blob: e1a937348a3ed2bb3a76820e1ffa6a542f6aa9fb [file] [log] [blame]
Roman Zippel80daa562008-01-14 04:51:16 +01001config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
Roman Zippelface4372006-06-08 22:12:45 -07009config DEFCONFIG_LIST
10 string
Paolo 'Blaisorblade' Giarrussob2670eac2006-10-19 23:28:23 -070011 depends on !UML
Roman Zippelface4372006-06-08 22:12:45 -070012 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
Sam Ravnborg73531902008-05-25 23:03:18 +020016 default "$ARCH_DEFCONFIG"
Roman Zippelface4372006-06-08 22:12:45 -070017 default "arch/$ARCH/defconfig"
18
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070019config CONSTRUCTORS
20 bool
21 depends on !UML
Peter Oberparleiterb99b87f2009-06-17 16:28:03 -070022
Peter Zijlstrae360adb2010-10-14 14:01:34 +080023config IRQ_WORK
24 bool
Peter Zijlstrae360adb2010-10-14 14:01:34 +080025
David Daney1dbdc6f2012-04-19 14:59:57 -070026config BUILDTIME_EXTABLE_SORT
27 bool
28
Andy Lutomirskic65eacb2016-09-13 14:29:24 -070029config THREAD_INFO_IN_TASK
30 bool
31 help
32 Select this to move thread_info off the stack into task_struct. To
33 make this work, an arch will need to remove all thread_info fields
34 except flags and fix any runtime bugs.
35
Andy Lutomirskic6c314a2016-09-15 22:45:43 -070036 One subtle change that will be needed is to use try_get_task_stack()
37 and put_task_stack() in save_thread_stack_tsk() and get_wchan().
38
Al Boldiff0cfc62007-07-31 00:39:23 -070039menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
Linus Torvalds1da177e2005-04-16 15:20:36 -070041config BROKEN
42 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44config BROKEN_ON_SMP
45 bool
46 depends on BROKEN || !SMP
47 default y
48
Linus Torvalds1da177e2005-04-16 15:20:36 -070049config INIT_ENV_ARG_LIMIT
50 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070051 default 32 if !UML
52 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 help
Randy Dunlap34ad92c2005-10-30 15:01:46 -080054 Maximum of each of the number of arguments and environment
55 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
Roland McGrath84336462009-12-21 16:24:06 -080058config CROSS_COMPILE
59 string "Cross-compiler tool prefix"
60 help
61 Same as running 'make CROSS_COMPILE=prefix-' but stored for
62 default make runs in this kernel build directory. You don't
63 need to set this unless you want the configured kernel build
64 directory to select the cross-compiler automatically.
65
Jiri Slaby4bb16672013-05-22 10:56:24 +020066config COMPILE_TEST
67 bool "Compile also drivers which will not load"
Richard Weinbergerbc083a62016-08-02 14:03:27 -070068 depends on !UML
Jiri Slaby4bb16672013-05-22 10:56:24 +020069 default n
70 help
71 Some drivers can be compiled on a different platform than they are
72 intended to be run on. Despite they cannot be loaded there (or even
73 when they load they cannot be used due to missing HW support),
74 developers still, opposing to distributors, might want to build such
75 drivers to compile-test them.
76
77 If you are a developer and want to build everything available, say Y
78 here. If you are a user/distributor, say N here to exclude useless
79 drivers to be distributed.
80
Linus Torvalds1da177e2005-04-16 15:20:36 -070081config LOCALVERSION
82 string "Local version - append to kernel release"
83 help
84 Append an extra string to the end of your kernel version.
85 This will show up when you type uname, for example.
86 The string you set here will be appended after the contents of
87 any files with a filename matching localversion* in your
88 object and source tree, in that order. Your total string can
89 be a maximum of 64 characters.
90
Ryan Andersonaaebf432005-07-31 04:57:49 -040091config LOCALVERSION_AUTO
92 bool "Automatically append version information to the version string"
93 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -070094 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -040095 help
96 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020097 release tree by looking for git tags that belong to the current
98 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -040099
100 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200101 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -0400102 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200103 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -0400104
Robert P. J. Day6e5a5422007-05-01 23:08:11 +0200105 (The actual string used here is the first eight characters produced
106 by running the command:
107
108 $ git rev-parse --verify HEAD
109
110 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400111
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800112config HAVE_KERNEL_GZIP
113 bool
114
115config HAVE_KERNEL_BZIP2
116 bool
117
118config HAVE_KERNEL_LZMA
119 bool
120
Lasse Collin3ebe1242011-01-12 17:01:23 -0800121config HAVE_KERNEL_XZ
122 bool
123
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800124config HAVE_KERNEL_LZO
125 bool
126
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700127config HAVE_KERNEL_LZ4
128 bool
129
Alain Knaff30d65db2009-01-04 22:46:17 +0100130choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800131 prompt "Kernel compression mode"
132 default KERNEL_GZIP
H. Peter Anvin2d3c6272013-11-14 21:43:47 -0800133 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800134 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100135 The linux kernel is a kind of self-extracting executable.
136 Several compression algorithms are available, which differ
137 in efficiency, compression and decompression speed.
138 Compression speed is only relevant when building a kernel.
139 Decompression speed is relevant at each boot.
140
141 If you have any problems with bzip2 or lzma compressed
142 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
143 version of this functionality (bzip2 only), for 2.4, was
144 supplied by Christian Ludwig)
145
146 High compression options are mostly useful for users, who
147 are low on disk space (embedded systems), but for whom ram
148 size matters less.
149
150 If in doubt, select 'gzip'
151
152config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800153 bool "Gzip"
154 depends on HAVE_KERNEL_GZIP
155 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800156 The old and tried gzip compression. It provides a good balance
157 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100158
159config KERNEL_BZIP2
160 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800161 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100162 help
163 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700164 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800165 size is about 10% smaller with bzip2, in comparison to gzip.
166 Bzip2 uses a large amount of memory. For modern kernels you
167 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100168
169config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800170 bool "LZMA"
171 depends on HAVE_KERNEL_LZMA
172 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700173 This compression algorithm's ratio is best. Decompression speed
174 is between gzip and bzip2. Compression is slowest.
175 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100176
Lasse Collin3ebe1242011-01-12 17:01:23 -0800177config KERNEL_XZ
178 bool "XZ"
179 depends on HAVE_KERNEL_XZ
180 help
181 XZ uses the LZMA2 algorithm and instruction set specific
182 BCJ filters which can improve compression ratio of executable
183 code. The size of the kernel is about 30% smaller with XZ in
184 comparison to gzip. On architectures for which there is a BCJ
185 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
186 will create a few percent smaller kernel than plain LZMA.
187
188 The speed is about the same as with LZMA: The decompression
189 speed of XZ is better than that of bzip2 but worse than gzip
190 and LZO. Compression is slow.
191
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800192config KERNEL_LZO
193 bool "LZO"
194 depends on HAVE_KERNEL_LZO
195 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700196 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200197 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800198 (both compression and decompression) is the fastest.
199
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700200config KERNEL_LZ4
201 bool "LZ4"
202 depends on HAVE_KERNEL_LZ4
203 help
204 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
205 A preliminary version of LZ4 de/compression tool is available at
206 <https://code.google.com/p/lz4/>.
207
208 Its compression ratio is worse than LZO. The size of the kernel
209 is about 8% bigger than LZO. But the decompression speed is
210 faster than LZO.
211
Alain Knaff30d65db2009-01-04 22:46:17 +0100212endchoice
213
Josh Triplettbd5dc172011-06-15 15:08:28 -0700214config DEFAULT_HOSTNAME
215 string "Default hostname"
216 default "(none)"
217 help
218 This option determines the default system hostname before userspace
219 calls sethostname(2). The kernel traditionally uses "(none)" here,
220 but you may wish to use a different default here to make a minimal
221 system more usable with less configuration.
222
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223config SWAP
224 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200225 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 default y
227 help
228 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100229 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 used to provide more virtual memory than the actual RAM present
231 in your computer. If unsure say Y.
232
233config SYSVIPC
234 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 ---help---
236 Inter Process Communication is a suite of library functions and
237 system calls which let processes (running programs) synchronize and
238 exchange information. It is generally considered to be a good thing,
239 and some programs won't run unless you say Y here. In particular, if
240 you want to run the DOS emulator dosemu under Linux (read the
241 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
242 you'll need to say Y here.
243
244 You can find documentation about IPC with "info ipc" and also in
245 section 6.4 of the Linux Programmer's Guide, available from
246 <http://www.tldp.org/guides.html>.
247
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800248config SYSVIPC_SYSCTL
249 bool
250 depends on SYSVIPC
251 depends on SYSCTL
252 default y
253
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254config POSIX_MQUEUE
255 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700256 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 ---help---
258 POSIX variant of message queues is a part of IPC. In POSIX message
259 queues every message has a priority which decides about succession
260 of receiving it by a process. If you want to compile and run
261 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200262 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
264 POSIX message queues are visible as a filesystem called 'mqueue'
265 and can be mounted somewhere if you want to do filesystem
266 operations on message queues.
267
268 If unsure, say Y.
269
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700270config POSIX_MQUEUE_SYSCTL
271 bool
272 depends on POSIX_MQUEUE
273 depends on SYSCTL
274 default y
275
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700276config CROSS_MEMORY_ATTACH
277 bool "Enable process_vm_readv/writev syscalls"
278 depends on MMU
279 default y
280 help
281 Enabling this option adds the system calls process_vm_readv and
282 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700283 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700284 See the man page for more details.
285
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530286config FHANDLE
Andi Kleenf76be612016-04-01 14:31:40 -0700287 bool "open by fhandle syscalls" if EXPERT
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530288 select EXPORTFS
Andi Kleenf76be612016-04-01 14:31:40 -0700289 default y
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530290 help
291 If you say Y here, a user level program will be able to map
292 file names to handle and then later use the handle for
293 different file system operations. This is useful in implementing
294 userspace file servers, which now track files using handles instead
295 of names. The handle would remain the same even if file names
296 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
297 syscalls.
298
Josh Triplett69369a72014-04-03 14:48:27 -0700299config USELIB
300 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800301 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700302 help
303 This option enables the uselib syscall, a system call used in the
304 dynamic linker from libc5 and earlier. glibc does not use this
305 system call. If you intend to run programs built on libc5 or
306 earlier, you may need to enable this syscall. Current systems
307 running glibc can safely disable this.
308
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309config AUDIT
310 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100311 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 help
313 Enable auditing infrastructure that can be used with another
314 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500315 logging of avc messages output). System call auditing is included
316 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900318config HAVE_ARCH_AUDITSYSCALL
319 bool
320
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500322 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900323 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
Eric Paris939a67f2009-12-17 20:12:06 -0500325config AUDIT_WATCH
326 def_bool y
327 depends on AUDITSYSCALL
328 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329
Al Viro74c3cbe2007-07-22 08:04:18 -0400330config AUDIT_TREE
331 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400332 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500333 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400334
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000335source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200336source "kernel/time/Kconfig"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000337
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200338menu "CPU/Task time and stats accounting"
339
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200340config VIRT_CPU_ACCOUNTING
341 bool
342
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200343choice
344 prompt "Cputime accounting"
345 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100346 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200347
348# Kind of a stub config for the pure tick based cputime accounting
349config TICK_CPU_ACCOUNTING
350 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200351 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200352 help
353 This is the basic tick based cputime accounting that maintains
354 statistics about user, system and idle time spent on per jiffies
355 granularity.
356
357 If unsure, say Y.
358
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200359config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200360 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200361 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200362 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200363 help
364 Select this option to enable more accurate task and CPU time
365 accounting. This is done by reading a CPU counter on each
366 kernel entry and exit and on transitions within the kernel
367 between system, softirq and hardirq state, so there is a
368 small performance impact. In the case of s390 or IBM POWER > 5,
369 this also enables accounting of stolen time on logically-partitioned
370 systems.
371
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200372config VIRT_CPU_ACCOUNTING_GEN
373 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700374 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700375 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200376 select VIRT_CPU_ACCOUNTING
377 select CONTEXT_TRACKING
378 help
379 Select this option to enable task and CPU time accounting on full
380 dynticks systems. This accounting is implemented by watching every
381 kernel-user boundaries using the context tracking subsystem.
382 The accounting is thus performed at the expense of some significant
383 overhead.
384
385 For now this is only useful if you are working on the full
386 dynticks subsystem development.
387
388 If unsure, say N.
389
Rik van Rielb58c3582016-07-13 16:50:02 +0200390endchoice
391
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200392config IRQ_TIME_ACCOUNTING
393 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200394 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200395 help
396 Select this option to enable fine granularity task irq time
397 accounting. This is done by reading a timestamp on each
398 transitions between softirq and hardirq state, so there can be a
399 small performance impact.
400
401 If in doubt, say N here.
402
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200403config BSD_PROCESS_ACCT
404 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700405 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200406 help
407 If you say Y here, a user level program will be able to instruct the
408 kernel (via a special system call) to write process accounting
409 information to a file: whenever a process exits, information about
410 that process will be appended to the file by the kernel. The
411 information includes things such as creation time, owning user,
412 command name, memory usage, controlling terminal etc. (the complete
413 list is in the struct acct in <file:include/linux/acct.h>). It is
414 up to the user level program to do useful things with this
415 information. This is generally a good idea, so say Y.
416
417config BSD_PROCESS_ACCT_V3
418 bool "BSD Process Accounting version 3 file format"
419 depends on BSD_PROCESS_ACCT
420 default n
421 help
422 If you say Y here, the process accounting information is written
423 in a new file format that also logs the process IDs of each
424 process and it's parent. Note that this file format is incompatible
425 with previous v0/v1/v2 file formats, so you will need updated tools
426 for processing it. A preliminary version of these tools is available
427 at <http://www.gnu.org/software/acct/>.
428
429config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700430 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200431 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700432 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200433 default n
434 help
435 Export selected statistics for tasks/processes through the
436 generic netlink interface. Unlike BSD process accounting, the
437 statistics are available during the lifetime of tasks/processes as
438 responses to commands. Like BSD accounting, they are sent to user
439 space on task exit.
440
441 Say N if unsure.
442
443config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700444 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200445 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530446 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200447 help
448 Collect information on time spent by a task waiting for system
449 resources like cpu, synchronous block I/O completion and swapping
450 in pages. Such statistics can help in setting a task's priorities
451 relative to other tasks for cpu, io, rss limits etc.
452
453 Say N if unsure.
454
455config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700456 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200457 depends on TASKSTATS
458 help
459 Collect extended task accounting data and send the data
460 to userland for processing over the taskstats interface.
461
462 Say N if unsure.
463
464config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700465 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200466 depends on TASK_XACCT
467 help
468 Collect information on the number of bytes of storage I/O which this
469 task has caused.
470
471 Say N if unsure.
472
473endmenu # "CPU/Task time and stats accounting"
474
Mike Travisc903ff82009-01-15 12:28:29 -0800475menu "RCU Subsystem"
476
Mike Travisc903ff82009-01-15 12:28:29 -0800477config TREE_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400478 bool
479 default y if !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800480 help
481 This option selects the RCU implementation that is
482 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700483 thousands of CPUs. It also scales down nicely to
484 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800485
Pranith Kumar28f65692014-09-22 14:00:48 -0400486config PREEMPT_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400487 bool
488 default y if PREEMPT
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700489 help
490 This option selects the RCU implementation that is
491 designed for very large SMP systems with hundreds or
492 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700493 is also required. It also scales down nicely to
494 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700495
Paul E. McKenney9fc52d82013-01-08 15:48:33 -0800496 Select this option if you are unsure.
497
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700498config TINY_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400499 bool
500 default y if !PREEMPT && !SMP
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700501 help
502 This option selects the RCU implementation that is
503 designed for UP systems from which real-time response
504 is not required. This option greatly reduces the
505 memory footprint of RCU.
506
Paul E. McKenney78cae102015-04-20 12:19:45 -0700507config RCU_EXPERT
508 bool "Make expert-level adjustments to RCU configuration"
509 default n
510 help
511 This option needs to be enabled if you wish to make
512 expert-level adjustments to RCU configuration. By default,
513 no such adjustments can be made, which has the often-beneficial
514 side-effect of preventing "make oldconfig" from asking you all
515 sorts of detailed questions about how you would like numerous
516 obscure RCU options to be set up.
517
518 Say Y if you need to make expert-level adjustments to RCU.
519
520 Say N if you are unsure.
521
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500522config SRCU
523 bool
524 help
525 This option selects the sleepable version of RCU. This version
526 permits arbitrary sleeping or blocking within RCU read-side critical
527 sections.
528
Paul E. McKenney8315f422014-06-27 13:42:20 -0700529config TASKS_RCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -0700530 bool
Paul E. McKenney8315f422014-06-27 13:42:20 -0700531 default n
Paul E. McKenney570dd3c2016-06-15 08:56:53 -0700532 depends on !UML
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500533 select SRCU
Paul E. McKenney8315f422014-06-27 13:42:20 -0700534 help
535 This option enables a task-based RCU implementation that uses
536 only voluntary context switch (not preemption!), idle, and
537 user-mode execution as quiescent states.
538
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700539config RCU_STALL_COMMON
Pranith Kumar28f65692014-09-22 14:00:48 -0400540 def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700541 help
542 This option enables RCU CPU stall code that is common between
543 the TINY and TREE variants of RCU. The purpose is to allow
544 the tiny variants to disable RCU CPU stall warnings, while
545 making these warnings mandatory for the tree variants.
546
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100547config CONTEXT_TRACKING
548 bool
549
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100550config CONTEXT_TRACKING_FORCE
551 bool "Force context tracking"
552 depends on CONTEXT_TRACKING
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200553 default y if !NO_HZ_FULL
Frederic Weisbecker1fd2b442012-07-11 20:26:40 +0200554 help
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200555 The major pre-requirement for full dynticks to work is to
556 support the context tracking subsystem. But there are also
557 other dependencies to provide in order to make the full
558 dynticks working.
559
560 This option stands for testing when an arch implements the
561 context tracking backend but doesn't yet fullfill all the
562 requirements to make the full dynticks feature working.
563 Without the full dynticks, there is no way to test the support
564 for context tracking and the subsystems that rely on it: RCU
565 userspace extended quiescent state and tickless cputime
566 accounting. This option copes with the absence of the full
567 dynticks subsystem by forcing the context tracking on all
568 CPUs in the system.
569
Paul Gortmaker99c8b1e2013-10-24 10:07:47 -0400570 Say Y only if you're working on the development of an
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200571 architecture backend for the context tracking.
572
573 Say N otherwise, this option brings an overhead that you
574 don't want in production.
575
Frederic Weisbeckerd6771242012-10-11 01:48:28 +0200576
Mike Travisc903ff82009-01-15 12:28:29 -0800577config RCU_FANOUT
578 int "Tree-based hierarchical RCU fanout value"
579 range 2 64 if 64BIT
580 range 2 32 if !64BIT
Paul E. McKenney05c5df32015-04-20 14:27:43 -0700581 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Mike Travisc903ff82009-01-15 12:28:29 -0800582 default 64 if 64BIT
583 default 32 if !64BIT
584 help
585 This option controls the fanout of hierarchical implementations
586 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700587 large numbers of CPUs. This value must be at least the fourth
588 root of NR_CPUS, which allows NR_CPUS to be insanely large.
589 The default value of RCU_FANOUT should be used for production
590 systems, but if you are stress-testing the RCU implementation
591 itself, small RCU_FANOUT values allow you to test large-system
592 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800593
594 Select a specific number if testing RCU itself.
595 Take the default if unsure.
596
Paul E. McKenney8932a632012-04-19 12:20:14 -0700597config RCU_FANOUT_LEAF
598 int "Tree-based hierarchical RCU leaf-level fanout value"
Paul E. McKenney8739c5c2015-04-20 18:27:54 -0700599 range 2 64 if 64BIT
600 range 2 32 if !64BIT
Paul E. McKenney47d631a2015-04-21 09:12:13 -0700601 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Paul E. McKenney8932a632012-04-19 12:20:14 -0700602 default 16
603 help
604 This option controls the leaf-level fanout of hierarchical
605 implementations of RCU, and allows trading off cache misses
606 against lock contention. Systems that synchronize their
607 scheduling-clock interrupts for energy-efficiency reasons will
608 want the default because the smaller leaf-level fanout keeps
609 lock contention levels acceptably low. Very large systems
610 (hundreds or thousands of CPUs) will instead want to set this
611 value to the maximum value possible in order to reduce the
612 number of cache misses incurred during RCU's grace-period
613 initialization. These systems tend to run CPU-bound, and thus
614 are not helped by synchronized interrupts, and thus tend to
615 skew them, which reduces lock contention enough that large
616 leaf-level fanouts work well.
617
618 Select a specific number if testing RCU itself.
619
620 Select the maximum permissible value for large systems.
621
622 Take the default if unsure.
623
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800624config RCU_FAST_NO_HZ
625 bool "Accelerate last non-dyntick-idle CPU's grace periods"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700626 depends on NO_HZ_COMMON && SMP && RCU_EXPERT
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800627 default n
628 help
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800629 This option permits CPUs to enter dynticks-idle state even if
630 they have RCU callbacks queued, and prevents RCU from waking
631 these CPUs up more than roughly once every four jiffies (by
632 default, you can adjust this using the rcutree.rcu_idle_gp_delay
633 parameter), thus improving energy efficiency. On the other
634 hand, this option increases the duration of RCU grace periods,
635 for example, slowing down synchronize_rcu().
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800636
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800637 Say Y if energy efficiency is critically important, and you
638 don't care about increased grace-period durations.
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800639
640 Say N if you are unsure.
641
Mike Travisc903ff82009-01-15 12:28:29 -0800642config TREE_RCU_TRACE
Pranith Kumar28f65692014-09-22 14:00:48 -0400643 def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800644 select DEBUG_FS
645 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700646 This option provides tracing for the TREE_RCU and
Pranith Kumar28f65692014-09-22 14:00:48 -0400647 PREEMPT_RCU implementations, permitting Makefile to
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700648 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800649
Paul E. McKenney24278d12010-09-27 17:25:23 -0700650config RCU_BOOST
651 bool "Enable RCU priority boosting"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700652 depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700653 default n
654 help
655 This option boosts the priority of preempted RCU readers that
656 block the current preemptible RCU grace period for too long.
657 This option also prevents heavy loads from blocking RCU
658 callback invocation for all flavors of RCU.
659
660 Say Y here if you are working with real-time apps or heavy loads
661 Say N here if you are unsure.
662
Clark Williams21871d72014-09-12 21:21:09 -0500663config RCU_KTHREAD_PRIO
664 int "Real-time priority to use for RCU worker threads"
Paul E. McKenneya94844b2014-12-12 07:37:48 -0800665 range 1 99 if RCU_BOOST
666 range 0 99 if !RCU_BOOST
667 default 1 if RCU_BOOST
668 default 0 if !RCU_BOOST
Paul E. McKenney26730f52015-04-21 09:22:14 -0700669 depends on RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700670 help
Clark Williams21871d72014-09-12 21:21:09 -0500671 This option specifies the SCHED_FIFO priority value that will be
672 assigned to the rcuc/n and rcub/n threads and is also the value
673 used for RCU_BOOST (if enabled). If you are working with a
674 real-time application that has one or more CPU-bound threads
675 running at a real-time priority level, you should set
676 RCU_KTHREAD_PRIO to a priority higher than the highest-priority
677 real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO
678 value of 1 is appropriate in the common case, which is real-time
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700679 applications that do not have any CPU-bound threads.
680
681 Some real-time applications might not have a single real-time
682 thread that saturates a given CPU, but instead might have
683 multiple real-time threads that, taken together, fully utilize
Clark Williams21871d72014-09-12 21:21:09 -0500684 that CPU. In this case, you should set RCU_KTHREAD_PRIO to
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700685 a priority higher than the lowest-priority thread that is
686 conspiring to prevent the CPU from running any non-real-time
687 tasks. For example, if one thread at priority 10 and another
688 thread at priority 5 are between themselves fully consuming
Clark Williams21871d72014-09-12 21:21:09 -0500689 the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700690 set to priority 6 or higher.
Paul E. McKenney24278d12010-09-27 17:25:23 -0700691
692 Specify the real-time priority, or take the default if unsure.
693
694config RCU_BOOST_DELAY
695 int "Milliseconds to delay boosting after RCU grace-period start"
696 range 0 3000
697 depends on RCU_BOOST
698 default 500
699 help
700 This option specifies the time to wait after the beginning of
701 a given grace period before priority-boosting preempted RCU
702 readers blocking that grace period. Note that any RCU reader
703 blocking an expedited RCU grace period is boosted immediately.
704
705 Accept the default if unsure.
706
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700707config RCU_NOCB_CPU
Paul E. McKenney9a5739d2013-03-28 20:48:36 -0700708 bool "Offload RCU callback processing from boot-selected CPUs"
Pranith Kumar28f65692014-09-22 14:00:48 -0400709 depends on TREE_RCU || PREEMPT_RCU
Paul E. McKenneybe55fa22015-06-02 05:29:18 -0700710 depends on RCU_EXPERT || NO_HZ_FULL
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700711 default n
712 help
713 Use this option to reduce OS jitter for aggressive HPC or
714 real-time workloads. It can also be used to offload RCU
715 callback invocation to energy-efficient CPUs in battery-powered
716 asymmetric multiprocessors.
717
718 This option offloads callback invocation from the set of
719 CPUs specified at boot time by the rcu_nocbs parameter.
Paul E. McKenneya4889852012-12-03 08:16:28 -0800720 For each such CPU, a kthread ("rcuox/N") will be created to
721 invoke callbacks, where the "N" is the CPU being offloaded,
722 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
723 "s" for RCU-sched. Nothing prevents this kthread from running
724 on the specified CPUs, but (1) the kthreads may be preempted
725 between each callback, and (2) affinity or cgroups can be used
726 to force the kthreads to run on whatever set of CPUs is desired.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700727
Paul E. McKenney34ed62462013-01-07 13:37:42 -0800728 Say Y here if you want to help to debug reduced OS jitter.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700729 Say N here if you are unsure.
730
Paul E. McKenney911af502013-02-11 10:23:27 -0800731choice
732 prompt "Build-forced no-CBs CPUs"
733 default RCU_NOCB_CPU_NONE
Stefan Hengelein45687792014-09-02 19:55:11 +0200734 depends on RCU_NOCB_CPU
Paul E. McKenney911af502013-02-11 10:23:27 -0800735 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700736 This option allows no-CBs CPUs (whose RCU callbacks are invoked
737 from kthreads rather than from softirq context) to be specified
738 at build time. Additional no-CBs CPUs may be specified by
739 the rcu_nocbs= boot parameter.
Paul E. McKenney911af502013-02-11 10:23:27 -0800740
741config RCU_NOCB_CPU_NONE
742 bool "No build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800743 help
744 This option does not force any of the CPUs to be no-CBs CPUs.
745 Only CPUs designated by the rcu_nocbs= boot parameter will be
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700746 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
747 kthreads whose names begin with "rcuo". All other CPUs will
748 invoke their own RCU callbacks in softirq context.
749
750 Select this option if you want to choose no-CBs CPUs at
751 boot time, for example, to allow testing of different no-CBs
752 configurations without having to rebuild the kernel each time.
Paul E. McKenney911af502013-02-11 10:23:27 -0800753
754config RCU_NOCB_CPU_ZERO
755 bool "CPU 0 is a build_forced no-CBs CPU"
Paul E. McKenney911af502013-02-11 10:23:27 -0800756 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700757 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
758 callbacks are invoked by a per-CPU kthread whose name begins
759 with "rcuo". Additional CPUs may be designated as no-CBs
760 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
761 All other CPUs will invoke their own RCU callbacks in softirq
762 context.
Paul E. McKenney911af502013-02-11 10:23:27 -0800763
764 Select this if CPU 0 needs to be a no-CBs CPU for real-time
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700765 or energy-efficiency reasons, but the real reason it exists
766 is to ensure that randconfig testing covers mixed systems.
Paul E. McKenney911af502013-02-11 10:23:27 -0800767
768config RCU_NOCB_CPU_ALL
769 bool "All CPUs are build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800770 help
771 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700772 boot parameter will be ignored. All CPUs' RCU callbacks will
773 be executed in the context of per-CPU rcuo kthreads created for
774 this purpose. Assuming that the kthreads whose names start with
775 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
776 on the remaining CPUs, but might decrease memory locality during
777 RCU-callback invocation, thus potentially degrading throughput.
Paul E. McKenney911af502013-02-11 10:23:27 -0800778
779 Select this if all CPUs need to be no-CBs CPUs for real-time
780 or energy-efficiency reasons.
781
782endchoice
783
Paul E. McKenneyee425712015-02-19 10:51:32 -0800784config RCU_EXPEDITE_BOOT
785 bool
786 default n
787 help
788 This option enables expedited grace periods at boot time,
789 as if rcu_expedite_gp() had been invoked early in boot.
790 The corresponding rcu_unexpedite_gp() is invoked from
791 rcu_end_inkernel_boot(), which is intended to be invoked
792 at the end of the kernel-only boot sequence, just before
793 init is exec'ed.
794
795 Accept the default if unsure.
796
Mike Travisc903ff82009-01-15 12:28:29 -0800797endmenu # "RCU Subsystem"
798
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700799config BUILD_BIN2C
800 bool
801 default n
802
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700804 tristate "Kernel .config support"
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700805 select BUILD_BIN2C
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 ---help---
807 This option enables the complete Linux kernel ".config" file
808 contents to be saved in the kernel. It provides documentation
809 of which kernel options are used in a running kernel or in an
810 on-disk kernel. This information can be extracted from the kernel
811 image file with the script scripts/extract-ikconfig and used as
812 input to rebuild the current kernel or to build another kernel.
813 It can also be extracted from a running kernel by reading
814 /proc/config.gz if enabled (below).
815
816config IKCONFIG_PROC
817 bool "Enable access to .config through /proc/config.gz"
818 depends on IKCONFIG && PROC_FS
819 ---help---
820 This option enables access to the kernel configuration file
821 through /proc/config.gz.
822
Alistair John Strachan794543a2007-05-08 00:31:15 -0700823config LOG_BUF_SHIFT
824 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200825 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700826 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700827 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700828 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700829 Select the minimal kernel log buffer size as a power of 2.
830 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
831 parameter, see below. Any higher size also might be forced
832 by "log_buf_len" boot parameter.
833
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700834 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700835 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700836 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700837 15 => 32 KB
838 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700839 13 => 8 KB
840 12 => 4 KB
841
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700842config LOG_CPU_MAX_BUF_SHIFT
843 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700844 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700845 range 0 21
846 default 12 if !BASE_SMALL
847 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700848 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700849 help
850 This option allows to increase the default ring buffer size
851 according to the number of CPUs. The value defines the contribution
852 of each CPU as a power of 2. The used space is typically only few
853 lines however it might be much more when problems are reported,
854 e.g. backtraces.
855
856 The increased size means that a new buffer has to be allocated and
857 the original static one is unused. It makes sense only on systems
858 with more CPUs. Therefore this value is used only when the sum of
859 contributions is greater than the half of the default kernel ring
860 buffer as defined by LOG_BUF_SHIFT. The default values are set
861 so that more than 64 CPUs are needed to trigger the allocation.
862
863 Also this option is ignored when "log_buf_len" kernel parameter is
864 used as it forces an exact (power of two) size of the ring buffer.
865
866 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200867 hotplugging making the computation optimal for the worst case
868 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700869
870 Examples shift values and their meaning:
871 17 => 128 KB for each CPU
872 16 => 64 KB for each CPU
873 15 => 32 KB for each CPU
874 14 => 16 KB for each CPU
875 13 => 8 KB for each CPU
876 12 => 4 KB for each CPU
877
Petr Mladek427934b2016-05-20 17:00:39 -0700878config NMI_LOG_BUF_SHIFT
879 int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
880 range 10 21
881 default 13
882 depends on PRINTK_NMI
883 help
884 Select the size of a per-CPU buffer where NMI messages are temporary
885 stored. They are copied to the main log buffer in a safe context
886 to avoid a deadlock. The value defines the size as a power of 2.
887
888 NMI messages are rare and limited. The largest one is when
889 a backtrace is printed. It usually fits into 4KB. Select
890 8KB if you want to be on the safe side.
891
892 Examples:
893 17 => 128 KB for each CPU
894 16 => 64 KB for each CPU
895 15 => 32 KB for each CPU
896 14 => 16 KB for each CPU
897 13 => 8 KB for each CPU
898 12 => 4 KB for each CPU
899
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800900#
901# Architectures with an unreliable sched_clock() should select this:
902#
903config HAVE_UNSTABLE_SCHED_CLOCK
904 bool
905
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700906config GENERIC_SCHED_CLOCK
907 bool
908
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200909#
910# For architectures that want to enable the support for NUMA-affine scheduler
911# balancing logic:
912#
913config ARCH_SUPPORTS_NUMA_BALANCING
914 bool
915
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100916#
Mel Gorman72b252a2015-09-04 15:47:32 -0700917# For architectures that prefer to flush all TLBs after a number of pages
918# are unmapped instead of sending one IPI per page to flush. The architecture
919# must provide guarantees on what happens if a clean TLB cache entry is
920# written after the unmap. Details are in mm/rmap.c near the check for
921# should_defer_flush. The architecture should also consider if the full flush
922# and the refill costs are offset by the savings of sending fewer IPIs.
923config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
924 bool
925
926#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100927# For architectures that know their GCC __int128 support is sound
928#
929config ARCH_SUPPORTS_INT128
930 bool
931
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200932# For architectures that (ab)use NUMA to represent different memory regions
933# all cpu-local but of different latencies, such as SuperH.
934#
935config ARCH_WANT_NUMA_VARIABLE_LOCALITY
936 bool
937
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200938config NUMA_BALANCING
939 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200940 depends on ARCH_SUPPORTS_NUMA_BALANCING
941 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
942 depends on SMP && NUMA && MIGRATION
943 help
944 This option adds support for automatic NUMA aware memory/task placement.
945 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400946 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200947
948 This system will be inactive on UMA systems.
949
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800950config NUMA_BALANCING_DEFAULT_ENABLED
951 bool "Automatically enable NUMA aware memory/task placement"
952 default y
953 depends on NUMA_BALANCING
954 help
955 If set, automatic NUMA balancing will be enabled if running on a NUMA
956 machine.
957
Li Zefan23964d22009-01-15 13:50:58 -0800958menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500959 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500960 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700961 help
Li Zefan23964d22009-01-15 13:50:58 -0800962 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800963 use with process control subsystems such as Cpusets, CFS, memory
964 controls or device isolation.
965 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800966 - Documentation/scheduler/sched-design-CFS.txt (CFS)
seokhoon.yoon9991a9c2016-08-02 14:03:13 -0700967 - Documentation/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800968 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700969
970 Say N if unsure.
971
Li Zefan23964d22009-01-15 13:50:58 -0800972if CGROUPS
973
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800974config PAGE_COUNTER
975 bool
976
Andrew Mortonc255a452012-07-31 16:43:02 -0700977config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500978 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800979 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500980 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800981 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500982 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800983
Andrew Mortonc255a452012-07-31 16:43:02 -0700984config MEMCG_SWAP
Johannes Weinera0166ec2015-12-17 17:19:56 -0500985 bool "Swap controller"
Andrew Mortonc255a452012-07-31 16:43:02 -0700986 depends on MEMCG && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800987 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500988 Provides control over the swap space consumed by tasks in a cgroup.
989
Andrew Mortonc255a452012-07-31 16:43:02 -0700990config MEMCG_SWAP_ENABLED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500991 bool "Swap controller enabled by default"
Andrew Mortonc255a452012-07-31 16:43:02 -0700992 depends on MEMCG_SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800993 default y
994 help
995 Memory Resource Controller Swap Extension comes with its price in
996 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -0700997 which want to enable the feature but keep it disabled by default
Michal Hocko07555ac2013-08-22 16:35:46 -0700998 and let the user enable it by swapaccount=1 boot command line
Michal Hockoa42c3902010-11-24 12:57:08 -0800999 parameter should have this option unselected.
1000 For those who want to have the feature enabled by default should
1001 select this option (if, for some reason, they need to disable it
WANG Cong00a66d22011-07-25 17:12:12 -07001002 then swapaccount=0 does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001003
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001004config BLK_CGROUP
1005 bool "IO controller"
1006 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001007 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001008 ---help---
1009 Generic block IO controller cgroup interface. This is the common
1010 cgroup interface which should be used by various IO controlling
1011 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001012
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001013 Currently, CFQ IO scheduler uses it to recognize task groups and
1014 control disk bandwidth allocation (proportional time slice allocation)
1015 to such task groups. It is also used by bio throttling logic in
1016 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +02001017
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001018 This option only enables generic Block IO controller infrastructure.
1019 One needs to also enable actual IO controlling logic/policy. For
1020 enabling proportional weight division of disk bandwidth in CFQ, set
1021 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1022 CONFIG_BLK_DEV_THROTTLING=y.
1023
seokhoon.yoon9991a9c2016-08-02 14:03:13 -07001024 See Documentation/cgroup-v1/blkio-controller.txt for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001025
1026config DEBUG_BLK_CGROUP
1027 bool "IO controller debugging"
1028 depends on BLK_CGROUP
1029 default n
1030 ---help---
1031 Enable some debugging help. Currently it exports additional stat
1032 files in a cgroup which can be useful for debugging.
1033
1034config CGROUP_WRITEBACK
1035 bool
1036 depends on MEMCG && BLK_CGROUP
1037 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +02001038
Dhaval Giani7c941432010-01-20 13:26:18 +01001039menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001040 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001041 default n
1042 help
1043 This feature lets CPU scheduler recognize task groups and control CPU
1044 bandwidth allocation to such task groups. It uses cgroups to group
1045 tasks.
1046
1047if CGROUP_SCHED
1048config FAIR_GROUP_SCHED
1049 bool "Group scheduling for SCHED_OTHER"
1050 depends on CGROUP_SCHED
1051 default CGROUP_SCHED
1052
Paul Turnerab84d312011-07-21 09:43:28 -07001053config CFS_BANDWIDTH
1054 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001055 depends on FAIR_GROUP_SCHED
1056 default n
1057 help
1058 This option allows users to define CPU bandwidth rates (limits) for
1059 tasks running within the fair group scheduler. Groups with no limit
1060 set are considered to be unconstrained and will run with no
1061 restriction.
1062 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1063
Dhaval Giani7c941432010-01-20 13:26:18 +01001064config RT_GROUP_SCHED
1065 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001066 depends on CGROUP_SCHED
1067 default n
1068 help
1069 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001070 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001071 schedule realtime tasks for non-root users until you allocate
1072 realtime bandwidth for them.
1073 See Documentation/scheduler/sched-rt-group.txt for more information.
1074
1075endif #CGROUP_SCHED
1076
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001077config CGROUP_PIDS
1078 bool "PIDs controller"
1079 help
1080 Provides enforcement of process number limits in the scope of a
1081 cgroup. Any attempt to fork more processes than is allowed in the
1082 cgroup will fail. PIDs are fundamentally a global resource because it
1083 is fairly trivial to reach PID exhaustion before you reach even a
1084 conservative kmemcg limit. As a result, it is possible to grind a
1085 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301086 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001087
1088 It should be noted that organisational operations (such as attaching
Parav Pandit6cc578d2016-03-05 11:30:56 +05301089 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001090 since the PIDs limit only affects a process's ability to fork, not to
1091 attach to a cgroup.
1092
1093config CGROUP_FREEZER
1094 bool "Freezer controller"
1095 help
1096 Provides a way to freeze and unfreeze all tasks in a
1097 cgroup.
1098
Johannes Weiner489c2a22016-01-20 15:02:41 -08001099 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1100 controller includes important in-kernel memory consumers per default.
1101
1102 If you're using cgroup2, say N.
1103
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001104config CGROUP_HUGETLB
1105 bool "HugeTLB controller"
1106 depends on HUGETLB_PAGE
1107 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001108 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001109 help
1110 Provides a cgroup controller for HugeTLB pages.
1111 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1112 The limit is enforced during page fault. Since HugeTLB doesn't
1113 support page reclaim, enforcing the limit at page fault time implies
1114 that, the application will get SIGBUS signal if it tries to access
1115 HugeTLB pages beyond its limit. This requires the application to know
1116 beforehand how much HugeTLB pages it would require for its use. The
1117 control group is tracked in the third page lru pointer. This means
1118 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001119
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001120config CPUSETS
1121 bool "Cpuset controller"
1122 help
1123 This option will let you create and manage CPUSETs which
1124 allow dynamically partitioning a system into sets of CPUs and
1125 Memory Nodes and assigning tasks to run only within those sets.
1126 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001127
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001128 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001129
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001130config PROC_PID_CPUSET
1131 bool "Include legacy /proc/<pid>/cpuset file"
1132 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001133 default y
1134
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001135config CGROUP_DEVICE
1136 bool "Device controller"
1137 help
1138 Provides a cgroup controller implementing whitelists for
1139 devices which a process in the cgroup can mknod or open.
1140
1141config CGROUP_CPUACCT
1142 bool "Simple CPU accounting controller"
1143 help
1144 Provides a simple controller for monitoring the
1145 total CPU consumed by the tasks in a cgroup.
1146
1147config CGROUP_PERF
1148 bool "Perf controller"
1149 depends on PERF_EVENTS
1150 help
1151 This option extends the perf per-cpu mode to restrict monitoring
1152 to threads which belong to the cgroup specified and run on the
1153 designated cpu.
1154
1155 Say N if unsure.
1156
Daniel Mack30070982016-11-23 16:52:26 +01001157config CGROUP_BPF
1158 bool "Support for eBPF programs attached to cgroups"
Andy Lutomirski483c4932016-12-16 08:33:45 -08001159 depends on BPF_SYSCALL
1160 select SOCK_CGROUP_DATA
Daniel Mack30070982016-11-23 16:52:26 +01001161 help
1162 Allow attaching eBPF programs to a cgroup using the bpf(2)
1163 syscall command BPF_PROG_ATTACH.
1164
1165 In which context these programs are accessed depends on the type
1166 of attachment. For instance, programs that are attached using
1167 BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1168 inet sockets.
1169
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001170config CGROUP_DEBUG
1171 bool "Example controller"
1172 default n
1173 help
1174 This option enables a simple controller that exports
1175 debugging information about the cgroups framework.
1176
1177 Say N.
1178
Arnd Bergmann73b35142017-01-10 13:08:06 +01001179config SOCK_CGROUP_DATA
1180 bool
1181 default n
1182
Li Zefan23964d22009-01-15 13:50:58 -08001183endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001184
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001185config CHECKPOINT_RESTORE
1186 bool "Checkpoint/restore support" if EXPERT
Iago López Galeiras2e13ba52015-06-25 15:00:57 -07001187 select PROC_CHILDREN
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001188 default n
1189 help
1190 Enables additional kernel features in a sake of checkpoint/restore.
1191 In particular it adds auxiliary prctl codes to setup process text,
1192 data and heap segment sizes, and a few additional /proc filesystem
1193 entries.
1194
1195 If unsure, say N here.
1196
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001197menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001198 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001199 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001200 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001201 help
1202 Provides the way to make tasks work with different objects using
1203 the same id. For example same IPC id may refer to different objects
1204 or same user id or pid may refer to different tasks when used in
1205 different namespaces.
1206
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001207if NAMESPACES
1208
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001209config UTS_NS
1210 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001211 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001212 help
1213 In this namespace tasks see different info provided with the
1214 uname() system call
1215
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001216config IPC_NS
1217 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001218 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001219 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001220 help
1221 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001222 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001223
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001224config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001225 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001226 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001227 help
1228 This allows containers, i.e. vservers, to use user namespaces
1229 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001230
1231 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001232 recommended that the MEMCG option also be enabled and that
1233 user-space use the memory control groups to limit the amount
1234 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001235
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001236 If unsure, say N.
1237
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001238config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001239 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001240 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001241 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001242 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001243 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001244 pid namespaces. This is a building block of containers.
1245
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001246config NET_NS
1247 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001248 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001249 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001250 help
1251 Allow user space to create what appear to be multiple instances
1252 of the network stack.
1253
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001254endif # NAMESPACES
1255
Mike Galbraith5091faa2010-11-30 14:18:03 +01001256config SCHED_AUTOGROUP
1257 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001258 select CGROUPS
1259 select CGROUP_SCHED
1260 select FAIR_GROUP_SCHED
1261 help
1262 This option optimizes the scheduler for common desktop workloads by
1263 automatically creating and populating task groups. This separation
1264 of workloads isolates aggressive CPU burners (like build jobs) from
1265 desktop applications. Task group autogeneration is currently based
1266 upon task session.
1267
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001268config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001269 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001270 depends on SYSFS
1271 default n
1272 help
1273 This option adds code that switches the layout of the "block" class
1274 devices, to not show up in /sys/class/block/, but only in
1275 /sys/block/.
1276
1277 This switch is only active when the sysfs.deprecated=1 boot option is
1278 passed or the SYSFS_DEPRECATED_V2 option is set.
1279
1280 This option allows new kernels to run on old distributions and tools,
1281 which might get confused by /sys/class/block/. Since 2007/2008 all
1282 major distributions and tools handle this just fine.
1283
1284 Recent distributions and userspace tools after 2009/2010 depend on
1285 the existence of /sys/class/block/, and will not work with this
1286 option enabled.
1287
1288 Only if you are using a new kernel on an old distribution, you might
1289 need to say Y here.
1290
1291config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001292 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001293 default n
1294 depends on SYSFS
1295 depends on SYSFS_DEPRECATED
1296 help
1297 Enable deprecated sysfs by default.
1298
1299 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1300 option.
1301
1302 Only if you are using a new kernel on an old distribution, you might
1303 need to say Y here. Even then, odds are you would not need it
1304 enabled, you can always pass the boot option if absolutely necessary.
1305
1306config RELAY
1307 bool "Kernel->user space relay support (formerly relayfs)"
Peter Zijlstra26b56792016-10-11 13:54:33 -07001308 select IRQ_WORK
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001309 help
1310 This option enables support for relay interface support in
1311 certain file systems (such as debugfs).
1312 It is designed to provide an efficient mechanism for tools and
1313 facilities to relay large amounts of data from kernel space to
1314 user space.
1315
1316 If unsure, say N.
1317
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001318config BLK_DEV_INITRD
1319 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1320 depends on BROKEN || !FRV
1321 help
1322 The initial RAM filesystem is a ramfs which is loaded by the
1323 boot loader (loadlin or lilo) and that is mounted as root
1324 before the normal boot procedure. It is typically used to
1325 load modules needed to mount the "real" root file system,
Mauro Carvalho Chehab8c27ceff32016-10-18 10:12:27 -02001326 etc. See <file:Documentation/admin-guide/initrd.rst> for details.
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001327
1328 If RAM disk support (BLK_DEV_RAM) is also included, this
1329 also enables initial RAM disk (initrd) support and adds
1330 15 Kbytes (more on some other architectures) to the kernel size.
1331
1332 If unsure say Y.
1333
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001334if BLK_DEV_INITRD
1335
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001336source "usr/Kconfig"
1337
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001338endif
1339
Arnd Bergmann877417e2016-04-25 17:35:27 +02001340choice
1341 prompt "Compiler optimization level"
1342 default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
1343
1344config CC_OPTIMIZE_FOR_PERFORMANCE
1345 bool "Optimize for performance"
1346 help
1347 This is the default optimization level for the kernel, building
1348 with the "-O2" compiler flag for best performance and most
1349 helpful compile-time warnings.
1350
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001351config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +02001352 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001353 help
Masahiro Yamada31a4af72014-08-05 14:43:07 +09001354 Enabling this option will pass "-Os" instead of "-O2" to
1355 your compiler resulting in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001356
Kirill Smelkov3a55fb02012-11-02 15:41:01 +04001357 If unsure, say N.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001358
Arnd Bergmann877417e2016-04-25 17:35:27 +02001359endchoice
1360
Randy Dunlap08470622006-09-30 23:28:13 -07001361config SYSCTL
1362 bool
1363
Randy Dunlapb943c462009-03-10 12:55:46 -07001364config ANON_INODES
1365 bool
1366
Mike Frysinger657a5202013-04-30 15:28:45 -07001367config HAVE_UID16
1368 bool
1369
1370config SYSCTL_EXCEPTION_TRACE
1371 bool
1372 help
1373 Enable support for /proc/sys/debug/exception-trace.
1374
1375config SYSCTL_ARCH_UNALIGN_NO_WARN
1376 bool
1377 help
1378 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1379 Allows arch to define/use @no_unaligned_warning to possibly warn
1380 about unaligned access emulation going on under the hood.
1381
1382config SYSCTL_ARCH_UNALIGN_ALLOW
1383 bool
1384 help
1385 Enable support for /proc/sys/kernel/unaligned-trap
1386 Allows arches to define/use @unaligned_enabled to runtime toggle
1387 the unaligned access emulation.
1388 see arch/parisc/kernel/unaligned.c for reference
1389
Mike Frysinger657a5202013-04-30 15:28:45 -07001390config HAVE_PCSPKR_PLATFORM
1391 bool
1392
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001393# interpreter that classic socket filters depend on
1394config BPF
1395 bool
1396
David Rientjes6a108a12011-01-20 14:44:16 -08001397menuconfig EXPERT
1398 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001399 # Unhide debug options, to make the on-by-default options visible
1400 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 help
1402 This option allows certain base kernel options and settings
1403 to be disabled or tweaked. This is for specialized
1404 environments which can tolerate a "non-standard" kernel.
1405 Only use this if you really know what you are doing.
1406
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001407config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001408 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001409 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001410 default y
1411 help
1412 This enables the legacy 16-bit UID syscall wrappers.
1413
Iulia Manda28138932015-04-15 16:16:41 -07001414config MULTIUSER
1415 bool "Multiple users, groups and capabilities support" if EXPERT
1416 default y
1417 help
1418 This option enables support for non-root users, groups and
1419 capabilities.
1420
1421 If you say N here, all processes will run with UID 0, GID 0, and all
1422 possible capabilities. Saying N here also compiles out support for
1423 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1424 setgid, and capset.
1425
1426 If unsure, say Y here.
1427
Fabian Frederickf6187762014-06-04 16:11:12 -07001428config SGETMASK_SYSCALL
1429 bool "sgetmask/ssetmask syscalls support" if EXPERT
1430 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1431 ---help---
1432 sys_sgetmask and sys_ssetmask are obsolete system calls
1433 no longer supported in libc but still enabled by default in some
1434 architectures.
1435
1436 If unsure, leave the default option here.
1437
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001438config SYSFS_SYSCALL
1439 bool "Sysfs syscall support" if EXPERT
1440 default y
1441 ---help---
1442 sys_sysfs is an obsolete system call no longer supported in libc.
1443 Note that disabling this option is more secure but might break
1444 compatibility with some systems.
1445
1446 If unsure say Y here.
1447
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001448config SYSCTL_SYSCALL
David Rientjes6a108a12011-01-20 14:44:16 -08001449 bool "Sysctl syscall support" if EXPERT
Eric W. Biederman26a70342009-11-05 05:26:41 -08001450 depends on PROC_SYSCTL
WANG Congc736de62011-11-02 13:39:25 -07001451 default n
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001452 select SYSCTL
1453 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001454 sys_sysctl uses binary paths that have been found challenging
1455 to properly maintain and use. The interface in /proc/sys
1456 using paths with ascii names is now the primary path to this
1457 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001458
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001459 Almost nothing using the binary sysctl interface so if you are
1460 trying to save some space it is probably safe to disable this,
1461 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001462
WANG Congc736de62011-11-02 13:39:25 -07001463 If unsure say N here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001464
Nicolas Pitrebaa73d92016-11-11 00:10:10 -05001465config POSIX_TIMERS
1466 bool "Posix Clocks & timers" if EXPERT
1467 default y
1468 help
1469 This includes native support for POSIX timers to the kernel.
1470 Some embedded systems have no use for them and therefore they
1471 can be configured out to reduce the size of the kernel image.
1472
1473 When this option is disabled, the following syscalls won't be
1474 available: timer_create, timer_gettime: timer_getoverrun,
1475 timer_settime, timer_delete, clock_adjtime, getitimer,
1476 setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1477 clock_getres and clock_nanosleep syscalls will be limited to
1478 CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1479
1480 If unsure say y.
1481
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482config KALLSYMS
David Rientjes6a108a12011-01-20 14:44:16 -08001483 bool "Load all symbols for debugging/ksymoops" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 default y
1485 help
1486 Say Y here to let the kernel print out symbolic crash information and
1487 symbolic stack backtraces. This increases the size of the kernel
1488 somewhat, as all symbols have to be loaded into the kernel image.
1489
1490config KALLSYMS_ALL
1491 bool "Include all symbols in kallsyms"
1492 depends on DEBUG_KERNEL && KALLSYMS
1493 help
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001494 Normally kallsyms only contains the symbols of functions for nicer
1495 OOPS messages and backtraces (i.e., symbols from the text and inittext
1496 sections). This is sufficient for most cases. And only in very rare
1497 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1498 names of variables from the data sections, etc).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001500 This option makes sure that all symbols are loaded into the kernel
1501 image (i.e., symbols from all sections) in cost of increased kernel
1502 size (depending on the kernel configuration, it may be 300KiB or
1503 something like this).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001505 Say N unless you really need all symbols.
Matt Mackalld59745c2005-05-01 08:59:02 -07001506
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001507config KALLSYMS_ABSOLUTE_PERCPU
1508 bool
Randy Dunlap076501f2016-07-06 16:06:53 -07001509 depends on KALLSYMS
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001510 default X86_64 && SMP
1511
Ard Biesheuvel2213e9a2016-03-15 14:58:19 -07001512config KALLSYMS_BASE_RELATIVE
1513 bool
1514 depends on KALLSYMS
1515 default !IA64 && !(TILE && 64BIT)
1516 help
1517 Instead of emitting them as absolute values in the native word size,
1518 emit the symbol references in the kallsyms table as 32-bit entries,
1519 each containing a relative value in the range [base, base + U32_MAX]
1520 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1521 an absolute value in the range [0, S32_MAX] or a relative value in the
1522 range [base, base + S32_MAX], where base is the lowest relative symbol
1523 address encountered in the image.
1524
1525 On 64-bit builds, this reduces the size of the address table by 50%,
1526 but more importantly, it results in entries whose values are build
1527 time constants, and no relocation pass is required at runtime to fix
1528 up the entries based on the runtime load address of the kernel.
1529
Matt Mackalld59745c2005-05-01 08:59:02 -07001530config PRINTK
1531 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001532 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001533 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001534 help
1535 This option enables normal printk support. Removing it
1536 eliminates most of the message strings from the kernel image
1537 and makes the kernel more or less silent. As this makes it
1538 very difficult to diagnose system problems, saying N here is
1539 strongly discouraged.
1540
Petr Mladek42a0bb32016-05-20 17:00:33 -07001541config PRINTK_NMI
1542 def_bool y
1543 depends on PRINTK
1544 depends on HAVE_NMI
1545
Matt Mackallc8538a72005-05-01 08:59:01 -07001546config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001547 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001548 default y
1549 help
1550 Disabling this option eliminates support for BUG and WARN, reducing
1551 the size of your kernel image and potentially quietly ignoring
1552 numerous fatal conditions. You should only consider disabling this
1553 option for embedded systems with no facilities for reporting errors.
1554 Just say Y.
1555
Matt Mackall708e9a72006-01-08 01:05:25 -08001556config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001557 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001558 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001559 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001560 help
1561 Enable support for generating core dumps. Disabling saves about 4k.
1562
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001563
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001564config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001565 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001566 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001567 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001568 default y
1569 help
1570 This option allows to disable the internal PC-Speaker
1571 support, saving some memory.
1572
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573config BASE_FULL
1574 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001575 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576 help
1577 Disabling this option reduces the size of miscellaneous core
1578 kernel data structures. This saves memory on small machines,
1579 but may reduce performance.
1580
1581config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001582 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -07001584 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585 help
1586 Disabling this option will cause the kernel to be built without
1587 support for "fast userspace mutexes". The resulting kernel may not
1588 run glibc-based applications correctly.
1589
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001590config HAVE_FUTEX_CMPXCHG
1591 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001592 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001593 help
1594 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1595 is implemented and always working. This removes a couple of runtime
1596 checks.
1597
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001599 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001601 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602 help
1603 Disabling this option will cause the kernel to be built without
1604 support for epoll family of system calls.
1605
Davide Libenzifba2afa2007-05-10 22:23:13 -07001606config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001607 bool "Enable signalfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001608 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001609 default y
1610 help
1611 Enable the signalfd() system call that allows to receive signals
1612 on a file descriptor.
1613
1614 If unsure, say Y.
1615
Davide Libenzib215e282007-05-10 22:23:16 -07001616config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001617 bool "Enable timerfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001618 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001619 default y
1620 help
1621 Enable the timerfd() system call that allows to receive timer
1622 events on a file descriptor.
1623
1624 If unsure, say Y.
1625
Davide Libenzie1ad7462007-05-10 22:23:19 -07001626config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001627 bool "Enable eventfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001628 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001629 default y
1630 help
1631 Enable the eventfd() system call that allows to receive both
1632 kernel notification (ie. KAIO) or userspace notifications.
1633
1634 If unsure, say Y.
1635
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001636# syscall, maps, verifier
1637config BPF_SYSCALL
Ingo Molnare1abf2c2015-04-02 15:51:39 +02001638 bool "Enable bpf() system call"
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001639 select ANON_INODES
1640 select BPF
1641 default n
1642 help
1643 Enable the bpf() system call that allows to manipulate eBPF
1644 programs and maps via file descriptors.
1645
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001647 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648 default y
1649 depends on MMU
1650 help
1651 The shmem is an internal filesystem used to manage shared memory.
1652 It is backed by swap and manages resource limits. It is also exported
1653 to userspace as tmpfs if TMPFS is enabled. Disabling this
1654 option replaces shmem and tmpfs with the much simpler ramfs code,
1655 which may be appropriate on small systems without swap.
1656
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001657config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001658 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001659 default y
1660 help
1661 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001662 by some high performance threaded applications. Disabling
1663 this option saves about 7k.
1664
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001665config ADVISE_SYSCALLS
1666 bool "Enable madvise/fadvise syscalls" if EXPERT
1667 default y
1668 help
1669 This option enables the madvise and fadvise syscalls, used by
1670 applications to advise the kernel about their future memory or file
1671 usage, improving performance. If building an embedded system where no
1672 applications use these syscalls, you can disable this option to save
1673 space.
1674
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001675config USERFAULTFD
1676 bool "Enable userfaultfd() system call"
1677 select ANON_INODES
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001678 depends on MMU
1679 help
1680 Enable the userfaultfd() system call that allows to intercept and
1681 handle page faults in userland.
1682
Mike Frysinger657a5202013-04-30 15:28:45 -07001683config PCI_QUIRKS
1684 default y
1685 bool "Enable PCI quirk workarounds" if EXPERT
1686 depends on PCI
1687 help
1688 This enables workarounds for various PCI chipset
1689 bugs/quirks. Disable this only if your target machine is
1690 unaffected by PCI quirks.
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001691
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001692config MEMBARRIER
1693 bool "Enable membarrier() system call" if EXPERT
1694 default y
1695 help
1696 Enable the membarrier() system call that allows issuing memory
1697 barriers across all running threads, which can be used to distribute
1698 the cost of user-space memory barriers asymmetrically by transforming
1699 pairs of memory barriers into pairs consisting of membarrier() and a
1700 compiler barrier.
1701
1702 If unsure, say Y.
1703
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001704config EMBEDDED
1705 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001706 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001707 select EXPERT
1708 help
1709 This option should be enabled if compiling the kernel for
1710 an embedded system so certain expert options are available
1711 for configuration.
1712
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001713config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001714 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001715 help
1716 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001717
Peter Zijlstra906010b2009-09-21 16:08:49 +02001718config PERF_USE_VMALLOC
1719 bool
1720 help
1721 See tools/perf/design.txt for details
1722
Ingo Molnar57c0c152009-09-21 12:20:38 +02001723menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001724
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001725config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001726 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001727 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001728 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001729 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001730 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001731 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001732 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001733 Enable kernel support for various performance events provided
1734 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001735
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001736 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001737 use of generic tracepoints.
1738
1739 Most modern CPUs support performance events via performance
1740 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001741 types of hw events: such as instructions executed, cachemisses
1742 suffered, or branches mis-predicted - without slowing down the
1743 kernel or applications. These registers can also trigger interrupts
1744 when a threshold number of events have passed - and can thus be
1745 used to profile the code that runs on that CPU.
1746
Ingo Molnar57c0c152009-09-21 12:20:38 +02001747 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001748 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001749 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001750 provides per task and per CPU counters, and it provides event
1751 capabilities on top of those.
1752
1753 Say Y if unsure.
1754
Peter Zijlstra906010b2009-09-21 16:08:49 +02001755config DEBUG_PERF_USE_VMALLOC
1756 default n
1757 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb307112015-05-04 16:26:39 +10001758 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001759 select PERF_USE_VMALLOC
1760 help
1761 Use vmalloc memory to back perf mmap() buffers.
1762
1763 Mostly useful for debugging the vmalloc code on platforms
1764 that don't require it.
1765
1766 Say N if unsure.
1767
Thomas Gleixner0793a612008-12-04 20:12:29 +01001768endmenu
1769
Christoph Lameterf8891e52006-06-30 01:55:45 -07001770config VM_EVENT_COUNTERS
1771 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001772 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001773 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001774 VM event counters are needed for event counts to be shown.
1775 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001776 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001777 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001778
Christoph Lameter41ecc552007-05-09 02:32:44 -07001779config SLUB_DEBUG
1780 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001781 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001782 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001783 help
1784 SLUB has extensive debug support features. Disabling these can
1785 result in significant savings in code size. This also disables
1786 SLUB sysfs support. /sys/slab will not exist and there will be
1787 no support for cache validation etc.
1788
Randy Dunlapb943c462009-03-10 12:55:46 -07001789config COMPAT_BRK
1790 bool "Disable heap randomization"
1791 default y
1792 help
1793 Randomizing heap placement makes heap exploits harder, but it
1794 also breaks ancient binaries (including anything libc5 based).
1795 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001796 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001797 /proc/sys/kernel/randomize_va_space to 2.
1798
1799 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1800
Christoph Lameter81819f02007-05-06 14:49:36 -07001801choice
1802 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001803 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001804 help
1805 This option allows to select a slab allocator.
1806
1807config SLAB
1808 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001809 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001810 help
1811 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001812 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001813 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001814
1815config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001816 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001817 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001818 help
1819 SLUB is a slab allocator that minimizes cache line usage
1820 instead of managing queues of cached objects (SLAB approach).
1821 Per cpu caching is realized using slabs of objects instead
1822 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001823 and has enhanced diagnostics. SLUB is the default choice for
1824 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001825
1826config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001827 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001828 bool "SLOB (Simple Allocator)"
1829 help
Matt Mackall37291452008-02-04 22:29:38 -08001830 SLOB replaces the stock allocator with a drastically simpler
1831 allocator. SLOB is generally more space efficient but
1832 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001833
1834endchoice
1835
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001836config SLAB_FREELIST_RANDOM
1837 default n
Thomas Garnier210e7a42016-07-26 15:21:59 -07001838 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001839 bool "SLAB freelist randomization"
1840 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07001841 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001842 security feature reduces the predictability of the kernel slab
1843 allocator against heap overflows.
1844
Joonsoo Kim345c9052013-06-19 14:05:52 +09001845config SLUB_CPU_PARTIAL
1846 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001847 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001848 bool "SLUB per cpu partial cache"
1849 help
1850 Per cpu partial caches accellerate objects allocation and freeing
1851 that is local to a processor at the price of more indeterminism
1852 in the latency of the free. On overflow these caches will be cleared
1853 which requires the taking of locks that may cause latency spikes.
1854 Typically one would choose no for a realtime system.
1855
Jie Zhangea637632009-12-14 18:00:02 -08001856config MMAP_ALLOW_UNINITIALIZED
1857 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001858 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001859 default n
1860 help
1861 Normally, and according to the Linux spec, anonymous memory obtained
1862 from mmap() has it's contents cleared before it is passed to
1863 userspace. Enabling this config option allows you to request that
1864 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1865 providing a huge performance boost. If this option is not enabled,
1866 then the flag will be ignored.
1867
1868 This is taken advantage of by uClibc's malloc(), and also by
1869 ELF-FDPIC binfmt's brk and stack allocator.
1870
1871 Because of the obvious security issues, this option should only be
1872 enabled on embedded devices where you control what is run in
1873 userspace. Since that isn't generally a problem on no-MMU systems,
1874 it is normally safe to say Y here.
1875
1876 See Documentation/nommu-mmap.txt for more information.
1877
David Howells091f6e22015-07-20 21:16:28 +01001878config SYSTEM_DATA_VERIFICATION
1879 def_bool n
1880 select SYSTEM_TRUSTED_KEYRING
1881 select KEYS
1882 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001883 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001884 select ASYMMETRIC_KEY_TYPE
1885 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001886 select ASN1
1887 select OID_REGISTRY
1888 select X509_CERTIFICATE_PARSER
1889 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001890 help
David Howells091f6e22015-07-20 21:16:28 +01001891 Provide PKCS#7 message verification using the contents of the system
1892 trusted keyring to provide public keys. This then can be used for
1893 module verification, kexec image verification and firmware blob
1894 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001895
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001896config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001897 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001898 help
1899 Say Y here to enable the extended profiling support mechanisms used
1900 by profilers such as OProfile.
1901
Ingo Molnar5f87f112008-07-23 14:15:22 +02001902#
1903# Place an empty function call at each tracepoint site. Can be
1904# dynamically changed for a probe function.
1905#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001906config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001907 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001908
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05001909source "arch/Kconfig"
1910
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911endmenu # General setup
1912
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04001913config HAVE_GENERIC_DMA_COHERENT
1914 bool
1915 default n
1916
Linus Torvalds158a9622008-01-02 13:04:48 -08001917config SLABINFO
1918 bool
1919 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03001920 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08001921 default y
1922
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001923config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001924 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001925
Linus Torvalds1da177e2005-04-16 15:20:36 -07001926config BASE_SMALL
1927 int
1928 default 0 if BASE_FULL
1929 default 1 if !BASE_FULL
1930
Jan Engelhardt66da5732007-07-15 23:39:29 -07001931menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02001933 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 help
1935 Kernel modules are small pieces of compiled code which can
1936 be inserted in the running kernel, rather than being
1937 permanently built into the kernel. You use the "modprobe"
1938 tool to add (and sometimes remove) them. If you say Y here,
1939 many parts of the kernel can be built as modules (by
1940 answering M instead of Y where indicated): this is most
1941 useful for infrequently used options which are not required
1942 for booting. For more information, see the man pages for
1943 modprobe, lsmod, modinfo, insmod and rmmod.
1944
1945 If you say Y here, you will need to run "make
1946 modules_install" to put the modules under /lib/modules/
1947 where modprobe can find them (you may need to be root to do
1948 this).
1949
1950 If unsure, say Y.
1951
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001952if MODULES
1953
Linus Torvalds826e4502008-05-04 17:04:16 -07001954config MODULE_FORCE_LOAD
1955 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001956 default n
1957 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001958 Allow loading of modules without version information (ie. modprobe
1959 --force). Forced module loading sets the 'F' (forced) taint flag and
1960 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001961
Linus Torvalds1da177e2005-04-16 15:20:36 -07001962config MODULE_UNLOAD
1963 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001964 help
1965 Without this option you will not be able to unload any
1966 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001967 anyway), which makes your kernel smaller, faster
1968 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969
1970config MODULE_FORCE_UNLOAD
1971 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07001972 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973 help
1974 This option allows you to force a module to unload, even if the
1975 kernel believes it is unsafe: the kernel will remove the module
1976 without waiting for anyone to stop using it (using the -f option to
1977 rmmod). This is mainly for kernel developers and desperate users.
1978 If unsure, say N.
1979
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001981 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 help
1983 Usually, you have to use modules compiled with your kernel.
1984 Saying Y here makes it sometimes possible to use modules
1985 compiled for different kernels, by adding enough information
1986 to the modules to (hopefully) spot any changes which would
1987 make them incompatible with the kernel you are running. If
1988 unsure, say N.
1989
1990config MODULE_SRCVERSION_ALL
1991 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001992 help
1993 Modules which contain a MODULE_VERSION get an extra "srcversion"
1994 field inserted into their modinfo section, which contains a
1995 sum of the source files which made it. This helps maintainers
1996 see exactly which source was used to build a module (since
1997 others sometimes change the module source without updating
1998 the version). With this option, such a "srcversion" field
1999 will be created for all modules. If unsure, say N.
2000
Rusty Russell106a4ee2012-09-26 10:09:40 +01002001config MODULE_SIG
2002 bool "Module signature verification"
2003 depends on MODULES
David Howells091f6e22015-07-20 21:16:28 +01002004 select SYSTEM_DATA_VERIFICATION
Rusty Russell106a4ee2012-09-26 10:09:40 +01002005 help
2006 Check modules for valid signatures upon load: the signature
2007 is simply appended to the module. For more information see
2008 Documentation/module-signing.txt.
2009
David Howells228c37f2015-08-11 12:38:54 +01002010 Note that this option adds the OpenSSL development packages as a
2011 kernel build dependency so that the signing tool can use its crypto
2012 library.
2013
David Howellsea0b6dc2012-09-26 10:09:50 +01002014 !!!WARNING!!! If you enable this option, you MUST make sure that the
2015 module DOES NOT get stripped after being signed. This includes the
2016 debuginfo strip done by some packagers (such as rpmbuild) and
2017 inclusion into an initramfs that wants the module size reduced.
2018
Rusty Russell106a4ee2012-09-26 10:09:40 +01002019config MODULE_SIG_FORCE
2020 bool "Require modules to be validly signed"
2021 depends on MODULE_SIG
2022 help
2023 Reject unsigned modules or signed modules for which we don't have a
2024 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01002025
Michal Marekd9d8d7e2013-01-25 13:41:31 +10302026config MODULE_SIG_ALL
2027 bool "Automatically sign all modules"
2028 default y
2029 depends on MODULE_SIG
2030 help
2031 Sign all modules during make modules_install. Without this option,
2032 modules must be signed manually, using the scripts/sign-file tool.
2033
2034comment "Do not forget to sign required modules with scripts/sign-file"
2035 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2036
David Howellsea0b6dc2012-09-26 10:09:50 +01002037choice
2038 prompt "Which hash algorithm should modules be signed with?"
2039 depends on MODULE_SIG
2040 help
2041 This determines which sort of hashing algorithm will be used during
2042 signature generation. This algorithm _must_ be built into the kernel
2043 directly so that signature verification can take place. It is not
2044 possible to load a signed module containing the algorithm to check
2045 the signature on that module.
2046
2047config MODULE_SIG_SHA1
2048 bool "Sign modules with SHA-1"
2049 select CRYPTO_SHA1
2050
2051config MODULE_SIG_SHA224
2052 bool "Sign modules with SHA-224"
2053 select CRYPTO_SHA256
2054
2055config MODULE_SIG_SHA256
2056 bool "Sign modules with SHA-256"
2057 select CRYPTO_SHA256
2058
2059config MODULE_SIG_SHA384
2060 bool "Sign modules with SHA-384"
2061 select CRYPTO_SHA512
2062
2063config MODULE_SIG_SHA512
2064 bool "Sign modules with SHA-512"
2065 select CRYPTO_SHA512
2066
2067endchoice
2068
Michal Marek22753672013-01-25 13:41:00 +10302069config MODULE_SIG_HASH
2070 string
2071 depends on MODULE_SIG
2072 default "sha1" if MODULE_SIG_SHA1
2073 default "sha224" if MODULE_SIG_SHA224
2074 default "sha256" if MODULE_SIG_SHA256
2075 default "sha384" if MODULE_SIG_SHA384
2076 default "sha512" if MODULE_SIG_SHA512
2077
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302078config MODULE_COMPRESS
2079 bool "Compress modules on installation"
2080 depends on MODULES
2081 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302082
Rusty Russellb6c09b52015-06-16 12:16:22 +09302083 Compresses kernel modules when 'make modules_install' is run; gzip or
2084 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302085
Rusty Russellb6c09b52015-06-16 12:16:22 +09302086 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302087
Rusty Russellb6c09b52015-06-16 12:16:22 +09302088 Out-of-tree kernel modules installed using Kbuild will also be
2089 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302090
Rusty Russellb6c09b52015-06-16 12:16:22 +09302091 Note: for modules inside an initrd or initramfs, it's more efficient
2092 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302093
Rusty Russellb6c09b52015-06-16 12:16:22 +09302094 Note: This is fully compatible with signed modules.
2095
2096 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302097
2098choice
2099 prompt "Compression algorithm"
2100 depends on MODULE_COMPRESS
2101 default MODULE_COMPRESS_GZIP
2102 help
2103 This determines which sort of compression will be used during
2104 'make modules_install'.
2105
2106 GZIP (default) and XZ are supported.
2107
2108config MODULE_COMPRESS_GZIP
2109 bool "GZIP"
2110
2111config MODULE_COMPRESS_XZ
2112 bool "XZ"
2113
2114endchoice
2115
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002116config TRIM_UNUSED_KSYMS
2117 bool "Trim unused exported kernel symbols"
2118 depends on MODULES && !UNUSED_SYMBOLS
2119 help
2120 The kernel and some modules make many symbols available for
2121 other modules to use via EXPORT_SYMBOL() and variants. Depending
2122 on the set of modules being selected in your kernel configuration,
2123 many of those exported symbols might never be used.
2124
2125 This option allows for unused exported symbols to be dropped from
2126 the build. In turn, this provides the compiler more opportunities
2127 (especially when using LTO) for optimizing the code and reducing
2128 binary size. This might have some security advantages as well.
2129
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002130 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002131
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002132endif # MODULES
2133
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302134config MODULES_TREE_LOOKUP
2135 def_bool y
2136 depends on PERF_EVENTS || TRACING
2137
Rusty Russell98a79d62008-12-13 21:19:41 +10302138config INIT_ALL_POSSIBLE
2139 bool
2140 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302141 Back when each arch used to define their own cpu_online_mask and
2142 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302143 with all 1s, and others with all 0s. When they were centralised,
2144 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002145 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302146
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002147source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002148
2149config PREEMPT_NOTIFIERS
2150 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002151
Steffen Klassert16295be2010-01-06 19:47:10 +11002152config PADATA
2153 depends on SMP
2154 bool
2155
David Howells4520c6a2012-09-21 23:31:13 +01002156config ASN1
2157 tristate
2158 help
2159 Build a simple ASN.1 grammar compiler that produces a bytecode output
2160 that can be interpreted by the ASN.1 stream decoder and used to
2161 inform it as to what tags are to be expected in a stream and what
2162 functions to call on what tags.
2163
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002164source "kernel/Kconfig.locks"