blob: cac3f096050d5b27a9bd5de8600469f3c5aa0ada [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
Al Boldiff0cfc62007-07-31 00:39:23 -070029menu "General setup"
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
Linus Torvalds1da177e2005-04-16 15:20:36 -070031config BROKEN
32 bool
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
34config BROKEN_ON_SMP
35 bool
36 depends on BROKEN || !SMP
37 default y
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039config INIT_ENV_ARG_LIMIT
40 int
Adrian Bunkdd673bc2006-06-30 01:55:51 -070041 default 32 if !UML
42 default 128 if UML
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 help
Randy Dunlap34ad92c2005-10-30 15:01:46 -080044 Maximum of each of the number of arguments and environment
45 variables passed to init from the kernel command line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
Roland McGrath84336462009-12-21 16:24:06 -080048config CROSS_COMPILE
49 string "Cross-compiler tool prefix"
50 help
51 Same as running 'make CROSS_COMPILE=prefix-' but stored for
52 default make runs in this kernel build directory. You don't
53 need to set this unless you want the configured kernel build
54 directory to select the cross-compiler automatically.
55
Jiri Slaby4bb16672013-05-22 10:56:24 +020056config COMPILE_TEST
57 bool "Compile also drivers which will not load"
Richard Weinbergerbc083a62016-08-02 14:03:27 -070058 depends on !UML
Jiri Slaby4bb16672013-05-22 10:56:24 +020059 default n
60 help
61 Some drivers can be compiled on a different platform than they are
62 intended to be run on. Despite they cannot be loaded there (or even
63 when they load they cannot be used due to missing HW support),
64 developers still, opposing to distributors, might want to build such
65 drivers to compile-test them.
66
67 If you are a developer and want to build everything available, say Y
68 here. If you are a user/distributor, say N here to exclude useless
69 drivers to be distributed.
70
Linus Torvalds1da177e2005-04-16 15:20:36 -070071config LOCALVERSION
72 string "Local version - append to kernel release"
73 help
74 Append an extra string to the end of your kernel version.
75 This will show up when you type uname, for example.
76 The string you set here will be appended after the contents of
77 any files with a filename matching localversion* in your
78 object and source tree, in that order. Your total string can
79 be a maximum of 64 characters.
80
Ryan Andersonaaebf432005-07-31 04:57:49 -040081config LOCALVERSION_AUTO
82 bool "Automatically append version information to the version string"
83 default y
Alexey Dobriyanac3339b2016-08-02 14:07:21 -070084 depends on !COMPILE_TEST
Ryan Andersonaaebf432005-07-31 04:57:49 -040085 help
86 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020087 release tree by looking for git tags that belong to the current
88 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -040089
90 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020091 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -040092 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020093 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -040094
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020095 (The actual string used here is the first eight characters produced
96 by running the command:
97
98 $ git rev-parse --verify HEAD
99
100 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -0400101
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800102config HAVE_KERNEL_GZIP
103 bool
104
105config HAVE_KERNEL_BZIP2
106 bool
107
108config HAVE_KERNEL_LZMA
109 bool
110
Lasse Collin3ebe1242011-01-12 17:01:23 -0800111config HAVE_KERNEL_XZ
112 bool
113
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800114config HAVE_KERNEL_LZO
115 bool
116
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700117config HAVE_KERNEL_LZ4
118 bool
119
Alain Knaff30d65db2009-01-04 22:46:17 +0100120choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800121 prompt "Kernel compression mode"
122 default KERNEL_GZIP
H. Peter Anvin2d3c6272013-11-14 21:43:47 -0800123 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 -0800124 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100125 The linux kernel is a kind of self-extracting executable.
126 Several compression algorithms are available, which differ
127 in efficiency, compression and decompression speed.
128 Compression speed is only relevant when building a kernel.
129 Decompression speed is relevant at each boot.
130
131 If you have any problems with bzip2 or lzma compressed
132 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
133 version of this functionality (bzip2 only), for 2.4, was
134 supplied by Christian Ludwig)
135
136 High compression options are mostly useful for users, who
137 are low on disk space (embedded systems), but for whom ram
138 size matters less.
139
140 If in doubt, select 'gzip'
141
142config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800143 bool "Gzip"
144 depends on HAVE_KERNEL_GZIP
145 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800146 The old and tried gzip compression. It provides a good balance
147 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100148
149config KERNEL_BZIP2
150 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800151 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100152 help
153 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700154 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800155 size is about 10% smaller with bzip2, in comparison to gzip.
156 Bzip2 uses a large amount of memory. For modern kernels you
157 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100158
159config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800160 bool "LZMA"
161 depends on HAVE_KERNEL_LZMA
162 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700163 This compression algorithm's ratio is best. Decompression speed
164 is between gzip and bzip2. Compression is slowest.
165 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100166
Lasse Collin3ebe1242011-01-12 17:01:23 -0800167config KERNEL_XZ
168 bool "XZ"
169 depends on HAVE_KERNEL_XZ
170 help
171 XZ uses the LZMA2 algorithm and instruction set specific
172 BCJ filters which can improve compression ratio of executable
173 code. The size of the kernel is about 30% smaller with XZ in
174 comparison to gzip. On architectures for which there is a BCJ
175 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
176 will create a few percent smaller kernel than plain LZMA.
177
178 The speed is about the same as with LZMA: The decompression
179 speed of XZ is better than that of bzip2 but worse than gzip
180 and LZO. Compression is slow.
181
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800182config KERNEL_LZO
183 bool "LZO"
184 depends on HAVE_KERNEL_LZO
185 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700186 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200187 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800188 (both compression and decompression) is the fastest.
189
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700190config KERNEL_LZ4
191 bool "LZ4"
192 depends on HAVE_KERNEL_LZ4
193 help
194 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
195 A preliminary version of LZ4 de/compression tool is available at
196 <https://code.google.com/p/lz4/>.
197
198 Its compression ratio is worse than LZO. The size of the kernel
199 is about 8% bigger than LZO. But the decompression speed is
200 faster than LZO.
201
Alain Knaff30d65db2009-01-04 22:46:17 +0100202endchoice
203
Josh Triplettbd5dc172011-06-15 15:08:28 -0700204config DEFAULT_HOSTNAME
205 string "Default hostname"
206 default "(none)"
207 help
208 This option determines the default system hostname before userspace
209 calls sethostname(2). The kernel traditionally uses "(none)" here,
210 but you may wish to use a different default here to make a minimal
211 system more usable with less configuration.
212
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213config SWAP
214 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200215 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 default y
217 help
218 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100219 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 used to provide more virtual memory than the actual RAM present
221 in your computer. If unsure say Y.
222
223config SYSVIPC
224 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 ---help---
226 Inter Process Communication is a suite of library functions and
227 system calls which let processes (running programs) synchronize and
228 exchange information. It is generally considered to be a good thing,
229 and some programs won't run unless you say Y here. In particular, if
230 you want to run the DOS emulator dosemu under Linux (read the
231 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
232 you'll need to say Y here.
233
234 You can find documentation about IPC with "info ipc" and also in
235 section 6.4 of the Linux Programmer's Guide, available from
236 <http://www.tldp.org/guides.html>.
237
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800238config SYSVIPC_SYSCTL
239 bool
240 depends on SYSVIPC
241 depends on SYSCTL
242 default y
243
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244config POSIX_MQUEUE
245 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700246 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 ---help---
248 POSIX variant of message queues is a part of IPC. In POSIX message
249 queues every message has a priority which decides about succession
250 of receiving it by a process. If you want to compile and run
251 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200252 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253
254 POSIX message queues are visible as a filesystem called 'mqueue'
255 and can be mounted somewhere if you want to do filesystem
256 operations on message queues.
257
258 If unsure, say Y.
259
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700260config POSIX_MQUEUE_SYSCTL
261 bool
262 depends on POSIX_MQUEUE
263 depends on SYSCTL
264 default y
265
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700266config CROSS_MEMORY_ATTACH
267 bool "Enable process_vm_readv/writev syscalls"
268 depends on MMU
269 default y
270 help
271 Enabling this option adds the system calls process_vm_readv and
272 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700273 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700274 See the man page for more details.
275
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530276config FHANDLE
Andi Kleenf76be612016-04-01 14:31:40 -0700277 bool "open by fhandle syscalls" if EXPERT
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530278 select EXPORTFS
Andi Kleenf76be612016-04-01 14:31:40 -0700279 default y
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530280 help
281 If you say Y here, a user level program will be able to map
282 file names to handle and then later use the handle for
283 different file system operations. This is useful in implementing
284 userspace file servers, which now track files using handles instead
285 of names. The handle would remain the same even if file names
286 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
287 syscalls.
288
Josh Triplett69369a72014-04-03 14:48:27 -0700289config USELIB
290 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800291 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700292 help
293 This option enables the uselib syscall, a system call used in the
294 dynamic linker from libc5 and earlier. glibc does not use this
295 system call. If you intend to run programs built on libc5 or
296 earlier, you may need to enable this syscall. Current systems
297 running glibc can safely disable this.
298
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299config AUDIT
300 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100301 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 help
303 Enable auditing infrastructure that can be used with another
304 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500305 logging of avc messages output). System call auditing is included
306 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900308config HAVE_ARCH_AUDITSYSCALL
309 bool
310
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500312 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900313 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314
Eric Paris939a67f2009-12-17 20:12:06 -0500315config AUDIT_WATCH
316 def_bool y
317 depends on AUDITSYSCALL
318 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319
Al Viro74c3cbe2007-07-22 08:04:18 -0400320config AUDIT_TREE
321 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400322 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500323 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400324
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000325source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200326source "kernel/time/Kconfig"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000327
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200328menu "CPU/Task time and stats accounting"
329
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200330config VIRT_CPU_ACCOUNTING
331 bool
332
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200333choice
334 prompt "Cputime accounting"
335 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100336 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200337
338# Kind of a stub config for the pure tick based cputime accounting
339config TICK_CPU_ACCOUNTING
340 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200341 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200342 help
343 This is the basic tick based cputime accounting that maintains
344 statistics about user, system and idle time spent on per jiffies
345 granularity.
346
347 If unsure, say Y.
348
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200349config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200350 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200351 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200352 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200353 help
354 Select this option to enable more accurate task and CPU time
355 accounting. This is done by reading a CPU counter on each
356 kernel entry and exit and on transitions within the kernel
357 between system, softirq and hardirq state, so there is a
358 small performance impact. In the case of s390 or IBM POWER > 5,
359 this also enables accounting of stolen time on logically-partitioned
360 systems.
361
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200362config VIRT_CPU_ACCOUNTING_GEN
363 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700364 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700365 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200366 select VIRT_CPU_ACCOUNTING
367 select CONTEXT_TRACKING
368 help
369 Select this option to enable task and CPU time accounting on full
370 dynticks systems. This accounting is implemented by watching every
371 kernel-user boundaries using the context tracking subsystem.
372 The accounting is thus performed at the expense of some significant
373 overhead.
374
375 For now this is only useful if you are working on the full
376 dynticks subsystem development.
377
378 If unsure, say N.
379
Rik van Rielb58c3582016-07-13 16:50:02 +0200380endchoice
381
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200382config IRQ_TIME_ACCOUNTING
383 bool "Fine granularity task level IRQ time accounting"
Rik van Rielb58c3582016-07-13 16:50:02 +0200384 depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200385 help
386 Select this option to enable fine granularity task irq time
387 accounting. This is done by reading a timestamp on each
388 transitions between softirq and hardirq state, so there can be a
389 small performance impact.
390
391 If in doubt, say N here.
392
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200393config BSD_PROCESS_ACCT
394 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700395 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200396 help
397 If you say Y here, a user level program will be able to instruct the
398 kernel (via a special system call) to write process accounting
399 information to a file: whenever a process exits, information about
400 that process will be appended to the file by the kernel. The
401 information includes things such as creation time, owning user,
402 command name, memory usage, controlling terminal etc. (the complete
403 list is in the struct acct in <file:include/linux/acct.h>). It is
404 up to the user level program to do useful things with this
405 information. This is generally a good idea, so say Y.
406
407config BSD_PROCESS_ACCT_V3
408 bool "BSD Process Accounting version 3 file format"
409 depends on BSD_PROCESS_ACCT
410 default n
411 help
412 If you say Y here, the process accounting information is written
413 in a new file format that also logs the process IDs of each
414 process and it's parent. Note that this file format is incompatible
415 with previous v0/v1/v2 file formats, so you will need updated tools
416 for processing it. A preliminary version of these tools is available
417 at <http://www.gnu.org/software/acct/>.
418
419config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700420 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200421 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700422 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200423 default n
424 help
425 Export selected statistics for tasks/processes through the
426 generic netlink interface. Unlike BSD process accounting, the
427 statistics are available during the lifetime of tasks/processes as
428 responses to commands. Like BSD accounting, they are sent to user
429 space on task exit.
430
431 Say N if unsure.
432
433config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700434 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200435 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530436 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200437 help
438 Collect information on time spent by a task waiting for system
439 resources like cpu, synchronous block I/O completion and swapping
440 in pages. Such statistics can help in setting a task's priorities
441 relative to other tasks for cpu, io, rss limits etc.
442
443 Say N if unsure.
444
445config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700446 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200447 depends on TASKSTATS
448 help
449 Collect extended task accounting data and send the data
450 to userland for processing over the taskstats interface.
451
452 Say N if unsure.
453
454config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700455 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200456 depends on TASK_XACCT
457 help
458 Collect information on the number of bytes of storage I/O which this
459 task has caused.
460
461 Say N if unsure.
462
463endmenu # "CPU/Task time and stats accounting"
464
Mike Travisc903ff82009-01-15 12:28:29 -0800465menu "RCU Subsystem"
466
Mike Travisc903ff82009-01-15 12:28:29 -0800467config TREE_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400468 bool
469 default y if !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800470 help
471 This option selects the RCU implementation that is
472 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700473 thousands of CPUs. It also scales down nicely to
474 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800475
Pranith Kumar28f65692014-09-22 14:00:48 -0400476config PREEMPT_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400477 bool
478 default y if PREEMPT
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700479 help
480 This option selects the RCU implementation that is
481 designed for very large SMP systems with hundreds or
482 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700483 is also required. It also scales down nicely to
484 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700485
Paul E. McKenney9fc52d82013-01-08 15:48:33 -0800486 Select this option if you are unsure.
487
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700488config TINY_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400489 bool
490 default y if !PREEMPT && !SMP
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700491 help
492 This option selects the RCU implementation that is
493 designed for UP systems from which real-time response
494 is not required. This option greatly reduces the
495 memory footprint of RCU.
496
Paul E. McKenney78cae102015-04-20 12:19:45 -0700497config RCU_EXPERT
498 bool "Make expert-level adjustments to RCU configuration"
499 default n
500 help
501 This option needs to be enabled if you wish to make
502 expert-level adjustments to RCU configuration. By default,
503 no such adjustments can be made, which has the often-beneficial
504 side-effect of preventing "make oldconfig" from asking you all
505 sorts of detailed questions about how you would like numerous
506 obscure RCU options to be set up.
507
508 Say Y if you need to make expert-level adjustments to RCU.
509
510 Say N if you are unsure.
511
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500512config SRCU
513 bool
514 help
515 This option selects the sleepable version of RCU. This version
516 permits arbitrary sleeping or blocking within RCU read-side critical
517 sections.
518
Paul E. McKenney8315f422014-06-27 13:42:20 -0700519config TASKS_RCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -0700520 bool
Paul E. McKenney8315f422014-06-27 13:42:20 -0700521 default n
Paul E. McKenney570dd3c2016-06-15 08:56:53 -0700522 depends on !UML
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500523 select SRCU
Paul E. McKenney8315f422014-06-27 13:42:20 -0700524 help
525 This option enables a task-based RCU implementation that uses
526 only voluntary context switch (not preemption!), idle, and
527 user-mode execution as quiescent states.
528
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700529config RCU_STALL_COMMON
Pranith Kumar28f65692014-09-22 14:00:48 -0400530 def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700531 help
532 This option enables RCU CPU stall code that is common between
533 the TINY and TREE variants of RCU. The purpose is to allow
534 the tiny variants to disable RCU CPU stall warnings, while
535 making these warnings mandatory for the tree variants.
536
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100537config CONTEXT_TRACKING
538 bool
539
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100540config CONTEXT_TRACKING_FORCE
541 bool "Force context tracking"
542 depends on CONTEXT_TRACKING
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200543 default y if !NO_HZ_FULL
Frederic Weisbecker1fd2b442012-07-11 20:26:40 +0200544 help
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200545 The major pre-requirement for full dynticks to work is to
546 support the context tracking subsystem. But there are also
547 other dependencies to provide in order to make the full
548 dynticks working.
549
550 This option stands for testing when an arch implements the
551 context tracking backend but doesn't yet fullfill all the
552 requirements to make the full dynticks feature working.
553 Without the full dynticks, there is no way to test the support
554 for context tracking and the subsystems that rely on it: RCU
555 userspace extended quiescent state and tickless cputime
556 accounting. This option copes with the absence of the full
557 dynticks subsystem by forcing the context tracking on all
558 CPUs in the system.
559
Paul Gortmaker99c8b1e2013-10-24 10:07:47 -0400560 Say Y only if you're working on the development of an
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200561 architecture backend for the context tracking.
562
563 Say N otherwise, this option brings an overhead that you
564 don't want in production.
565
Frederic Weisbeckerd6771242012-10-11 01:48:28 +0200566
Mike Travisc903ff82009-01-15 12:28:29 -0800567config RCU_FANOUT
568 int "Tree-based hierarchical RCU fanout value"
569 range 2 64 if 64BIT
570 range 2 32 if !64BIT
Paul E. McKenney05c5df32015-04-20 14:27:43 -0700571 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Mike Travisc903ff82009-01-15 12:28:29 -0800572 default 64 if 64BIT
573 default 32 if !64BIT
574 help
575 This option controls the fanout of hierarchical implementations
576 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700577 large numbers of CPUs. This value must be at least the fourth
578 root of NR_CPUS, which allows NR_CPUS to be insanely large.
579 The default value of RCU_FANOUT should be used for production
580 systems, but if you are stress-testing the RCU implementation
581 itself, small RCU_FANOUT values allow you to test large-system
582 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800583
584 Select a specific number if testing RCU itself.
585 Take the default if unsure.
586
Paul E. McKenney8932a632012-04-19 12:20:14 -0700587config RCU_FANOUT_LEAF
588 int "Tree-based hierarchical RCU leaf-level fanout value"
Paul E. McKenney8739c5c2015-04-20 18:27:54 -0700589 range 2 64 if 64BIT
590 range 2 32 if !64BIT
Paul E. McKenney47d631a2015-04-21 09:12:13 -0700591 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Paul E. McKenney8932a632012-04-19 12:20:14 -0700592 default 16
593 help
594 This option controls the leaf-level fanout of hierarchical
595 implementations of RCU, and allows trading off cache misses
596 against lock contention. Systems that synchronize their
597 scheduling-clock interrupts for energy-efficiency reasons will
598 want the default because the smaller leaf-level fanout keeps
599 lock contention levels acceptably low. Very large systems
600 (hundreds or thousands of CPUs) will instead want to set this
601 value to the maximum value possible in order to reduce the
602 number of cache misses incurred during RCU's grace-period
603 initialization. These systems tend to run CPU-bound, and thus
604 are not helped by synchronized interrupts, and thus tend to
605 skew them, which reduces lock contention enough that large
606 leaf-level fanouts work well.
607
608 Select a specific number if testing RCU itself.
609
610 Select the maximum permissible value for large systems.
611
612 Take the default if unsure.
613
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800614config RCU_FAST_NO_HZ
615 bool "Accelerate last non-dyntick-idle CPU's grace periods"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700616 depends on NO_HZ_COMMON && SMP && RCU_EXPERT
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800617 default n
618 help
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800619 This option permits CPUs to enter dynticks-idle state even if
620 they have RCU callbacks queued, and prevents RCU from waking
621 these CPUs up more than roughly once every four jiffies (by
622 default, you can adjust this using the rcutree.rcu_idle_gp_delay
623 parameter), thus improving energy efficiency. On the other
624 hand, this option increases the duration of RCU grace periods,
625 for example, slowing down synchronize_rcu().
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800626
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800627 Say Y if energy efficiency is critically important, and you
628 don't care about increased grace-period durations.
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800629
630 Say N if you are unsure.
631
Mike Travisc903ff82009-01-15 12:28:29 -0800632config TREE_RCU_TRACE
Pranith Kumar28f65692014-09-22 14:00:48 -0400633 def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800634 select DEBUG_FS
635 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700636 This option provides tracing for the TREE_RCU and
Pranith Kumar28f65692014-09-22 14:00:48 -0400637 PREEMPT_RCU implementations, permitting Makefile to
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700638 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800639
Paul E. McKenney24278d12010-09-27 17:25:23 -0700640config RCU_BOOST
641 bool "Enable RCU priority boosting"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700642 depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700643 default n
644 help
645 This option boosts the priority of preempted RCU readers that
646 block the current preemptible RCU grace period for too long.
647 This option also prevents heavy loads from blocking RCU
648 callback invocation for all flavors of RCU.
649
650 Say Y here if you are working with real-time apps or heavy loads
651 Say N here if you are unsure.
652
Clark Williams21871d72014-09-12 21:21:09 -0500653config RCU_KTHREAD_PRIO
654 int "Real-time priority to use for RCU worker threads"
Paul E. McKenneya94844b2014-12-12 07:37:48 -0800655 range 1 99 if RCU_BOOST
656 range 0 99 if !RCU_BOOST
657 default 1 if RCU_BOOST
658 default 0 if !RCU_BOOST
Paul E. McKenney26730f52015-04-21 09:22:14 -0700659 depends on RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700660 help
Clark Williams21871d72014-09-12 21:21:09 -0500661 This option specifies the SCHED_FIFO priority value that will be
662 assigned to the rcuc/n and rcub/n threads and is also the value
663 used for RCU_BOOST (if enabled). If you are working with a
664 real-time application that has one or more CPU-bound threads
665 running at a real-time priority level, you should set
666 RCU_KTHREAD_PRIO to a priority higher than the highest-priority
667 real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO
668 value of 1 is appropriate in the common case, which is real-time
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700669 applications that do not have any CPU-bound threads.
670
671 Some real-time applications might not have a single real-time
672 thread that saturates a given CPU, but instead might have
673 multiple real-time threads that, taken together, fully utilize
Clark Williams21871d72014-09-12 21:21:09 -0500674 that CPU. In this case, you should set RCU_KTHREAD_PRIO to
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700675 a priority higher than the lowest-priority thread that is
676 conspiring to prevent the CPU from running any non-real-time
677 tasks. For example, if one thread at priority 10 and another
678 thread at priority 5 are between themselves fully consuming
Clark Williams21871d72014-09-12 21:21:09 -0500679 the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700680 set to priority 6 or higher.
Paul E. McKenney24278d12010-09-27 17:25:23 -0700681
682 Specify the real-time priority, or take the default if unsure.
683
684config RCU_BOOST_DELAY
685 int "Milliseconds to delay boosting after RCU grace-period start"
686 range 0 3000
687 depends on RCU_BOOST
688 default 500
689 help
690 This option specifies the time to wait after the beginning of
691 a given grace period before priority-boosting preempted RCU
692 readers blocking that grace period. Note that any RCU reader
693 blocking an expedited RCU grace period is boosted immediately.
694
695 Accept the default if unsure.
696
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700697config RCU_NOCB_CPU
Paul E. McKenney9a5739d2013-03-28 20:48:36 -0700698 bool "Offload RCU callback processing from boot-selected CPUs"
Pranith Kumar28f65692014-09-22 14:00:48 -0400699 depends on TREE_RCU || PREEMPT_RCU
Paul E. McKenneybe55fa22015-06-02 05:29:18 -0700700 depends on RCU_EXPERT || NO_HZ_FULL
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700701 default n
702 help
703 Use this option to reduce OS jitter for aggressive HPC or
704 real-time workloads. It can also be used to offload RCU
705 callback invocation to energy-efficient CPUs in battery-powered
706 asymmetric multiprocessors.
707
708 This option offloads callback invocation from the set of
709 CPUs specified at boot time by the rcu_nocbs parameter.
Paul E. McKenneya4889852012-12-03 08:16:28 -0800710 For each such CPU, a kthread ("rcuox/N") will be created to
711 invoke callbacks, where the "N" is the CPU being offloaded,
712 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
713 "s" for RCU-sched. Nothing prevents this kthread from running
714 on the specified CPUs, but (1) the kthreads may be preempted
715 between each callback, and (2) affinity or cgroups can be used
716 to force the kthreads to run on whatever set of CPUs is desired.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700717
Paul E. McKenney34ed62462013-01-07 13:37:42 -0800718 Say Y here if you want to help to debug reduced OS jitter.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700719 Say N here if you are unsure.
720
Paul E. McKenney911af502013-02-11 10:23:27 -0800721choice
722 prompt "Build-forced no-CBs CPUs"
723 default RCU_NOCB_CPU_NONE
Stefan Hengelein45687792014-09-02 19:55:11 +0200724 depends on RCU_NOCB_CPU
Paul E. McKenney911af502013-02-11 10:23:27 -0800725 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700726 This option allows no-CBs CPUs (whose RCU callbacks are invoked
727 from kthreads rather than from softirq context) to be specified
728 at build time. Additional no-CBs CPUs may be specified by
729 the rcu_nocbs= boot parameter.
Paul E. McKenney911af502013-02-11 10:23:27 -0800730
731config RCU_NOCB_CPU_NONE
732 bool "No build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800733 help
734 This option does not force any of the CPUs to be no-CBs CPUs.
735 Only CPUs designated by the rcu_nocbs= boot parameter will be
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700736 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
737 kthreads whose names begin with "rcuo". All other CPUs will
738 invoke their own RCU callbacks in softirq context.
739
740 Select this option if you want to choose no-CBs CPUs at
741 boot time, for example, to allow testing of different no-CBs
742 configurations without having to rebuild the kernel each time.
Paul E. McKenney911af502013-02-11 10:23:27 -0800743
744config RCU_NOCB_CPU_ZERO
745 bool "CPU 0 is a build_forced no-CBs CPU"
Paul E. McKenney911af502013-02-11 10:23:27 -0800746 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700747 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
748 callbacks are invoked by a per-CPU kthread whose name begins
749 with "rcuo". Additional CPUs may be designated as no-CBs
750 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
751 All other CPUs will invoke their own RCU callbacks in softirq
752 context.
Paul E. McKenney911af502013-02-11 10:23:27 -0800753
754 Select this if CPU 0 needs to be a no-CBs CPU for real-time
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700755 or energy-efficiency reasons, but the real reason it exists
756 is to ensure that randconfig testing covers mixed systems.
Paul E. McKenney911af502013-02-11 10:23:27 -0800757
758config RCU_NOCB_CPU_ALL
759 bool "All CPUs are build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800760 help
761 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700762 boot parameter will be ignored. All CPUs' RCU callbacks will
763 be executed in the context of per-CPU rcuo kthreads created for
764 this purpose. Assuming that the kthreads whose names start with
765 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
766 on the remaining CPUs, but might decrease memory locality during
767 RCU-callback invocation, thus potentially degrading throughput.
Paul E. McKenney911af502013-02-11 10:23:27 -0800768
769 Select this if all CPUs need to be no-CBs CPUs for real-time
770 or energy-efficiency reasons.
771
772endchoice
773
Paul E. McKenneyee425712015-02-19 10:51:32 -0800774config RCU_EXPEDITE_BOOT
775 bool
776 default n
777 help
778 This option enables expedited grace periods at boot time,
779 as if rcu_expedite_gp() had been invoked early in boot.
780 The corresponding rcu_unexpedite_gp() is invoked from
781 rcu_end_inkernel_boot(), which is intended to be invoked
782 at the end of the kernel-only boot sequence, just before
783 init is exec'ed.
784
785 Accept the default if unsure.
786
Mike Travisc903ff82009-01-15 12:28:29 -0800787endmenu # "RCU Subsystem"
788
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700789config BUILD_BIN2C
790 bool
791 default n
792
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700794 tristate "Kernel .config support"
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700795 select BUILD_BIN2C
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 ---help---
797 This option enables the complete Linux kernel ".config" file
798 contents to be saved in the kernel. It provides documentation
799 of which kernel options are used in a running kernel or in an
800 on-disk kernel. This information can be extracted from the kernel
801 image file with the script scripts/extract-ikconfig and used as
802 input to rebuild the current kernel or to build another kernel.
803 It can also be extracted from a running kernel by reading
804 /proc/config.gz if enabled (below).
805
806config IKCONFIG_PROC
807 bool "Enable access to .config through /proc/config.gz"
808 depends on IKCONFIG && PROC_FS
809 ---help---
810 This option enables access to the kernel configuration file
811 through /proc/config.gz.
812
Alistair John Strachan794543a2007-05-08 00:31:15 -0700813config LOG_BUF_SHIFT
814 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200815 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700816 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700817 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700818 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700819 Select the minimal kernel log buffer size as a power of 2.
820 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
821 parameter, see below. Any higher size also might be forced
822 by "log_buf_len" boot parameter.
823
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700824 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700825 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700826 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700827 15 => 32 KB
828 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700829 13 => 8 KB
830 12 => 4 KB
831
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700832config LOG_CPU_MAX_BUF_SHIFT
833 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700834 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700835 range 0 21
836 default 12 if !BASE_SMALL
837 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700838 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700839 help
840 This option allows to increase the default ring buffer size
841 according to the number of CPUs. The value defines the contribution
842 of each CPU as a power of 2. The used space is typically only few
843 lines however it might be much more when problems are reported,
844 e.g. backtraces.
845
846 The increased size means that a new buffer has to be allocated and
847 the original static one is unused. It makes sense only on systems
848 with more CPUs. Therefore this value is used only when the sum of
849 contributions is greater than the half of the default kernel ring
850 buffer as defined by LOG_BUF_SHIFT. The default values are set
851 so that more than 64 CPUs are needed to trigger the allocation.
852
853 Also this option is ignored when "log_buf_len" kernel parameter is
854 used as it forces an exact (power of two) size of the ring buffer.
855
856 The number of possible CPUs is used for this computation ignoring
Geert Uytterhoeven5e0d8d52016-06-05 10:47:02 +0200857 hotplugging making the computation optimal for the worst case
858 scenario while allowing a simple algorithm to be used from bootup.
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700859
860 Examples shift values and their meaning:
861 17 => 128 KB for each CPU
862 16 => 64 KB for each CPU
863 15 => 32 KB for each CPU
864 14 => 16 KB for each CPU
865 13 => 8 KB for each CPU
866 12 => 4 KB for each CPU
867
Petr Mladek427934b2016-05-20 17:00:39 -0700868config NMI_LOG_BUF_SHIFT
869 int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
870 range 10 21
871 default 13
872 depends on PRINTK_NMI
873 help
874 Select the size of a per-CPU buffer where NMI messages are temporary
875 stored. They are copied to the main log buffer in a safe context
876 to avoid a deadlock. The value defines the size as a power of 2.
877
878 NMI messages are rare and limited. The largest one is when
879 a backtrace is printed. It usually fits into 4KB. Select
880 8KB if you want to be on the safe side.
881
882 Examples:
883 17 => 128 KB for each CPU
884 16 => 64 KB for each CPU
885 15 => 32 KB for each CPU
886 14 => 16 KB for each CPU
887 13 => 8 KB for each CPU
888 12 => 4 KB for each CPU
889
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800890#
891# Architectures with an unreliable sched_clock() should select this:
892#
893config HAVE_UNSTABLE_SCHED_CLOCK
894 bool
895
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700896config GENERIC_SCHED_CLOCK
897 bool
898
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200899#
900# For architectures that want to enable the support for NUMA-affine scheduler
901# balancing logic:
902#
903config ARCH_SUPPORTS_NUMA_BALANCING
904 bool
905
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100906#
Mel Gorman72b252a2015-09-04 15:47:32 -0700907# For architectures that prefer to flush all TLBs after a number of pages
908# are unmapped instead of sending one IPI per page to flush. The architecture
909# must provide guarantees on what happens if a clean TLB cache entry is
910# written after the unmap. Details are in mm/rmap.c near the check for
911# should_defer_flush. The architecture should also consider if the full flush
912# and the refill costs are offset by the savings of sending fewer IPIs.
913config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
914 bool
915
916#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100917# For architectures that know their GCC __int128 support is sound
918#
919config ARCH_SUPPORTS_INT128
920 bool
921
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200922# For architectures that (ab)use NUMA to represent different memory regions
923# all cpu-local but of different latencies, such as SuperH.
924#
925config ARCH_WANT_NUMA_VARIABLE_LOCALITY
926 bool
927
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200928config NUMA_BALANCING
929 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200930 depends on ARCH_SUPPORTS_NUMA_BALANCING
931 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
932 depends on SMP && NUMA && MIGRATION
933 help
934 This option adds support for automatic NUMA aware memory/task placement.
935 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400936 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200937
938 This system will be inactive on UMA systems.
939
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800940config NUMA_BALANCING_DEFAULT_ENABLED
941 bool "Automatically enable NUMA aware memory/task placement"
942 default y
943 depends on NUMA_BALANCING
944 help
945 If set, automatic NUMA balancing will be enabled if running on a NUMA
946 machine.
947
Li Zefan23964d22009-01-15 13:50:58 -0800948menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500949 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500950 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700951 help
Li Zefan23964d22009-01-15 13:50:58 -0800952 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800953 use with process control subsystems such as Cpusets, CFS, memory
954 controls or device isolation.
955 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800956 - Documentation/scheduler/sched-design-CFS.txt (CFS)
seokhoon.yoon9991a9c2016-08-02 14:03:13 -0700957 - Documentation/cgroup-v1/ (features for grouping, isolation
Li Zefan45ce80f2009-01-15 13:50:59 -0800958 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700959
960 Say N if unsure.
961
Li Zefan23964d22009-01-15 13:50:58 -0800962if CGROUPS
963
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800964config PAGE_COUNTER
965 bool
966
Andrew Mortonc255a452012-07-31 16:43:02 -0700967config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500968 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800969 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500970 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800971 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500972 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800973
Andrew Mortonc255a452012-07-31 16:43:02 -0700974config MEMCG_SWAP
Johannes Weinera0166ec2015-12-17 17:19:56 -0500975 bool "Swap controller"
Andrew Mortonc255a452012-07-31 16:43:02 -0700976 depends on MEMCG && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800977 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500978 Provides control over the swap space consumed by tasks in a cgroup.
979
Andrew Mortonc255a452012-07-31 16:43:02 -0700980config MEMCG_SWAP_ENABLED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500981 bool "Swap controller enabled by default"
Andrew Mortonc255a452012-07-31 16:43:02 -0700982 depends on MEMCG_SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800983 default y
984 help
985 Memory Resource Controller Swap Extension comes with its price in
986 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -0700987 which want to enable the feature but keep it disabled by default
Michal Hocko07555ac2013-08-22 16:35:46 -0700988 and let the user enable it by swapaccount=1 boot command line
Michal Hockoa42c3902010-11-24 12:57:08 -0800989 parameter should have this option unselected.
990 For those who want to have the feature enabled by default should
991 select this option (if, for some reason, they need to disable it
WANG Cong00a66d22011-07-25 17:12:12 -0700992 then swapaccount=0 does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800993
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500994config BLK_CGROUP
995 bool "IO controller"
996 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700997 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500998 ---help---
999 Generic block IO controller cgroup interface. This is the common
1000 cgroup interface which should be used by various IO controlling
1001 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -07001002
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001003 Currently, CFQ IO scheduler uses it to recognize task groups and
1004 control disk bandwidth allocation (proportional time slice allocation)
1005 to such task groups. It is also used by bio throttling logic in
1006 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +02001007
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001008 This option only enables generic Block IO controller infrastructure.
1009 One needs to also enable actual IO controlling logic/policy. For
1010 enabling proportional weight division of disk bandwidth in CFQ, set
1011 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
1012 CONFIG_BLK_DEV_THROTTLING=y.
1013
seokhoon.yoon9991a9c2016-08-02 14:03:13 -07001014 See Documentation/cgroup-v1/blkio-controller.txt for more information.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001015
1016config DEBUG_BLK_CGROUP
1017 bool "IO controller debugging"
1018 depends on BLK_CGROUP
1019 default n
1020 ---help---
1021 Enable some debugging help. Currently it exports additional stat
1022 files in a cgroup which can be useful for debugging.
1023
1024config CGROUP_WRITEBACK
1025 bool
1026 depends on MEMCG && BLK_CGROUP
1027 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +02001028
Dhaval Giani7c941432010-01-20 13:26:18 +01001029menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001030 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001031 default n
1032 help
1033 This feature lets CPU scheduler recognize task groups and control CPU
1034 bandwidth allocation to such task groups. It uses cgroups to group
1035 tasks.
1036
1037if CGROUP_SCHED
1038config FAIR_GROUP_SCHED
1039 bool "Group scheduling for SCHED_OTHER"
1040 depends on CGROUP_SCHED
1041 default CGROUP_SCHED
1042
Paul Turnerab84d312011-07-21 09:43:28 -07001043config CFS_BANDWIDTH
1044 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001045 depends on FAIR_GROUP_SCHED
1046 default n
1047 help
1048 This option allows users to define CPU bandwidth rates (limits) for
1049 tasks running within the fair group scheduler. Groups with no limit
1050 set are considered to be unconstrained and will run with no
1051 restriction.
1052 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1053
Dhaval Giani7c941432010-01-20 13:26:18 +01001054config RT_GROUP_SCHED
1055 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001056 depends on CGROUP_SCHED
1057 default n
1058 help
1059 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001060 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001061 schedule realtime tasks for non-root users until you allocate
1062 realtime bandwidth for them.
1063 See Documentation/scheduler/sched-rt-group.txt for more information.
1064
1065endif #CGROUP_SCHED
1066
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001067config CGROUP_PIDS
1068 bool "PIDs controller"
1069 help
1070 Provides enforcement of process number limits in the scope of a
1071 cgroup. Any attempt to fork more processes than is allowed in the
1072 cgroup will fail. PIDs are fundamentally a global resource because it
1073 is fairly trivial to reach PID exhaustion before you reach even a
1074 conservative kmemcg limit. As a result, it is possible to grind a
1075 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301076 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001077
1078 It should be noted that organisational operations (such as attaching
Parav Pandit6cc578d2016-03-05 11:30:56 +05301079 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001080 since the PIDs limit only affects a process's ability to fork, not to
1081 attach to a cgroup.
1082
1083config CGROUP_FREEZER
1084 bool "Freezer controller"
1085 help
1086 Provides a way to freeze and unfreeze all tasks in a
1087 cgroup.
1088
Johannes Weiner489c2a22016-01-20 15:02:41 -08001089 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1090 controller includes important in-kernel memory consumers per default.
1091
1092 If you're using cgroup2, say N.
1093
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001094config CGROUP_HUGETLB
1095 bool "HugeTLB controller"
1096 depends on HUGETLB_PAGE
1097 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001098 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001099 help
1100 Provides a cgroup controller for HugeTLB pages.
1101 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1102 The limit is enforced during page fault. Since HugeTLB doesn't
1103 support page reclaim, enforcing the limit at page fault time implies
1104 that, the application will get SIGBUS signal if it tries to access
1105 HugeTLB pages beyond its limit. This requires the application to know
1106 beforehand how much HugeTLB pages it would require for its use. The
1107 control group is tracked in the third page lru pointer. This means
1108 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001109
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001110config CPUSETS
1111 bool "Cpuset controller"
1112 help
1113 This option will let you create and manage CPUSETs which
1114 allow dynamically partitioning a system into sets of CPUs and
1115 Memory Nodes and assigning tasks to run only within those sets.
1116 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001117
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001118 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001119
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001120config PROC_PID_CPUSET
1121 bool "Include legacy /proc/<pid>/cpuset file"
1122 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001123 default y
1124
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001125config CGROUP_DEVICE
1126 bool "Device controller"
1127 help
1128 Provides a cgroup controller implementing whitelists for
1129 devices which a process in the cgroup can mknod or open.
1130
1131config CGROUP_CPUACCT
1132 bool "Simple CPU accounting controller"
1133 help
1134 Provides a simple controller for monitoring the
1135 total CPU consumed by the tasks in a cgroup.
1136
1137config CGROUP_PERF
1138 bool "Perf controller"
1139 depends on PERF_EVENTS
1140 help
1141 This option extends the perf per-cpu mode to restrict monitoring
1142 to threads which belong to the cgroup specified and run on the
1143 designated cpu.
1144
1145 Say N if unsure.
1146
1147config CGROUP_DEBUG
1148 bool "Example controller"
1149 default n
1150 help
1151 This option enables a simple controller that exports
1152 debugging information about the cgroups framework.
1153
1154 Say N.
1155
Li Zefan23964d22009-01-15 13:50:58 -08001156endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001157
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001158config CHECKPOINT_RESTORE
1159 bool "Checkpoint/restore support" if EXPERT
Iago López Galeiras2e13ba52015-06-25 15:00:57 -07001160 select PROC_CHILDREN
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001161 default n
1162 help
1163 Enables additional kernel features in a sake of checkpoint/restore.
1164 In particular it adds auxiliary prctl codes to setup process text,
1165 data and heap segment sizes, and a few additional /proc filesystem
1166 entries.
1167
1168 If unsure, say N here.
1169
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001170menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001171 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001172 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001173 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001174 help
1175 Provides the way to make tasks work with different objects using
1176 the same id. For example same IPC id may refer to different objects
1177 or same user id or pid may refer to different tasks when used in
1178 different namespaces.
1179
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001180if NAMESPACES
1181
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001182config UTS_NS
1183 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001184 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001185 help
1186 In this namespace tasks see different info provided with the
1187 uname() system call
1188
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001189config IPC_NS
1190 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001191 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001192 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001193 help
1194 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001195 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001196
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001197config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001198 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001199 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001200 help
1201 This allows containers, i.e. vservers, to use user namespaces
1202 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001203
1204 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001205 recommended that the MEMCG option also be enabled and that
1206 user-space use the memory control groups to limit the amount
1207 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001208
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001209 If unsure, say N.
1210
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001211config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001212 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001213 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001214 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001215 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001216 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001217 pid namespaces. This is a building block of containers.
1218
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001219config NET_NS
1220 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001221 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001222 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001223 help
1224 Allow user space to create what appear to be multiple instances
1225 of the network stack.
1226
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001227endif # NAMESPACES
1228
Mike Galbraith5091faa2010-11-30 14:18:03 +01001229config SCHED_AUTOGROUP
1230 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001231 select CGROUPS
1232 select CGROUP_SCHED
1233 select FAIR_GROUP_SCHED
1234 help
1235 This option optimizes the scheduler for common desktop workloads by
1236 automatically creating and populating task groups. This separation
1237 of workloads isolates aggressive CPU burners (like build jobs) from
1238 desktop applications. Task group autogeneration is currently based
1239 upon task session.
1240
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001241config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001242 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001243 depends on SYSFS
1244 default n
1245 help
1246 This option adds code that switches the layout of the "block" class
1247 devices, to not show up in /sys/class/block/, but only in
1248 /sys/block/.
1249
1250 This switch is only active when the sysfs.deprecated=1 boot option is
1251 passed or the SYSFS_DEPRECATED_V2 option is set.
1252
1253 This option allows new kernels to run on old distributions and tools,
1254 which might get confused by /sys/class/block/. Since 2007/2008 all
1255 major distributions and tools handle this just fine.
1256
1257 Recent distributions and userspace tools after 2009/2010 depend on
1258 the existence of /sys/class/block/, and will not work with this
1259 option enabled.
1260
1261 Only if you are using a new kernel on an old distribution, you might
1262 need to say Y here.
1263
1264config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001265 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001266 default n
1267 depends on SYSFS
1268 depends on SYSFS_DEPRECATED
1269 help
1270 Enable deprecated sysfs by default.
1271
1272 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1273 option.
1274
1275 Only if you are using a new kernel on an old distribution, you might
1276 need to say Y here. Even then, odds are you would not need it
1277 enabled, you can always pass the boot option if absolutely necessary.
1278
1279config RELAY
1280 bool "Kernel->user space relay support (formerly relayfs)"
1281 help
1282 This option enables support for relay interface support in
1283 certain file systems (such as debugfs).
1284 It is designed to provide an efficient mechanism for tools and
1285 facilities to relay large amounts of data from kernel space to
1286 user space.
1287
1288 If unsure, say N.
1289
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001290config BLK_DEV_INITRD
1291 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1292 depends on BROKEN || !FRV
1293 help
1294 The initial RAM filesystem is a ramfs which is loaded by the
1295 boot loader (loadlin or lilo) and that is mounted as root
1296 before the normal boot procedure. It is typically used to
1297 load modules needed to mount the "real" root file system,
1298 etc. See <file:Documentation/initrd.txt> for details.
1299
1300 If RAM disk support (BLK_DEV_RAM) is also included, this
1301 also enables initial RAM disk (initrd) support and adds
1302 15 Kbytes (more on some other architectures) to the kernel size.
1303
1304 If unsure say Y.
1305
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001306if BLK_DEV_INITRD
1307
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001308source "usr/Kconfig"
1309
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001310endif
1311
Arnd Bergmann877417e2016-04-25 17:35:27 +02001312choice
1313 prompt "Compiler optimization level"
1314 default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
1315
1316config CC_OPTIMIZE_FOR_PERFORMANCE
1317 bool "Optimize for performance"
1318 help
1319 This is the default optimization level for the kernel, building
1320 with the "-O2" compiler flag for best performance and most
1321 helpful compile-time warnings.
1322
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001323config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +02001324 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001325 help
Masahiro Yamada31a4af72014-08-05 14:43:07 +09001326 Enabling this option will pass "-Os" instead of "-O2" to
1327 your compiler resulting in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001328
Kirill Smelkov3a55fb02012-11-02 15:41:01 +04001329 If unsure, say N.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001330
Arnd Bergmann877417e2016-04-25 17:35:27 +02001331endchoice
1332
Randy Dunlap08470622006-09-30 23:28:13 -07001333config SYSCTL
1334 bool
1335
Randy Dunlapb943c462009-03-10 12:55:46 -07001336config ANON_INODES
1337 bool
1338
Mike Frysinger657a5202013-04-30 15:28:45 -07001339config HAVE_UID16
1340 bool
1341
1342config SYSCTL_EXCEPTION_TRACE
1343 bool
1344 help
1345 Enable support for /proc/sys/debug/exception-trace.
1346
1347config SYSCTL_ARCH_UNALIGN_NO_WARN
1348 bool
1349 help
1350 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1351 Allows arch to define/use @no_unaligned_warning to possibly warn
1352 about unaligned access emulation going on under the hood.
1353
1354config SYSCTL_ARCH_UNALIGN_ALLOW
1355 bool
1356 help
1357 Enable support for /proc/sys/kernel/unaligned-trap
1358 Allows arches to define/use @unaligned_enabled to runtime toggle
1359 the unaligned access emulation.
1360 see arch/parisc/kernel/unaligned.c for reference
1361
Mike Frysinger657a5202013-04-30 15:28:45 -07001362config HAVE_PCSPKR_PLATFORM
1363 bool
1364
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001365# interpreter that classic socket filters depend on
1366config BPF
1367 bool
1368
David Rientjes6a108a12011-01-20 14:44:16 -08001369menuconfig EXPERT
1370 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001371 # Unhide debug options, to make the on-by-default options visible
1372 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 help
1374 This option allows certain base kernel options and settings
1375 to be disabled or tweaked. This is for specialized
1376 environments which can tolerate a "non-standard" kernel.
1377 Only use this if you really know what you are doing.
1378
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001379config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001380 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001381 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001382 default y
1383 help
1384 This enables the legacy 16-bit UID syscall wrappers.
1385
Iulia Manda28138932015-04-15 16:16:41 -07001386config MULTIUSER
1387 bool "Multiple users, groups and capabilities support" if EXPERT
1388 default y
1389 help
1390 This option enables support for non-root users, groups and
1391 capabilities.
1392
1393 If you say N here, all processes will run with UID 0, GID 0, and all
1394 possible capabilities. Saying N here also compiles out support for
1395 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1396 setgid, and capset.
1397
1398 If unsure, say Y here.
1399
Fabian Frederickf6187762014-06-04 16:11:12 -07001400config SGETMASK_SYSCALL
1401 bool "sgetmask/ssetmask syscalls support" if EXPERT
1402 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1403 ---help---
1404 sys_sgetmask and sys_ssetmask are obsolete system calls
1405 no longer supported in libc but still enabled by default in some
1406 architectures.
1407
1408 If unsure, leave the default option here.
1409
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001410config SYSFS_SYSCALL
1411 bool "Sysfs syscall support" if EXPERT
1412 default y
1413 ---help---
1414 sys_sysfs is an obsolete system call no longer supported in libc.
1415 Note that disabling this option is more secure but might break
1416 compatibility with some systems.
1417
1418 If unsure say Y here.
1419
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001420config SYSCTL_SYSCALL
David Rientjes6a108a12011-01-20 14:44:16 -08001421 bool "Sysctl syscall support" if EXPERT
Eric W. Biederman26a70342009-11-05 05:26:41 -08001422 depends on PROC_SYSCTL
WANG Congc736de62011-11-02 13:39:25 -07001423 default n
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001424 select SYSCTL
1425 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001426 sys_sysctl uses binary paths that have been found challenging
1427 to properly maintain and use. The interface in /proc/sys
1428 using paths with ascii names is now the primary path to this
1429 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001430
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001431 Almost nothing using the binary sysctl interface so if you are
1432 trying to save some space it is probably safe to disable this,
1433 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001434
WANG Congc736de62011-11-02 13:39:25 -07001435 If unsure say N here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001436
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437config KALLSYMS
David Rientjes6a108a12011-01-20 14:44:16 -08001438 bool "Load all symbols for debugging/ksymoops" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 default y
1440 help
1441 Say Y here to let the kernel print out symbolic crash information and
1442 symbolic stack backtraces. This increases the size of the kernel
1443 somewhat, as all symbols have to be loaded into the kernel image.
1444
1445config KALLSYMS_ALL
1446 bool "Include all symbols in kallsyms"
1447 depends on DEBUG_KERNEL && KALLSYMS
1448 help
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001449 Normally kallsyms only contains the symbols of functions for nicer
1450 OOPS messages and backtraces (i.e., symbols from the text and inittext
1451 sections). This is sufficient for most cases. And only in very rare
1452 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1453 names of variables from the data sections, etc).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001455 This option makes sure that all symbols are loaded into the kernel
1456 image (i.e., symbols from all sections) in cost of increased kernel
1457 size (depending on the kernel configuration, it may be 300KiB or
1458 something like this).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001460 Say N unless you really need all symbols.
Matt Mackalld59745c2005-05-01 08:59:02 -07001461
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001462config KALLSYMS_ABSOLUTE_PERCPU
1463 bool
Randy Dunlap076501f2016-07-06 16:06:53 -07001464 depends on KALLSYMS
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001465 default X86_64 && SMP
1466
Ard Biesheuvel2213e9a2016-03-15 14:58:19 -07001467config KALLSYMS_BASE_RELATIVE
1468 bool
1469 depends on KALLSYMS
1470 default !IA64 && !(TILE && 64BIT)
1471 help
1472 Instead of emitting them as absolute values in the native word size,
1473 emit the symbol references in the kallsyms table as 32-bit entries,
1474 each containing a relative value in the range [base, base + U32_MAX]
1475 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1476 an absolute value in the range [0, S32_MAX] or a relative value in the
1477 range [base, base + S32_MAX], where base is the lowest relative symbol
1478 address encountered in the image.
1479
1480 On 64-bit builds, this reduces the size of the address table by 50%,
1481 but more importantly, it results in entries whose values are build
1482 time constants, and no relocation pass is required at runtime to fix
1483 up the entries based on the runtime load address of the kernel.
1484
Matt Mackalld59745c2005-05-01 08:59:02 -07001485config PRINTK
1486 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001487 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001488 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001489 help
1490 This option enables normal printk support. Removing it
1491 eliminates most of the message strings from the kernel image
1492 and makes the kernel more or less silent. As this makes it
1493 very difficult to diagnose system problems, saying N here is
1494 strongly discouraged.
1495
Petr Mladek42a0bb32016-05-20 17:00:33 -07001496config PRINTK_NMI
1497 def_bool y
1498 depends on PRINTK
1499 depends on HAVE_NMI
1500
Matt Mackallc8538a72005-05-01 08:59:01 -07001501config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001502 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001503 default y
1504 help
1505 Disabling this option eliminates support for BUG and WARN, reducing
1506 the size of your kernel image and potentially quietly ignoring
1507 numerous fatal conditions. You should only consider disabling this
1508 option for embedded systems with no facilities for reporting errors.
1509 Just say Y.
1510
Matt Mackall708e9a72006-01-08 01:05:25 -08001511config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001512 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001513 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001514 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001515 help
1516 Enable support for generating core dumps. Disabling saves about 4k.
1517
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001518
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001519config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001520 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001521 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001522 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001523 default y
1524 help
1525 This option allows to disable the internal PC-Speaker
1526 support, saving some memory.
1527
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528config BASE_FULL
1529 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001530 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 help
1532 Disabling this option reduces the size of miscellaneous core
1533 kernel data structures. This saves memory on small machines,
1534 but may reduce performance.
1535
1536config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001537 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -07001539 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 help
1541 Disabling this option will cause the kernel to be built without
1542 support for "fast userspace mutexes". The resulting kernel may not
1543 run glibc-based applications correctly.
1544
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001545config HAVE_FUTEX_CMPXCHG
1546 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001547 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001548 help
1549 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1550 is implemented and always working. This removes a couple of runtime
1551 checks.
1552
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001554 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001556 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 help
1558 Disabling this option will cause the kernel to be built without
1559 support for epoll family of system calls.
1560
Davide Libenzifba2afa2007-05-10 22:23:13 -07001561config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001562 bool "Enable signalfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001563 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001564 default y
1565 help
1566 Enable the signalfd() system call that allows to receive signals
1567 on a file descriptor.
1568
1569 If unsure, say Y.
1570
Davide Libenzib215e282007-05-10 22:23:16 -07001571config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001572 bool "Enable timerfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001573 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001574 default y
1575 help
1576 Enable the timerfd() system call that allows to receive timer
1577 events on a file descriptor.
1578
1579 If unsure, say Y.
1580
Davide Libenzie1ad7462007-05-10 22:23:19 -07001581config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001582 bool "Enable eventfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001583 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001584 default y
1585 help
1586 Enable the eventfd() system call that allows to receive both
1587 kernel notification (ie. KAIO) or userspace notifications.
1588
1589 If unsure, say Y.
1590
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001591# syscall, maps, verifier
1592config BPF_SYSCALL
Ingo Molnare1abf2c2015-04-02 15:51:39 +02001593 bool "Enable bpf() system call"
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001594 select ANON_INODES
1595 select BPF
1596 default n
1597 help
1598 Enable the bpf() system call that allows to manipulate eBPF
1599 programs and maps via file descriptors.
1600
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001602 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 default y
1604 depends on MMU
1605 help
1606 The shmem is an internal filesystem used to manage shared memory.
1607 It is backed by swap and manages resource limits. It is also exported
1608 to userspace as tmpfs if TMPFS is enabled. Disabling this
1609 option replaces shmem and tmpfs with the much simpler ramfs code,
1610 which may be appropriate on small systems without swap.
1611
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001612config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001613 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001614 default y
1615 help
1616 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001617 by some high performance threaded applications. Disabling
1618 this option saves about 7k.
1619
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001620config ADVISE_SYSCALLS
1621 bool "Enable madvise/fadvise syscalls" if EXPERT
1622 default y
1623 help
1624 This option enables the madvise and fadvise syscalls, used by
1625 applications to advise the kernel about their future memory or file
1626 usage, improving performance. If building an embedded system where no
1627 applications use these syscalls, you can disable this option to save
1628 space.
1629
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001630config USERFAULTFD
1631 bool "Enable userfaultfd() system call"
1632 select ANON_INODES
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001633 depends on MMU
1634 help
1635 Enable the userfaultfd() system call that allows to intercept and
1636 handle page faults in userland.
1637
Mike Frysinger657a5202013-04-30 15:28:45 -07001638config PCI_QUIRKS
1639 default y
1640 bool "Enable PCI quirk workarounds" if EXPERT
1641 depends on PCI
1642 help
1643 This enables workarounds for various PCI chipset
1644 bugs/quirks. Disable this only if your target machine is
1645 unaffected by PCI quirks.
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001646
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001647config MEMBARRIER
1648 bool "Enable membarrier() system call" if EXPERT
1649 default y
1650 help
1651 Enable the membarrier() system call that allows issuing memory
1652 barriers across all running threads, which can be used to distribute
1653 the cost of user-space memory barriers asymmetrically by transforming
1654 pairs of memory barriers into pairs consisting of membarrier() and a
1655 compiler barrier.
1656
1657 If unsure, say Y.
1658
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001659config EMBEDDED
1660 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001661 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001662 select EXPERT
1663 help
1664 This option should be enabled if compiling the kernel for
1665 an embedded system so certain expert options are available
1666 for configuration.
1667
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001668config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001669 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001670 help
1671 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001672
Peter Zijlstra906010b2009-09-21 16:08:49 +02001673config PERF_USE_VMALLOC
1674 bool
1675 help
1676 See tools/perf/design.txt for details
1677
Ingo Molnar57c0c152009-09-21 12:20:38 +02001678menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001679
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001680config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001681 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001682 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001683 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001684 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001685 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001686 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001687 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001688 Enable kernel support for various performance events provided
1689 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001690
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001691 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001692 use of generic tracepoints.
1693
1694 Most modern CPUs support performance events via performance
1695 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001696 types of hw events: such as instructions executed, cachemisses
1697 suffered, or branches mis-predicted - without slowing down the
1698 kernel or applications. These registers can also trigger interrupts
1699 when a threshold number of events have passed - and can thus be
1700 used to profile the code that runs on that CPU.
1701
Ingo Molnar57c0c152009-09-21 12:20:38 +02001702 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001703 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001704 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001705 provides per task and per CPU counters, and it provides event
1706 capabilities on top of those.
1707
1708 Say Y if unsure.
1709
Peter Zijlstra906010b2009-09-21 16:08:49 +02001710config DEBUG_PERF_USE_VMALLOC
1711 default n
1712 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb307112015-05-04 16:26:39 +10001713 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001714 select PERF_USE_VMALLOC
1715 help
1716 Use vmalloc memory to back perf mmap() buffers.
1717
1718 Mostly useful for debugging the vmalloc code on platforms
1719 that don't require it.
1720
1721 Say N if unsure.
1722
Thomas Gleixner0793a612008-12-04 20:12:29 +01001723endmenu
1724
Christoph Lameterf8891e52006-06-30 01:55:45 -07001725config VM_EVENT_COUNTERS
1726 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001727 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001728 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001729 VM event counters are needed for event counts to be shown.
1730 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001731 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001732 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001733
Christoph Lameter41ecc552007-05-09 02:32:44 -07001734config SLUB_DEBUG
1735 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001736 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001737 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001738 help
1739 SLUB has extensive debug support features. Disabling these can
1740 result in significant savings in code size. This also disables
1741 SLUB sysfs support. /sys/slab will not exist and there will be
1742 no support for cache validation etc.
1743
Randy Dunlapb943c462009-03-10 12:55:46 -07001744config COMPAT_BRK
1745 bool "Disable heap randomization"
1746 default y
1747 help
1748 Randomizing heap placement makes heap exploits harder, but it
1749 also breaks ancient binaries (including anything libc5 based).
1750 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001751 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001752 /proc/sys/kernel/randomize_va_space to 2.
1753
1754 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1755
Christoph Lameter81819f02007-05-06 14:49:36 -07001756choice
1757 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001758 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001759 help
1760 This option allows to select a slab allocator.
1761
1762config SLAB
1763 bool "SLAB"
Kees Cook04385fc2016-06-23 15:20:59 -07001764 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001765 help
1766 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001767 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001768 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001769
1770config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001771 bool "SLUB (Unqueued Allocator)"
Kees Cooked18adc2016-06-23 15:24:05 -07001772 select HAVE_HARDENED_USERCOPY_ALLOCATOR
Christoph Lameter81819f02007-05-06 14:49:36 -07001773 help
1774 SLUB is a slab allocator that minimizes cache line usage
1775 instead of managing queues of cached objects (SLAB approach).
1776 Per cpu caching is realized using slabs of objects instead
1777 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001778 and has enhanced diagnostics. SLUB is the default choice for
1779 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001780
1781config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001782 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001783 bool "SLOB (Simple Allocator)"
1784 help
Matt Mackall37291452008-02-04 22:29:38 -08001785 SLOB replaces the stock allocator with a drastically simpler
1786 allocator. SLOB is generally more space efficient but
1787 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001788
1789endchoice
1790
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001791config SLAB_FREELIST_RANDOM
1792 default n
Thomas Garnier210e7a42016-07-26 15:21:59 -07001793 depends on SLAB || SLUB
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001794 bool "SLAB freelist randomization"
1795 help
Thomas Garnier210e7a42016-07-26 15:21:59 -07001796 Randomizes the freelist order used on creating new pages. This
Thomas Garnierc7ce4f602016-05-19 17:10:37 -07001797 security feature reduces the predictability of the kernel slab
1798 allocator against heap overflows.
1799
Joonsoo Kim345c9052013-06-19 14:05:52 +09001800config SLUB_CPU_PARTIAL
1801 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001802 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001803 bool "SLUB per cpu partial cache"
1804 help
1805 Per cpu partial caches accellerate objects allocation and freeing
1806 that is local to a processor at the price of more indeterminism
1807 in the latency of the free. On overflow these caches will be cleared
1808 which requires the taking of locks that may cause latency spikes.
1809 Typically one would choose no for a realtime system.
1810
Jie Zhangea637632009-12-14 18:00:02 -08001811config MMAP_ALLOW_UNINITIALIZED
1812 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001813 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001814 default n
1815 help
1816 Normally, and according to the Linux spec, anonymous memory obtained
1817 from mmap() has it's contents cleared before it is passed to
1818 userspace. Enabling this config option allows you to request that
1819 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1820 providing a huge performance boost. If this option is not enabled,
1821 then the flag will be ignored.
1822
1823 This is taken advantage of by uClibc's malloc(), and also by
1824 ELF-FDPIC binfmt's brk and stack allocator.
1825
1826 Because of the obvious security issues, this option should only be
1827 enabled on embedded devices where you control what is run in
1828 userspace. Since that isn't generally a problem on no-MMU systems,
1829 it is normally safe to say Y here.
1830
1831 See Documentation/nommu-mmap.txt for more information.
1832
David Howells091f6e22015-07-20 21:16:28 +01001833config SYSTEM_DATA_VERIFICATION
1834 def_bool n
1835 select SYSTEM_TRUSTED_KEYRING
1836 select KEYS
1837 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001838 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001839 select ASYMMETRIC_KEY_TYPE
1840 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001841 select ASN1
1842 select OID_REGISTRY
1843 select X509_CERTIFICATE_PARSER
1844 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001845 help
David Howells091f6e22015-07-20 21:16:28 +01001846 Provide PKCS#7 message verification using the contents of the system
1847 trusted keyring to provide public keys. This then can be used for
1848 module verification, kexec image verification and firmware blob
1849 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001850
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001851config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001852 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001853 help
1854 Say Y here to enable the extended profiling support mechanisms used
1855 by profilers such as OProfile.
1856
Ingo Molnar5f87f112008-07-23 14:15:22 +02001857#
1858# Place an empty function call at each tracepoint site. Can be
1859# dynamically changed for a probe function.
1860#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001861config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001862 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001863
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05001864source "arch/Kconfig"
1865
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866endmenu # General setup
1867
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04001868config HAVE_GENERIC_DMA_COHERENT
1869 bool
1870 default n
1871
Linus Torvalds158a9622008-01-02 13:04:48 -08001872config SLABINFO
1873 bool
1874 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03001875 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08001876 default y
1877
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001878config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001879 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001880
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881config BASE_SMALL
1882 int
1883 default 0 if BASE_FULL
1884 default 1 if !BASE_FULL
1885
Jan Engelhardt66da5732007-07-15 23:39:29 -07001886menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02001888 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889 help
1890 Kernel modules are small pieces of compiled code which can
1891 be inserted in the running kernel, rather than being
1892 permanently built into the kernel. You use the "modprobe"
1893 tool to add (and sometimes remove) them. If you say Y here,
1894 many parts of the kernel can be built as modules (by
1895 answering M instead of Y where indicated): this is most
1896 useful for infrequently used options which are not required
1897 for booting. For more information, see the man pages for
1898 modprobe, lsmod, modinfo, insmod and rmmod.
1899
1900 If you say Y here, you will need to run "make
1901 modules_install" to put the modules under /lib/modules/
1902 where modprobe can find them (you may need to be root to do
1903 this).
1904
1905 If unsure, say Y.
1906
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001907if MODULES
1908
Linus Torvalds826e4502008-05-04 17:04:16 -07001909config MODULE_FORCE_LOAD
1910 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001911 default n
1912 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001913 Allow loading of modules without version information (ie. modprobe
1914 --force). Forced module loading sets the 'F' (forced) taint flag and
1915 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001916
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917config MODULE_UNLOAD
1918 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 help
1920 Without this option you will not be able to unload any
1921 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001922 anyway), which makes your kernel smaller, faster
1923 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924
1925config MODULE_FORCE_UNLOAD
1926 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07001927 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 help
1929 This option allows you to force a module to unload, even if the
1930 kernel believes it is unsafe: the kernel will remove the module
1931 without waiting for anyone to stop using it (using the -f option to
1932 rmmod). This is mainly for kernel developers and desperate users.
1933 If unsure, say N.
1934
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001936 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937 help
1938 Usually, you have to use modules compiled with your kernel.
1939 Saying Y here makes it sometimes possible to use modules
1940 compiled for different kernels, by adding enough information
1941 to the modules to (hopefully) spot any changes which would
1942 make them incompatible with the kernel you are running. If
1943 unsure, say N.
1944
1945config MODULE_SRCVERSION_ALL
1946 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947 help
1948 Modules which contain a MODULE_VERSION get an extra "srcversion"
1949 field inserted into their modinfo section, which contains a
1950 sum of the source files which made it. This helps maintainers
1951 see exactly which source was used to build a module (since
1952 others sometimes change the module source without updating
1953 the version). With this option, such a "srcversion" field
1954 will be created for all modules. If unsure, say N.
1955
Rusty Russell106a4ee2012-09-26 10:09:40 +01001956config MODULE_SIG
1957 bool "Module signature verification"
1958 depends on MODULES
David Howells091f6e22015-07-20 21:16:28 +01001959 select SYSTEM_DATA_VERIFICATION
Rusty Russell106a4ee2012-09-26 10:09:40 +01001960 help
1961 Check modules for valid signatures upon load: the signature
1962 is simply appended to the module. For more information see
1963 Documentation/module-signing.txt.
1964
David Howells228c37f2015-08-11 12:38:54 +01001965 Note that this option adds the OpenSSL development packages as a
1966 kernel build dependency so that the signing tool can use its crypto
1967 library.
1968
David Howellsea0b6dc2012-09-26 10:09:50 +01001969 !!!WARNING!!! If you enable this option, you MUST make sure that the
1970 module DOES NOT get stripped after being signed. This includes the
1971 debuginfo strip done by some packagers (such as rpmbuild) and
1972 inclusion into an initramfs that wants the module size reduced.
1973
Rusty Russell106a4ee2012-09-26 10:09:40 +01001974config MODULE_SIG_FORCE
1975 bool "Require modules to be validly signed"
1976 depends on MODULE_SIG
1977 help
1978 Reject unsigned modules or signed modules for which we don't have a
1979 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01001980
Michal Marekd9d8d7e2013-01-25 13:41:31 +10301981config MODULE_SIG_ALL
1982 bool "Automatically sign all modules"
1983 default y
1984 depends on MODULE_SIG
1985 help
1986 Sign all modules during make modules_install. Without this option,
1987 modules must be signed manually, using the scripts/sign-file tool.
1988
1989comment "Do not forget to sign required modules with scripts/sign-file"
1990 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1991
David Howellsea0b6dc2012-09-26 10:09:50 +01001992choice
1993 prompt "Which hash algorithm should modules be signed with?"
1994 depends on MODULE_SIG
1995 help
1996 This determines which sort of hashing algorithm will be used during
1997 signature generation. This algorithm _must_ be built into the kernel
1998 directly so that signature verification can take place. It is not
1999 possible to load a signed module containing the algorithm to check
2000 the signature on that module.
2001
2002config MODULE_SIG_SHA1
2003 bool "Sign modules with SHA-1"
2004 select CRYPTO_SHA1
2005
2006config MODULE_SIG_SHA224
2007 bool "Sign modules with SHA-224"
2008 select CRYPTO_SHA256
2009
2010config MODULE_SIG_SHA256
2011 bool "Sign modules with SHA-256"
2012 select CRYPTO_SHA256
2013
2014config MODULE_SIG_SHA384
2015 bool "Sign modules with SHA-384"
2016 select CRYPTO_SHA512
2017
2018config MODULE_SIG_SHA512
2019 bool "Sign modules with SHA-512"
2020 select CRYPTO_SHA512
2021
2022endchoice
2023
Michal Marek22753672013-01-25 13:41:00 +10302024config MODULE_SIG_HASH
2025 string
2026 depends on MODULE_SIG
2027 default "sha1" if MODULE_SIG_SHA1
2028 default "sha224" if MODULE_SIG_SHA224
2029 default "sha256" if MODULE_SIG_SHA256
2030 default "sha384" if MODULE_SIG_SHA384
2031 default "sha512" if MODULE_SIG_SHA512
2032
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302033config MODULE_COMPRESS
2034 bool "Compress modules on installation"
2035 depends on MODULES
2036 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302037
Rusty Russellb6c09b52015-06-16 12:16:22 +09302038 Compresses kernel modules when 'make modules_install' is run; gzip or
2039 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302040
Rusty Russellb6c09b52015-06-16 12:16:22 +09302041 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302042
Rusty Russellb6c09b52015-06-16 12:16:22 +09302043 Out-of-tree kernel modules installed using Kbuild will also be
2044 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302045
Rusty Russellb6c09b52015-06-16 12:16:22 +09302046 Note: for modules inside an initrd or initramfs, it's more efficient
2047 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302048
Rusty Russellb6c09b52015-06-16 12:16:22 +09302049 Note: This is fully compatible with signed modules.
2050
2051 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09302052
2053choice
2054 prompt "Compression algorithm"
2055 depends on MODULE_COMPRESS
2056 default MODULE_COMPRESS_GZIP
2057 help
2058 This determines which sort of compression will be used during
2059 'make modules_install'.
2060
2061 GZIP (default) and XZ are supported.
2062
2063config MODULE_COMPRESS_GZIP
2064 bool "GZIP"
2065
2066config MODULE_COMPRESS_XZ
2067 bool "XZ"
2068
2069endchoice
2070
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002071config TRIM_UNUSED_KSYMS
2072 bool "Trim unused exported kernel symbols"
2073 depends on MODULES && !UNUSED_SYMBOLS
2074 help
2075 The kernel and some modules make many symbols available for
2076 other modules to use via EXPORT_SYMBOL() and variants. Depending
2077 on the set of modules being selected in your kernel configuration,
2078 many of those exported symbols might never be used.
2079
2080 This option allows for unused exported symbols to be dropped from
2081 the build. In turn, this provides the compiler more opportunities
2082 (especially when using LTO) for optimizing the code and reducing
2083 binary size. This might have some security advantages as well.
2084
Valdis Kletnieksf1cb6372016-08-02 14:07:27 -07002085 If unsure, or if you need to build out-of-tree modules, say N.
Nicolas Pitredbacb0e2016-01-26 21:51:05 -05002086
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002087endif # MODULES
2088
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302089config MODULES_TREE_LOOKUP
2090 def_bool y
2091 depends on PERF_EVENTS || TRACING
2092
Rusty Russell98a79d62008-12-13 21:19:41 +10302093config INIT_ALL_POSSIBLE
2094 bool
2095 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302096 Back when each arch used to define their own cpu_online_mask and
2097 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302098 with all 1s, and others with all 0s. When they were centralised,
2099 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002100 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302101
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002102source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002103
2104config PREEMPT_NOTIFIERS
2105 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002106
Steffen Klassert16295be2010-01-06 19:47:10 +11002107config PADATA
2108 depends on SMP
2109 bool
2110
Andi Kleen754b7b62012-10-04 17:11:27 -07002111# Can be selected by architectures with broken toolchains
2112# that get confused by correct const<->read_only section
2113# mappings
2114config BROKEN_RODATA
2115 bool
2116
David Howells4520c6a2012-09-21 23:31:13 +01002117config ASN1
2118 tristate
2119 help
2120 Build a simple ASN.1 grammar compiler that produces a bytecode output
2121 that can be interpreted by the ASN.1 stream decoder and used to
2122 inform it as to what tags are to be expected in a stream and what
2123 functions to call on what tags.
2124
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002125source "kernel/Kconfig.locks"