blob: 0dfd09d54c6519fb8a5069bf6153f4245184d01f [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"
58 default n
59 help
60 Some drivers can be compiled on a different platform than they are
61 intended to be run on. Despite they cannot be loaded there (or even
62 when they load they cannot be used due to missing HW support),
63 developers still, opposing to distributors, might want to build such
64 drivers to compile-test them.
65
66 If you are a developer and want to build everything available, say Y
67 here. If you are a user/distributor, say N here to exclude useless
68 drivers to be distributed.
69
Linus Torvalds1da177e2005-04-16 15:20:36 -070070config LOCALVERSION
71 string "Local version - append to kernel release"
72 help
73 Append an extra string to the end of your kernel version.
74 This will show up when you type uname, for example.
75 The string you set here will be appended after the contents of
76 any files with a filename matching localversion* in your
77 object and source tree, in that order. Your total string can
78 be a maximum of 64 characters.
79
Ryan Andersonaaebf432005-07-31 04:57:49 -040080config LOCALVERSION_AUTO
81 bool "Automatically append version information to the version string"
82 default y
83 help
84 This will try to automatically determine if the current tree is a
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020085 release tree by looking for git tags that belong to the current
86 top of tree revision.
Ryan Andersonaaebf432005-07-31 04:57:49 -040087
88 A string of the format -gxxxxxxxx will be added to the localversion
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020089 if a git-based tree is found. The string generated by this will be
Ryan Andersonaaebf432005-07-31 04:57:49 -040090 appended after any matching localversion* files, and after the value
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020091 set in CONFIG_LOCALVERSION.
Ryan Andersonaaebf432005-07-31 04:57:49 -040092
Robert P. J. Day6e5a5422007-05-01 23:08:11 +020093 (The actual string used here is the first eight characters produced
94 by running the command:
95
96 $ git rev-parse --verify HEAD
97
98 which is done within the script "scripts/setlocalversion".)
Ryan Andersonaaebf432005-07-31 04:57:49 -040099
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800100config HAVE_KERNEL_GZIP
101 bool
102
103config HAVE_KERNEL_BZIP2
104 bool
105
106config HAVE_KERNEL_LZMA
107 bool
108
Lasse Collin3ebe1242011-01-12 17:01:23 -0800109config HAVE_KERNEL_XZ
110 bool
111
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800112config HAVE_KERNEL_LZO
113 bool
114
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700115config HAVE_KERNEL_LZ4
116 bool
117
Alain Knaff30d65db2009-01-04 22:46:17 +0100118choice
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800119 prompt "Kernel compression mode"
120 default KERNEL_GZIP
H. Peter Anvin2d3c6272013-11-14 21:43:47 -0800121 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 -0800122 help
Alain Knaff30d65db2009-01-04 22:46:17 +0100123 The linux kernel is a kind of self-extracting executable.
124 Several compression algorithms are available, which differ
125 in efficiency, compression and decompression speed.
126 Compression speed is only relevant when building a kernel.
127 Decompression speed is relevant at each boot.
128
129 If you have any problems with bzip2 or lzma compressed
130 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
131 version of this functionality (bzip2 only), for 2.4, was
132 supplied by Christian Ludwig)
133
134 High compression options are mostly useful for users, who
135 are low on disk space (embedded systems), but for whom ram
136 size matters less.
137
138 If in doubt, select 'gzip'
139
140config KERNEL_GZIP
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800141 bool "Gzip"
142 depends on HAVE_KERNEL_GZIP
143 help
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800144 The old and tried gzip compression. It provides a good balance
145 between compression ratio and decompression speed.
Alain Knaff30d65db2009-01-04 22:46:17 +0100146
147config KERNEL_BZIP2
148 bool "Bzip2"
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800149 depends on HAVE_KERNEL_BZIP2
Alain Knaff30d65db2009-01-04 22:46:17 +0100150 help
151 Its compression ratio and speed is intermediate.
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700152 Decompression speed is slowest among the choices. The kernel
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800153 size is about 10% smaller with bzip2, in comparison to gzip.
154 Bzip2 uses a large amount of memory. For modern kernels you
155 will need at least 8MB RAM or more for booting.
Alain Knaff30d65db2009-01-04 22:46:17 +0100156
157config KERNEL_LZMA
H. Peter Anvin2e9f3bd2009-01-04 15:41:25 -0800158 bool "LZMA"
159 depends on HAVE_KERNEL_LZMA
160 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700161 This compression algorithm's ratio is best. Decompression speed
162 is between gzip and bzip2. Compression is slowest.
163 The kernel size is about 33% smaller with LZMA in comparison to gzip.
Alain Knaff30d65db2009-01-04 22:46:17 +0100164
Lasse Collin3ebe1242011-01-12 17:01:23 -0800165config KERNEL_XZ
166 bool "XZ"
167 depends on HAVE_KERNEL_XZ
168 help
169 XZ uses the LZMA2 algorithm and instruction set specific
170 BCJ filters which can improve compression ratio of executable
171 code. The size of the kernel is about 30% smaller with XZ in
172 comparison to gzip. On architectures for which there is a BCJ
173 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
174 will create a few percent smaller kernel than plain LZMA.
175
176 The speed is about the same as with LZMA: The decompression
177 speed of XZ is better than that of bzip2 but worse than gzip
178 and LZO. Compression is slow.
179
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800180config KERNEL_LZO
181 bool "LZO"
182 depends on HAVE_KERNEL_LZO
183 help
Randy Dunlap0a4dd352012-05-31 16:26:46 -0700184 Its compression ratio is the poorest among the choices. The kernel
Stephan Sperber681b3042010-07-14 11:23:08 +0200185 size is about 10% bigger than gzip; however its speed
Albin Tonnerre7dd65fe2010-01-08 14:42:42 -0800186 (both compression and decompression) is the fastest.
187
Kyungsik Leee76e1fd2013-07-08 16:01:46 -0700188config KERNEL_LZ4
189 bool "LZ4"
190 depends on HAVE_KERNEL_LZ4
191 help
192 LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
193 A preliminary version of LZ4 de/compression tool is available at
194 <https://code.google.com/p/lz4/>.
195
196 Its compression ratio is worse than LZO. The size of the kernel
197 is about 8% bigger than LZO. But the decompression speed is
198 faster than LZO.
199
Alain Knaff30d65db2009-01-04 22:46:17 +0100200endchoice
201
Josh Triplettbd5dc172011-06-15 15:08:28 -0700202config DEFAULT_HOSTNAME
203 string "Default hostname"
204 default "(none)"
205 help
206 This option determines the default system hostname before userspace
207 calls sethostname(2). The kernel traditionally uses "(none)" here,
208 but you may wish to use a different default here to make a minimal
209 system more usable with less configuration.
210
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211config SWAP
212 bool "Support for paging of anonymous memory (swap)"
David Howells93614012006-09-30 20:45:40 +0200213 depends on MMU && BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 default y
215 help
216 This option allows you to choose whether you want to have support
Jesper Juhl92c35042006-01-15 02:40:08 +0100217 for so called swap devices or swap files in your kernel that are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 used to provide more virtual memory than the actual RAM present
219 in your computer. If unsure say Y.
220
221config SYSVIPC
222 bool "System V IPC"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 ---help---
224 Inter Process Communication is a suite of library functions and
225 system calls which let processes (running programs) synchronize and
226 exchange information. It is generally considered to be a good thing,
227 and some programs won't run unless you say Y here. In particular, if
228 you want to run the DOS emulator dosemu under Linux (read the
229 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
230 you'll need to say Y here.
231
232 You can find documentation about IPC with "info ipc" and also in
233 section 6.4 of the Linux Programmer's Guide, available from
234 <http://www.tldp.org/guides.html>.
235
Eric W. Biedermana5494dc2007-02-14 00:34:06 -0800236config SYSVIPC_SYSCTL
237 bool
238 depends on SYSVIPC
239 depends on SYSCTL
240 default y
241
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242config POSIX_MQUEUE
243 bool "POSIX Message Queues"
Kees Cook19c92392012-10-02 11:19:29 -0700244 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 ---help---
246 POSIX variant of message queues is a part of IPC. In POSIX message
247 queues every message has a priority which decides about succession
248 of receiving it by a process. If you want to compile and run
249 programs written e.g. for Solaris with use of its POSIX message
Robert P. J. Dayb0e37652007-05-09 07:25:13 +0200250 queues (functions mq_*) say Y here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251
252 POSIX message queues are visible as a filesystem called 'mqueue'
253 and can be mounted somewhere if you want to do filesystem
254 operations on message queues.
255
256 If unsure, say Y.
257
Serge E. Hallynbdc8e5f2009-04-06 19:01:11 -0700258config POSIX_MQUEUE_SYSCTL
259 bool
260 depends on POSIX_MQUEUE
261 depends on SYSCTL
262 default y
263
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700264config CROSS_MEMORY_ATTACH
265 bool "Enable process_vm_readv/writev syscalls"
266 depends on MMU
267 default y
268 help
269 Enabling this option adds the system calls process_vm_readv and
270 process_vm_writev which allow a process with the correct privileges
Geert Uytterhoevena2a368d2014-08-12 13:46:11 -0700271 to directly read from or write to another process' address space.
Konstantin Khlebnikov226b4cc2014-06-04 16:10:50 -0700272 See the man page for more details.
273
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530274config FHANDLE
Andi Kleenf76be612016-04-01 14:31:40 -0700275 bool "open by fhandle syscalls" if EXPERT
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530276 select EXPORTFS
Andi Kleenf76be612016-04-01 14:31:40 -0700277 default y
Aneesh Kumar K.V990d6c22011-01-29 18:43:26 +0530278 help
279 If you say Y here, a user level program will be able to map
280 file names to handle and then later use the handle for
281 different file system operations. This is useful in implementing
282 userspace file servers, which now track files using handles instead
283 of names. The handle would remain the same even if file names
284 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
285 syscalls.
286
Josh Triplett69369a72014-04-03 14:48:27 -0700287config USELIB
288 bool "uselib syscall"
Riku Voipiob2113a42016-01-15 16:58:13 -0800289 def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
Josh Triplett69369a72014-04-03 14:48:27 -0700290 help
291 This option enables the uselib syscall, a system call used in the
292 dynamic linker from libc5 and earlier. glibc does not use this
293 system call. If you intend to run programs built on libc5 or
294 earlier, you may need to enable this syscall. Current systems
295 running glibc can safely disable this.
296
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297config AUDIT
298 bool "Auditing support"
Chris Wright804a6a492005-05-11 10:52:45 +0100299 depends on NET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 help
301 Enable auditing infrastructure that can be used with another
302 kernel subsystem, such as SELinux (which requires this for
Paul Moorecb74ed22016-01-13 09:18:55 -0500303 logging of avc messages output). System call auditing is included
304 on architectures which support it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900306config HAVE_ARCH_AUDITSYSCALL
307 bool
308
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309config AUDITSYSCALL
Paul Moorecb74ed22016-01-13 09:18:55 -0500310 def_bool y
AKASHI Takahiro7a017722014-02-25 18:16:24 +0900311 depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312
Eric Paris939a67f2009-12-17 20:12:06 -0500313config AUDIT_WATCH
314 def_bool y
315 depends on AUDITSYSCALL
316 select FSNOTIFY
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
Al Viro74c3cbe2007-07-22 08:04:18 -0400318config AUDIT_TREE
319 def_bool y
Eric Paris63c882a2009-05-21 17:02:01 -0400320 depends on AUDITSYSCALL
Eric Paris28a3a7e2009-12-17 20:12:05 -0500321 select FSNOTIFY
Al Viro74c3cbe2007-07-22 08:04:18 -0400322
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000323source "kernel/irq/Kconfig"
Thomas Gleixner764e0da2012-05-21 23:16:18 +0200324source "kernel/time/Kconfig"
Thomas Gleixnerd9817eb2010-09-27 12:45:59 +0000325
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200326menu "CPU/Task time and stats accounting"
327
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200328config VIRT_CPU_ACCOUNTING
329 bool
330
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200331choice
332 prompt "Cputime accounting"
333 default TICK_CPU_ACCOUNTING if !PPC64
Stephen Rothwell02fc8d32013-02-08 14:19:38 +1100334 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200335
336# Kind of a stub config for the pure tick based cputime accounting
337config TICK_CPU_ACCOUNTING
338 bool "Simple tick based cputime accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200339 depends on !S390 && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200340 help
341 This is the basic tick based cputime accounting that maintains
342 statistics about user, system and idle time spent on per jiffies
343 granularity.
344
345 If unsure, say Y.
346
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200347config VIRT_CPU_ACCOUNTING_NATIVE
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200348 bool "Deterministic task and CPU time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200349 depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200350 select VIRT_CPU_ACCOUNTING
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200351 help
352 Select this option to enable more accurate task and CPU time
353 accounting. This is done by reading a CPU counter on each
354 kernel entry and exit and on transitions within the kernel
355 between system, softirq and hardirq state, so there is a
356 small performance impact. In the case of s390 or IBM POWER > 5,
357 this also enables accounting of stolen time on logically-partitioned
358 systems.
359
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200360config VIRT_CPU_ACCOUNTING_GEN
361 bool "Full dynticks CPU time accounting"
Kevin Hilmanff3fb252013-09-16 15:28:19 -0700362 depends on HAVE_CONTEXT_TRACKING
Kevin Hilman554b0002013-09-16 15:28:21 -0700363 depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
Frederic Weisbeckerabf917c2012-07-25 07:56:04 +0200364 select VIRT_CPU_ACCOUNTING
365 select CONTEXT_TRACKING
366 help
367 Select this option to enable task and CPU time accounting on full
368 dynticks systems. This accounting is implemented by watching every
369 kernel-user boundaries using the context tracking subsystem.
370 The accounting is thus performed at the expense of some significant
371 overhead.
372
373 For now this is only useful if you are working on the full
374 dynticks subsystem development.
375
376 If unsure, say N.
377
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200378config IRQ_TIME_ACCOUNTING
379 bool "Fine granularity task level IRQ time accounting"
Frederic Weisbeckerc58b0df2013-04-26 15:16:31 +0200380 depends on HAVE_IRQ_TIME_ACCOUNTING && !NO_HZ_FULL
Frederic Weisbeckerfdf9c352012-09-09 14:56:31 +0200381 help
382 Select this option to enable fine granularity task irq time
383 accounting. This is done by reading a timestamp on each
384 transitions between softirq and hardirq state, so there can be a
385 small performance impact.
386
387 If in doubt, say N here.
388
389endchoice
390
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200391config BSD_PROCESS_ACCT
392 bool "BSD Process Accounting"
Iulia Manda28138932015-04-15 16:16:41 -0700393 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200394 help
395 If you say Y here, a user level program will be able to instruct the
396 kernel (via a special system call) to write process accounting
397 information to a file: whenever a process exits, information about
398 that process will be appended to the file by the kernel. The
399 information includes things such as creation time, owning user,
400 command name, memory usage, controlling terminal etc. (the complete
401 list is in the struct acct in <file:include/linux/acct.h>). It is
402 up to the user level program to do useful things with this
403 information. This is generally a good idea, so say Y.
404
405config BSD_PROCESS_ACCT_V3
406 bool "BSD Process Accounting version 3 file format"
407 depends on BSD_PROCESS_ACCT
408 default n
409 help
410 If you say Y here, the process accounting information is written
411 in a new file format that also logs the process IDs of each
412 process and it's parent. Note that this file format is incompatible
413 with previous v0/v1/v2 file formats, so you will need updated tools
414 for processing it. A preliminary version of these tools is available
415 at <http://www.gnu.org/software/acct/>.
416
417config TASKSTATS
Kees Cook19c92392012-10-02 11:19:29 -0700418 bool "Export task/process statistics through netlink"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200419 depends on NET
Iulia Manda28138932015-04-15 16:16:41 -0700420 depends on MULTIUSER
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200421 default n
422 help
423 Export selected statistics for tasks/processes through the
424 generic netlink interface. Unlike BSD process accounting, the
425 statistics are available during the lifetime of tasks/processes as
426 responses to commands. Like BSD accounting, they are sent to user
427 space on task exit.
428
429 Say N if unsure.
430
431config TASK_DELAY_ACCT
Kees Cook19c92392012-10-02 11:19:29 -0700432 bool "Enable per-task delay accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200433 depends on TASKSTATS
Naveen N. Raof6db8342015-06-25 23:53:37 +0530434 select SCHED_INFO
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200435 help
436 Collect information on time spent by a task waiting for system
437 resources like cpu, synchronous block I/O completion and swapping
438 in pages. Such statistics can help in setting a task's priorities
439 relative to other tasks for cpu, io, rss limits etc.
440
441 Say N if unsure.
442
443config TASK_XACCT
Kees Cook19c92392012-10-02 11:19:29 -0700444 bool "Enable extended accounting over taskstats"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200445 depends on TASKSTATS
446 help
447 Collect extended task accounting data and send the data
448 to userland for processing over the taskstats interface.
449
450 Say N if unsure.
451
452config TASK_IO_ACCOUNTING
Kees Cook19c92392012-10-02 11:19:29 -0700453 bool "Enable per-task storage I/O accounting"
Frederic Weisbecker391dc692012-09-09 14:22:07 +0200454 depends on TASK_XACCT
455 help
456 Collect information on the number of bytes of storage I/O which this
457 task has caused.
458
459 Say N if unsure.
460
461endmenu # "CPU/Task time and stats accounting"
462
Mike Travisc903ff82009-01-15 12:28:29 -0800463menu "RCU Subsystem"
464
Mike Travisc903ff82009-01-15 12:28:29 -0800465config TREE_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400466 bool
467 default y if !PREEMPT && SMP
Mike Travisc903ff82009-01-15 12:28:29 -0800468 help
469 This option selects the RCU implementation that is
470 designed for very large SMP system with hundreds or
Paul E. McKenneyc17ef452009-06-23 17:12:47 -0700471 thousands of CPUs. It also scales down nicely to
472 smaller systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800473
Pranith Kumar28f65692014-09-22 14:00:48 -0400474config PREEMPT_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400475 bool
476 default y if PREEMPT
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700477 help
478 This option selects the RCU implementation that is
479 designed for very large SMP systems with hundreds or
480 thousands of CPUs, but for which real-time response
Paul E. McKenneybbe3eae2009-09-13 09:15:08 -0700481 is also required. It also scales down nicely to
482 smaller systems.
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700483
Paul E. McKenney9fc52d82013-01-08 15:48:33 -0800484 Select this option if you are unsure.
485
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700486config TINY_RCU
Pranith Kumare72aeaf2015-04-21 17:29:42 -0400487 bool
488 default y if !PREEMPT && !SMP
Paul E. McKenney9b1d82f2009-10-25 19:03:50 -0700489 help
490 This option selects the RCU implementation that is
491 designed for UP systems from which real-time response
492 is not required. This option greatly reduces the
493 memory footprint of RCU.
494
Paul E. McKenney78cae102015-04-20 12:19:45 -0700495config RCU_EXPERT
496 bool "Make expert-level adjustments to RCU configuration"
497 default n
498 help
499 This option needs to be enabled if you wish to make
500 expert-level adjustments to RCU configuration. By default,
501 no such adjustments can be made, which has the often-beneficial
502 side-effect of preventing "make oldconfig" from asking you all
503 sorts of detailed questions about how you would like numerous
504 obscure RCU options to be set up.
505
506 Say Y if you need to make expert-level adjustments to RCU.
507
508 Say N if you are unsure.
509
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500510config SRCU
511 bool
512 help
513 This option selects the sleepable version of RCU. This version
514 permits arbitrary sleeping or blocking within RCU read-side critical
515 sections.
516
Paul E. McKenney8315f422014-06-27 13:42:20 -0700517config TASKS_RCU
Paul E. McKenney82d0f4c2015-04-20 05:42:50 -0700518 bool
Paul E. McKenney8315f422014-06-27 13:42:20 -0700519 default n
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500520 select SRCU
Paul E. McKenney8315f422014-06-27 13:42:20 -0700521 help
522 This option enables a task-based RCU implementation that uses
523 only voluntary context switch (not preemption!), idle, and
524 user-mode execution as quiescent states.
525
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700526config RCU_STALL_COMMON
Pranith Kumar28f65692014-09-22 14:00:48 -0400527 def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
Paul E. McKenney6bfc09e2012-10-19 12:49:17 -0700528 help
529 This option enables RCU CPU stall code that is common between
530 the TINY and TREE variants of RCU. The purpose is to allow
531 the tiny variants to disable RCU CPU stall warnings, while
532 making these warnings mandatory for the tree variants.
533
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100534config CONTEXT_TRACKING
535 bool
536
Frederic Weisbecker91d1aa432012-11-27 19:33:25 +0100537config CONTEXT_TRACKING_FORCE
538 bool "Force context tracking"
539 depends on CONTEXT_TRACKING
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200540 default y if !NO_HZ_FULL
Frederic Weisbecker1fd2b442012-07-11 20:26:40 +0200541 help
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200542 The major pre-requirement for full dynticks to work is to
543 support the context tracking subsystem. But there are also
544 other dependencies to provide in order to make the full
545 dynticks working.
546
547 This option stands for testing when an arch implements the
548 context tracking backend but doesn't yet fullfill all the
549 requirements to make the full dynticks feature working.
550 Without the full dynticks, there is no way to test the support
551 for context tracking and the subsystems that rely on it: RCU
552 userspace extended quiescent state and tickless cputime
553 accounting. This option copes with the absence of the full
554 dynticks subsystem by forcing the context tracking on all
555 CPUs in the system.
556
Paul Gortmaker99c8b1e2013-10-24 10:07:47 -0400557 Say Y only if you're working on the development of an
Frederic Weisbeckerd84d27a2013-07-24 21:59:29 +0200558 architecture backend for the context tracking.
559
560 Say N otherwise, this option brings an overhead that you
561 don't want in production.
562
Frederic Weisbeckerd6771242012-10-11 01:48:28 +0200563
Mike Travisc903ff82009-01-15 12:28:29 -0800564config RCU_FANOUT
565 int "Tree-based hierarchical RCU fanout value"
566 range 2 64 if 64BIT
567 range 2 32 if !64BIT
Paul E. McKenney05c5df32015-04-20 14:27:43 -0700568 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Mike Travisc903ff82009-01-15 12:28:29 -0800569 default 64 if 64BIT
570 default 32 if !64BIT
571 help
572 This option controls the fanout of hierarchical implementations
573 of RCU, allowing RCU to work efficiently on machines with
Paul E. McKenney4d87ffa2010-08-04 17:31:12 -0700574 large numbers of CPUs. This value must be at least the fourth
575 root of NR_CPUS, which allows NR_CPUS to be insanely large.
576 The default value of RCU_FANOUT should be used for production
577 systems, but if you are stress-testing the RCU implementation
578 itself, small RCU_FANOUT values allow you to test large-system
579 code paths on small(er) systems.
Mike Travisc903ff82009-01-15 12:28:29 -0800580
581 Select a specific number if testing RCU itself.
582 Take the default if unsure.
583
Paul E. McKenney8932a632012-04-19 12:20:14 -0700584config RCU_FANOUT_LEAF
585 int "Tree-based hierarchical RCU leaf-level fanout value"
Paul E. McKenney8739c5c2015-04-20 18:27:54 -0700586 range 2 64 if 64BIT
587 range 2 32 if !64BIT
Paul E. McKenney47d631a2015-04-21 09:12:13 -0700588 depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
Paul E. McKenney8932a632012-04-19 12:20:14 -0700589 default 16
590 help
591 This option controls the leaf-level fanout of hierarchical
592 implementations of RCU, and allows trading off cache misses
593 against lock contention. Systems that synchronize their
594 scheduling-clock interrupts for energy-efficiency reasons will
595 want the default because the smaller leaf-level fanout keeps
596 lock contention levels acceptably low. Very large systems
597 (hundreds or thousands of CPUs) will instead want to set this
598 value to the maximum value possible in order to reduce the
599 number of cache misses incurred during RCU's grace-period
600 initialization. These systems tend to run CPU-bound, and thus
601 are not helped by synchronized interrupts, and thus tend to
602 skew them, which reduces lock contention enough that large
603 leaf-level fanouts work well.
604
605 Select a specific number if testing RCU itself.
606
607 Select the maximum permissible value for large systems.
608
609 Take the default if unsure.
610
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800611config RCU_FAST_NO_HZ
612 bool "Accelerate last non-dyntick-idle CPU's grace periods"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700613 depends on NO_HZ_COMMON && SMP && RCU_EXPERT
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800614 default n
615 help
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800616 This option permits CPUs to enter dynticks-idle state even if
617 they have RCU callbacks queued, and prevents RCU from waking
618 these CPUs up more than roughly once every four jiffies (by
619 default, you can adjust this using the rcutree.rcu_idle_gp_delay
620 parameter), thus improving energy efficiency. On the other
621 hand, this option increases the duration of RCU grace periods,
622 for example, slowing down synchronize_rcu().
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800623
Paul E. McKenneyc0f4dfd2012-12-28 11:30:36 -0800624 Say Y if energy efficiency is critically important, and you
625 don't care about increased grace-period durations.
Paul E. McKenney8bd93a22010-02-22 17:04:59 -0800626
627 Say N if you are unsure.
628
Mike Travisc903ff82009-01-15 12:28:29 -0800629config TREE_RCU_TRACE
Pranith Kumar28f65692014-09-22 14:00:48 -0400630 def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
Mike Travisc903ff82009-01-15 12:28:29 -0800631 select DEBUG_FS
632 help
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700633 This option provides tracing for the TREE_RCU and
Pranith Kumar28f65692014-09-22 14:00:48 -0400634 PREEMPT_RCU implementations, permitting Makefile to
Paul E. McKenneyf41d9112009-08-22 13:56:52 -0700635 trivially select kernel/rcutree_trace.c.
Mike Travisc903ff82009-01-15 12:28:29 -0800636
Paul E. McKenney24278d12010-09-27 17:25:23 -0700637config RCU_BOOST
638 bool "Enable RCU priority boosting"
Paul E. McKenney78cae102015-04-20 12:19:45 -0700639 depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700640 default n
641 help
642 This option boosts the priority of preempted RCU readers that
643 block the current preemptible RCU grace period for too long.
644 This option also prevents heavy loads from blocking RCU
645 callback invocation for all flavors of RCU.
646
647 Say Y here if you are working with real-time apps or heavy loads
648 Say N here if you are unsure.
649
Clark Williams21871d72014-09-12 21:21:09 -0500650config RCU_KTHREAD_PRIO
651 int "Real-time priority to use for RCU worker threads"
Paul E. McKenneya94844b2014-12-12 07:37:48 -0800652 range 1 99 if RCU_BOOST
653 range 0 99 if !RCU_BOOST
654 default 1 if RCU_BOOST
655 default 0 if !RCU_BOOST
Paul E. McKenney26730f52015-04-21 09:22:14 -0700656 depends on RCU_EXPERT
Paul E. McKenney24278d12010-09-27 17:25:23 -0700657 help
Clark Williams21871d72014-09-12 21:21:09 -0500658 This option specifies the SCHED_FIFO priority value that will be
659 assigned to the rcuc/n and rcub/n threads and is also the value
660 used for RCU_BOOST (if enabled). If you are working with a
661 real-time application that has one or more CPU-bound threads
662 running at a real-time priority level, you should set
663 RCU_KTHREAD_PRIO to a priority higher than the highest-priority
664 real-time CPU-bound application thread. The default RCU_KTHREAD_PRIO
665 value of 1 is appropriate in the common case, which is real-time
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700666 applications that do not have any CPU-bound threads.
667
668 Some real-time applications might not have a single real-time
669 thread that saturates a given CPU, but instead might have
670 multiple real-time threads that, taken together, fully utilize
Clark Williams21871d72014-09-12 21:21:09 -0500671 that CPU. In this case, you should set RCU_KTHREAD_PRIO to
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700672 a priority higher than the lowest-priority thread that is
673 conspiring to prevent the CPU from running any non-real-time
674 tasks. For example, if one thread at priority 10 and another
675 thread at priority 5 are between themselves fully consuming
Clark Williams21871d72014-09-12 21:21:09 -0500676 the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
Paul E. McKenneyc9336642012-04-18 16:20:18 -0700677 set to priority 6 or higher.
Paul E. McKenney24278d12010-09-27 17:25:23 -0700678
679 Specify the real-time priority, or take the default if unsure.
680
681config RCU_BOOST_DELAY
682 int "Milliseconds to delay boosting after RCU grace-period start"
683 range 0 3000
684 depends on RCU_BOOST
685 default 500
686 help
687 This option specifies the time to wait after the beginning of
688 a given grace period before priority-boosting preempted RCU
689 readers blocking that grace period. Note that any RCU reader
690 blocking an expedited RCU grace period is boosted immediately.
691
692 Accept the default if unsure.
693
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700694config RCU_NOCB_CPU
Paul E. McKenney9a5739d2013-03-28 20:48:36 -0700695 bool "Offload RCU callback processing from boot-selected CPUs"
Pranith Kumar28f65692014-09-22 14:00:48 -0400696 depends on TREE_RCU || PREEMPT_RCU
Paul E. McKenneybe55fa22015-06-02 05:29:18 -0700697 depends on RCU_EXPERT || NO_HZ_FULL
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700698 default n
699 help
700 Use this option to reduce OS jitter for aggressive HPC or
701 real-time workloads. It can also be used to offload RCU
702 callback invocation to energy-efficient CPUs in battery-powered
703 asymmetric multiprocessors.
704
705 This option offloads callback invocation from the set of
706 CPUs specified at boot time by the rcu_nocbs parameter.
Paul E. McKenneya4889852012-12-03 08:16:28 -0800707 For each such CPU, a kthread ("rcuox/N") will be created to
708 invoke callbacks, where the "N" is the CPU being offloaded,
709 and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and
710 "s" for RCU-sched. Nothing prevents this kthread from running
711 on the specified CPUs, but (1) the kthreads may be preempted
712 between each callback, and (2) affinity or cgroups can be used
713 to force the kthreads to run on whatever set of CPUs is desired.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700714
Paul E. McKenney34ed62462013-01-07 13:37:42 -0800715 Say Y here if you want to help to debug reduced OS jitter.
Paul E. McKenney3fbfbf72012-08-19 21:35:53 -0700716 Say N here if you are unsure.
717
Paul E. McKenney911af502013-02-11 10:23:27 -0800718choice
719 prompt "Build-forced no-CBs CPUs"
720 default RCU_NOCB_CPU_NONE
Stefan Hengelein45687792014-09-02 19:55:11 +0200721 depends on RCU_NOCB_CPU
Paul E. McKenney911af502013-02-11 10:23:27 -0800722 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700723 This option allows no-CBs CPUs (whose RCU callbacks are invoked
724 from kthreads rather than from softirq context) to be specified
725 at build time. Additional no-CBs CPUs may be specified by
726 the rcu_nocbs= boot parameter.
Paul E. McKenney911af502013-02-11 10:23:27 -0800727
728config RCU_NOCB_CPU_NONE
729 bool "No build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800730 help
731 This option does not force any of the CPUs to be no-CBs CPUs.
732 Only CPUs designated by the rcu_nocbs= boot parameter will be
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700733 no-CBs CPUs, whose RCU callbacks will be invoked by per-CPU
734 kthreads whose names begin with "rcuo". All other CPUs will
735 invoke their own RCU callbacks in softirq context.
736
737 Select this option if you want to choose no-CBs CPUs at
738 boot time, for example, to allow testing of different no-CBs
739 configurations without having to rebuild the kernel each time.
Paul E. McKenney911af502013-02-11 10:23:27 -0800740
741config RCU_NOCB_CPU_ZERO
742 bool "CPU 0 is a build_forced no-CBs CPU"
Paul E. McKenney911af502013-02-11 10:23:27 -0800743 help
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700744 This option forces CPU 0 to be a no-CBs CPU, so that its RCU
745 callbacks are invoked by a per-CPU kthread whose name begins
746 with "rcuo". Additional CPUs may be designated as no-CBs
747 CPUs using the rcu_nocbs= boot parameter will be no-CBs CPUs.
748 All other CPUs will invoke their own RCU callbacks in softirq
749 context.
Paul E. McKenney911af502013-02-11 10:23:27 -0800750
751 Select this if CPU 0 needs to be a no-CBs CPU for real-time
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700752 or energy-efficiency reasons, but the real reason it exists
753 is to ensure that randconfig testing covers mixed systems.
Paul E. McKenney911af502013-02-11 10:23:27 -0800754
755config RCU_NOCB_CPU_ALL
756 bool "All CPUs are build_forced no-CBs CPUs"
Paul E. McKenney911af502013-02-11 10:23:27 -0800757 help
758 This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs=
Paul E. McKenney676c3dc2013-04-30 14:49:42 -0700759 boot parameter will be ignored. All CPUs' RCU callbacks will
760 be executed in the context of per-CPU rcuo kthreads created for
761 this purpose. Assuming that the kthreads whose names start with
762 "rcuo" are bound to "housekeeping" CPUs, this reduces OS jitter
763 on the remaining CPUs, but might decrease memory locality during
764 RCU-callback invocation, thus potentially degrading throughput.
Paul E. McKenney911af502013-02-11 10:23:27 -0800765
766 Select this if all CPUs need to be no-CBs CPUs for real-time
767 or energy-efficiency reasons.
768
769endchoice
770
Paul E. McKenneyee425712015-02-19 10:51:32 -0800771config RCU_EXPEDITE_BOOT
772 bool
773 default n
774 help
775 This option enables expedited grace periods at boot time,
776 as if rcu_expedite_gp() had been invoked early in boot.
777 The corresponding rcu_unexpedite_gp() is invoked from
778 rcu_end_inkernel_boot(), which is intended to be invoked
779 at the end of the kernel-only boot sequence, just before
780 init is exec'ed.
781
782 Accept the default if unsure.
783
Mike Travisc903ff82009-01-15 12:28:29 -0800784endmenu # "RCU Subsystem"
785
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700786config BUILD_BIN2C
787 bool
788 default n
789
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790config IKCONFIG
Ross Birof2443ab2006-09-30 23:27:25 -0700791 tristate "Kernel .config support"
Vivek Goyalde5b56b2014-08-08 14:25:41 -0700792 select BUILD_BIN2C
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 ---help---
794 This option enables the complete Linux kernel ".config" file
795 contents to be saved in the kernel. It provides documentation
796 of which kernel options are used in a running kernel or in an
797 on-disk kernel. This information can be extracted from the kernel
798 image file with the script scripts/extract-ikconfig and used as
799 input to rebuild the current kernel or to build another kernel.
800 It can also be extracted from a running kernel by reading
801 /proc/config.gz if enabled (below).
802
803config IKCONFIG_PROC
804 bool "Enable access to .config through /proc/config.gz"
805 depends on IKCONFIG && PROC_FS
806 ---help---
807 This option enables access to the kernel configuration file
808 through /proc/config.gz.
809
Alistair John Strachan794543a2007-05-08 00:31:15 -0700810config LOG_BUF_SHIFT
811 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
Ingo Molnarfb39f982015-07-01 10:19:11 +0200812 range 12 25
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700813 default 17
Josh Triplett361e9df2014-10-03 16:00:54 -0700814 depends on PRINTK
Alistair John Strachan794543a2007-05-08 00:31:15 -0700815 help
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700816 Select the minimal kernel log buffer size as a power of 2.
817 The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
818 parameter, see below. Any higher size also might be forced
819 by "log_buf_len" boot parameter.
820
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700821 Examples:
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700822 17 => 128 KB
Adrian Bunkf17a32e2008-04-29 00:58:58 -0700823 16 => 64 KB
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700824 15 => 32 KB
825 14 => 16 KB
Alistair John Strachan794543a2007-05-08 00:31:15 -0700826 13 => 8 KB
827 12 => 4 KB
828
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700829config LOG_CPU_MAX_BUF_SHIFT
830 int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
Geert Uytterhoeven2240a312014-10-13 15:51:11 -0700831 depends on SMP
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700832 range 0 21
833 default 12 if !BASE_SMALL
834 default 0 if BASE_SMALL
Josh Triplett361e9df2014-10-03 16:00:54 -0700835 depends on PRINTK
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700836 help
837 This option allows to increase the default ring buffer size
838 according to the number of CPUs. The value defines the contribution
839 of each CPU as a power of 2. The used space is typically only few
840 lines however it might be much more when problems are reported,
841 e.g. backtraces.
842
843 The increased size means that a new buffer has to be allocated and
844 the original static one is unused. It makes sense only on systems
845 with more CPUs. Therefore this value is used only when the sum of
846 contributions is greater than the half of the default kernel ring
847 buffer as defined by LOG_BUF_SHIFT. The default values are set
848 so that more than 64 CPUs are needed to trigger the allocation.
849
850 Also this option is ignored when "log_buf_len" kernel parameter is
851 used as it forces an exact (power of two) size of the ring buffer.
852
853 The number of possible CPUs is used for this computation ignoring
854 hotplugging making the compuation optimal for the the worst case
855 scenerio while allowing a simple algorithm to be used from bootup.
856
857 Examples shift values and their meaning:
858 17 => 128 KB for each CPU
859 16 => 64 KB for each CPU
860 15 => 32 KB for each CPU
861 14 => 16 KB for each CPU
862 13 => 8 KB for each CPU
863 12 => 4 KB for each CPU
864
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800865#
866# Architectures with an unreliable sched_clock() should select this:
867#
868config HAVE_UNSTABLE_SCHED_CLOCK
869 bool
870
Stephen Boyd38ff87f2013-06-01 23:39:40 -0700871config GENERIC_SCHED_CLOCK
872 bool
873
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200874#
875# For architectures that want to enable the support for NUMA-affine scheduler
876# balancing logic:
877#
878config ARCH_SUPPORTS_NUMA_BALANCING
879 bool
880
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100881#
Mel Gorman72b252a2015-09-04 15:47:32 -0700882# For architectures that prefer to flush all TLBs after a number of pages
883# are unmapped instead of sending one IPI per page to flush. The architecture
884# must provide guarantees on what happens if a clean TLB cache entry is
885# written after the unmap. Details are in mm/rmap.c near the check for
886# should_defer_flush. The architecture should also consider if the full flush
887# and the refill costs are offset by the savings of sending fewer IPIs.
888config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
889 bool
890
891#
Peter Zijlstrabe5e6102013-11-18 18:27:06 +0100892# For architectures that know their GCC __int128 support is sound
893#
894config ARCH_SUPPORTS_INT128
895 bool
896
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200897# For architectures that (ab)use NUMA to represent different memory regions
898# all cpu-local but of different latencies, such as SuperH.
899#
900config ARCH_WANT_NUMA_VARIABLE_LOCALITY
901 bool
902
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200903config NUMA_BALANCING
904 bool "Memory placement aware NUMA scheduler"
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200905 depends on ARCH_SUPPORTS_NUMA_BALANCING
906 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
907 depends on SMP && NUMA && MIGRATION
908 help
909 This option adds support for automatic NUMA aware memory/task placement.
910 The mechanism is quite primitive and is based on migrating memory when
Paul Gortmaker6d56a412013-08-13 11:06:50 -0400911 it has references to the node the task is running on.
Andrea Arcangelibe3a7282012-10-04 01:50:47 +0200912
913 This system will be inactive on UMA systems.
914
Aneesh Kumar K.V6f7c97e2014-12-10 15:43:37 -0800915config NUMA_BALANCING_DEFAULT_ENABLED
916 bool "Automatically enable NUMA aware memory/task placement"
917 default y
918 depends on NUMA_BALANCING
919 help
920 If set, automatic NUMA balancing will be enabled if running on a NUMA
921 machine.
922
Li Zefan23964d22009-01-15 13:50:58 -0800923menuconfig CGROUPS
Christoph Jaeger6341e622014-12-20 15:41:11 -0500924 bool "Control Group support"
Tejun Heo2bd59d42014-02-11 11:52:49 -0500925 select KERNFS
Paul Menageddbcc7e2007-10-18 23:39:30 -0700926 help
Li Zefan23964d22009-01-15 13:50:58 -0800927 This option adds support for grouping sets of processes together, for
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800928 use with process control subsystems such as Cpusets, CFS, memory
929 controls or device isolation.
930 See
KAMEZAWA Hiroyuki5cdc38f2009-01-07 18:07:30 -0800931 - Documentation/scheduler/sched-design-CFS.txt (CFS)
Li Zefan45ce80f2009-01-15 13:50:59 -0800932 - Documentation/cgroups/ (features for grouping, isolation
933 and resource control)
Paul Menageddbcc7e2007-10-18 23:39:30 -0700934
935 Say N if unsure.
936
Li Zefan23964d22009-01-15 13:50:58 -0800937if CGROUPS
938
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800939config PAGE_COUNTER
940 bool
941
Andrew Mortonc255a452012-07-31 16:43:02 -0700942config MEMCG
Johannes Weinera0166ec2015-12-17 17:19:56 -0500943 bool "Memory controller"
Johannes Weiner3e32cb22014-12-10 15:42:31 -0800944 select PAGE_COUNTER
Tejun Heo79bd9812013-11-22 18:20:42 -0500945 select EVENTFD
Balbir Singh00f0b822008-03-04 14:28:39 -0800946 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500947 Provides control over the memory footprint of tasks in a cgroup.
Balbir Singh00f0b822008-03-04 14:28:39 -0800948
Andrew Mortonc255a452012-07-31 16:43:02 -0700949config MEMCG_SWAP
Johannes Weinera0166ec2015-12-17 17:19:56 -0500950 bool "Swap controller"
Andrew Mortonc255a452012-07-31 16:43:02 -0700951 depends on MEMCG && SWAP
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800952 help
Johannes Weinera0166ec2015-12-17 17:19:56 -0500953 Provides control over the swap space consumed by tasks in a cgroup.
954
Andrew Mortonc255a452012-07-31 16:43:02 -0700955config MEMCG_SWAP_ENABLED
Johannes Weinera0166ec2015-12-17 17:19:56 -0500956 bool "Swap controller enabled by default"
Andrew Mortonc255a452012-07-31 16:43:02 -0700957 depends on MEMCG_SWAP
Michal Hockoa42c3902010-11-24 12:57:08 -0800958 default y
959 help
960 Memory Resource Controller Swap Extension comes with its price in
961 a bigger memory consumption. General purpose distribution kernels
Jim Cromie43d547f2010-12-17 14:32:36 -0700962 which want to enable the feature but keep it disabled by default
Michal Hocko07555ac2013-08-22 16:35:46 -0700963 and let the user enable it by swapaccount=1 boot command line
Michal Hockoa42c3902010-11-24 12:57:08 -0800964 parameter should have this option unselected.
965 For those who want to have the feature enabled by default should
966 select this option (if, for some reason, they need to disable it
WANG Cong00a66d22011-07-25 17:12:12 -0700967 then swapaccount=0 does the trick).
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -0800968
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500969config BLK_CGROUP
970 bool "IO controller"
971 depends on BLOCK
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700972 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500973 ---help---
974 Generic block IO controller cgroup interface. This is the common
975 cgroup interface which should be used by various IO controlling
976 policies.
Aneesh Kumar K.V2bc64a22012-07-31 16:42:12 -0700977
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500978 Currently, CFQ IO scheduler uses it to recognize task groups and
979 control disk bandwidth allocation (proportional time slice allocation)
980 to such task groups. It is also used by bio throttling logic in
981 block layer to implement upper limit in IO rates on a device.
Stephane Eraniane5d13672011-02-14 11:20:01 +0200982
Johannes Weiner6bf024e2015-12-17 17:19:57 -0500983 This option only enables generic Block IO controller infrastructure.
984 One needs to also enable actual IO controlling logic/policy. For
985 enabling proportional weight division of disk bandwidth in CFQ, set
986 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
987 CONFIG_BLK_DEV_THROTTLING=y.
988
989 See Documentation/cgroups/blkio-controller.txt for more information.
990
991config DEBUG_BLK_CGROUP
992 bool "IO controller debugging"
993 depends on BLK_CGROUP
994 default n
995 ---help---
996 Enable some debugging help. Currently it exports additional stat
997 files in a cgroup which can be useful for debugging.
998
999config CGROUP_WRITEBACK
1000 bool
1001 depends on MEMCG && BLK_CGROUP
1002 default y
Stephane Eraniane5d13672011-02-14 11:20:01 +02001003
Dhaval Giani7c941432010-01-20 13:26:18 +01001004menuconfig CGROUP_SCHED
Johannes Weinera0166ec2015-12-17 17:19:56 -05001005 bool "CPU controller"
Dhaval Giani7c941432010-01-20 13:26:18 +01001006 default n
1007 help
1008 This feature lets CPU scheduler recognize task groups and control CPU
1009 bandwidth allocation to such task groups. It uses cgroups to group
1010 tasks.
1011
1012if CGROUP_SCHED
1013config FAIR_GROUP_SCHED
1014 bool "Group scheduling for SCHED_OTHER"
1015 depends on CGROUP_SCHED
1016 default CGROUP_SCHED
1017
Paul Turnerab84d312011-07-21 09:43:28 -07001018config CFS_BANDWIDTH
1019 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
Paul Turnerab84d312011-07-21 09:43:28 -07001020 depends on FAIR_GROUP_SCHED
1021 default n
1022 help
1023 This option allows users to define CPU bandwidth rates (limits) for
1024 tasks running within the fair group scheduler. Groups with no limit
1025 set are considered to be unconstrained and will run with no
1026 restriction.
1027 See tip/Documentation/scheduler/sched-bwc.txt for more information.
1028
Dhaval Giani7c941432010-01-20 13:26:18 +01001029config RT_GROUP_SCHED
1030 bool "Group scheduling for SCHED_RR/FIFO"
Dhaval Giani7c941432010-01-20 13:26:18 +01001031 depends on CGROUP_SCHED
1032 default n
1033 help
1034 This feature lets you explicitly allocate real CPU bandwidth
Li Zefan32bd7eb2010-03-24 13:17:19 +08001035 to task groups. If enabled, it will also make it impossible to
Dhaval Giani7c941432010-01-20 13:26:18 +01001036 schedule realtime tasks for non-root users until you allocate
1037 realtime bandwidth for them.
1038 See Documentation/scheduler/sched-rt-group.txt for more information.
1039
1040endif #CGROUP_SCHED
1041
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001042config CGROUP_PIDS
1043 bool "PIDs controller"
1044 help
1045 Provides enforcement of process number limits in the scope of a
1046 cgroup. Any attempt to fork more processes than is allowed in the
1047 cgroup will fail. PIDs are fundamentally a global resource because it
1048 is fairly trivial to reach PID exhaustion before you reach even a
1049 conservative kmemcg limit. As a result, it is possible to grind a
1050 system to halt without being limited by other cgroup policies. The
Parav Pandit6cc578d2016-03-05 11:30:56 +05301051 PIDs controller is designed to stop this from happening.
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001052
1053 It should be noted that organisational operations (such as attaching
Parav Pandit6cc578d2016-03-05 11:30:56 +05301054 to a cgroup hierarchy will *not* be blocked by the PIDs controller),
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001055 since the PIDs limit only affects a process's ability to fork, not to
1056 attach to a cgroup.
1057
1058config CGROUP_FREEZER
1059 bool "Freezer controller"
1060 help
1061 Provides a way to freeze and unfreeze all tasks in a
1062 cgroup.
1063
Johannes Weiner489c2a22016-01-20 15:02:41 -08001064 This option affects the ORIGINAL cgroup interface. The cgroup2 memory
1065 controller includes important in-kernel memory consumers per default.
1066
1067 If you're using cgroup2, say N.
1068
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001069config CGROUP_HUGETLB
1070 bool "HugeTLB controller"
1071 depends on HUGETLB_PAGE
1072 select PAGE_COUNTER
Vivek Goyalafc24d42010-04-26 19:27:56 +02001073 default n
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001074 help
1075 Provides a cgroup controller for HugeTLB pages.
1076 When you enable this, you can put a per cgroup limit on HugeTLB usage.
1077 The limit is enforced during page fault. Since HugeTLB doesn't
1078 support page reclaim, enforcing the limit at page fault time implies
1079 that, the application will get SIGBUS signal if it tries to access
1080 HugeTLB pages beyond its limit. This requires the application to know
1081 beforehand how much HugeTLB pages it would require for its use. The
1082 control group is tracked in the third page lru pointer. This means
1083 that we cannot use the controller with huge page less than 3 pages.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001084
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001085config CPUSETS
1086 bool "Cpuset controller"
1087 help
1088 This option will let you create and manage CPUSETs which
1089 allow dynamically partitioning a system into sets of CPUs and
1090 Memory Nodes and assigning tasks to run only within those sets.
1091 This is primarily useful on large SMP or NUMA systems.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001092
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001093 Say N if unsure.
Vivek Goyalafc24d42010-04-26 19:27:56 +02001094
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001095config PROC_PID_CPUSET
1096 bool "Include legacy /proc/<pid>/cpuset file"
1097 depends on CPUSETS
Tejun Heo89e9b9e2015-05-22 17:13:36 -04001098 default y
1099
Johannes Weiner6bf024e2015-12-17 17:19:57 -05001100config CGROUP_DEVICE
1101 bool "Device controller"
1102 help
1103 Provides a cgroup controller implementing whitelists for
1104 devices which a process in the cgroup can mknod or open.
1105
1106config CGROUP_CPUACCT
1107 bool "Simple CPU accounting controller"
1108 help
1109 Provides a simple controller for monitoring the
1110 total CPU consumed by the tasks in a cgroup.
1111
1112config CGROUP_PERF
1113 bool "Perf controller"
1114 depends on PERF_EVENTS
1115 help
1116 This option extends the perf per-cpu mode to restrict monitoring
1117 to threads which belong to the cgroup specified and run on the
1118 designated cpu.
1119
1120 Say N if unsure.
1121
1122config CGROUP_DEBUG
1123 bool "Example controller"
1124 default n
1125 help
1126 This option enables a simple controller that exports
1127 debugging information about the cgroups framework.
1128
1129 Say N.
1130
Li Zefan23964d22009-01-15 13:50:58 -08001131endif # CGROUPS
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001132
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001133config CHECKPOINT_RESTORE
1134 bool "Checkpoint/restore support" if EXPERT
Iago López Galeiras2e13ba52015-06-25 15:00:57 -07001135 select PROC_CHILDREN
Cyrill Gorcunov067bce12012-01-12 17:20:49 -08001136 default n
1137 help
1138 Enables additional kernel features in a sake of checkpoint/restore.
1139 In particular it adds auxiliary prctl codes to setup process text,
1140 data and heap segment sizes, and a few additional /proc filesystem
1141 entries.
1142
1143 If unsure, say N here.
1144
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001145menuconfig NAMESPACES
David Rientjes6a108a12011-01-20 14:44:16 -08001146 bool "Namespaces support" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001147 depends on MULTIUSER
David Rientjes6a108a12011-01-20 14:44:16 -08001148 default !EXPERT
Pavel Emelyanovc5289a62008-02-08 04:18:19 -08001149 help
1150 Provides the way to make tasks work with different objects using
1151 the same id. For example same IPC id may refer to different objects
1152 or same user id or pid may refer to different tasks when used in
1153 different namespaces.
1154
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001155if NAMESPACES
1156
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001157config UTS_NS
1158 bool "UTS namespace"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001159 default y
Pavel Emelyanov58bfdd6d2008-02-08 04:18:21 -08001160 help
1161 In this namespace tasks see different info provided with the
1162 uname() system call
1163
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001164config IPC_NS
1165 bool "IPC namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001166 depends on (SYSVIPC || POSIX_MQUEUE)
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001167 default y
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001168 help
1169 In this namespace tasks work with IPC ids which correspond to
Serge E. Hallyn614b84c2009-04-06 19:01:08 -07001170 different IPC objects in different namespaces.
Pavel Emelyanovae5e1b22008-02-08 04:18:22 -08001171
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001172config USER_NS
Kees Cook19c92392012-10-02 11:19:29 -07001173 bool "User namespace"
Eric W. Biederman5673a942011-11-17 10:23:55 -08001174 default n
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001175 help
1176 This allows containers, i.e. vservers, to use user namespaces
1177 to provide different user info for different servers.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001178
1179 When user namespaces are enabled in the kernel it is
Johannes Weinerd886f4e2016-01-20 15:02:47 -08001180 recommended that the MEMCG option also be enabled and that
1181 user-space use the memory control groups to limit the amount
1182 of memory a memory unprivileged users can use.
Eric W. Biedermane11f0ae2013-01-25 16:48:31 -08001183
Pavel Emelyanovaee16ce2008-02-08 04:18:23 -08001184 If unsure, say N.
1185
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001186config PID_NS
Daniel Lezcano9bd38c22010-10-27 15:34:37 -07001187 bool "PID Namespaces"
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001188 default y
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001189 help
Heikki Orsila12d2b8f2008-07-06 15:48:02 +03001190 Support process id namespaces. This allows having multiple
Matt LaPlante692105b2009-01-26 11:12:25 +01001191 processes with the same pid as long as they are in different
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001192 pid namespaces. This is a building block of containers.
1193
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001194config NET_NS
1195 bool "Network namespace"
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001196 depends on NET
Daniel Lezcano17a6d442010-10-27 15:34:37 -07001197 default y
Matt Helsleyd6eb6332009-01-26 12:25:55 -08001198 help
1199 Allow user space to create what appear to be multiple instances
1200 of the network stack.
1201
Daniel Lezcano8dd2a822010-10-27 15:34:38 -07001202endif # NAMESPACES
1203
Mike Galbraith5091faa2010-11-30 14:18:03 +01001204config SCHED_AUTOGROUP
1205 bool "Automatic process group scheduling"
Mike Galbraith5091faa2010-11-30 14:18:03 +01001206 select CGROUPS
1207 select CGROUP_SCHED
1208 select FAIR_GROUP_SCHED
1209 help
1210 This option optimizes the scheduler for common desktop workloads by
1211 automatically creating and populating task groups. This separation
1212 of workloads isolates aggressive CPU burners (like build jobs) from
1213 desktop applications. Task group autogeneration is currently based
1214 upon task session.
1215
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001216config SYSFS_DEPRECATED
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001217 bool "Enable deprecated sysfs features to support old userspace tools"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001218 depends on SYSFS
1219 default n
1220 help
1221 This option adds code that switches the layout of the "block" class
1222 devices, to not show up in /sys/class/block/, but only in
1223 /sys/block/.
1224
1225 This switch is only active when the sysfs.deprecated=1 boot option is
1226 passed or the SYSFS_DEPRECATED_V2 option is set.
1227
1228 This option allows new kernels to run on old distributions and tools,
1229 which might get confused by /sys/class/block/. Since 2007/2008 all
1230 major distributions and tools handle this just fine.
1231
1232 Recent distributions and userspace tools after 2009/2010 depend on
1233 the existence of /sys/class/block/, and will not work with this
1234 option enabled.
1235
1236 Only if you are using a new kernel on an old distribution, you might
1237 need to say Y here.
1238
1239config SYSFS_DEPRECATED_V2
Ferenc Wagner5d6a4ea2011-01-10 19:04:22 +01001240 bool "Enable deprecated sysfs features by default"
Daniel Lezcano7af37be2010-10-27 15:34:41 -07001241 default n
1242 depends on SYSFS
1243 depends on SYSFS_DEPRECATED
1244 help
1245 Enable deprecated sysfs by default.
1246
1247 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1248 option.
1249
1250 Only if you are using a new kernel on an old distribution, you might
1251 need to say Y here. Even then, odds are you would not need it
1252 enabled, you can always pass the boot option if absolutely necessary.
1253
1254config RELAY
1255 bool "Kernel->user space relay support (formerly relayfs)"
1256 help
1257 This option enables support for relay interface support in
1258 certain file systems (such as debugfs).
1259 It is designed to provide an efficient mechanism for tools and
1260 facilities to relay large amounts of data from kernel space to
1261 user space.
1262
1263 If unsure, say N.
1264
Dimitri Gorokhovikf9916332007-03-06 01:42:17 -08001265config BLK_DEV_INITRD
1266 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1267 depends on BROKEN || !FRV
1268 help
1269 The initial RAM filesystem is a ramfs which is loaded by the
1270 boot loader (loadlin or lilo) and that is mounted as root
1271 before the normal boot procedure. It is typically used to
1272 load modules needed to mount the "real" root file system,
1273 etc. See <file:Documentation/initrd.txt> for details.
1274
1275 If RAM disk support (BLK_DEV_RAM) is also included, this
1276 also enables initial RAM disk (initrd) support and adds
1277 15 Kbytes (more on some other architectures) to the kernel size.
1278
1279 If unsure say Y.
1280
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001281if BLK_DEV_INITRD
1282
Sam Ravnborgdbec4862005-08-10 20:44:50 +02001283source "usr/Kconfig"
1284
Jean-Paul Samanc33df4e2007-02-10 01:44:43 -08001285endif
1286
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001287config CC_OPTIMIZE_FOR_SIZE
Ingo Molnar96fffeb2008-04-28 01:39:43 +02001288 bool "Optimize for size"
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001289 help
Masahiro Yamada31a4af72014-08-05 14:43:07 +09001290 Enabling this option will pass "-Os" instead of "-O2" to
1291 your compiler resulting in a smaller kernel.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001292
Kirill Smelkov3a55fb02012-11-02 15:41:01 +04001293 If unsure, say N.
Linus Torvaldsc45b4f12005-12-14 18:52:21 -08001294
Randy Dunlap08470622006-09-30 23:28:13 -07001295config SYSCTL
1296 bool
1297
Randy Dunlapb943c462009-03-10 12:55:46 -07001298config ANON_INODES
1299 bool
1300
Mike Frysinger657a5202013-04-30 15:28:45 -07001301config HAVE_UID16
1302 bool
1303
1304config SYSCTL_EXCEPTION_TRACE
1305 bool
1306 help
1307 Enable support for /proc/sys/debug/exception-trace.
1308
1309config SYSCTL_ARCH_UNALIGN_NO_WARN
1310 bool
1311 help
1312 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1313 Allows arch to define/use @no_unaligned_warning to possibly warn
1314 about unaligned access emulation going on under the hood.
1315
1316config SYSCTL_ARCH_UNALIGN_ALLOW
1317 bool
1318 help
1319 Enable support for /proc/sys/kernel/unaligned-trap
1320 Allows arches to define/use @unaligned_enabled to runtime toggle
1321 the unaligned access emulation.
1322 see arch/parisc/kernel/unaligned.c for reference
1323
Mike Frysinger657a5202013-04-30 15:28:45 -07001324config HAVE_PCSPKR_PLATFORM
1325 bool
1326
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001327# interpreter that classic socket filters depend on
1328config BPF
1329 bool
1330
David Rientjes6a108a12011-01-20 14:44:16 -08001331menuconfig EXPERT
1332 bool "Configure standard kernel features (expert users)"
Josh Triplettf505c552011-06-05 18:23:58 -07001333 # Unhide debug options, to make the on-by-default options visible
1334 select DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 help
1336 This option allows certain base kernel options and settings
1337 to be disabled or tweaked. This is for specialized
1338 environments which can tolerate a "non-standard" kernel.
1339 Only use this if you really know what you are doing.
1340
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001341config UID16
David Rientjes6a108a12011-01-20 14:44:16 -08001342 bool "Enable 16-bit UID system calls" if EXPERT
Iulia Manda28138932015-04-15 16:16:41 -07001343 depends on HAVE_UID16 && MULTIUSER
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001344 default y
1345 help
1346 This enables the legacy 16-bit UID syscall wrappers.
1347
Iulia Manda28138932015-04-15 16:16:41 -07001348config MULTIUSER
1349 bool "Multiple users, groups and capabilities support" if EXPERT
1350 default y
1351 help
1352 This option enables support for non-root users, groups and
1353 capabilities.
1354
1355 If you say N here, all processes will run with UID 0, GID 0, and all
1356 possible capabilities. Saying N here also compiles out support for
1357 system calls related to UIDs, GIDs, and capabilities, such as setuid,
1358 setgid, and capset.
1359
1360 If unsure, say Y here.
1361
Fabian Frederickf6187762014-06-04 16:11:12 -07001362config SGETMASK_SYSCALL
1363 bool "sgetmask/ssetmask syscalls support" if EXPERT
1364 def_bool PARISC || MN10300 || BLACKFIN || M68K || PPC || MIPS || X86 || SPARC || CRIS || MICROBLAZE || SUPERH
1365 ---help---
1366 sys_sgetmask and sys_ssetmask are obsolete system calls
1367 no longer supported in libc but still enabled by default in some
1368 architectures.
1369
1370 If unsure, leave the default option here.
1371
Fabian Frederick6af9f7b2014-04-03 14:48:25 -07001372config SYSFS_SYSCALL
1373 bool "Sysfs syscall support" if EXPERT
1374 default y
1375 ---help---
1376 sys_sysfs is an obsolete system call no longer supported in libc.
1377 Note that disabling this option is more secure but might break
1378 compatibility with some systems.
1379
1380 If unsure say Y here.
1381
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001382config SYSCTL_SYSCALL
David Rientjes6a108a12011-01-20 14:44:16 -08001383 bool "Sysctl syscall support" if EXPERT
Eric W. Biederman26a70342009-11-05 05:26:41 -08001384 depends on PROC_SYSCTL
WANG Congc736de62011-11-02 13:39:25 -07001385 default n
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001386 select SYSCTL
1387 ---help---
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001388 sys_sysctl uses binary paths that have been found challenging
1389 to properly maintain and use. The interface in /proc/sys
1390 using paths with ascii names is now the primary path to this
1391 information.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001392
Eric W. Biederman13bb7e32006-11-08 17:44:51 -08001393 Almost nothing using the binary sysctl interface so if you are
1394 trying to save some space it is probably safe to disable this,
1395 making your kernel marginally smaller.
Eric W. Biedermanb89a8172006-09-27 01:51:04 -07001396
WANG Congc736de62011-11-02 13:39:25 -07001397 If unsure say N here.
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001398
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399config KALLSYMS
David Rientjes6a108a12011-01-20 14:44:16 -08001400 bool "Load all symbols for debugging/ksymoops" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 default y
1402 help
1403 Say Y here to let the kernel print out symbolic crash information and
1404 symbolic stack backtraces. This increases the size of the kernel
1405 somewhat, as all symbols have to be loaded into the kernel image.
1406
1407config KALLSYMS_ALL
1408 bool "Include all symbols in kallsyms"
1409 depends on DEBUG_KERNEL && KALLSYMS
1410 help
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001411 Normally kallsyms only contains the symbols of functions for nicer
1412 OOPS messages and backtraces (i.e., symbols from the text and inittext
1413 sections). This is sufficient for most cases. And only in very rare
1414 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1415 names of variables from the data sections, etc).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001417 This option makes sure that all symbols are loaded into the kernel
1418 image (i.e., symbols from all sections) in cost of increased kernel
1419 size (depending on the kernel configuration, it may be 300KiB or
1420 something like this).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421
Artem Bityutskiy71a83ec2011-04-05 13:24:57 +03001422 Say N unless you really need all symbols.
Matt Mackalld59745c2005-05-01 08:59:02 -07001423
Ard Biesheuvel4d5d5662016-03-15 14:58:12 -07001424config KALLSYMS_ABSOLUTE_PERCPU
1425 bool
1426 default X86_64 && SMP
1427
Ard Biesheuvel2213e9a2016-03-15 14:58:19 -07001428config KALLSYMS_BASE_RELATIVE
1429 bool
1430 depends on KALLSYMS
1431 default !IA64 && !(TILE && 64BIT)
1432 help
1433 Instead of emitting them as absolute values in the native word size,
1434 emit the symbol references in the kallsyms table as 32-bit entries,
1435 each containing a relative value in the range [base, base + U32_MAX]
1436 or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1437 an absolute value in the range [0, S32_MAX] or a relative value in the
1438 range [base, base + S32_MAX], where base is the lowest relative symbol
1439 address encountered in the image.
1440
1441 On 64-bit builds, this reduces the size of the address table by 50%,
1442 but more importantly, it results in entries whose values are build
1443 time constants, and no relocation pass is required at runtime to fix
1444 up the entries based on the runtime load address of the kernel.
1445
Matt Mackalld59745c2005-05-01 08:59:02 -07001446config PRINTK
1447 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001448 bool "Enable support for printk" if EXPERT
Frederic Weisbecker74876a92012-10-12 18:00:23 +02001449 select IRQ_WORK
Matt Mackalld59745c2005-05-01 08:59:02 -07001450 help
1451 This option enables normal printk support. Removing it
1452 eliminates most of the message strings from the kernel image
1453 and makes the kernel more or less silent. As this makes it
1454 very difficult to diagnose system problems, saying N here is
1455 strongly discouraged.
1456
Matt Mackallc8538a72005-05-01 08:59:01 -07001457config BUG
David Rientjes6a108a12011-01-20 14:44:16 -08001458 bool "BUG() support" if EXPERT
Matt Mackallc8538a72005-05-01 08:59:01 -07001459 default y
1460 help
1461 Disabling this option eliminates support for BUG and WARN, reducing
1462 the size of your kernel image and potentially quietly ignoring
1463 numerous fatal conditions. You should only consider disabling this
1464 option for embedded systems with no facilities for reporting errors.
1465 Just say Y.
1466
Matt Mackall708e9a72006-01-08 01:05:25 -08001467config ELF_CORE
Alex Kelly046d6622012-10-04 17:15:23 -07001468 depends on COREDUMP
Matt Mackall708e9a72006-01-08 01:05:25 -08001469 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001470 bool "Enable ELF core dumps" if EXPERT
Matt Mackall708e9a72006-01-08 01:05:25 -08001471 help
1472 Enable support for generating core dumps. Disabling saves about 4k.
1473
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001474
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001475config PCSPKR_PLATFORM
David Rientjes6a108a12011-01-20 14:44:16 -08001476 bool "Enable PC-Speaker support" if EXPERT
Ralf Baechle8761f1a2011-06-01 19:05:09 +01001477 depends on HAVE_PCSPKR_PLATFORM
Ralf Baechle15f304b2011-06-01 19:04:59 +01001478 select I8253_LOCK
Stas Sergeeve5e1d3c2008-05-07 12:39:56 +02001479 default y
1480 help
1481 This option allows to disable the internal PC-Speaker
1482 support, saving some memory.
1483
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484config BASE_FULL
1485 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001486 bool "Enable full-sized data structures for core" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 help
1488 Disabling this option reduces the size of miscellaneous core
1489 kernel data structures. This saves memory on small machines,
1490 but may reduce performance.
1491
1492config FUTEX
David Rientjes6a108a12011-01-20 14:44:16 -08001493 bool "Enable futex support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494 default y
Ingo Molnar23f78d4a2006-06-27 02:54:53 -07001495 select RT_MUTEXES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496 help
1497 Disabling this option will cause the kernel to be built without
1498 support for "fast userspace mutexes". The resulting kernel may not
1499 run glibc-based applications correctly.
1500
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001501config HAVE_FUTEX_CMPXCHG
1502 bool
Josh Triplett62b4d202014-10-03 16:19:24 -07001503 depends on FUTEX
Heiko Carstens03b8c7b2014-03-02 13:09:47 +01001504 help
1505 Architectures should select this if futex_atomic_cmpxchg_inatomic()
1506 is implemented and always working. This removes a couple of runtime
1507 checks.
1508
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509config EPOLL
David Rientjes6a108a12011-01-20 14:44:16 -08001510 bool "Enable eventpoll support" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 default y
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001512 select ANON_INODES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513 help
1514 Disabling this option will cause the kernel to be built without
1515 support for epoll family of system calls.
1516
Davide Libenzifba2afa2007-05-10 22:23:13 -07001517config SIGNALFD
David Rientjes6a108a12011-01-20 14:44:16 -08001518 bool "Enable signalfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001519 select ANON_INODES
Davide Libenzifba2afa2007-05-10 22:23:13 -07001520 default y
1521 help
1522 Enable the signalfd() system call that allows to receive signals
1523 on a file descriptor.
1524
1525 If unsure, say Y.
1526
Davide Libenzib215e282007-05-10 22:23:16 -07001527config TIMERFD
David Rientjes6a108a12011-01-20 14:44:16 -08001528 bool "Enable timerfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001529 select ANON_INODES
Davide Libenzib215e282007-05-10 22:23:16 -07001530 default y
1531 help
1532 Enable the timerfd() system call that allows to receive timer
1533 events on a file descriptor.
1534
1535 If unsure, say Y.
1536
Davide Libenzie1ad7462007-05-10 22:23:19 -07001537config EVENTFD
David Rientjes6a108a12011-01-20 14:44:16 -08001538 bool "Enable eventfd() system call" if EXPERT
Adrian Bunk448e3ce2007-07-31 00:39:10 -07001539 select ANON_INODES
Davide Libenzie1ad7462007-05-10 22:23:19 -07001540 default y
1541 help
1542 Enable the eventfd() system call that allows to receive both
1543 kernel notification (ie. KAIO) or userspace notifications.
1544
1545 If unsure, say Y.
1546
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001547# syscall, maps, verifier
1548config BPF_SYSCALL
Ingo Molnare1abf2c2015-04-02 15:51:39 +02001549 bool "Enable bpf() system call"
Alexei Starovoitovf89b7752014-10-23 18:41:08 -07001550 select ANON_INODES
1551 select BPF
1552 default n
1553 help
1554 Enable the bpf() system call that allows to manipulate eBPF
1555 programs and maps via file descriptors.
1556
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557config SHMEM
David Rientjes6a108a12011-01-20 14:44:16 -08001558 bool "Use full shmem filesystem" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 default y
1560 depends on MMU
1561 help
1562 The shmem is an internal filesystem used to manage shared memory.
1563 It is backed by swap and manages resource limits. It is also exported
1564 to userspace as tmpfs if TMPFS is enabled. Disabling this
1565 option replaces shmem and tmpfs with the much simpler ramfs code,
1566 which may be appropriate on small systems without swap.
1567
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001568config AIO
David Rientjes6a108a12011-01-20 14:44:16 -08001569 bool "Enable AIO support" if EXPERT
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001570 default y
1571 help
1572 This option enables POSIX asynchronous I/O which may by used
Mike Frysinger657a5202013-04-30 15:28:45 -07001573 by some high performance threaded applications. Disabling
1574 this option saves about 7k.
1575
Josh Triplettd3ac21c2014-08-17 19:41:09 -05001576config ADVISE_SYSCALLS
1577 bool "Enable madvise/fadvise syscalls" if EXPERT
1578 default y
1579 help
1580 This option enables the madvise and fadvise syscalls, used by
1581 applications to advise the kernel about their future memory or file
1582 usage, improving performance. If building an embedded system where no
1583 applications use these syscalls, you can disable this option to save
1584 space.
1585
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001586config USERFAULTFD
1587 bool "Enable userfaultfd() system call"
1588 select ANON_INODES
Andrea Arcangelia14c1512015-09-04 15:46:54 -07001589 depends on MMU
1590 help
1591 Enable the userfaultfd() system call that allows to intercept and
1592 handle page faults in userland.
1593
Mike Frysinger657a5202013-04-30 15:28:45 -07001594config PCI_QUIRKS
1595 default y
1596 bool "Enable PCI quirk workarounds" if EXPERT
1597 depends on PCI
1598 help
1599 This enables workarounds for various PCI chipset
1600 bugs/quirks. Disable this only if your target machine is
1601 unaffected by PCI quirks.
Thomas Petazzoniebf3f092008-10-15 22:05:12 -07001602
Mathieu Desnoyers5b25b132015-09-11 13:07:39 -07001603config MEMBARRIER
1604 bool "Enable membarrier() system call" if EXPERT
1605 default y
1606 help
1607 Enable the membarrier() system call that allows issuing memory
1608 barriers across all running threads, which can be used to distribute
1609 the cost of user-space memory barriers asymmetrically by transforming
1610 pairs of memory barriers into pairs consisting of membarrier() and a
1611 compiler barrier.
1612
1613 If unsure, say Y.
1614
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001615config EMBEDDED
1616 bool "Embedded system"
Josh Triplett5d2acfc2014-04-07 15:39:09 -07001617 option allnoconfig_y
Randy Dunlap6befe5f2011-04-26 12:33:21 -07001618 select EXPERT
1619 help
1620 This option should be enabled if compiling the kernel for
1621 an embedded system so certain expert options are available
1622 for configuration.
1623
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001624config HAVE_PERF_EVENTS
Thomas Gleixner0793a612008-12-04 20:12:29 +01001625 bool
Mike Frysinger018df722009-06-12 13:17:43 -04001626 help
1627 See tools/perf/design.txt for details.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001628
Peter Zijlstra906010b2009-09-21 16:08:49 +02001629config PERF_USE_VMALLOC
1630 bool
1631 help
1632 See tools/perf/design.txt for details
1633
Ingo Molnar57c0c152009-09-21 12:20:38 +02001634menu "Kernel Performance Events And Counters"
Thomas Gleixner0793a612008-12-04 20:12:29 +01001635
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001636config PERF_EVENTS
Ingo Molnar57c0c152009-09-21 12:20:38 +02001637 bool "Kernel performance events and counters"
Robert Richter392d65a2012-04-05 18:24:44 +02001638 default y if PROFILING
Ingo Molnarcdd6c482009-09-21 12:02:48 +02001639 depends on HAVE_PERF_EVENTS
Ingo Molnar4c59e462008-12-08 19:38:33 +01001640 select ANON_INODES
Peter Zijlstrae360adb2010-10-14 14:01:34 +08001641 select IRQ_WORK
Pranith Kumar83fe27e2014-12-05 11:24:45 -05001642 select SRCU
Thomas Gleixner0793a612008-12-04 20:12:29 +01001643 help
Ingo Molnar57c0c152009-09-21 12:20:38 +02001644 Enable kernel support for various performance events provided
1645 by software and hardware.
Thomas Gleixner0793a612008-12-04 20:12:29 +01001646
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001647 Software events are supported either built-in or via the
Ingo Molnar57c0c152009-09-21 12:20:38 +02001648 use of generic tracepoints.
1649
1650 Most modern CPUs support performance events via performance
1651 counter registers. These registers count the number of certain
Thomas Gleixner0793a612008-12-04 20:12:29 +01001652 types of hw events: such as instructions executed, cachemisses
1653 suffered, or branches mis-predicted - without slowing down the
1654 kernel or applications. These registers can also trigger interrupts
1655 when a threshold number of events have passed - and can thus be
1656 used to profile the code that runs on that CPU.
1657
Ingo Molnar57c0c152009-09-21 12:20:38 +02001658 The Linux Performance Event subsystem provides an abstraction of
Thadeu Lima de Souza Cascardodd770382009-10-30 19:32:25 -02001659 these software and hardware event capabilities, available via a
Ingo Molnar57c0c152009-09-21 12:20:38 +02001660 system call and used by the "perf" utility in tools/perf/. It
Thomas Gleixner0793a612008-12-04 20:12:29 +01001661 provides per task and per CPU counters, and it provides event
1662 capabilities on top of those.
1663
1664 Say Y if unsure.
1665
Peter Zijlstra906010b2009-09-21 16:08:49 +02001666config DEBUG_PERF_USE_VMALLOC
1667 default n
1668 bool "Debug: use vmalloc to back perf mmap() buffers"
Michael Ellermancb307112015-05-04 16:26:39 +10001669 depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
Peter Zijlstra906010b2009-09-21 16:08:49 +02001670 select PERF_USE_VMALLOC
1671 help
1672 Use vmalloc memory to back perf mmap() buffers.
1673
1674 Mostly useful for debugging the vmalloc code on platforms
1675 that don't require it.
1676
1677 Say N if unsure.
1678
Thomas Gleixner0793a612008-12-04 20:12:29 +01001679endmenu
1680
Christoph Lameterf8891e52006-06-30 01:55:45 -07001681config VM_EVENT_COUNTERS
1682 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001683 bool "Enable VM event counters for /proc/vmstat" if EXPERT
Christoph Lameterf8891e52006-06-30 01:55:45 -07001684 help
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001685 VM event counters are needed for event counts to be shown.
1686 This option allows the disabling of the VM event counters
David Rientjes6a108a12011-01-20 14:44:16 -08001687 on EXPERT systems. /proc/vmstat will only show page counts
Paul Jackson2aea4fb2006-12-22 01:06:10 -08001688 if VM event counters are disabled.
Christoph Lameterf8891e52006-06-30 01:55:45 -07001689
Christoph Lameter41ecc552007-05-09 02:32:44 -07001690config SLUB_DEBUG
1691 default y
David Rientjes6a108a12011-01-20 14:44:16 -08001692 bool "Enable SLUB debugging support" if EXPERT
Christoph Lameterf6acb632008-04-29 16:16:06 -07001693 depends on SLUB && SYSFS
Christoph Lameter41ecc552007-05-09 02:32:44 -07001694 help
1695 SLUB has extensive debug support features. Disabling these can
1696 result in significant savings in code size. This also disables
1697 SLUB sysfs support. /sys/slab will not exist and there will be
1698 no support for cache validation etc.
1699
Randy Dunlapb943c462009-03-10 12:55:46 -07001700config COMPAT_BRK
1701 bool "Disable heap randomization"
1702 default y
1703 help
1704 Randomizing heap placement makes heap exploits harder, but it
1705 also breaks ancient binaries (including anything libc5 based).
1706 This option changes the bootup default to heap randomization
Matt LaPlante692105b2009-01-26 11:12:25 +01001707 disabled, and can be overridden at runtime by setting
Randy Dunlapb943c462009-03-10 12:55:46 -07001708 /proc/sys/kernel/randomize_va_space to 2.
1709
1710 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1711
Christoph Lameter81819f02007-05-06 14:49:36 -07001712choice
1713 prompt "Choose SLAB allocator"
Christoph Lametera0acd822007-07-17 04:03:32 -07001714 default SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001715 help
1716 This option allows to select a slab allocator.
1717
1718config SLAB
1719 bool "SLAB"
1720 help
1721 The regular slab allocator that is established and known to work
Christoph Lameter34013882007-05-09 02:32:47 -07001722 well in all environments. It organizes cache hot objects in
Simon Arlott02f56212008-11-05 22:18:19 +00001723 per cpu and per node queues.
Christoph Lameter81819f02007-05-06 14:49:36 -07001724
1725config SLUB
Christoph Lameter81819f02007-05-06 14:49:36 -07001726 bool "SLUB (Unqueued Allocator)"
1727 help
1728 SLUB is a slab allocator that minimizes cache line usage
1729 instead of managing queues of cached objects (SLAB approach).
1730 Per cpu caching is realized using slabs of objects instead
1731 of queues of objects. SLUB can use memory efficiently
Simon Arlott02f56212008-11-05 22:18:19 +00001732 and has enhanced diagnostics. SLUB is the default choice for
1733 a slab allocator.
Christoph Lameter81819f02007-05-06 14:49:36 -07001734
1735config SLOB
David Rientjes6a108a12011-01-20 14:44:16 -08001736 depends on EXPERT
Christoph Lameter81819f02007-05-06 14:49:36 -07001737 bool "SLOB (Simple Allocator)"
1738 help
Matt Mackall37291452008-02-04 22:29:38 -08001739 SLOB replaces the stock allocator with a drastically simpler
1740 allocator. SLOB is generally more space efficient but
1741 does not perform as well on large systems.
Christoph Lameter81819f02007-05-06 14:49:36 -07001742
1743endchoice
1744
Joonsoo Kim345c9052013-06-19 14:05:52 +09001745config SLUB_CPU_PARTIAL
1746 default y
Uwe Kleine-Königb39ffbf2013-07-17 16:54:59 +02001747 depends on SLUB && SMP
Joonsoo Kim345c9052013-06-19 14:05:52 +09001748 bool "SLUB per cpu partial cache"
1749 help
1750 Per cpu partial caches accellerate objects allocation and freeing
1751 that is local to a processor at the price of more indeterminism
1752 in the latency of the free. On overflow these caches will be cleared
1753 which requires the taking of locks that may cause latency spikes.
1754 Typically one would choose no for a realtime system.
1755
Jie Zhangea637632009-12-14 18:00:02 -08001756config MMAP_ALLOW_UNINITIALIZED
1757 bool "Allow mmapped anonymous memory to be uninitialized"
David Rientjes6a108a12011-01-20 14:44:16 -08001758 depends on EXPERT && !MMU
Jie Zhangea637632009-12-14 18:00:02 -08001759 default n
1760 help
1761 Normally, and according to the Linux spec, anonymous memory obtained
1762 from mmap() has it's contents cleared before it is passed to
1763 userspace. Enabling this config option allows you to request that
1764 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1765 providing a huge performance boost. If this option is not enabled,
1766 then the flag will be ignored.
1767
1768 This is taken advantage of by uClibc's malloc(), and also by
1769 ELF-FDPIC binfmt's brk and stack allocator.
1770
1771 Because of the obvious security issues, this option should only be
1772 enabled on embedded devices where you control what is run in
1773 userspace. Since that isn't generally a problem on no-MMU systems,
1774 it is normally safe to say Y here.
1775
1776 See Documentation/nommu-mmap.txt for more information.
1777
David Howells091f6e22015-07-20 21:16:28 +01001778config SYSTEM_DATA_VERIFICATION
1779 def_bool n
1780 select SYSTEM_TRUSTED_KEYRING
1781 select KEYS
1782 select CRYPTO
David Howellsd43de6c2016-03-03 21:49:27 +00001783 select CRYPTO_RSA
David Howells091f6e22015-07-20 21:16:28 +01001784 select ASYMMETRIC_KEY_TYPE
1785 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
David Howells091f6e22015-07-20 21:16:28 +01001786 select ASN1
1787 select OID_REGISTRY
1788 select X509_CERTIFICATE_PARSER
1789 select PKCS7_MESSAGE_PARSER
Peter Foley82c04ff2014-04-18 15:07:11 -07001790 help
David Howells091f6e22015-07-20 21:16:28 +01001791 Provide PKCS#7 message verification using the contents of the system
1792 trusted keyring to provide public keys. This then can be used for
1793 module verification, kexec image verification and firmware blob
1794 verification.
Peter Foley82c04ff2014-04-18 15:07:11 -07001795
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001796config PROFILING
Robert Richterb309a292010-02-26 15:01:23 +01001797 bool "Profiling support"
Mathieu Desnoyers125e5642008-02-02 15:10:36 -05001798 help
1799 Say Y here to enable the extended profiling support mechanisms used
1800 by profilers such as OProfile.
1801
Ingo Molnar5f87f112008-07-23 14:15:22 +02001802#
1803# Place an empty function call at each tracepoint site. Can be
1804# dynamically changed for a probe function.
1805#
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001806config TRACEPOINTS
Ingo Molnar5f87f112008-07-23 14:15:22 +02001807 bool
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001808
Mathieu Desnoyersfb32e032008-02-02 15:10:33 -05001809source "arch/Kconfig"
1810
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811endmenu # General setup
1812
Dmitry Baryshkovee7e5512008-06-29 14:18:46 +04001813config HAVE_GENERIC_DMA_COHERENT
1814 bool
1815 default n
1816
Linus Torvalds158a9622008-01-02 13:04:48 -08001817config SLABINFO
1818 bool
1819 depends on PROC_FS
Christoph Lameter0f389ec2008-04-14 18:53:02 +03001820 depends on SLAB || SLUB_DEBUG
Linus Torvalds158a9622008-01-02 13:04:48 -08001821 default y
1822
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001823config RT_MUTEXES
Christoph Jaeger6341e622014-12-20 15:41:11 -05001824 bool
Chuck Ebbertae81f9e2006-09-16 12:15:53 -07001825
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826config BASE_SMALL
1827 int
1828 default 0 if BASE_FULL
1829 default 1 if !BASE_FULL
1830
Jan Engelhardt66da5732007-07-15 23:39:29 -07001831menuconfig MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 bool "Enable loadable module support"
Yann E. MORIN11097a02013-08-11 16:07:50 +02001833 option modules
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834 help
1835 Kernel modules are small pieces of compiled code which can
1836 be inserted in the running kernel, rather than being
1837 permanently built into the kernel. You use the "modprobe"
1838 tool to add (and sometimes remove) them. If you say Y here,
1839 many parts of the kernel can be built as modules (by
1840 answering M instead of Y where indicated): this is most
1841 useful for infrequently used options which are not required
1842 for booting. For more information, see the man pages for
1843 modprobe, lsmod, modinfo, insmod and rmmod.
1844
1845 If you say Y here, you will need to run "make
1846 modules_install" to put the modules under /lib/modules/
1847 where modprobe can find them (you may need to be root to do
1848 this).
1849
1850 If unsure, say Y.
1851
Robert P. J. Day0b0de142008-08-04 13:31:32 -04001852if MODULES
1853
Linus Torvalds826e4502008-05-04 17:04:16 -07001854config MODULE_FORCE_LOAD
1855 bool "Forced module loading"
Linus Torvalds826e4502008-05-04 17:04:16 -07001856 default n
1857 help
Rusty Russell91e37a72008-05-09 16:25:28 +10001858 Allow loading of modules without version information (ie. modprobe
1859 --force). Forced module loading sets the 'F' (forced) taint flag and
1860 is usually a really bad idea.
Linus Torvalds826e4502008-05-04 17:04:16 -07001861
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862config MODULE_UNLOAD
1863 bool "Module unloading"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001864 help
1865 Without this option you will not be able to unload any
1866 modules (note that some modules may not be unloadable
Denys Vlasenkof7f5b672008-07-22 19:24:26 -05001867 anyway), which makes your kernel smaller, faster
1868 and simpler. If unsure, say Y.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869
1870config MODULE_FORCE_UNLOAD
1871 bool "Forced module unloading"
Kees Cook19c92392012-10-02 11:19:29 -07001872 depends on MODULE_UNLOAD
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873 help
1874 This option allows you to force a module to unload, even if the
1875 kernel believes it is unsafe: the kernel will remove the module
1876 without waiting for anyone to stop using it (using the -f option to
1877 rmmod). This is mainly for kernel developers and desperate users.
1878 If unsure, say N.
1879
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880config MODVERSIONS
Sam Ravnborg0d541642005-12-26 23:04:02 +01001881 bool "Module versioning support"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 help
1883 Usually, you have to use modules compiled with your kernel.
1884 Saying Y here makes it sometimes possible to use modules
1885 compiled for different kernels, by adding enough information
1886 to the modules to (hopefully) spot any changes which would
1887 make them incompatible with the kernel you are running. If
1888 unsure, say N.
1889
1890config MODULE_SRCVERSION_ALL
1891 bool "Source checksum for all modules"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 help
1893 Modules which contain a MODULE_VERSION get an extra "srcversion"
1894 field inserted into their modinfo section, which contains a
1895 sum of the source files which made it. This helps maintainers
1896 see exactly which source was used to build a module (since
1897 others sometimes change the module source without updating
1898 the version). With this option, such a "srcversion" field
1899 will be created for all modules. If unsure, say N.
1900
Rusty Russell106a4ee2012-09-26 10:09:40 +01001901config MODULE_SIG
1902 bool "Module signature verification"
1903 depends on MODULES
David Howells091f6e22015-07-20 21:16:28 +01001904 select SYSTEM_DATA_VERIFICATION
Rusty Russell106a4ee2012-09-26 10:09:40 +01001905 help
1906 Check modules for valid signatures upon load: the signature
1907 is simply appended to the module. For more information see
1908 Documentation/module-signing.txt.
1909
David Howells228c37f2015-08-11 12:38:54 +01001910 Note that this option adds the OpenSSL development packages as a
1911 kernel build dependency so that the signing tool can use its crypto
1912 library.
1913
David Howellsea0b6dc2012-09-26 10:09:50 +01001914 !!!WARNING!!! If you enable this option, you MUST make sure that the
1915 module DOES NOT get stripped after being signed. This includes the
1916 debuginfo strip done by some packagers (such as rpmbuild) and
1917 inclusion into an initramfs that wants the module size reduced.
1918
Rusty Russell106a4ee2012-09-26 10:09:40 +01001919config MODULE_SIG_FORCE
1920 bool "Require modules to be validly signed"
1921 depends on MODULE_SIG
1922 help
1923 Reject unsigned modules or signed modules for which we don't have a
1924 key. Without this, such modules will simply taint the kernel.
David Howellsea0b6dc2012-09-26 10:09:50 +01001925
Michal Marekd9d8d7e2013-01-25 13:41:31 +10301926config MODULE_SIG_ALL
1927 bool "Automatically sign all modules"
1928 default y
1929 depends on MODULE_SIG
1930 help
1931 Sign all modules during make modules_install. Without this option,
1932 modules must be signed manually, using the scripts/sign-file tool.
1933
1934comment "Do not forget to sign required modules with scripts/sign-file"
1935 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1936
David Howellsea0b6dc2012-09-26 10:09:50 +01001937choice
1938 prompt "Which hash algorithm should modules be signed with?"
1939 depends on MODULE_SIG
1940 help
1941 This determines which sort of hashing algorithm will be used during
1942 signature generation. This algorithm _must_ be built into the kernel
1943 directly so that signature verification can take place. It is not
1944 possible to load a signed module containing the algorithm to check
1945 the signature on that module.
1946
1947config MODULE_SIG_SHA1
1948 bool "Sign modules with SHA-1"
1949 select CRYPTO_SHA1
1950
1951config MODULE_SIG_SHA224
1952 bool "Sign modules with SHA-224"
1953 select CRYPTO_SHA256
1954
1955config MODULE_SIG_SHA256
1956 bool "Sign modules with SHA-256"
1957 select CRYPTO_SHA256
1958
1959config MODULE_SIG_SHA384
1960 bool "Sign modules with SHA-384"
1961 select CRYPTO_SHA512
1962
1963config MODULE_SIG_SHA512
1964 bool "Sign modules with SHA-512"
1965 select CRYPTO_SHA512
1966
1967endchoice
1968
Michal Marek22753672013-01-25 13:41:00 +10301969config MODULE_SIG_HASH
1970 string
1971 depends on MODULE_SIG
1972 default "sha1" if MODULE_SIG_SHA1
1973 default "sha224" if MODULE_SIG_SHA224
1974 default "sha256" if MODULE_SIG_SHA256
1975 default "sha384" if MODULE_SIG_SHA384
1976 default "sha512" if MODULE_SIG_SHA512
1977
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301978config MODULE_COMPRESS
1979 bool "Compress modules on installation"
1980 depends on MODULES
1981 help
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301982
Rusty Russellb6c09b52015-06-16 12:16:22 +09301983 Compresses kernel modules when 'make modules_install' is run; gzip or
1984 xz depending on "Compression algorithm" below.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301985
Rusty Russellb6c09b52015-06-16 12:16:22 +09301986 module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301987
Rusty Russellb6c09b52015-06-16 12:16:22 +09301988 Out-of-tree kernel modules installed using Kbuild will also be
1989 compressed upon installation.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301990
Rusty Russellb6c09b52015-06-16 12:16:22 +09301991 Note: for modules inside an initrd or initramfs, it's more efficient
1992 to compress the whole initrd or initramfs instead.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301993
Rusty Russellb6c09b52015-06-16 12:16:22 +09301994 Note: This is fully compatible with signed modules.
1995
1996 If in doubt, say N.
Bertrand Jacquinbeb50df2014-08-27 20:31:56 +09301997
1998choice
1999 prompt "Compression algorithm"
2000 depends on MODULE_COMPRESS
2001 default MODULE_COMPRESS_GZIP
2002 help
2003 This determines which sort of compression will be used during
2004 'make modules_install'.
2005
2006 GZIP (default) and XZ are supported.
2007
2008config MODULE_COMPRESS_GZIP
2009 bool "GZIP"
2010
2011config MODULE_COMPRESS_XZ
2012 bool "XZ"
2013
2014endchoice
2015
Robert P. J. Day0b0de142008-08-04 13:31:32 -04002016endif # MODULES
2017
Peter Zijlstra6c9692e2015-05-27 11:09:37 +09302018config MODULES_TREE_LOOKUP
2019 def_bool y
2020 depends on PERF_EVENTS || TRACING
2021
Rusty Russell98a79d62008-12-13 21:19:41 +10302022config INIT_ALL_POSSIBLE
2023 bool
2024 help
Rusty Russell5f054e32012-03-29 15:38:31 +10302025 Back when each arch used to define their own cpu_online_mask and
2026 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
Rusty Russell98a79d62008-12-13 21:19:41 +10302027 with all 1s, and others with all 0s. When they were centralised,
2028 it was better to provide this option than to break all the archs
Matt LaPlante692105b2009-01-26 11:12:25 +01002029 and have several arch maintainers pursuing me down dark alleys.
Rusty Russell98a79d62008-12-13 21:19:41 +10302030
Jens Axboe3a65dfe2005-11-04 08:43:35 +01002031source "block/Kconfig"
Avi Kivitye98c3202007-10-16 23:27:31 -07002032
2033config PREEMPT_NOTIFIERS
2034 bool
Paul E. McKenneye260be62008-01-25 21:08:24 +01002035
Steffen Klassert16295be2010-01-06 19:47:10 +11002036config PADATA
2037 depends on SMP
2038 bool
2039
Andi Kleen754b7b62012-10-04 17:11:27 -07002040# Can be selected by architectures with broken toolchains
2041# that get confused by correct const<->read_only section
2042# mappings
2043config BROKEN_RODATA
2044 bool
2045
David Howells4520c6a2012-09-21 23:31:13 +01002046config ASN1
2047 tristate
2048 help
2049 Build a simple ASN.1 grammar compiler that produces a bytecode output
2050 that can be interpreted by the ASN.1 stream decoder and used to
2051 inform it as to what tags are to be expected in a stream and what
2052 functions to call on what tags.
2053
Thomas Gleixner6beb0002009-11-09 15:21:34 +00002054source "kernel/Kconfig.locks"