIRT_CPU_ACCOUNTING
518 help 422 help
519 Select this option to enable more ac 423 Select this option to enable more accurate task and CPU time
520 accounting. This is done by reading 424 accounting. This is done by reading a CPU counter on each
521 kernel entry and exit and on transit 425 kernel entry and exit and on transitions within the kernel
522 between system, softirq and hardirq 426 between system, softirq and hardirq state, so there is a
523 small performance impact. In the ca 427 small performance impact. In the case of s390 or IBM POWER > 5,
524 this also enables accounting of stol 428 this also enables accounting of stolen time on logically-partitioned
525 systems. 429 systems.
526 430
527 config VIRT_CPU_ACCOUNTING_GEN 431 config VIRT_CPU_ACCOUNTING_GEN
528 bool "Full dynticks CPU time accountin 432 bool "Full dynticks CPU time accounting"
529 depends on HAVE_CONTEXT_TRACKING_USER !! 433 depends on HAVE_CONTEXT_TRACKING
530 depends on HAVE_VIRT_CPU_ACCOUNTING_GE 434 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
531 depends on GENERIC_CLOCKEVENTS 435 depends on GENERIC_CLOCKEVENTS
532 select VIRT_CPU_ACCOUNTING 436 select VIRT_CPU_ACCOUNTING
533 select CONTEXT_TRACKING_USER !! 437 select CONTEXT_TRACKING
534 help 438 help
535 Select this option to enable task an 439 Select this option to enable task and CPU time accounting on full
536 dynticks systems. This accounting is 440 dynticks systems. This accounting is implemented by watching every
537 kernel-user boundaries using the con 441 kernel-user boundaries using the context tracking subsystem.
538 The accounting is thus performed at 442 The accounting is thus performed at the expense of some significant
539 overhead. 443 overhead.
540 444
541 For now this is only useful if you a 445 For now this is only useful if you are working on the full
542 dynticks subsystem development. 446 dynticks subsystem development.
543 447
544 If unsure, say N. 448 If unsure, say N.
545 449
546 endchoice 450 endchoice
547 451
548 config IRQ_TIME_ACCOUNTING 452 config IRQ_TIME_ACCOUNTING
549 bool "Fine granularity task level IRQ 453 bool "Fine granularity task level IRQ time accounting"
550 depends on HAVE_IRQ_TIME_ACCOUNTING && 454 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
551 help 455 help
552 Select this option to enable fine gr 456 Select this option to enable fine granularity task irq time
553 accounting. This is done by reading 457 accounting. This is done by reading a timestamp on each
554 transitions between softirq and hard 458 transitions between softirq and hardirq state, so there can be a
555 small performance impact. 459 small performance impact.
556 460
557 If in doubt, say N here. 461 If in doubt, say N here.
558 462
559 config HAVE_SCHED_AVG_IRQ 463 config HAVE_SCHED_AVG_IRQ
560 def_bool y 464 def_bool y
561 depends on IRQ_TIME_ACCOUNTING || PARA 465 depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
562 depends on SMP 466 depends on SMP
563 467
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 468 config BSD_PROCESS_ACCT
584 bool "BSD Process Accounting" 469 bool "BSD Process Accounting"
585 depends on MULTIUSER 470 depends on MULTIUSER
586 help 471 help
587 If you say Y here, a user level prog 472 If you say Y here, a user level program will be able to instruct the
588 kernel (via a special system call) t 473 kernel (via a special system call) to write process accounting
589 information to a file: whenever a pr 474 information to a file: whenever a process exits, information about
590 that process will be appended to the 475 that process will be appended to the file by the kernel. The
591 information includes things such as 476 information includes things such as creation time, owning user,
592 command name, memory usage, controll 477 command name, memory usage, controlling terminal etc. (the complete
593 list is in the struct acct in <file: 478 list is in the struct acct in <file:include/linux/acct.h>). It is
594 up to the user level program to do u 479 up to the user level program to do useful things with this
595 information. This is generally a go 480 information. This is generally a good idea, so say Y.
596 481
597 config BSD_PROCESS_ACCT_V3 482 config BSD_PROCESS_ACCT_V3
598 bool "BSD Process Accounting version 3 483 bool "BSD Process Accounting version 3 file format"
599 depends on BSD_PROCESS_ACCT 484 depends on BSD_PROCESS_ACCT
600 default n 485 default n
601 help 486 help
602 If you say Y here, the process accou 487 If you say Y here, the process accounting information is written
603 in a new file format that also logs 488 in a new file format that also logs the process IDs of each
604 process and its parent. Note that th 489 process and its parent. Note that this file format is incompatible
605 with previous v0/v1/v2 file formats, 490 with previous v0/v1/v2 file formats, so you will need updated tools
606 for processing it. A preliminary ver 491 for processing it. A preliminary version of these tools is available
607 at <http://www.gnu.org/software/acct 492 at <http://www.gnu.org/software/acct/>.
608 493
609 config TASKSTATS 494 config TASKSTATS
610 bool "Export task/process statistics t 495 bool "Export task/process statistics through netlink"
611 depends on NET 496 depends on NET
612 depends on MULTIUSER 497 depends on MULTIUSER
613 default n 498 default n
614 help 499 help
615 Export selected statistics for tasks 500 Export selected statistics for tasks/processes through the
616 generic netlink interface. Unlike BS 501 generic netlink interface. Unlike BSD process accounting, the
617 statistics are available during the 502 statistics are available during the lifetime of tasks/processes as
618 responses to commands. Like BSD acco 503 responses to commands. Like BSD accounting, they are sent to user
619 space on task exit. 504 space on task exit.
620 505
621 Say N if unsure. 506 Say N if unsure.
622 507
623 config TASK_DELAY_ACCT 508 config TASK_DELAY_ACCT
624 bool "Enable per-task delay accounting 509 bool "Enable per-task delay accounting"
625 depends on TASKSTATS 510 depends on TASKSTATS
626 select SCHED_INFO 511 select SCHED_INFO
627 help 512 help
628 Collect information on time spent by 513 Collect information on time spent by a task waiting for system
629 resources like cpu, synchronous bloc 514 resources like cpu, synchronous block I/O completion and swapping
630 in pages. Such statistics can help i 515 in pages. Such statistics can help in setting a task's priorities
631 relative to other tasks for cpu, io, 516 relative to other tasks for cpu, io, rss limits etc.
632 517
633 Say N if unsure. 518 Say N if unsure.
634 519
635 config TASK_XACCT 520 config TASK_XACCT
636 bool "Enable extended accounting over 521 bool "Enable extended accounting over taskstats"
637 depends on TASKSTATS 522 depends on TASKSTATS
638 help 523 help
639 Collect extended task accounting dat 524 Collect extended task accounting data and send the data
640 to userland for processing over the 525 to userland for processing over the taskstats interface.
641 526
642 Say N if unsure. 527 Say N if unsure.
643 528
644 config TASK_IO_ACCOUNTING 529 config TASK_IO_ACCOUNTING
645 bool "Enable per-task storage I/O acco 530 bool "Enable per-task storage I/O accounting"
646 depends on TASK_XACCT 531 depends on TASK_XACCT
647 help 532 help
648 Collect information on the number of 533 Collect information on the number of bytes of storage I/O which this
649 task has caused. 534 task has caused.
650 535
651 Say N if unsure. 536 Say N if unsure.
652 537
653 config PSI 538 config PSI
654 bool "Pressure stall information track 539 bool "Pressure stall information tracking"
655 select KERNFS <<
656 help 540 help
657 Collect metrics that indicate how ov 541 Collect metrics that indicate how overcommitted the CPU, memory,
658 and IO capacity are in the system. 542 and IO capacity are in the system.
659 543
660 If you say Y here, the kernel will c 544 If you say Y here, the kernel will create /proc/pressure/ with the
661 pressure statistics files cpu, memor 545 pressure statistics files cpu, memory, and io. These will indicate
662 the share of walltime in which some 546 the share of walltime in which some or all tasks in the system are
663 delayed due to contention of the res 547 delayed due to contention of the respective resource.
664 548
665 In kernels with cgroup support, cgro 549 In kernels with cgroup support, cgroups (cgroup2 only) will
666 have cpu.pressure, memory.pressure, 550 have cpu.pressure, memory.pressure, and io.pressure files,
667 which aggregate pressure stalls for 551 which aggregate pressure stalls for the grouped tasks only.
668 552
669 For more details see Documentation/a 553 For more details see Documentation/accounting/psi.rst.
670 554
671 Say N if unsure. 555 Say N if unsure.
672 556
673 config PSI_DEFAULT_DISABLED 557 config PSI_DEFAULT_DISABLED
674 bool "Require boot parameter to enable 558 bool "Require boot parameter to enable pressure stall information tracking"
675 default n 559 default n
676 depends on PSI 560 depends on PSI
677 help 561 help
678 If set, pressure stall information t 562 If set, pressure stall information tracking will be disabled
679 per default but can be enabled throu 563 per default but can be enabled through passing psi=1 on the
680 kernel commandline during boot. 564 kernel commandline during boot.
681 565
682 This feature adds some code to the t 566 This feature adds some code to the task wakeup and sleep
683 paths of the scheduler. The overhead 567 paths of the scheduler. The overhead is too low to affect
684 common scheduling-intense workloads 568 common scheduling-intense workloads in practice (such as
685 webservers, memcache), but it does s 569 webservers, memcache), but it does show up in artificial
686 scheduler stress tests, such as hack 570 scheduler stress tests, such as hackbench.
687 571
688 If you are paranoid and not sure wha 572 If you are paranoid and not sure what the kernel will be
689 used for, say Y. 573 used for, say Y.
690 574
691 Say N if unsure. 575 Say N if unsure.
692 576
693 endmenu # "CPU/Task time and stats accounting" 577 endmenu # "CPU/Task time and stats accounting"
694 578
695 config CPU_ISOLATION 579 config CPU_ISOLATION
696 bool "CPU isolation" 580 bool "CPU isolation"
697 depends on SMP || COMPILE_TEST 581 depends on SMP || COMPILE_TEST
698 default y 582 default y
699 help 583 help
700 Make sure that CPUs running critical 584 Make sure that CPUs running critical tasks are not disturbed by
701 any source of "noise" such as unboun 585 any source of "noise" such as unbound workqueues, timers, kthreads...
702 Unbound jobs get offloaded to housek 586 Unbound jobs get offloaded to housekeeping CPUs. This is driven by
703 the "isolcpus=" boot parameter. 587 the "isolcpus=" boot parameter.
704 588
705 Say Y if unsure. 589 Say Y if unsure.
706 590
707 source "kernel/rcu/Kconfig" 591 source "kernel/rcu/Kconfig"
708 592
>> 593 config BUILD_BIN2C
>> 594 bool
>> 595 default n
>> 596
709 config IKCONFIG 597 config IKCONFIG
710 tristate "Kernel .config support" 598 tristate "Kernel .config support"
711 help !! 599 ---help---
712 This option enables the complete Lin 600 This option enables the complete Linux kernel ".config" file
713 contents to be saved in the kernel. 601 contents to be saved in the kernel. It provides documentation
714 of which kernel options are used in 602 of which kernel options are used in a running kernel or in an
715 on-disk kernel. This information ca 603 on-disk kernel. This information can be extracted from the kernel
716 image file with the script scripts/e 604 image file with the script scripts/extract-ikconfig and used as
717 input to rebuild the current kernel 605 input to rebuild the current kernel or to build another kernel.
718 It can also be extracted from a runn 606 It can also be extracted from a running kernel by reading
719 /proc/config.gz if enabled (below). 607 /proc/config.gz if enabled (below).
720 608
721 config IKCONFIG_PROC 609 config IKCONFIG_PROC
722 bool "Enable access to .config through 610 bool "Enable access to .config through /proc/config.gz"
723 depends on IKCONFIG && PROC_FS 611 depends on IKCONFIG && PROC_FS
724 help !! 612 ---help---
725 This option enables access to the ke 613 This option enables access to the kernel configuration file
726 through /proc/config.gz. 614 through /proc/config.gz.
727 615
728 config IKHEADERS 616 config IKHEADERS
729 tristate "Enable kernel headers throug 617 tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
730 depends on SYSFS 618 depends on SYSFS
731 help 619 help
732 This option enables access to the in 620 This option enables access to the in-kernel headers that are generated during
733 the build process. These can be used 621 the build process. These can be used to build eBPF tracing programs,
734 or similar programs. If you build t 622 or similar programs. If you build the headers as a module, a module called
735 kheaders.ko is built which can be lo 623 kheaders.ko is built which can be loaded on-demand to get access to headers.
736 624
737 config LOG_BUF_SHIFT 625 config LOG_BUF_SHIFT
738 int "Kernel log buffer size (16 => 64K 626 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
739 range 12 25 627 range 12 25
740 default 17 628 default 17
741 depends on PRINTK 629 depends on PRINTK
742 help 630 help
743 Select the minimal kernel log buffer 631 Select the minimal kernel log buffer size as a power of 2.
744 The final size is affected by LOG_CP 632 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
745 parameter, see below. Any higher siz 633 parameter, see below. Any higher size also might be forced
746 by "log_buf_len" boot parameter. 634 by "log_buf_len" boot parameter.
747 635
748 Examples: 636 Examples:
749 17 => 128 KB 637 17 => 128 KB
750 16 => 64 KB 638 16 => 64 KB
751 15 => 32 KB 639 15 => 32 KB
752 14 => 16 KB 640 14 => 16 KB
753 13 => 8 KB 641 13 => 8 KB
754 12 => 4 KB 642 12 => 4 KB
755 643
756 config LOG_CPU_MAX_BUF_SHIFT 644 config LOG_CPU_MAX_BUF_SHIFT
757 int "CPU kernel log buffer size contri 645 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
758 depends on SMP 646 depends on SMP
759 range 0 21 647 range 0 21
>> 648 default 12 if !BASE_SMALL
760 default 0 if BASE_SMALL 649 default 0 if BASE_SMALL
761 default 12 <<
762 depends on PRINTK 650 depends on PRINTK
763 help 651 help
764 This option allows to increase the d 652 This option allows to increase the default ring buffer size
765 according to the number of CPUs. The 653 according to the number of CPUs. The value defines the contribution
766 of each CPU as a power of 2. The use 654 of each CPU as a power of 2. The used space is typically only few
767 lines however it might be much more 655 lines however it might be much more when problems are reported,
768 e.g. backtraces. 656 e.g. backtraces.
769 657
770 The increased size means that a new 658 The increased size means that a new buffer has to be allocated and
771 the original static one is unused. I 659 the original static one is unused. It makes sense only on systems
772 with more CPUs. Therefore this value 660 with more CPUs. Therefore this value is used only when the sum of
773 contributions is greater than the ha 661 contributions is greater than the half of the default kernel ring
774 buffer as defined by LOG_BUF_SHIFT. 662 buffer as defined by LOG_BUF_SHIFT. The default values are set
775 so that more than 16 CPUs are needed !! 663 so that more than 64 CPUs are needed to trigger the allocation.
776 664
777 Also this option is ignored when "lo 665 Also this option is ignored when "log_buf_len" kernel parameter is
778 used as it forces an exact (power of 666 used as it forces an exact (power of two) size of the ring buffer.
779 667
780 The number of possible CPUs is used 668 The number of possible CPUs is used for this computation ignoring
781 hotplugging making the computation o 669 hotplugging making the computation optimal for the worst case
782 scenario while allowing a simple alg 670 scenario while allowing a simple algorithm to be used from bootup.
783 671
784 Examples shift values and their mean 672 Examples shift values and their meaning:
785 17 => 128 KB for each CPU 673 17 => 128 KB for each CPU
786 16 => 64 KB for each CPU 674 16 => 64 KB for each CPU
787 15 => 32 KB for each CPU 675 15 => 32 KB for each CPU
788 14 => 16 KB for each CPU 676 14 => 16 KB for each CPU
789 13 => 8 KB for each CPU 677 13 => 8 KB for each CPU
790 12 => 4 KB for each CPU 678 12 => 4 KB for each CPU
791 679
792 config PRINTK_INDEX !! 680 config PRINTK_SAFE_LOG_BUF_SHIFT
793 bool "Printk indexing debugfs interfac !! 681 int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
794 depends on PRINTK && DEBUG_FS !! 682 range 10 21
795 help !! 683 default 13
796 Add support for indexing of all prin !! 684 depends on PRINTK
797 at <debugfs>/printk/index/<module>. !! 685 help
798 !! 686 Select the size of an alternate printk per-CPU buffer where messages
799 This can be used as part of maintain !! 687 printed from usafe contexts are temporary stored. One example would
800 /dev/kmsg, as it permits auditing th !! 688 be NMI messages, another one - printk recursion. The messages are
801 kernel, allowing detection of cases !! 689 copied to the main log buffer in a safe context to avoid a deadlock.
802 changed or no longer present. !! 690 The value defines the size as a power of 2.
>> 691
>> 692 Those messages are rare and limited. The largest one is when
>> 693 a backtrace is printed. It usually fits into 4KB. Select
>> 694 8KB if you want to be on the safe side.
803 695
804 There is no additional runtime cost !! 696 Examples:
>> 697 17 => 128 KB for each CPU
>> 698 16 => 64 KB for each CPU
>> 699 15 => 32 KB for each CPU
>> 700 14 => 16 KB for each CPU
>> 701 13 => 8 KB for each CPU
>> 702 12 => 4 KB for each CPU
805 703
806 # 704 #
807 # Architectures with an unreliable sched_clock 705 # Architectures with an unreliable sched_clock() should select this:
808 # 706 #
809 config HAVE_UNSTABLE_SCHED_CLOCK 707 config HAVE_UNSTABLE_SCHED_CLOCK
810 bool 708 bool
811 709
812 config GENERIC_SCHED_CLOCK 710 config GENERIC_SCHED_CLOCK
813 bool 711 bool
814 712
815 menu "Scheduler features" 713 menu "Scheduler features"
816 714
817 config UCLAMP_TASK 715 config UCLAMP_TASK
818 bool "Enable utilization clamping for 716 bool "Enable utilization clamping for RT/FAIR tasks"
819 depends on CPU_FREQ_GOV_SCHEDUTIL 717 depends on CPU_FREQ_GOV_SCHEDUTIL
820 help 718 help
821 This feature enables the scheduler t 719 This feature enables the scheduler to track the clamped utilization
822 of each CPU based on RUNNABLE tasks 720 of each CPU based on RUNNABLE tasks scheduled on that CPU.
823 721
824 With this option, the user can speci 722 With this option, the user can specify the min and max CPU
825 utilization allowed for RUNNABLE tas 723 utilization allowed for RUNNABLE tasks. The max utilization defines
826 the maximum frequency a task should 724 the maximum frequency a task should use while the min utilization
827 defines the minimum frequency it sho 725 defines the minimum frequency it should use.
828 726
829 Both min and max utilization clamp v 727 Both min and max utilization clamp values are hints to the scheduler,
830 aiming at improving its frequency se 728 aiming at improving its frequency selection policy, but they do not
831 enforce or grant any specific bandwi 729 enforce or grant any specific bandwidth for tasks.
832 730
833 If in doubt, say N. 731 If in doubt, say N.
834 732
835 config UCLAMP_BUCKETS_COUNT 733 config UCLAMP_BUCKETS_COUNT
836 int "Number of supported utilization c 734 int "Number of supported utilization clamp buckets"
837 range 5 20 735 range 5 20
838 default 5 736 default 5
839 depends on UCLAMP_TASK 737 depends on UCLAMP_TASK
840 help 738 help
841 Defines the number of clamp buckets 739 Defines the number of clamp buckets to use. The range of each bucket
842 will be SCHED_CAPACITY_SCALE/UCLAMP_ 740 will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
843 number of clamp buckets the finer th 741 number of clamp buckets the finer their granularity and the higher
844 the precision of clamping aggregatio 742 the precision of clamping aggregation and tracking at run-time.
845 743
846 For example, with the minimum config 744 For example, with the minimum configuration value we will have 5
847 clamp buckets tracking 20% utilizati 745 clamp buckets tracking 20% utilization each. A 25% boosted tasks will
848 be refcounted in the [20..39]% bucke 746 be refcounted in the [20..39]% bucket and will set the bucket clamp
849 effective value to 25%. 747 effective value to 25%.
850 If a second 30% boosted task should 748 If a second 30% boosted task should be co-scheduled on the same CPU,
851 that task will be refcounted in the 749 that task will be refcounted in the same bucket of the first task and
852 it will boost the bucket clamp effec 750 it will boost the bucket clamp effective value to 30%.
853 The clamp effective value of a bucke 751 The clamp effective value of a bucket is reset to its nominal value
854 (20% in the example above) when ther 752 (20% in the example above) when there are no more tasks refcounted in
855 that bucket. 753 that bucket.
856 754
857 An additional boost/capping margin c 755 An additional boost/capping margin can be added to some tasks. In the
858 example above the 25% task will be b 756 example above the 25% task will be boosted to 30% until it exits the
859 CPU. If that should be considered no 757 CPU. If that should be considered not acceptable on certain systems,
860 it's always possible to reduce the m 758 it's always possible to reduce the margin by increasing the number of
861 clamp buckets to trade off used memo 759 clamp buckets to trade off used memory for run-time tracking
862 precision. 760 precision.
863 761
864 If in doubt, use the default value. 762 If in doubt, use the default value.
865 763
866 endmenu 764 endmenu
867 765
868 # 766 #
869 # For architectures that want to enable the su 767 # For architectures that want to enable the support for NUMA-affine scheduler
870 # balancing logic: 768 # balancing logic:
871 # 769 #
872 config ARCH_SUPPORTS_NUMA_BALANCING 770 config ARCH_SUPPORTS_NUMA_BALANCING
873 bool 771 bool
874 772
875 # 773 #
876 # For architectures that prefer to flush all T 774 # For architectures that prefer to flush all TLBs after a number of pages
877 # are unmapped instead of sending one IPI per 775 # are unmapped instead of sending one IPI per page to flush. The architecture
878 # must provide guarantees on what happens if a 776 # must provide guarantees on what happens if a clean TLB cache entry is
879 # written after the unmap. Details are in mm/r 777 # written after the unmap. Details are in mm/rmap.c near the check for
880 # should_defer_flush. The architecture should 778 # should_defer_flush. The architecture should also consider if the full flush
881 # and the refill costs are offset by the savin 779 # and the refill costs are offset by the savings of sending fewer IPIs.
882 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 780 config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
883 bool 781 bool
884 782
885 config CC_HAS_INT128 <<
886 def_bool !$(cc-option,$(m64-flag) -D__ <<
887 <<
888 config CC_IMPLICIT_FALLTHROUGH <<
889 string <<
890 default "-Wimplicit-fallthrough=5" if <<
891 default "-Wimplicit-fallthrough" if CC <<
892 <<
893 # Currently, disable gcc-10+ array-bounds glob <<
894 # It's still broken in gcc-13, so no upper bou <<
895 config GCC10_NO_ARRAY_BOUNDS <<
896 def_bool y <<
897 <<
898 config CC_NO_ARRAY_BOUNDS <<
899 bool <<
900 default y if CC_IS_GCC && GCC_VERSION <<
901 <<
902 # Currently, disable -Wstringop-overflow for G <<
903 config GCC_NO_STRINGOP_OVERFLOW <<
904 def_bool y <<
905 <<
906 config CC_NO_STRINGOP_OVERFLOW <<
907 bool <<
908 default y if CC_IS_GCC && GCC_NO_STRIN <<
909 <<
910 config CC_STRINGOP_OVERFLOW <<
911 bool <<
912 default y if CC_IS_GCC && !CC_NO_STRIN <<
913 <<
914 # 783 #
915 # For architectures that know their GCC __int1 784 # For architectures that know their GCC __int128 support is sound
916 # 785 #
917 config ARCH_SUPPORTS_INT128 786 config ARCH_SUPPORTS_INT128
918 bool 787 bool
919 788
920 # For architectures that (ab)use NUMA to repre 789 # For architectures that (ab)use NUMA to represent different memory regions
921 # all cpu-local but of different latencies, su 790 # all cpu-local but of different latencies, such as SuperH.
922 # 791 #
923 config ARCH_WANT_NUMA_VARIABLE_LOCALITY 792 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
924 bool 793 bool
925 794
926 config NUMA_BALANCING 795 config NUMA_BALANCING
927 bool "Memory placement aware NUMA sche 796 bool "Memory placement aware NUMA scheduler"
928 depends on ARCH_SUPPORTS_NUMA_BALANCIN 797 depends on ARCH_SUPPORTS_NUMA_BALANCING
929 depends on !ARCH_WANT_NUMA_VARIABLE_LO 798 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
930 depends on SMP && NUMA && MIGRATION && !! 799 depends on SMP && NUMA && MIGRATION
931 help 800 help
932 This option adds support for automat 801 This option adds support for automatic NUMA aware memory/task placement.
933 The mechanism is quite primitive and 802 The mechanism is quite primitive and is based on migrating memory when
934 it has references to the node the ta 803 it has references to the node the task is running on.
935 804
936 This system will be inactive on UMA 805 This system will be inactive on UMA systems.
937 806
938 config NUMA_BALANCING_DEFAULT_ENABLED 807 config NUMA_BALANCING_DEFAULT_ENABLED
939 bool "Automatically enable NUMA aware 808 bool "Automatically enable NUMA aware memory/task placement"
940 default y 809 default y
941 depends on NUMA_BALANCING 810 depends on NUMA_BALANCING
942 help 811 help
943 If set, automatic NUMA balancing wil 812 If set, automatic NUMA balancing will be enabled if running on a NUMA
944 machine. 813 machine.
945 814
946 config SLAB_OBJ_EXT <<
947 bool <<
948 <<
949 menuconfig CGROUPS 815 menuconfig CGROUPS
950 bool "Control Group support" 816 bool "Control Group support"
951 select KERNFS 817 select KERNFS
952 help 818 help
953 This option adds support for groupin 819 This option adds support for grouping sets of processes together, for
954 use with process control subsystems 820 use with process control subsystems such as Cpusets, CFS, memory
955 controls or device isolation. 821 controls or device isolation.
956 See 822 See
957 - Documentation/scheduler/sche 823 - Documentation/scheduler/sched-design-CFS.rst (CFS)
958 - Documentation/admin-guide/cg 824 - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
959 and 825 and resource control)
960 826
961 Say N if unsure. 827 Say N if unsure.
962 828
963 if CGROUPS 829 if CGROUPS
964 830
965 config PAGE_COUNTER 831 config PAGE_COUNTER
966 bool !! 832 bool
967 <<
968 config CGROUP_FAVOR_DYNMODS <<
969 bool "Favor dynamic modification laten <<
970 help <<
971 This option enables the "favordynmod <<
972 which reduces the latencies of dynam <<
973 as task migrations and controller on <<
974 hot path operations such as forks an <<
975 <<
976 Say N if unsure. <<
977 833
978 config MEMCG 834 config MEMCG
979 bool "Memory controller" 835 bool "Memory controller"
980 select PAGE_COUNTER 836 select PAGE_COUNTER
981 select EVENTFD 837 select EVENTFD
982 select SLAB_OBJ_EXT <<
983 help 838 help
984 Provides control over the memory foo 839 Provides control over the memory footprint of tasks in a cgroup.
985 840
986 config MEMCG_V1 !! 841 config MEMCG_SWAP
987 bool "Legacy cgroup v1 memory controll !! 842 bool "Swap controller"
988 depends on MEMCG !! 843 depends on MEMCG && SWAP
989 default n <<
990 help 844 help
991 Legacy cgroup v1 memory controller w !! 845 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 846
1001 Say N if unsure. !! 847 config MEMCG_SWAP_ENABLED
>> 848 bool "Swap controller enabled by default"
>> 849 depends on MEMCG_SWAP
>> 850 default y
>> 851 help
>> 852 Memory Resource Controller Swap Extension comes with its price in
>> 853 a bigger memory consumption. General purpose distribution kernels
>> 854 which want to enable the feature but keep it disabled by default
>> 855 and let the user enable it by swapaccount=1 boot command line
>> 856 parameter should have this option unselected.
>> 857 For those who want to have the feature enabled by default should
>> 858 select this option (if, for some reason, they need to disable it
>> 859 then swapaccount=0 does the trick).
>> 860
>> 861 config MEMCG_KMEM
>> 862 bool
>> 863 depends on MEMCG && !SLOB
>> 864 default y
1002 865
1003 config BLK_CGROUP 866 config BLK_CGROUP
1004 bool "IO controller" 867 bool "IO controller"
1005 depends on BLOCK 868 depends on BLOCK
1006 default n 869 default n
1007 help !! 870 ---help---
1008 Generic block IO controller cgroup in 871 Generic block IO controller cgroup interface. This is the common
1009 cgroup interface which should be used 872 cgroup interface which should be used by various IO controlling
1010 policies. 873 policies.
1011 874
1012 Currently, CFQ IO scheduler uses it t 875 Currently, CFQ IO scheduler uses it to recognize task groups and
1013 control disk bandwidth allocation (pr 876 control disk bandwidth allocation (proportional time slice allocation)
1014 to such task groups. It is also used 877 to such task groups. It is also used by bio throttling logic in
1015 block layer to implement upper limit 878 block layer to implement upper limit in IO rates on a device.
1016 879
1017 This option only enables generic Bloc 880 This option only enables generic Block IO controller infrastructure.
1018 One needs to also enable actual IO co 881 One needs to also enable actual IO controlling logic/policy. For
1019 enabling proportional weight division 882 enabling proportional weight division of disk bandwidth in CFQ, set
1020 CONFIG_BFQ_GROUP_IOSCHED=y; for enabl !! 883 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1021 CONFIG_BLK_DEV_THROTTLING=y. 884 CONFIG_BLK_DEV_THROTTLING=y.
1022 885
1023 See Documentation/admin-guide/cgroup- 886 See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
1024 887
1025 config CGROUP_WRITEBACK 888 config CGROUP_WRITEBACK
1026 bool 889 bool
1027 depends on MEMCG && BLK_CGROUP 890 depends on MEMCG && BLK_CGROUP
1028 default y 891 default y
1029 892
1030 menuconfig CGROUP_SCHED 893 menuconfig CGROUP_SCHED
1031 bool "CPU controller" 894 bool "CPU controller"
1032 default n 895 default n
1033 help 896 help
1034 This feature lets CPU scheduler rec 897 This feature lets CPU scheduler recognize task groups and control CPU
1035 bandwidth allocation to such task g 898 bandwidth allocation to such task groups. It uses cgroups to group
1036 tasks. 899 tasks.
1037 900
1038 if CGROUP_SCHED 901 if CGROUP_SCHED
1039 config GROUP_SCHED_WEIGHT <<
1040 def_bool n <<
1041 <<
1042 config FAIR_GROUP_SCHED 902 config FAIR_GROUP_SCHED
1043 bool "Group scheduling for SCHED_OTHE 903 bool "Group scheduling for SCHED_OTHER"
1044 depends on CGROUP_SCHED 904 depends on CGROUP_SCHED
1045 select GROUP_SCHED_WEIGHT <<
1046 default CGROUP_SCHED 905 default CGROUP_SCHED
1047 906
1048 config CFS_BANDWIDTH 907 config CFS_BANDWIDTH
1049 bool "CPU bandwidth provisioning for 908 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
1050 depends on FAIR_GROUP_SCHED 909 depends on FAIR_GROUP_SCHED
1051 default n 910 default n
1052 help 911 help
1053 This option allows users to define 912 This option allows users to define CPU bandwidth rates (limits) for
1054 tasks running within the fair group 913 tasks running within the fair group scheduler. Groups with no limit
1055 set are considered to be unconstrai 914 set are considered to be unconstrained and will run with no
1056 restriction. 915 restriction.
1057 See Documentation/scheduler/sched-b 916 See Documentation/scheduler/sched-bwc.rst for more information.
1058 917
1059 config RT_GROUP_SCHED 918 config RT_GROUP_SCHED
1060 bool "Group scheduling for SCHED_RR/F 919 bool "Group scheduling for SCHED_RR/FIFO"
1061 depends on CGROUP_SCHED 920 depends on CGROUP_SCHED
1062 default n 921 default n
1063 help 922 help
1064 This feature lets you explicitly al 923 This feature lets you explicitly allocate real CPU bandwidth
1065 to task groups. If enabled, it will 924 to task groups. If enabled, it will also make it impossible to
1066 schedule realtime tasks for non-roo 925 schedule realtime tasks for non-root users until you allocate
1067 realtime bandwidth for them. 926 realtime bandwidth for them.
1068 See Documentation/scheduler/sched-r 927 See Documentation/scheduler/sched-rt-group.rst for more information.
1069 928
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 929 endif #CGROUP_SCHED
1077 930
1078 config SCHED_MM_CID <<
1079 def_bool y <<
1080 depends on SMP && RSEQ <<
1081 <<
1082 config UCLAMP_TASK_GROUP <<
1083 bool "Utilization clamping per group <<
1084 depends on CGROUP_SCHED <<
1085 depends on UCLAMP_TASK <<
1086 default n <<
1087 help <<
1088 This feature enables the scheduler <<
1089 of each CPU based on RUNNABLE tasks <<
1090 <<
1091 When this option is enabled, the us <<
1092 CPU bandwidth which is allowed for <<
1093 The max bandwidth allows to clamp t <<
1094 can use, while the min bandwidth al <<
1095 frequency a task will always use. <<
1096 <<
1097 When task group based utilization c <<
1098 specified task-specific clamp value <<
1099 specified clamp value. Both minimum <<
1100 be bigger than the corresponding cl <<
1101 <<
1102 If in doubt, say N. <<
1103 <<
1104 config CGROUP_PIDS 931 config CGROUP_PIDS
1105 bool "PIDs controller" 932 bool "PIDs controller"
1106 help 933 help
1107 Provides enforcement of process num 934 Provides enforcement of process number limits in the scope of a
1108 cgroup. Any attempt to fork more pr 935 cgroup. Any attempt to fork more processes than is allowed in the
1109 cgroup will fail. PIDs are fundamen 936 cgroup will fail. PIDs are fundamentally a global resource because it
1110 is fairly trivial to reach PID exha 937 is fairly trivial to reach PID exhaustion before you reach even a
1111 conservative kmemcg limit. As a res 938 conservative kmemcg limit. As a result, it is possible to grind a
1112 system to halt without being limite 939 system to halt without being limited by other cgroup policies. The
1113 PIDs controller is designed to stop 940 PIDs controller is designed to stop this from happening.
1114 941
1115 It should be noted that organisatio 942 It should be noted that organisational operations (such as attaching
1116 to a cgroup hierarchy) will *not* b 943 to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
1117 since the PIDs limit only affects a 944 since the PIDs limit only affects a process's ability to fork, not to
1118 attach to a cgroup. 945 attach to a cgroup.
1119 946
1120 config CGROUP_RDMA 947 config CGROUP_RDMA
1121 bool "RDMA controller" 948 bool "RDMA controller"
1122 help 949 help
1123 Provides enforcement of RDMA resour 950 Provides enforcement of RDMA resources defined by IB stack.
1124 It is fairly easy for consumers to 951 It is fairly easy for consumers to exhaust RDMA resources, which
1125 can result into resource unavailabi 952 can result into resource unavailability to other consumers.
1126 RDMA controller is designed to stop 953 RDMA controller is designed to stop this from happening.
1127 Attaching processes with active RDM 954 Attaching processes with active RDMA resources to the cgroup
1128 hierarchy is allowed even if can cr 955 hierarchy is allowed even if can cross the hierarchy's limit.
1129 956
1130 config CGROUP_FREEZER 957 config CGROUP_FREEZER
1131 bool "Freezer controller" 958 bool "Freezer controller"
1132 help 959 help
1133 Provides a way to freeze and unfree 960 Provides a way to freeze and unfreeze all tasks in a
1134 cgroup. 961 cgroup.
1135 962
1136 This option affects the ORIGINAL cg 963 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1137 controller includes important in-ke 964 controller includes important in-kernel memory consumers per default.
1138 965
1139 If you're using cgroup2, say N. 966 If you're using cgroup2, say N.
1140 967
1141 config CGROUP_HUGETLB 968 config CGROUP_HUGETLB
1142 bool "HugeTLB controller" 969 bool "HugeTLB controller"
1143 depends on HUGETLB_PAGE 970 depends on HUGETLB_PAGE
1144 select PAGE_COUNTER 971 select PAGE_COUNTER
1145 default n 972 default n
1146 help 973 help
1147 Provides a cgroup controller for Hu 974 Provides a cgroup controller for HugeTLB pages.
1148 When you enable this, you can put a 975 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1149 The limit is enforced during page f 976 The limit is enforced during page fault. Since HugeTLB doesn't
1150 support page reclaim, enforcing the 977 support page reclaim, enforcing the limit at page fault time implies
1151 that, the application will get SIGB 978 that, the application will get SIGBUS signal if it tries to access
1152 HugeTLB pages beyond its limit. Thi 979 HugeTLB pages beyond its limit. This requires the application to know
1153 beforehand how much HugeTLB pages i 980 beforehand how much HugeTLB pages it would require for its use. The
1154 control group is tracked in the thi 981 control group is tracked in the third page lru pointer. This means
1155 that we cannot use the controller w 982 that we cannot use the controller with huge page less than 3 pages.
1156 983
1157 config CPUSETS 984 config CPUSETS
1158 bool "Cpuset controller" 985 bool "Cpuset controller"
1159 depends on SMP 986 depends on SMP
1160 help 987 help
1161 This option will let you create and 988 This option will let you create and manage CPUSETs which
1162 allow dynamically partitioning a sy 989 allow dynamically partitioning a system into sets of CPUs and
1163 Memory Nodes and assigning tasks to 990 Memory Nodes and assigning tasks to run only within those sets.
1164 This is primarily useful on large S 991 This is primarily useful on large SMP or NUMA systems.
1165 992
1166 Say N if unsure. 993 Say N if unsure.
1167 994
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 995 config PROC_PID_CPUSET
1182 bool "Include legacy /proc/<pid>/cpus 996 bool "Include legacy /proc/<pid>/cpuset file"
1183 depends on CPUSETS 997 depends on CPUSETS
1184 default y 998 default y
1185 999
1186 config CGROUP_DEVICE 1000 config CGROUP_DEVICE
1187 bool "Device controller" 1001 bool "Device controller"
1188 help 1002 help
1189 Provides a cgroup controller implem 1003 Provides a cgroup controller implementing whitelists for
1190 devices which a process in the cgro 1004 devices which a process in the cgroup can mknod or open.
1191 1005
1192 config CGROUP_CPUACCT 1006 config CGROUP_CPUACCT
1193 bool "Simple CPU accounting controlle 1007 bool "Simple CPU accounting controller"
1194 help 1008 help
1195 Provides a simple controller for mo 1009 Provides a simple controller for monitoring the
1196 total CPU consumed by the tasks in 1010 total CPU consumed by the tasks in a cgroup.
1197 1011
1198 config CGROUP_PERF 1012 config CGROUP_PERF
1199 bool "Perf controller" 1013 bool "Perf controller"
1200 depends on PERF_EVENTS 1014 depends on PERF_EVENTS
1201 help 1015 help
1202 This option extends the perf per-cp 1016 This option extends the perf per-cpu mode to restrict monitoring
1203 to threads which belong to the cgro 1017 to threads which belong to the cgroup specified and run on the
1204 designated cpu. Or this can be use !! 1018 designated cpu.
1205 so that it can monitor performance <<
1206 1019
1207 Say N if unsure. 1020 Say N if unsure.
1208 1021
1209 config CGROUP_BPF 1022 config CGROUP_BPF
1210 bool "Support for eBPF programs attac 1023 bool "Support for eBPF programs attached to cgroups"
1211 depends on BPF_SYSCALL 1024 depends on BPF_SYSCALL
1212 select SOCK_CGROUP_DATA 1025 select SOCK_CGROUP_DATA
1213 help 1026 help
1214 Allow attaching eBPF programs to a 1027 Allow attaching eBPF programs to a cgroup using the bpf(2)
1215 syscall command BPF_PROG_ATTACH. 1028 syscall command BPF_PROG_ATTACH.
1216 1029
1217 In which context these programs are 1030 In which context these programs are accessed depends on the type
1218 of attachment. For instance, progra 1031 of attachment. For instance, programs that are attached using
1219 BPF_CGROUP_INET_INGRESS will be exe 1032 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1220 inet sockets. 1033 inet sockets.
1221 1034
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 1035 config CGROUP_DEBUG
1237 bool "Debug controller" 1036 bool "Debug controller"
1238 default n 1037 default n
1239 depends on DEBUG_KERNEL 1038 depends on DEBUG_KERNEL
1240 help 1039 help
1241 This option enables a simple contro 1040 This option enables a simple controller that exports
1242 debugging information about the cgr 1041 debugging information about the cgroups framework. This
1243 controller is for control cgroup de 1042 controller is for control cgroup debugging only. Its
1244 interfaces are not stable. 1043 interfaces are not stable.
1245 1044
1246 Say N. 1045 Say N.
1247 1046
1248 config SOCK_CGROUP_DATA 1047 config SOCK_CGROUP_DATA
1249 bool 1048 bool
1250 default n 1049 default n
1251 1050
1252 endif # CGROUPS 1051 endif # CGROUPS
1253 1052
1254 menuconfig NAMESPACES 1053 menuconfig NAMESPACES
1255 bool "Namespaces support" if EXPERT 1054 bool "Namespaces support" if EXPERT
1256 depends on MULTIUSER 1055 depends on MULTIUSER
1257 default !EXPERT 1056 default !EXPERT
1258 help 1057 help
1259 Provides the way to make tasks work 1058 Provides the way to make tasks work with different objects using
1260 the same id. For example same IPC i 1059 the same id. For example same IPC id may refer to different objects
1261 or same user id or pid may refer to 1060 or same user id or pid may refer to different tasks when used in
1262 different namespaces. 1061 different namespaces.
1263 1062
1264 if NAMESPACES 1063 if NAMESPACES
1265 1064
1266 config UTS_NS 1065 config UTS_NS
1267 bool "UTS namespace" 1066 bool "UTS namespace"
1268 default y 1067 default y
1269 help 1068 help
1270 In this namespace tasks see differe 1069 In this namespace tasks see different info provided with the
1271 uname() system call 1070 uname() system call
1272 1071
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 1072 config IPC_NS
1282 bool "IPC namespace" 1073 bool "IPC namespace"
1283 depends on (SYSVIPC || POSIX_MQUEUE) 1074 depends on (SYSVIPC || POSIX_MQUEUE)
1284 default y 1075 default y
1285 help 1076 help
1286 In this namespace tasks work with I 1077 In this namespace tasks work with IPC ids which correspond to
1287 different IPC objects in different 1078 different IPC objects in different namespaces.
1288 1079
1289 config USER_NS 1080 config USER_NS
1290 bool "User namespace" 1081 bool "User namespace"
1291 default n 1082 default n
1292 help 1083 help
1293 This allows containers, i.e. vserve 1084 This allows containers, i.e. vservers, to use user namespaces
1294 to provide different user info for 1085 to provide different user info for different servers.
1295 1086
1296 When user namespaces are enabled in 1087 When user namespaces are enabled in the kernel it is
1297 recommended that the MEMCG option a 1088 recommended that the MEMCG option also be enabled and that
1298 user-space use the memory control g 1089 user-space use the memory control groups to limit the amount
1299 of memory a memory unprivileged use 1090 of memory a memory unprivileged users can use.
1300 1091
1301 If unsure, say N. 1092 If unsure, say N.
1302 1093
1303 config PID_NS 1094 config PID_NS
1304 bool "PID Namespaces" 1095 bool "PID Namespaces"
1305 default y 1096 default y
1306 help 1097 help
1307 Support process id namespaces. Thi 1098 Support process id namespaces. This allows having multiple
1308 processes with the same pid as long 1099 processes with the same pid as long as they are in different
1309 pid namespaces. This is a building 1100 pid namespaces. This is a building block of containers.
1310 1101
1311 config NET_NS 1102 config NET_NS
1312 bool "Network namespace" 1103 bool "Network namespace"
1313 depends on NET 1104 depends on NET
1314 default y 1105 default y
1315 help 1106 help
1316 Allow user space to create what app 1107 Allow user space to create what appear to be multiple instances
1317 of the network stack. 1108 of the network stack.
1318 1109
1319 endif # NAMESPACES 1110 endif # NAMESPACES
1320 1111
1321 config CHECKPOINT_RESTORE 1112 config CHECKPOINT_RESTORE
1322 bool "Checkpoint/restore support" 1113 bool "Checkpoint/restore support"
1323 depends on PROC_FS <<
1324 select PROC_CHILDREN 1114 select PROC_CHILDREN
1325 select KCMP <<
1326 default n 1115 default n
1327 help 1116 help
1328 Enables additional kernel features 1117 Enables additional kernel features in a sake of checkpoint/restore.
1329 In particular it adds auxiliary prc 1118 In particular it adds auxiliary prctl codes to setup process text,
1330 data and heap segment sizes, and a 1119 data and heap segment sizes, and a few additional /proc filesystem
1331 entries. 1120 entries.
1332 1121
1333 If unsure, say N here. 1122 If unsure, say N here.
1334 1123
1335 config SCHED_AUTOGROUP 1124 config SCHED_AUTOGROUP
1336 bool "Automatic process group schedul 1125 bool "Automatic process group scheduling"
1337 select CGROUPS 1126 select CGROUPS
1338 select CGROUP_SCHED 1127 select CGROUP_SCHED
1339 select FAIR_GROUP_SCHED 1128 select FAIR_GROUP_SCHED
1340 help 1129 help
1341 This option optimizes the scheduler 1130 This option optimizes the scheduler for common desktop workloads by
1342 automatically creating and populati 1131 automatically creating and populating task groups. This separation
1343 of workloads isolates aggressive CP 1132 of workloads isolates aggressive CPU burners (like build jobs) from
1344 desktop applications. Task group a 1133 desktop applications. Task group autogeneration is currently based
1345 upon task session. 1134 upon task session.
1346 1135
>> 1136 config SYSFS_DEPRECATED
>> 1137 bool "Enable deprecated sysfs features to support old userspace tools"
>> 1138 depends on SYSFS
>> 1139 default n
>> 1140 help
>> 1141 This option adds code that switches the layout of the "block" class
>> 1142 devices, to not show up in /sys/class/block/, but only in
>> 1143 /sys/block/.
>> 1144
>> 1145 This switch is only active when the sysfs.deprecated=1 boot option is
>> 1146 passed or the SYSFS_DEPRECATED_V2 option is set.
>> 1147
>> 1148 This option allows new kernels to run on old distributions and tools,
>> 1149 which might get confused by /sys/class/block/. Since 2007/2008 all
>> 1150 major distributions and tools handle this just fine.
>> 1151
>> 1152 Recent distributions and userspace tools after 2009/2010 depend on
>> 1153 the existence of /sys/class/block/, and will not work with this
>> 1154 option enabled.
>> 1155
>> 1156 Only if you are using a new kernel on an old distribution, you might
>> 1157 need to say Y here.
>> 1158
>> 1159 config SYSFS_DEPRECATED_V2
>> 1160 bool "Enable deprecated sysfs features by default"
>> 1161 default n
>> 1162 depends on SYSFS
>> 1163 depends on SYSFS_DEPRECATED
>> 1164 help
>> 1165 Enable deprecated sysfs by default.
>> 1166
>> 1167 See the CONFIG_SYSFS_DEPRECATED option for more details about this
>> 1168 option.
>> 1169
>> 1170 Only if you are using a new kernel on an old distribution, you might
>> 1171 need to say Y here. Even then, odds are you would not need it
>> 1172 enabled, you can always pass the boot option if absolutely necessary.
>> 1173
1347 config RELAY 1174 config RELAY
1348 bool "Kernel->user space relay suppor 1175 bool "Kernel->user space relay support (formerly relayfs)"
1349 select IRQ_WORK 1176 select IRQ_WORK
1350 help 1177 help
1351 This option enables support for rel 1178 This option enables support for relay interface support in
1352 certain file systems (such as debug 1179 certain file systems (such as debugfs).
1353 It is designed to provide an effici 1180 It is designed to provide an efficient mechanism for tools and
1354 facilities to relay large amounts o 1181 facilities to relay large amounts of data from kernel space to
1355 user space. 1182 user space.
1356 1183
1357 If unsure, say N. 1184 If unsure, say N.
1358 1185
1359 config BLK_DEV_INITRD 1186 config BLK_DEV_INITRD
1360 bool "Initial RAM filesystem and RAM 1187 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1361 help 1188 help
1362 The initial RAM filesystem is a ram 1189 The initial RAM filesystem is a ramfs which is loaded by the
1363 boot loader (loadlin or lilo) and t 1190 boot loader (loadlin or lilo) and that is mounted as root
1364 before the normal boot procedure. I 1191 before the normal boot procedure. It is typically used to
1365 load modules needed to mount the "r 1192 load modules needed to mount the "real" root file system,
1366 etc. See <file:Documentation/admin- 1193 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1367 1194
1368 If RAM disk support (BLK_DEV_RAM) i 1195 If RAM disk support (BLK_DEV_RAM) is also included, this
1369 also enables initial RAM disk (init 1196 also enables initial RAM disk (initrd) support and adds
1370 15 Kbytes (more on some other archi 1197 15 Kbytes (more on some other architectures) to the kernel size.
1371 1198
1372 If unsure say Y. 1199 If unsure say Y.
1373 1200
1374 if BLK_DEV_INITRD 1201 if BLK_DEV_INITRD
1375 1202
1376 source "usr/Kconfig" 1203 source "usr/Kconfig"
1377 1204
1378 endif 1205 endif
1379 1206
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 1207 choice
1435 prompt "Compiler optimization level" 1208 prompt "Compiler optimization level"
1436 default CC_OPTIMIZE_FOR_PERFORMANCE 1209 default CC_OPTIMIZE_FOR_PERFORMANCE
1437 1210
1438 config CC_OPTIMIZE_FOR_PERFORMANCE 1211 config CC_OPTIMIZE_FOR_PERFORMANCE
1439 bool "Optimize for performance (-O2)" !! 1212 bool "Optimize for performance"
1440 help 1213 help
1441 This is the default optimization le 1214 This is the default optimization level for the kernel, building
1442 with the "-O2" compiler flag for be 1215 with the "-O2" compiler flag for best performance and most
1443 helpful compile-time warnings. 1216 helpful compile-time warnings.
1444 1217
1445 config CC_OPTIMIZE_FOR_SIZE 1218 config CC_OPTIMIZE_FOR_SIZE
1446 bool "Optimize for size (-Os)" !! 1219 bool "Optimize for size"
>> 1220 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
1447 help 1221 help
1448 Choosing this option will pass "-Os !! 1222 Enabling this option will pass "-Os" instead of "-O2" to
1449 in a smaller kernel. !! 1223 your compiler resulting in a smaller kernel.
>> 1224
>> 1225 If unsure, say N.
1450 1226
1451 endchoice 1227 endchoice
1452 1228
1453 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION 1229 config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1454 bool 1230 bool
1455 help 1231 help
1456 This requires that the arch annotat 1232 This requires that the arch annotates or otherwise protects
1457 its external entry points from bein 1233 its external entry points from being discarded. Linker scripts
1458 must also merge .text.*, .data.*, a 1234 must also merge .text.*, .data.*, and .bss.* correctly into
1459 output sections. Care must be taken 1235 output sections. Care must be taken not to pull in unrelated
1460 sections (e.g., '.text.init'). Typi 1236 sections (e.g., '.text.init'). Typically '.' in section names
1461 is used to distinguish them from la 1237 is used to distinguish them from label names / C identifiers.
1462 1238
1463 config LD_DEAD_CODE_DATA_ELIMINATION 1239 config LD_DEAD_CODE_DATA_ELIMINATION
1464 bool "Dead code and data elimination 1240 bool "Dead code and data elimination (EXPERIMENTAL)"
1465 depends on HAVE_LD_DEAD_CODE_DATA_ELI 1241 depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1466 depends on EXPERT 1242 depends on EXPERT
>> 1243 depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1467 depends on $(cc-option,-ffunction-sec 1244 depends on $(cc-option,-ffunction-sections -fdata-sections)
1468 depends on $(ld-option,--gc-sections) 1245 depends on $(ld-option,--gc-sections)
1469 help 1246 help
1470 Enable this if you want to do dead 1247 Enable this if you want to do dead code and data elimination with
1471 the linker by compiling with -ffunc 1248 the linker by compiling with -ffunction-sections -fdata-sections,
1472 and linking with --gc-sections. 1249 and linking with --gc-sections.
1473 1250
1474 This can reduce on disk and in-memo 1251 This can reduce on disk and in-memory size of the kernel
1475 code and static data, particularly 1252 code and static data, particularly for small configs and
1476 on small systems. This has the poss 1253 on small systems. This has the possibility of introducing
1477 silently broken kernel if the requi 1254 silently broken kernel if the required annotations are not
1478 present. This option is not well te 1255 present. This option is not well tested yet, so use at your
1479 own risk. 1256 own risk.
1480 1257
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 1258 config SYSCTL
1494 bool 1259 bool
1495 1260
1496 config HAVE_UID16 1261 config HAVE_UID16
1497 bool 1262 bool
1498 1263
1499 config SYSCTL_EXCEPTION_TRACE 1264 config SYSCTL_EXCEPTION_TRACE
1500 bool 1265 bool
1501 help 1266 help
1502 Enable support for /proc/sys/debug/ 1267 Enable support for /proc/sys/debug/exception-trace.
1503 1268
1504 config SYSCTL_ARCH_UNALIGN_NO_WARN 1269 config SYSCTL_ARCH_UNALIGN_NO_WARN
1505 bool 1270 bool
1506 help 1271 help
1507 Enable support for /proc/sys/kernel 1272 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1508 Allows arch to define/use @no_unali 1273 Allows arch to define/use @no_unaligned_warning to possibly warn
1509 about unaligned access emulation go 1274 about unaligned access emulation going on under the hood.
1510 1275
1511 config SYSCTL_ARCH_UNALIGN_ALLOW 1276 config SYSCTL_ARCH_UNALIGN_ALLOW
1512 bool 1277 bool
1513 help 1278 help
1514 Enable support for /proc/sys/kernel 1279 Enable support for /proc/sys/kernel/unaligned-trap
1515 Allows arches to define/use @unalig 1280 Allows arches to define/use @unaligned_enabled to runtime toggle
1516 the unaligned access emulation. 1281 the unaligned access emulation.
1517 see arch/parisc/kernel/unaligned.c 1282 see arch/parisc/kernel/unaligned.c for reference
1518 1283
1519 config HAVE_PCSPKR_PLATFORM 1284 config HAVE_PCSPKR_PLATFORM
1520 bool 1285 bool
1521 1286
>> 1287 # interpreter that classic socket filters depend on
>> 1288 config BPF
>> 1289 bool
>> 1290
1522 menuconfig EXPERT 1291 menuconfig EXPERT
1523 bool "Configure standard kernel featu 1292 bool "Configure standard kernel features (expert users)"
1524 # Unhide debug options, to make the o 1293 # Unhide debug options, to make the on-by-default options visible
1525 select DEBUG_KERNEL 1294 select DEBUG_KERNEL
1526 help 1295 help
1527 This option allows certain base ker 1296 This option allows certain base kernel options and settings
1528 to be disabled or tweaked. This is !! 1297 to be disabled or tweaked. This is for specialized
1529 environments which can tolerate a " !! 1298 environments which can tolerate a "non-standard" kernel.
1530 Only use this if you really know wh !! 1299 Only use this if you really know what you are doing.
1531 1300
1532 config UID16 1301 config UID16
1533 bool "Enable 16-bit UID system calls" 1302 bool "Enable 16-bit UID system calls" if EXPERT
1534 depends on HAVE_UID16 && MULTIUSER 1303 depends on HAVE_UID16 && MULTIUSER
1535 default y 1304 default y
1536 help 1305 help
1537 This enables the legacy 16-bit UID 1306 This enables the legacy 16-bit UID syscall wrappers.
1538 1307
1539 config MULTIUSER 1308 config MULTIUSER
1540 bool "Multiple users, groups and capa 1309 bool "Multiple users, groups and capabilities support" if EXPERT
1541 default y 1310 default y
1542 help 1311 help
1543 This option enables support for non 1312 This option enables support for non-root users, groups and
1544 capabilities. 1313 capabilities.
1545 1314
1546 If you say N here, all processes wi 1315 If you say N here, all processes will run with UID 0, GID 0, and all
1547 possible capabilities. Saying N he 1316 possible capabilities. Saying N here also compiles out support for
1548 system calls related to UIDs, GIDs, 1317 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1549 setgid, and capset. 1318 setgid, and capset.
1550 1319
1551 If unsure, say Y here. 1320 If unsure, say Y here.
1552 1321
1553 config SGETMASK_SYSCALL 1322 config SGETMASK_SYSCALL
1554 bool "sgetmask/ssetmask syscalls supp 1323 bool "sgetmask/ssetmask syscalls support" if EXPERT
1555 default PARISC || M68K || PPC || MIPS !! 1324 def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1556 help !! 1325 ---help---
1557 sys_sgetmask and sys_ssetmask are o 1326 sys_sgetmask and sys_ssetmask are obsolete system calls
1558 no longer supported in libc but sti 1327 no longer supported in libc but still enabled by default in some
1559 architectures. 1328 architectures.
1560 1329
1561 If unsure, leave the default option 1330 If unsure, leave the default option here.
1562 1331
1563 config SYSFS_SYSCALL 1332 config SYSFS_SYSCALL
1564 bool "Sysfs syscall support" if EXPER 1333 bool "Sysfs syscall support" if EXPERT
1565 default y 1334 default y
1566 help !! 1335 ---help---
1567 sys_sysfs is an obsolete system cal 1336 sys_sysfs is an obsolete system call no longer supported in libc.
1568 Note that disabling this option is 1337 Note that disabling this option is more secure but might break
1569 compatibility with some systems. 1338 compatibility with some systems.
1570 1339
1571 If unsure say Y here. 1340 If unsure say Y here.
1572 1341
>> 1342 config SYSCTL_SYSCALL
>> 1343 bool "Sysctl syscall support" if EXPERT
>> 1344 depends on PROC_SYSCTL
>> 1345 default n
>> 1346 select SYSCTL
>> 1347 ---help---
>> 1348 sys_sysctl uses binary paths that have been found challenging
>> 1349 to properly maintain and use. The interface in /proc/sys
>> 1350 using paths with ascii names is now the primary path to this
>> 1351 information.
>> 1352
>> 1353 Almost nothing using the binary sysctl interface so if you are
>> 1354 trying to save some space it is probably safe to disable this,
>> 1355 making your kernel marginally smaller.
>> 1356
>> 1357 If unsure say N here.
>> 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
1718 select IO_WQ !! 1517 select ANON_INODES
1719 default y 1518 default y
1720 help 1519 help
1721 This option enables support for the 1520 This option enables support for the io_uring interface, enabling
1722 applications to submit and complete 1521 applications to submit and complete IO through submission and
1723 completion rings that are shared be 1522 completion rings that are shared between the kernel and application.
1724 1523
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 1524 config ADVISE_SYSCALLS
1739 bool "Enable madvise/fadvise syscalls 1525 bool "Enable madvise/fadvise syscalls" if EXPERT
1740 default y 1526 default y
1741 help 1527 help
1742 This option enables the madvise and 1528 This option enables the madvise and fadvise syscalls, used by
1743 applications to advise the kernel a 1529 applications to advise the kernel about their future memory or file
1744 usage, improving performance. If bu 1530 usage, improving performance. If building an embedded system where no
1745 applications use these syscalls, yo 1531 applications use these syscalls, you can disable this option to save
1746 space. 1532 space.
1747 1533
1748 config MEMBARRIER 1534 config MEMBARRIER
1749 bool "Enable membarrier() system call 1535 bool "Enable membarrier() system call" if EXPERT
1750 default y 1536 default y
1751 help 1537 help
1752 Enable the membarrier() system call 1538 Enable the membarrier() system call that allows issuing memory
1753 barriers across all running threads 1539 barriers across all running threads, which can be used to distribute
1754 the cost of user-space memory barri 1540 the cost of user-space memory barriers asymmetrically by transforming
1755 pairs of memory barriers into pairs 1541 pairs of memory barriers into pairs consisting of membarrier() and a
1756 compiler barrier. 1542 compiler barrier.
1757 1543
1758 If unsure, say Y. 1544 If unsure, say Y.
1759 1545
1760 config KCMP !! 1546 config KALLSYMS
1761 bool "Enable kcmp() system call" if E !! 1547 bool "Load all symbols for debugging/ksymoops" if EXPERT
>> 1548 default y
>> 1549 help
>> 1550 Say Y here to let the kernel print out symbolic crash information and
>> 1551 symbolic stack backtraces. This increases the size of the kernel
>> 1552 somewhat, as all symbols have to be loaded into the kernel image.
>> 1553
>> 1554 config KALLSYMS_ALL
>> 1555 bool "Include all symbols in kallsyms"
>> 1556 depends on DEBUG_KERNEL && KALLSYMS
1762 help 1557 help
1763 Enable the kernel resource comparis !! 1558 Normally kallsyms only contains the symbols of functions for nicer
1764 user-space with the ability to comp !! 1559 OOPS messages and backtraces (i.e., symbols from the text and inittext
1765 share a common resource, such as a !! 1560 sections). This is sufficient for most cases. And only in very rare
1766 memory space. !! 1561 cases (e.g., when a debugger is used) all symbols are required (e.g.,
>> 1562 names of variables from the data sections, etc).
>> 1563
>> 1564 This option makes sure that all symbols are loaded into the kernel
>> 1565 image (i.e., symbols from all sections) in cost of increased kernel
>> 1566 size (depending on the kernel configuration, it may be 300KiB or
>> 1567 something like this).
1767 1568
1768 If unsure, say N. !! 1569 Say N unless you really need all symbols.
>> 1570
>> 1571 config KALLSYMS_ABSOLUTE_PERCPU
>> 1572 bool
>> 1573 depends on KALLSYMS
>> 1574 default X86_64 && SMP
>> 1575
>> 1576 config KALLSYMS_BASE_RELATIVE
>> 1577 bool
>> 1578 depends on KALLSYMS
>> 1579 default !IA64
>> 1580 help
>> 1581 Instead of emitting them as absolute values in the native word size,
>> 1582 emit the symbol references in the kallsyms table as 32-bit entries,
>> 1583 each containing a relative value in the range [base, base + U32_MAX]
>> 1584 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
>> 1585 an absolute value in the range [0, S32_MAX] or a relative value in the
>> 1586 range [base, base + S32_MAX], where base is the lowest relative symbol
>> 1587 address encountered in the image.
>> 1588
>> 1589 On 64-bit builds, this reduces the size of the address table by 50%,
>> 1590 but more importantly, it results in entries whose values are build
>> 1591 time constants, and no relocation pass is required at runtime to fix
>> 1592 up the entries based on the runtime load address of the kernel.
>> 1593
>> 1594 # end of the "standard kernel features (expert users)" menu
>> 1595
>> 1596 # syscall, maps, verifier
>> 1597 config BPF_SYSCALL
>> 1598 bool "Enable bpf() system call"
>> 1599 select BPF
>> 1600 select IRQ_WORK
>> 1601 default n
>> 1602 help
>> 1603 Enable the bpf() system call that allows to manipulate eBPF
>> 1604 programs and maps via file descriptors.
>> 1605
>> 1606 config BPF_JIT_ALWAYS_ON
>> 1607 bool "Permanently enable BPF JIT and remove BPF interpreter"
>> 1608 depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
>> 1609 help
>> 1610 Enables BPF JIT and removes BPF interpreter to avoid
>> 1611 speculative execution of BPF instructions by the interpreter
>> 1612
>> 1613 config USERFAULTFD
>> 1614 bool "Enable userfaultfd() system call"
>> 1615 depends on MMU
>> 1616 help
>> 1617 Enable the userfaultfd() system call that allows to intercept and
>> 1618 handle page faults in userland.
>> 1619
>> 1620 config ARCH_HAS_MEMBARRIER_CALLBACKS
>> 1621 bool
>> 1622
>> 1623 config ARCH_HAS_MEMBARRIER_SYNC_CORE
>> 1624 bool
1769 1625
1770 config RSEQ 1626 config RSEQ
1771 bool "Enable rseq() system call" if E 1627 bool "Enable rseq() system call" if EXPERT
1772 default y 1628 default y
1773 depends on HAVE_RSEQ 1629 depends on HAVE_RSEQ
1774 select MEMBARRIER 1630 select MEMBARRIER
1775 help 1631 help
1776 Enable the restartable sequences sy 1632 Enable the restartable sequences system call. It provides a
1777 user-space cache for the current CP 1633 user-space cache for the current CPU number value, which
1778 speeds up getting the current CPU n 1634 speeds up getting the current CPU number from user-space,
1779 as well as an ABI to speed up user- 1635 as well as an ABI to speed up user-space operations on
1780 per-CPU data. 1636 per-CPU data.
1781 1637
1782 If unsure, say Y. 1638 If unsure, say Y.
1783 1639
1784 config DEBUG_RSEQ 1640 config DEBUG_RSEQ
1785 default n 1641 default n
1786 bool "Enable debugging of rseq() syst !! 1642 bool "Enabled debugging of rseq() system call" if EXPERT
1787 depends on RSEQ && DEBUG_KERNEL 1643 depends on RSEQ && DEBUG_KERNEL
1788 help 1644 help
1789 Enable extra debugging checks for t 1645 Enable extra debugging checks for the rseq system call.
1790 1646
1791 If unsure, say N. 1647 If unsure, say N.
1792 1648
1793 config CACHESTAT_SYSCALL !! 1649 config EMBEDDED
1794 bool "Enable cachestat() system call" !! 1650 bool "Embedded system"
1795 default y !! 1651 option allnoconfig_y
1796 help !! 1652 select EXPERT
1797 Enable the cachestat system call, w !! 1653 help
1798 statistics of a file (number of cac !! 1654 This option should be enabled if compiling the kernel for
1799 pages marked for writeback, (recent !! 1655 an embedded system so certain expert options are available
1800 !! 1656 for configuration.
1801 If unsure say Y here. <<
1802 <<
1803 config PC104 <<
1804 bool "PC/104 support" if EXPERT <<
1805 help <<
1806 Expose PC/104 form factor device dr <<
1807 selection and configuration. Enable <<
1808 machine has a PC/104 bus. <<
1809 <<
1810 config KALLSYMS <<
1811 bool "Load all symbols for debugging/ <<
1812 default y <<
1813 help <<
1814 Say Y here to let the kernel print <<
1815 symbolic stack backtraces. This inc <<
1816 somewhat, as all symbols have to be <<
1817 <<
1818 config KALLSYMS_SELFTEST <<
1819 bool "Test the basic functions and pe <<
1820 depends on KALLSYMS <<
1821 default n <<
1822 help <<
1823 Test the basic functions and perfor <<
1824 kallsyms_lookup_name. It also calcu <<
1825 kallsyms compression algorithm for <<
1826 <<
1827 Start self-test automatically after <<
1828 "dmesg | grep kallsyms_selftest" to <<
1829 displayed in the last line, indicat <<
1830 <<
1831 config KALLSYMS_ALL <<
1832 bool "Include all symbols in kallsyms <<
1833 depends on DEBUG_KERNEL && KALLSYMS <<
1834 help <<
1835 Normally kallsyms only contains the <<
1836 OOPS messages and backtraces (i.e., <<
1837 sections). This is sufficient for m <<
1838 enable kernel live patching, or oth <<
1839 when a debugger is used) all symbol <<
1840 variables from the data sections, e <<
1841 <<
1842 This option makes sure that all sym <<
1843 image (i.e., symbols from all secti <<
1844 size (depending on the kernel confi <<
1845 something like this). <<
1846 <<
1847 Say N unless you really need all sy <<
1848 <<
1849 config KALLSYMS_ABSOLUTE_PERCPU <<
1850 bool <<
1851 depends on KALLSYMS <<
1852 default X86_64 && SMP <<
1853 <<
1854 # end of the "standard kernel features (exper <<
1855 <<
1856 config ARCH_HAS_MEMBARRIER_CALLBACKS <<
1857 bool <<
1858 <<
1859 config ARCH_HAS_MEMBARRIER_SYNC_CORE <<
1860 bool <<
1861 1657
1862 config HAVE_PERF_EVENTS 1658 config HAVE_PERF_EVENTS
1863 bool 1659 bool
1864 help 1660 help
1865 See tools/perf/design.txt for detai 1661 See tools/perf/design.txt for details.
1866 1662
1867 config GUEST_PERF_EVENTS <<
1868 bool <<
1869 depends on HAVE_PERF_EVENTS <<
1870 <<
1871 config PERF_USE_VMALLOC 1663 config PERF_USE_VMALLOC
1872 bool 1664 bool
1873 help 1665 help
1874 See tools/perf/design.txt for detai 1666 See tools/perf/design.txt for details
1875 1667
>> 1668 config PC104
>> 1669 bool "PC/104 support" if EXPERT
>> 1670 help
>> 1671 Expose PC/104 form factor device drivers and options available for
>> 1672 selection and configuration. Enable this option if your target
>> 1673 machine has a PC/104 bus.
>> 1674
1876 menu "Kernel Performance Events And Counters" 1675 menu "Kernel Performance Events And Counters"
1877 1676
1878 config PERF_EVENTS 1677 config PERF_EVENTS
1879 bool "Kernel performance events and c 1678 bool "Kernel performance events and counters"
1880 default y if PROFILING 1679 default y if PROFILING
1881 depends on HAVE_PERF_EVENTS 1680 depends on HAVE_PERF_EVENTS
1882 select IRQ_WORK 1681 select IRQ_WORK
>> 1682 select SRCU
1883 help 1683 help
1884 Enable kernel support for various p 1684 Enable kernel support for various performance events provided
1885 by software and hardware. 1685 by software and hardware.
1886 1686
1887 Software events are supported eithe 1687 Software events are supported either built-in or via the
1888 use of generic tracepoints. 1688 use of generic tracepoints.
1889 1689
1890 Most modern CPUs support performanc 1690 Most modern CPUs support performance events via performance
1891 counter registers. These registers 1691 counter registers. These registers count the number of certain
1892 types of hw events: such as instruc 1692 types of hw events: such as instructions executed, cachemisses
1893 suffered, or branches mis-predicted 1693 suffered, or branches mis-predicted - without slowing down the
1894 kernel or applications. These regis 1694 kernel or applications. These registers can also trigger interrupts
1895 when a threshold number of events h 1695 when a threshold number of events have passed - and can thus be
1896 used to profile the code that runs 1696 used to profile the code that runs on that CPU.
1897 1697
1898 The Linux Performance Event subsyst 1698 The Linux Performance Event subsystem provides an abstraction of
1899 these software and hardware event c 1699 these software and hardware event capabilities, available via a
1900 system call and used by the "perf" 1700 system call and used by the "perf" utility in tools/perf/. It
1901 provides per task and per CPU count 1701 provides per task and per CPU counters, and it provides event
1902 capabilities on top of those. 1702 capabilities on top of those.
1903 1703
1904 Say Y if unsure. 1704 Say Y if unsure.
1905 1705
1906 config DEBUG_PERF_USE_VMALLOC 1706 config DEBUG_PERF_USE_VMALLOC
1907 default n 1707 default n
1908 bool "Debug: use vmalloc to back perf 1708 bool "Debug: use vmalloc to back perf mmap() buffers"
1909 depends on PERF_EVENTS && DEBUG_KERNE 1709 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1910 select PERF_USE_VMALLOC 1710 select PERF_USE_VMALLOC
1911 help 1711 help
1912 Use vmalloc memory to back perf mma !! 1712 Use vmalloc memory to back perf mmap() buffers.
1913 1713
1914 Mostly useful for debugging the vma !! 1714 Mostly useful for debugging the vmalloc code on platforms
1915 that don't require it. !! 1715 that don't require it.
1916 1716
1917 Say N if unsure. !! 1717 Say N if unsure.
1918 1718
1919 endmenu 1719 endmenu
1920 1720
>> 1721 config VM_EVENT_COUNTERS
>> 1722 default y
>> 1723 bool "Enable VM event counters for /proc/vmstat" if EXPERT
>> 1724 help
>> 1725 VM event counters are needed for event counts to be shown.
>> 1726 This option allows the disabling of the VM event counters
>> 1727 on EXPERT systems. /proc/vmstat will only show page counts
>> 1728 if VM event counters are disabled.
>> 1729
>> 1730 config SLUB_DEBUG
>> 1731 default y
>> 1732 bool "Enable SLUB debugging support" if EXPERT
>> 1733 depends on SLUB && SYSFS
>> 1734 help
>> 1735 SLUB has extensive debug support features. Disabling these can
>> 1736 result in significant savings in code size. This also disables
>> 1737 SLUB sysfs support. /sys/slab will not exist and there will be
>> 1738 no support for cache validation etc.
>> 1739
>> 1740 config SLUB_MEMCG_SYSFS_ON
>> 1741 default n
>> 1742 bool "Enable memcg SLUB sysfs support by default" if EXPERT
>> 1743 depends on SLUB && SYSFS && MEMCG
>> 1744 help
>> 1745 SLUB creates a directory under /sys/kernel/slab for each
>> 1746 allocation cache to host info and debug files. If memory
>> 1747 cgroup is enabled, each cache can have per memory cgroup
>> 1748 caches. SLUB can create the same sysfs directories for these
>> 1749 caches under /sys/kernel/slab/CACHE/cgroup but it can lead
>> 1750 to a very high number of debug files being created. This is
>> 1751 controlled by slub_memcg_sysfs boot parameter and this
>> 1752 config option determines the parameter's default value.
>> 1753
>> 1754 config COMPAT_BRK
>> 1755 bool "Disable heap randomization"
>> 1756 default y
>> 1757 help
>> 1758 Randomizing heap placement makes heap exploits harder, but it
>> 1759 also breaks ancient binaries (including anything libc5 based).
>> 1760 This option changes the bootup default to heap randomization
>> 1761 disabled, and can be overridden at runtime by setting
>> 1762 /proc/sys/kernel/randomize_va_space to 2.
>> 1763
>> 1764 On non-ancient distros (post-2000 ones) N is usually a safe choice.
>> 1765
>> 1766 choice
>> 1767 prompt "Choose SLAB allocator"
>> 1768 default SLUB
>> 1769 help
>> 1770 This option allows to select a slab allocator.
>> 1771
>> 1772 config SLAB
>> 1773 bool "SLAB"
>> 1774 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1775 help
>> 1776 The regular slab allocator that is established and known to work
>> 1777 well in all environments. It organizes cache hot objects in
>> 1778 per cpu and per node queues.
>> 1779
>> 1780 config SLUB
>> 1781 bool "SLUB (Unqueued Allocator)"
>> 1782 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 1783 help
>> 1784 SLUB is a slab allocator that minimizes cache line usage
>> 1785 instead of managing queues of cached objects (SLAB approach).
>> 1786 Per cpu caching is realized using slabs of objects instead
>> 1787 of queues of objects. SLUB can use memory efficiently
>> 1788 and has enhanced diagnostics. SLUB is the default choice for
>> 1789 a slab allocator.
>> 1790
>> 1791 config SLOB
>> 1792 depends on EXPERT
>> 1793 bool "SLOB (Simple Allocator)"
>> 1794 help
>> 1795 SLOB replaces the stock allocator with a drastically simpler
>> 1796 allocator. SLOB is generally more space efficient but
>> 1797 does not perform as well on large systems.
>> 1798
>> 1799 endchoice
>> 1800
>> 1801 config SLAB_MERGE_DEFAULT
>> 1802 bool "Allow slab caches to be merged"
>> 1803 default y
>> 1804 help
>> 1805 For reduced kernel memory fragmentation, slab caches can be
>> 1806 merged when they share the same size and other characteristics.
>> 1807 This carries a risk of kernel heap overflows being able to
>> 1808 overwrite objects from merged caches (and more easily control
>> 1809 cache layout), which makes such heap attacks easier to exploit
>> 1810 by attackers. By keeping caches unmerged, these kinds of exploits
>> 1811 can usually only damage objects in the same cache. To disable
>> 1812 merging at runtime, "slab_nomerge" can be passed on the kernel
>> 1813 command line.
>> 1814
>> 1815 config SLAB_FREELIST_RANDOM
>> 1816 default n
>> 1817 depends on SLAB || SLUB
>> 1818 bool "SLAB freelist randomization"
>> 1819 help
>> 1820 Randomizes the freelist order used on creating new pages. This
>> 1821 security feature reduces the predictability of the kernel slab
>> 1822 allocator against heap overflows.
>> 1823
>> 1824 config SLAB_FREELIST_HARDENED
>> 1825 bool "Harden slab freelist metadata"
>> 1826 depends on SLUB
>> 1827 help
>> 1828 Many kernel heap attacks try to target slab cache metadata and
>> 1829 other infrastructure. This options makes minor performance
>> 1830 sacrifices to harden the kernel slab allocator against common
>> 1831 freelist exploit methods.
>> 1832
>> 1833 config SHUFFLE_PAGE_ALLOCATOR
>> 1834 bool "Page allocator randomization"
>> 1835 default SLAB_FREELIST_RANDOM && ACPI_NUMA
>> 1836 help
>> 1837 Randomization of the page allocator improves the average
>> 1838 utilization of a direct-mapped memory-side-cache. See section
>> 1839 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
>> 1840 6.2a specification for an example of how a platform advertises
>> 1841 the presence of a memory-side-cache. There are also incidental
>> 1842 security benefits as it reduces the predictability of page
>> 1843 allocations to compliment SLAB_FREELIST_RANDOM, but the
>> 1844 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
>> 1845 10th order of pages is selected based on cache utilization
>> 1846 benefits on x86.
>> 1847
>> 1848 While the randomization improves cache utilization it may
>> 1849 negatively impact workloads on platforms without a cache. For
>> 1850 this reason, by default, the randomization is enabled only
>> 1851 after runtime detection of a direct-mapped memory-side-cache.
>> 1852 Otherwise, the randomization may be force enabled with the
>> 1853 'page_alloc.shuffle' kernel command line parameter.
>> 1854
>> 1855 Say Y if unsure.
>> 1856
>> 1857 config SLUB_CPU_PARTIAL
>> 1858 default y
>> 1859 depends on SLUB && SMP
>> 1860 bool "SLUB per cpu partial cache"
>> 1861 help
>> 1862 Per cpu partial caches accelerate objects allocation and freeing
>> 1863 that is local to a processor at the price of more indeterminism
>> 1864 in the latency of the free. On overflow these caches will be cleared
>> 1865 which requires the taking of locks that may cause latency spikes.
>> 1866 Typically one would choose no for a realtime system.
>> 1867
>> 1868 config MMAP_ALLOW_UNINITIALIZED
>> 1869 bool "Allow mmapped anonymous memory to be uninitialized"
>> 1870 depends on EXPERT && !MMU
>> 1871 default n
>> 1872 help
>> 1873 Normally, and according to the Linux spec, anonymous memory obtained
>> 1874 from mmap() has its contents cleared before it is passed to
>> 1875 userspace. Enabling this config option allows you to request that
>> 1876 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
>> 1877 providing a huge performance boost. If this option is not enabled,
>> 1878 then the flag will be ignored.
>> 1879
>> 1880 This is taken advantage of by uClibc's malloc(), and also by
>> 1881 ELF-FDPIC binfmt's brk and stack allocator.
>> 1882
>> 1883 Because of the obvious security issues, this option should only be
>> 1884 enabled on embedded devices where you control what is run in
>> 1885 userspace. Since that isn't generally a problem on no-MMU systems,
>> 1886 it is normally safe to say Y here.
>> 1887
>> 1888 See Documentation/nommu-mmap.txt for more information.
>> 1889
1921 config SYSTEM_DATA_VERIFICATION 1890 config SYSTEM_DATA_VERIFICATION
1922 def_bool n 1891 def_bool n
1923 select SYSTEM_TRUSTED_KEYRING 1892 select SYSTEM_TRUSTED_KEYRING
1924 select KEYS 1893 select KEYS
1925 select CRYPTO 1894 select CRYPTO
1926 select CRYPTO_RSA 1895 select CRYPTO_RSA
1927 select ASYMMETRIC_KEY_TYPE 1896 select ASYMMETRIC_KEY_TYPE
1928 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1897 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1929 select ASN1 1898 select ASN1
1930 select OID_REGISTRY 1899 select OID_REGISTRY
1931 select X509_CERTIFICATE_PARSER 1900 select X509_CERTIFICATE_PARSER
1932 select PKCS7_MESSAGE_PARSER 1901 select PKCS7_MESSAGE_PARSER
1933 help 1902 help
1934 Provide PKCS#7 message verification 1903 Provide PKCS#7 message verification using the contents of the system
1935 trusted keyring to provide public k 1904 trusted keyring to provide public keys. This then can be used for
1936 module verification, kexec image ve 1905 module verification, kexec image verification and firmware blob
1937 verification. 1906 verification.
1938 1907
1939 config PROFILING 1908 config PROFILING
1940 bool "Profiling support" 1909 bool "Profiling support"
1941 help 1910 help
1942 Say Y here to enable the extended p 1911 Say Y here to enable the extended profiling support mechanisms used
1943 by profilers. !! 1912 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 1913
1986 # 1914 #
1987 # Place an empty function call at each tracep 1915 # Place an empty function call at each tracepoint site. Can be
1988 # dynamically changed for a probe function. 1916 # dynamically changed for a probe function.
1989 # 1917 #
1990 config TRACEPOINTS 1918 config TRACEPOINTS
1991 bool 1919 bool
1992 1920
1993 source "kernel/Kconfig.kexec" <<
1994 <<
1995 endmenu # General setup 1921 endmenu # General setup
1996 1922
1997 source "arch/Kconfig" 1923 source "arch/Kconfig"
1998 1924
1999 config RT_MUTEXES 1925 config RT_MUTEXES
2000 bool 1926 bool
2001 default y if PREEMPT_RT <<
2002 1927
2003 config MODULE_SIG_FORMAT !! 1928 config BASE_SMALL
2004 def_bool n !! 1929 int
>> 1930 default 0 if BASE_FULL
>> 1931 default 1 if !BASE_FULL
>> 1932
>> 1933 menuconfig MODULES
>> 1934 bool "Enable loadable module support"
>> 1935 option modules
>> 1936 help
>> 1937 Kernel modules are small pieces of compiled code which can
>> 1938 be inserted in the running kernel, rather than being
>> 1939 permanently built into the kernel. You use the "modprobe"
>> 1940 tool to add (and sometimes remove) them. If you say Y here,
>> 1941 many parts of the kernel can be built as modules (by
>> 1942 answering M instead of Y where indicated): this is most
>> 1943 useful for infrequently used options which are not required
>> 1944 for booting. For more information, see the man pages for
>> 1945 modprobe, lsmod, modinfo, insmod and rmmod.
>> 1946
>> 1947 If you say Y here, you will need to run "make
>> 1948 modules_install" to put the modules under /lib/modules/
>> 1949 where modprobe can find them (you may need to be root to do
>> 1950 this).
>> 1951
>> 1952 If unsure, say Y.
>> 1953
>> 1954 if MODULES
>> 1955
>> 1956 config MODULE_FORCE_LOAD
>> 1957 bool "Forced module loading"
>> 1958 default n
>> 1959 help
>> 1960 Allow loading of modules without version information (ie. modprobe
>> 1961 --force). Forced module loading sets the 'F' (forced) taint flag and
>> 1962 is usually a really bad idea.
>> 1963
>> 1964 config MODULE_UNLOAD
>> 1965 bool "Module unloading"
>> 1966 help
>> 1967 Without this option you will not be able to unload any
>> 1968 modules (note that some modules may not be unloadable
>> 1969 anyway), which makes your kernel smaller, faster
>> 1970 and simpler. If unsure, say Y.
>> 1971
>> 1972 config MODULE_FORCE_UNLOAD
>> 1973 bool "Forced module unloading"
>> 1974 depends on MODULE_UNLOAD
>> 1975 help
>> 1976 This option allows you to force a module to unload, even if the
>> 1977 kernel believes it is unsafe: the kernel will remove the module
>> 1978 without waiting for anyone to stop using it (using the -f option to
>> 1979 rmmod). This is mainly for kernel developers and desperate users.
>> 1980 If unsure, say N.
>> 1981
>> 1982 config MODVERSIONS
>> 1983 bool "Module versioning support"
>> 1984 help
>> 1985 Usually, you have to use modules compiled with your kernel.
>> 1986 Saying Y here makes it sometimes possible to use modules
>> 1987 compiled for different kernels, by adding enough information
>> 1988 to the modules to (hopefully) spot any changes which would
>> 1989 make them incompatible with the kernel you are running. If
>> 1990 unsure, say N.
>> 1991
>> 1992 config MODULE_REL_CRCS
>> 1993 bool
>> 1994 depends on MODVERSIONS
>> 1995
>> 1996 config MODULE_SRCVERSION_ALL
>> 1997 bool "Source checksum for all modules"
>> 1998 help
>> 1999 Modules which contain a MODULE_VERSION get an extra "srcversion"
>> 2000 field inserted into their modinfo section, which contains a
>> 2001 sum of the source files which made it. This helps maintainers
>> 2002 see exactly which source was used to build a module (since
>> 2003 others sometimes change the module source without updating
>> 2004 the version). With this option, such a "srcversion" field
>> 2005 will be created for all modules. If unsure, say N.
>> 2006
>> 2007 config MODULE_SIG
>> 2008 bool "Module signature verification"
>> 2009 depends on MODULES
2005 select SYSTEM_DATA_VERIFICATION 2010 select SYSTEM_DATA_VERIFICATION
>> 2011 help
>> 2012 Check modules for valid signatures upon load: the signature
>> 2013 is simply appended to the module. For more information see
>> 2014 <file:Documentation/admin-guide/module-signing.rst>.
>> 2015
>> 2016 Note that this option adds the OpenSSL development packages as a
>> 2017 kernel build dependency so that the signing tool can use its crypto
>> 2018 library.
>> 2019
>> 2020 !!!WARNING!!! If you enable this option, you MUST make sure that the
>> 2021 module DOES NOT get stripped after being signed. This includes the
>> 2022 debuginfo strip done by some packagers (such as rpmbuild) and
>> 2023 inclusion into an initramfs that wants the module size reduced.
>> 2024
>> 2025 config MODULE_SIG_FORCE
>> 2026 bool "Require modules to be validly signed"
>> 2027 depends on MODULE_SIG
>> 2028 help
>> 2029 Reject unsigned modules or signed modules for which we don't have a
>> 2030 key. Without this, such modules will simply taint the kernel.
>> 2031
>> 2032 config MODULE_SIG_ALL
>> 2033 bool "Automatically sign all modules"
>> 2034 default y
>> 2035 depends on MODULE_SIG
>> 2036 help
>> 2037 Sign all modules during make modules_install. Without this option,
>> 2038 modules must be signed manually, using the scripts/sign-file tool.
>> 2039
>> 2040 comment "Do not forget to sign required modules with scripts/sign-file"
>> 2041 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
>> 2042
>> 2043 choice
>> 2044 prompt "Which hash algorithm should modules be signed with?"
>> 2045 depends on MODULE_SIG
>> 2046 help
>> 2047 This determines which sort of hashing algorithm will be used during
>> 2048 signature generation. This algorithm _must_ be built into the kernel
>> 2049 directly so that signature verification can take place. It is not
>> 2050 possible to load a signed module containing the algorithm to check
>> 2051 the signature on that module.
>> 2052
>> 2053 config MODULE_SIG_SHA1
>> 2054 bool "Sign modules with SHA-1"
>> 2055 select CRYPTO_SHA1
>> 2056
>> 2057 config MODULE_SIG_SHA224
>> 2058 bool "Sign modules with SHA-224"
>> 2059 select CRYPTO_SHA256
>> 2060
>> 2061 config MODULE_SIG_SHA256
>> 2062 bool "Sign modules with SHA-256"
>> 2063 select CRYPTO_SHA256
>> 2064
>> 2065 config MODULE_SIG_SHA384
>> 2066 bool "Sign modules with SHA-384"
>> 2067 select CRYPTO_SHA512
>> 2068
>> 2069 config MODULE_SIG_SHA512
>> 2070 bool "Sign modules with SHA-512"
>> 2071 select CRYPTO_SHA512
>> 2072
>> 2073 endchoice
>> 2074
>> 2075 config MODULE_SIG_HASH
>> 2076 string
>> 2077 depends on MODULE_SIG
>> 2078 default "sha1" if MODULE_SIG_SHA1
>> 2079 default "sha224" if MODULE_SIG_SHA224
>> 2080 default "sha256" if MODULE_SIG_SHA256
>> 2081 default "sha384" if MODULE_SIG_SHA384
>> 2082 default "sha512" if MODULE_SIG_SHA512
>> 2083
>> 2084 config MODULE_COMPRESS
>> 2085 bool "Compress modules on installation"
>> 2086 depends on MODULES
>> 2087 help
>> 2088
>> 2089 Compresses kernel modules when 'make modules_install' is run; gzip or
>> 2090 xz depending on "Compression algorithm" below.
>> 2091
>> 2092 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
>> 2093
>> 2094 Out-of-tree kernel modules installed using Kbuild will also be
>> 2095 compressed upon installation.
2006 2096
2007 source "kernel/module/Kconfig" !! 2097 Note: for modules inside an initrd or initramfs, it's more efficient
>> 2098 to compress the whole initrd or initramfs instead.
>> 2099
>> 2100 Note: This is fully compatible with signed modules.
>> 2101
>> 2102 If in doubt, say N.
>> 2103
>> 2104 choice
>> 2105 prompt "Compression algorithm"
>> 2106 depends on MODULE_COMPRESS
>> 2107 default MODULE_COMPRESS_GZIP
>> 2108 help
>> 2109 This determines which sort of compression will be used during
>> 2110 'make modules_install'.
>> 2111
>> 2112 GZIP (default) and XZ are supported.
>> 2113
>> 2114 config MODULE_COMPRESS_GZIP
>> 2115 bool "GZIP"
>> 2116
>> 2117 config MODULE_COMPRESS_XZ
>> 2118 bool "XZ"
>> 2119
>> 2120 endchoice
>> 2121
>> 2122 config TRIM_UNUSED_KSYMS
>> 2123 bool "Trim unused exported kernel symbols"
>> 2124 depends on MODULES && !UNUSED_SYMBOLS
>> 2125 help
>> 2126 The kernel and some modules make many symbols available for
>> 2127 other modules to use via EXPORT_SYMBOL() and variants. Depending
>> 2128 on the set of modules being selected in your kernel configuration,
>> 2129 many of those exported symbols might never be used.
>> 2130
>> 2131 This option allows for unused exported symbols to be dropped from
>> 2132 the build. In turn, this provides the compiler more opportunities
>> 2133 (especially when using LTO) for optimizing the code and reducing
>> 2134 binary size. This might have some security advantages as well.
>> 2135
>> 2136 If unsure, or if you need to build out-of-tree modules, say N.
>> 2137
>> 2138 endif # MODULES
>> 2139
>> 2140 config MODULES_TREE_LOOKUP
>> 2141 def_bool y
>> 2142 depends on PERF_EVENTS || TRACING
2008 2143
2009 config INIT_ALL_POSSIBLE 2144 config INIT_ALL_POSSIBLE
2010 bool 2145 bool
2011 help 2146 help
2012 Back when each arch used to define 2147 Back when each arch used to define their own cpu_online_mask and
2013 cpu_possible_mask, some of them cho 2148 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2014 with all 1s, and others with all 0s 2149 with all 1s, and others with all 0s. When they were centralised,
2015 it was better to provide this optio 2150 it was better to provide this option than to break all the archs
2016 and have several arch maintainers p 2151 and have several arch maintainers pursuing me down dark alleys.
2017 2152
2018 source "block/Kconfig" 2153 source "block/Kconfig"
2019 2154
2020 config PREEMPT_NOTIFIERS 2155 config PREEMPT_NOTIFIERS
2021 bool 2156 bool
2022 2157
2023 config PADATA 2158 config PADATA
2024 depends on SMP 2159 depends on SMP
2025 bool 2160 bool
2026 2161
2027 config ASN1 2162 config ASN1
2028 tristate 2163 tristate
2029 help 2164 help
2030 Build a simple ASN.1 grammar compil 2165 Build a simple ASN.1 grammar compiler that produces a bytecode output
2031 that can be interpreted by the ASN. 2166 that can be interpreted by the ASN.1 stream decoder and used to
2032 inform it as to what tags are to be 2167 inform it as to what tags are to be expected in a stream and what
2033 functions to call on what tags. 2168 functions to call on what tags.
2034 2169
2035 source "kernel/Kconfig.locks" 2170 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 2171
2043 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 2172 config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2044 bool 2173 bool
2045 2174
2046 # It may be useful for an architecture to ove 2175 # It may be useful for an architecture to override the definitions of the
2047 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() ma 2176 # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2048 # and the COMPAT_ variants in <linux/compat.h 2177 # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2049 # different calling convention for syscalls. 2178 # different calling convention for syscalls. They can also override the
2050 # macros for not-implemented syscalls in kern 2179 # macros for not-implemented syscalls in kernel/sys_ni.c and
2051 # kernel/time/posix-stubs.c. All these overri 2180 # kernel/time/posix-stubs.c. All these overrides need to be available in
2052 # <asm/syscall_wrapper.h>. 2181 # <asm/syscall_wrapper.h>.
2053 config ARCH_HAS_SYSCALL_WRAPPER 2182 config ARCH_HAS_SYSCALL_WRAPPER
2054 def_bool n 2183 def_bool n
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