]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blame - init/Kconfig
cputime: Gather time/stats accounting config options into a single menu
[mirror_ubuntu-artful-kernel.git] / init / Kconfig
CommitLineData
80daa560
RZ
1config ARCH
2 string
3 option env="ARCH"
4
5config KERNELVERSION
6 string
7 option env="KERNELVERSION"
8
face4374
RZ
9config DEFCONFIG_LIST
10 string
b2670eac 11 depends on !UML
face4374
RZ
12 option defconfig_list
13 default "/lib/modules/$UNAME_RELEASE/.config"
14 default "/etc/kernel-config"
15 default "/boot/config-$UNAME_RELEASE"
73531905 16 default "$ARCH_DEFCONFIG"
face4374
RZ
17 default "arch/$ARCH/defconfig"
18
b99b87f7
PO
19config CONSTRUCTORS
20 bool
21 depends on !UML
b99b87f7 22
e360adbe
PZ
23config HAVE_IRQ_WORK
24 bool
25
26config IRQ_WORK
27 bool
28 depends on HAVE_IRQ_WORK
29
1dbdc6f1
DD
30config BUILDTIME_EXTABLE_SORT
31 bool
32
ff0cfc66 33menu "General setup"
1da177e4
LT
34
35config EXPERIMENTAL
36 bool "Prompt for development and/or incomplete code/drivers"
37 ---help---
38 Some of the various things that Linux supports (such as network
39 drivers, file systems, network protocols, etc.) can be in a state
40 of development where the functionality, stability, or the level of
41 testing is not yet high enough for general use. This is usually
42 known as the "alpha-test" phase among developers. If a feature is
43 currently in alpha-test, then the developers usually discourage
44 uninformed widespread use of this feature by the general public to
45 avoid "Why doesn't this work?" type mail messages. However, active
46 testing and use of these systems is welcomed. Just be aware that it
47 may not meet the normal level of reliability or it may fail to work
48 in some special cases. Detailed bug reports from people familiar
49 with the kernel internals are usually welcomed by the developers
50 (before submitting bug reports, please read the documents
51 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
52 <file:Documentation/BUG-HUNTING>, and
53 <file:Documentation/oops-tracing.txt> in the kernel source).
54
55 This option will also make obsoleted drivers available. These are
56 drivers that have been replaced by something else, and/or are
57 scheduled to be removed in a future kernel release.
58
59 Unless you intend to help test and develop a feature or driver that
60 falls into this category, or you have a situation that requires
61 using these features, you should probably say N here, which will
62 cause the configurator to present you with fewer choices. If
63 you say Y here, you will be offered the choice of using features or
64 drivers that are currently considered to be in the alpha-test phase.
65
1da177e4
LT
66config BROKEN
67 bool
1da177e4
LT
68
69config BROKEN_ON_SMP
70 bool
71 depends on BROKEN || !SMP
72 default y
73
1da177e4
LT
74config INIT_ENV_ARG_LIMIT
75 int
dd673bca
AB
76 default 32 if !UML
77 default 128 if UML
1da177e4 78 help
34ad92c2
RD
79 Maximum of each of the number of arguments and environment
80 variables passed to init from the kernel command line.
1da177e4 81
1da177e4 82
84336466
RM
83config CROSS_COMPILE
84 string "Cross-compiler tool prefix"
85 help
86 Same as running 'make CROSS_COMPILE=prefix-' but stored for
87 default make runs in this kernel build directory. You don't
88 need to set this unless you want the configured kernel build
89 directory to select the cross-compiler automatically.
90
1da177e4
LT
91config LOCALVERSION
92 string "Local version - append to kernel release"
93 help
94 Append an extra string to the end of your kernel version.
95 This will show up when you type uname, for example.
96 The string you set here will be appended after the contents of
97 any files with a filename matching localversion* in your
98 object and source tree, in that order. Your total string can
99 be a maximum of 64 characters.
100
aaebf433
RA
101config LOCALVERSION_AUTO
102 bool "Automatically append version information to the version string"
103 default y
104 help
105 This will try to automatically determine if the current tree is a
6e5a5420
RD
106 release tree by looking for git tags that belong to the current
107 top of tree revision.
aaebf433
RA
108
109 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 110 if a git-based tree is found. The string generated by this will be
aaebf433 111 appended after any matching localversion* files, and after the value
6e5a5420 112 set in CONFIG_LOCALVERSION.
aaebf433 113
6e5a5420
RD
114 (The actual string used here is the first eight characters produced
115 by running the command:
116
117 $ git rev-parse --verify HEAD
118
119 which is done within the script "scripts/setlocalversion".)
aaebf433 120
2e9f3bdd
PA
121config HAVE_KERNEL_GZIP
122 bool
123
124config HAVE_KERNEL_BZIP2
125 bool
126
127config HAVE_KERNEL_LZMA
128 bool
129
3ebe1243
LC
130config HAVE_KERNEL_XZ
131 bool
132
7dd65feb
AT
133config HAVE_KERNEL_LZO
134 bool
135
30d65dbf 136choice
2e9f3bdd
PA
137 prompt "Kernel compression mode"
138 default KERNEL_GZIP
3ebe1243 139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
2e9f3bdd 140 help
30d65dbf
AK
141 The linux kernel is a kind of self-extracting executable.
142 Several compression algorithms are available, which differ
143 in efficiency, compression and decompression speed.
144 Compression speed is only relevant when building a kernel.
145 Decompression speed is relevant at each boot.
146
147 If you have any problems with bzip2 or lzma compressed
148 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
149 version of this functionality (bzip2 only), for 2.4, was
150 supplied by Christian Ludwig)
151
152 High compression options are mostly useful for users, who
153 are low on disk space (embedded systems), but for whom ram
154 size matters less.
155
156 If in doubt, select 'gzip'
157
158config KERNEL_GZIP
2e9f3bdd
PA
159 bool "Gzip"
160 depends on HAVE_KERNEL_GZIP
161 help
7dd65feb
AT
162 The old and tried gzip compression. It provides a good balance
163 between compression ratio and decompression speed.
30d65dbf
AK
164
165config KERNEL_BZIP2
166 bool "Bzip2"
2e9f3bdd 167 depends on HAVE_KERNEL_BZIP2
30d65dbf
AK
168 help
169 Its compression ratio and speed is intermediate.
0a4dd35c 170 Decompression speed is slowest among the choices. The kernel
2e9f3bdd
PA
171 size is about 10% smaller with bzip2, in comparison to gzip.
172 Bzip2 uses a large amount of memory. For modern kernels you
173 will need at least 8MB RAM or more for booting.
30d65dbf
AK
174
175config KERNEL_LZMA
2e9f3bdd
PA
176 bool "LZMA"
177 depends on HAVE_KERNEL_LZMA
178 help
0a4dd35c
RD
179 This compression algorithm's ratio is best. Decompression speed
180 is between gzip and bzip2. Compression is slowest.
181 The kernel size is about 33% smaller with LZMA in comparison to gzip.
30d65dbf 182
3ebe1243
LC
183config KERNEL_XZ
184 bool "XZ"
185 depends on HAVE_KERNEL_XZ
186 help
187 XZ uses the LZMA2 algorithm and instruction set specific
188 BCJ filters which can improve compression ratio of executable
189 code. The size of the kernel is about 30% smaller with XZ in
190 comparison to gzip. On architectures for which there is a BCJ
191 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
192 will create a few percent smaller kernel than plain LZMA.
193
194 The speed is about the same as with LZMA: The decompression
195 speed of XZ is better than that of bzip2 but worse than gzip
196 and LZO. Compression is slow.
197
7dd65feb
AT
198config KERNEL_LZO
199 bool "LZO"
200 depends on HAVE_KERNEL_LZO
201 help
0a4dd35c 202 Its compression ratio is the poorest among the choices. The kernel
681b3049 203 size is about 10% bigger than gzip; however its speed
7dd65feb
AT
204 (both compression and decompression) is the fastest.
205
30d65dbf
AK
206endchoice
207
bd5dc17b
JT
208config DEFAULT_HOSTNAME
209 string "Default hostname"
210 default "(none)"
211 help
212 This option determines the default system hostname before userspace
213 calls sethostname(2). The kernel traditionally uses "(none)" here,
214 but you may wish to use a different default here to make a minimal
215 system more usable with less configuration.
216
1da177e4
LT
217config SWAP
218 bool "Support for paging of anonymous memory (swap)"
9361401e 219 depends on MMU && BLOCK
1da177e4
LT
220 default y
221 help
222 This option allows you to choose whether you want to have support
92c3504e 223 for so called swap devices or swap files in your kernel that are
1da177e4
LT
224 used to provide more virtual memory than the actual RAM present
225 in your computer. If unsure say Y.
226
227config SYSVIPC
228 bool "System V IPC"
1da177e4
LT
229 ---help---
230 Inter Process Communication is a suite of library functions and
231 system calls which let processes (running programs) synchronize and
232 exchange information. It is generally considered to be a good thing,
233 and some programs won't run unless you say Y here. In particular, if
234 you want to run the DOS emulator dosemu under Linux (read the
235 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
236 you'll need to say Y here.
237
238 You can find documentation about IPC with "info ipc" and also in
239 section 6.4 of the Linux Programmer's Guide, available from
240 <http://www.tldp.org/guides.html>.
241
a5494dcd
EB
242config SYSVIPC_SYSCTL
243 bool
244 depends on SYSVIPC
245 depends on SYSCTL
246 default y
247
1da177e4
LT
248config POSIX_MQUEUE
249 bool "POSIX Message Queues"
250 depends on NET && EXPERIMENTAL
251 ---help---
252 POSIX variant of message queues is a part of IPC. In POSIX message
253 queues every message has a priority which decides about succession
254 of receiving it by a process. If you want to compile and run
255 programs written e.g. for Solaris with use of its POSIX message
b0e37650 256 queues (functions mq_*) say Y here.
1da177e4
LT
257
258 POSIX message queues are visible as a filesystem called 'mqueue'
259 and can be mounted somewhere if you want to do filesystem
260 operations on message queues.
261
262 If unsure, say Y.
263
bdc8e5f8
SH
264config POSIX_MQUEUE_SYSCTL
265 bool
266 depends on POSIX_MQUEUE
267 depends on SYSCTL
268 default y
269
391dc69c
FW
270config FHANDLE
271 bool "open by fhandle syscalls"
272 select EXPORTFS
273 help
274 If you say Y here, a user level program will be able to map
275 file names to handle and then later use the handle for
276 different file system operations. This is useful in implementing
277 userspace file servers, which now track files using handles instead
278 of names. The handle would remain the same even if file names
279 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
280 syscalls.
281
282config AUDIT
283 bool "Auditing support"
284 depends on NET
285 help
286 Enable auditing infrastructure that can be used with another
287 kernel subsystem, such as SELinux (which requires this for
288 logging of avc messages output). Does not do system-call
289 auditing without CONFIG_AUDITSYSCALL.
290
291config AUDITSYSCALL
292 bool "Enable system-call auditing support"
293 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
294 default y if SECURITY_SELINUX
295 help
296 Enable low-overhead system-call auditing infrastructure that
297 can be used independently or with another kernel subsystem,
298 such as SELinux.
299
300config AUDIT_WATCH
301 def_bool y
302 depends on AUDITSYSCALL
303 select FSNOTIFY
304
305config AUDIT_TREE
306 def_bool y
307 depends on AUDITSYSCALL
308 select FSNOTIFY
309
310config AUDIT_LOGINUID_IMMUTABLE
311 bool "Make audit loginuid immutable"
312 depends on AUDIT
313 help
314 The config option toggles if a task setting its loginuid requires
315 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
316 but should instead only allow setting its loginuid if it was never
317 previously set. On systems which use systemd or a similar central
318 process to restart login services this should be set to true. On older
319 systems in which an admin would typically have to directly stop and
320 start processes this should be set to false. Setting this to true allows
321 one to drop potentially dangerous capabilites from the login tasks,
322 but may not be backwards compatible with older init systems.
323
324source "kernel/irq/Kconfig"
325source "kernel/time/Kconfig"
326
327menu "CPU/Task time and stats accounting"
328
b952741c
FW
329config VIRT_CPU_ACCOUNTING
330 bool "Deterministic task and CPU time accounting"
331 depends on HAVE_VIRT_CPU_ACCOUNTING
332 default y if PPC64
333 help
334 Select this option to enable more accurate task and CPU time
335 accounting. This is done by reading a CPU counter on each
336 kernel entry and exit and on transitions within the kernel
337 between system, softirq and hardirq state, so there is a
338 small performance impact. In the case of s390 or IBM POWER > 5,
339 this also enables accounting of stolen time on logically-partitioned
340 systems.
341
1da177e4
LT
342config BSD_PROCESS_ACCT
343 bool "BSD Process Accounting"
344 help
345 If you say Y here, a user level program will be able to instruct the
346 kernel (via a special system call) to write process accounting
347 information to a file: whenever a process exits, information about
348 that process will be appended to the file by the kernel. The
349 information includes things such as creation time, owning user,
350 command name, memory usage, controlling terminal etc. (the complete
351 list is in the struct acct in <file:include/linux/acct.h>). It is
352 up to the user level program to do useful things with this
353 information. This is generally a good idea, so say Y.
354
355config BSD_PROCESS_ACCT_V3
356 bool "BSD Process Accounting version 3 file format"
357 depends on BSD_PROCESS_ACCT
358 default n
359 help
360 If you say Y here, the process accounting information is written
361 in a new file format that also logs the process IDs of each
362 process and it's parent. Note that this file format is incompatible
363 with previous v0/v1/v2 file formats, so you will need updated tools
364 for processing it. A preliminary version of these tools is available
37a4c940 365 at <http://www.gnu.org/software/acct/>.
1da177e4 366
c757249a
SN
367config TASKSTATS
368 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
369 depends on NET
370 default n
371 help
372 Export selected statistics for tasks/processes through the
373 generic netlink interface. Unlike BSD process accounting, the
374 statistics are available during the lifetime of tasks/processes as
375 responses to commands. Like BSD accounting, they are sent to user
376 space on task exit.
377
378 Say N if unsure.
379
ca74e92b
SN
380config TASK_DELAY_ACCT
381 bool "Enable per-task delay accounting (EXPERIMENTAL)"
6f44993f 382 depends on TASKSTATS
ca74e92b
SN
383 help
384 Collect information on time spent by a task waiting for system
385 resources like cpu, synchronous block I/O completion and swapping
386 in pages. Such statistics can help in setting a task's priorities
387 relative to other tasks for cpu, io, rss limits etc.
388
389 Say N if unsure.
390
18f705f4
AD
391config TASK_XACCT
392 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
393 depends on TASKSTATS
394 help
395 Collect extended task accounting data and send the data
396 to userland for processing over the taskstats interface.
397
398 Say N if unsure.
399
400config TASK_IO_ACCOUNTING
401 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
402 depends on TASK_XACCT
403 help
404 Collect information on the number of bytes of storage I/O which this
405 task has caused.
406
407 Say N if unsure.
408
391dc69c 409endmenu # "CPU/Task time and stats accounting"
d9817ebe 410
c903ff83
MT
411menu "RCU Subsystem"
412
413choice
414 prompt "RCU Implementation"
31c9a24e 415 default TREE_RCU
c903ff83 416
c903ff83
MT
417config TREE_RCU
418 bool "Tree-based hierarchical RCU"
687d7a96 419 depends on !PREEMPT && SMP
c903ff83
MT
420 help
421 This option selects the RCU implementation that is
422 designed for very large SMP system with hundreds or
c17ef453
PM
423 thousands of CPUs. It also scales down nicely to
424 smaller systems.
c903ff83 425
f41d911f 426config TREE_PREEMPT_RCU
a57eb940 427 bool "Preemptible tree-based hierarchical RCU"
8008e129 428 depends on PREEMPT && SMP
f41d911f
PM
429 help
430 This option selects the RCU implementation that is
431 designed for very large SMP systems with hundreds or
432 thousands of CPUs, but for which real-time response
bbe3eae8
PM
433 is also required. It also scales down nicely to
434 smaller systems.
f41d911f 435
9b1d82fa
PM
436config TINY_RCU
437 bool "UP-only small-memory-footprint RCU"
8008e129 438 depends on !PREEMPT && !SMP
9b1d82fa
PM
439 help
440 This option selects the RCU implementation that is
441 designed for UP systems from which real-time response
442 is not required. This option greatly reduces the
443 memory footprint of RCU.
444
a57eb940
PM
445config TINY_PREEMPT_RCU
446 bool "Preemptible UP-only small-memory-footprint RCU"
8008e129 447 depends on PREEMPT && !SMP
a57eb940
PM
448 help
449 This option selects the RCU implementation that is designed
450 for real-time UP systems. This option greatly reduces the
451 memory footprint of RCU.
452
c903ff83
MT
453endchoice
454
a57eb940
PM
455config PREEMPT_RCU
456 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
457 help
458 This option enables preemptible-RCU code that is common between
459 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
460
c903ff83
MT
461config RCU_FANOUT
462 int "Tree-based hierarchical RCU fanout value"
463 range 2 64 if 64BIT
464 range 2 32 if !64BIT
f41d911f 465 depends on TREE_RCU || TREE_PREEMPT_RCU
c903ff83
MT
466 default 64 if 64BIT
467 default 32 if !64BIT
468 help
469 This option controls the fanout of hierarchical implementations
470 of RCU, allowing RCU to work efficiently on machines with
4d87ffad
PM
471 large numbers of CPUs. This value must be at least the fourth
472 root of NR_CPUS, which allows NR_CPUS to be insanely large.
473 The default value of RCU_FANOUT should be used for production
474 systems, but if you are stress-testing the RCU implementation
475 itself, small RCU_FANOUT values allow you to test large-system
476 code paths on small(er) systems.
c903ff83
MT
477
478 Select a specific number if testing RCU itself.
479 Take the default if unsure.
480
8932a63d
PM
481config RCU_FANOUT_LEAF
482 int "Tree-based hierarchical RCU leaf-level fanout value"
483 range 2 RCU_FANOUT if 64BIT
484 range 2 RCU_FANOUT if !64BIT
485 depends on TREE_RCU || TREE_PREEMPT_RCU
486 default 16
487 help
488 This option controls the leaf-level fanout of hierarchical
489 implementations of RCU, and allows trading off cache misses
490 against lock contention. Systems that synchronize their
491 scheduling-clock interrupts for energy-efficiency reasons will
492 want the default because the smaller leaf-level fanout keeps
493 lock contention levels acceptably low. Very large systems
494 (hundreds or thousands of CPUs) will instead want to set this
495 value to the maximum value possible in order to reduce the
496 number of cache misses incurred during RCU's grace-period
497 initialization. These systems tend to run CPU-bound, and thus
498 are not helped by synchronized interrupts, and thus tend to
499 skew them, which reduces lock contention enough that large
500 leaf-level fanouts work well.
501
502 Select a specific number if testing RCU itself.
503
504 Select the maximum permissible value for large systems.
505
506 Take the default if unsure.
507
c903ff83
MT
508config RCU_FANOUT_EXACT
509 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 510 depends on TREE_RCU || TREE_PREEMPT_RCU
c903ff83
MT
511 default n
512 help
513 This option forces use of the exact RCU_FANOUT value specified,
514 regardless of imbalances in the hierarchy. This is useful for
515 testing RCU itself, and might one day be useful on systems with
516 strong NUMA behavior.
517
518 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
519
520 Say N if unsure.
521
8bd93a2c
PM
522config RCU_FAST_NO_HZ
523 bool "Accelerate last non-dyntick-idle CPU's grace periods"
b807fbff 524 depends on NO_HZ && SMP
8bd93a2c
PM
525 default n
526 help
527 This option causes RCU to attempt to accelerate grace periods
b807fbff
PM
528 in order to allow CPUs to enter dynticks-idle state more
529 quickly. On the other hand, this option increases the overhead
530 of the dynticks-idle checking, particularly on systems with
531 large numbers of CPUs.
8bd93a2c
PM
532
533 Say Y if energy efficiency is critically important, particularly
534 if you have relatively few CPUs.
535
536 Say N if you are unsure.
537
c903ff83 538config TREE_RCU_TRACE
f41d911f 539 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
c903ff83
MT
540 select DEBUG_FS
541 help
f41d911f
PM
542 This option provides tracing for the TREE_RCU and
543 TREE_PREEMPT_RCU implementations, permitting Makefile to
544 trivially select kernel/rcutree_trace.c.
c903ff83 545
24278d14
PM
546config RCU_BOOST
547 bool "Enable RCU priority boosting"
27f4d280 548 depends on RT_MUTEXES && PREEMPT_RCU
24278d14
PM
549 default n
550 help
551 This option boosts the priority of preempted RCU readers that
552 block the current preemptible RCU grace period for too long.
553 This option also prevents heavy loads from blocking RCU
554 callback invocation for all flavors of RCU.
555
556 Say Y here if you are working with real-time apps or heavy loads
557 Say N here if you are unsure.
558
559config RCU_BOOST_PRIO
560 int "Real-time priority to boost RCU readers to"
561 range 1 99
562 depends on RCU_BOOST
563 default 1
564 help
c9336643
PM
565 This option specifies the real-time priority to which long-term
566 preempted RCU readers are to be boosted. If you are working
567 with a real-time application that has one or more CPU-bound
568 threads running at a real-time priority level, you should set
569 RCU_BOOST_PRIO to a priority higher then the highest-priority
570 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
571 of 1 is appropriate in the common case, which is real-time
572 applications that do not have any CPU-bound threads.
573
574 Some real-time applications might not have a single real-time
575 thread that saturates a given CPU, but instead might have
576 multiple real-time threads that, taken together, fully utilize
577 that CPU. In this case, you should set RCU_BOOST_PRIO to
578 a priority higher than the lowest-priority thread that is
579 conspiring to prevent the CPU from running any non-real-time
580 tasks. For example, if one thread at priority 10 and another
581 thread at priority 5 are between themselves fully consuming
582 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
583 set to priority 6 or higher.
24278d14
PM
584
585 Specify the real-time priority, or take the default if unsure.
586
587config RCU_BOOST_DELAY
588 int "Milliseconds to delay boosting after RCU grace-period start"
589 range 0 3000
590 depends on RCU_BOOST
591 default 500
592 help
593 This option specifies the time to wait after the beginning of
594 a given grace period before priority-boosting preempted RCU
595 readers blocking that grace period. Note that any RCU reader
596 blocking an expedited RCU grace period is boosted immediately.
597
598 Accept the default if unsure.
599
c903ff83
MT
600endmenu # "RCU Subsystem"
601
1da177e4 602config IKCONFIG
f2443ab6 603 tristate "Kernel .config support"
1da177e4
LT
604 ---help---
605 This option enables the complete Linux kernel ".config" file
606 contents to be saved in the kernel. It provides documentation
607 of which kernel options are used in a running kernel or in an
608 on-disk kernel. This information can be extracted from the kernel
609 image file with the script scripts/extract-ikconfig and used as
610 input to rebuild the current kernel or to build another kernel.
611 It can also be extracted from a running kernel by reading
612 /proc/config.gz if enabled (below).
613
614config IKCONFIG_PROC
615 bool "Enable access to .config through /proc/config.gz"
616 depends on IKCONFIG && PROC_FS
617 ---help---
618 This option enables access to the kernel configuration file
619 through /proc/config.gz.
620
794543a2
AJS
621config LOG_BUF_SHIFT
622 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
623 range 12 21
f17a32e9 624 default 17
794543a2
AJS
625 help
626 Select kernel log buffer size as a power of 2.
f17a32e9
AB
627 Examples:
628 17 => 128 KB
629 16 => 64 KB
630 15 => 32 KB
631 14 => 16 KB
794543a2
AJS
632 13 => 8 KB
633 12 => 4 KB
634
a5574cf6
IM
635#
636# Architectures with an unreliable sched_clock() should select this:
637#
638config HAVE_UNSTABLE_SCHED_CLOCK
639 bool
640
23964d2d
LZ
641menuconfig CGROUPS
642 boolean "Control Group support"
0dea1168 643 depends on EVENTFD
5cdc38f9 644 help
23964d2d 645 This option adds support for grouping sets of processes together, for
5cdc38f9
KH
646 use with process control subsystems such as Cpusets, CFS, memory
647 controls or device isolation.
648 See
5cdc38f9 649 - Documentation/scheduler/sched-design-CFS.txt (CFS)
45ce80fb
LZ
650 - Documentation/cgroups/ (features for grouping, isolation
651 and resource control)
5cdc38f9
KH
652
653 Say N if unsure.
654
23964d2d
LZ
655if CGROUPS
656
5cdc38f9
KH
657config CGROUP_DEBUG
658 bool "Example debug cgroup subsystem"
5cdc38f9
KH
659 default n
660 help
661 This option enables a simple cgroup subsystem that
662 exports useful debugging information about the cgroups
23964d2d 663 framework.
5cdc38f9 664
23964d2d 665 Say N if unsure.
5cdc38f9 666
5cdc38f9 667config CGROUP_FREEZER
23964d2d 668 bool "Freezer cgroup subsystem"
23964d2d
LZ
669 help
670 Provides a way to freeze and unfreeze all tasks in a
5cdc38f9
KH
671 cgroup.
672
673config CGROUP_DEVICE
674 bool "Device controller for cgroups"
5cdc38f9
KH
675 help
676 Provides a cgroup implementing whitelists for devices which
677 a process in the cgroup can mknod or open.
678
679config CPUSETS
680 bool "Cpuset support"
5cdc38f9
KH
681 help
682 This option will let you create and manage CPUSETs which
683 allow dynamically partitioning a system into sets of CPUs and
684 Memory Nodes and assigning tasks to run only within those sets.
685 This is primarily useful on large SMP or NUMA systems.
686
687 Say N if unsure.
688
23964d2d
LZ
689config PROC_PID_CPUSET
690 bool "Include legacy /proc/<pid>/cpuset file"
691 depends on CPUSETS
692 default y
693
d842de87
SV
694config CGROUP_CPUACCT
695 bool "Simple CPU accounting cgroup subsystem"
d842de87
SV
696 help
697 Provides a simple Resource Controller for monitoring the
23964d2d 698 total CPU consumed by the tasks in a cgroup.
d842de87 699
e552b661
PE
700config RESOURCE_COUNTERS
701 bool "Resource counters"
702 help
703 This option enables controller independent resource accounting
23964d2d 704 infrastructure that works with cgroups.
e552b661 705
c255a458 706config MEMCG
00f0b825 707 bool "Memory Resource Controller for Control Groups"
79ae9c29 708 depends on RESOURCE_COUNTERS
cf475ad2 709 select MM_OWNER
00f0b825 710 help
84ad6d70 711 Provides a memory resource controller that manages both anonymous
21acb9ca 712 memory and page cache. (See Documentation/cgroups/memory.txt)
00f0b825
BS
713
714 Note that setting this option increases fixed memory overhead
84ad6d70
KH
715 associated with each page of memory in the system. By this,
716 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
717 usage tracking struct at boot. Total amount of this is printed out
718 at boot.
00f0b825
BS
719
720 Only enable when you're ok with these trade offs and really
84ad6d70
KH
721 sure you need the memory resource controller. Even when you enable
722 this, you can set "cgroup_disable=memory" at your boot option to
723 disable memory resource controller and you can avoid overheads.
c9d5409f 724 (and lose benefits of memory resource controller)
00f0b825 725
cf475ad2
BS
726 This config option also selects MM_OWNER config option, which
727 could in turn add some fork/exit overhead.
728
c255a458 729config MEMCG_SWAP
65e0e811 730 bool "Memory Resource Controller Swap Extension"
c255a458 731 depends on MEMCG && SWAP
c077719b
KH
732 help
733 Add swap management feature to memory resource controller. When you
734 enable this, you can limit mem+swap usage per cgroup. In other words,
735 when you disable this, memory resource controller has no cares to
736 usage of swap...a process can exhaust all of the swap. This extension
737 is useful when you want to avoid exhaustion swap but this itself
738 adds more overheads and consumes memory for remembering information.
739 Especially if you use 32bit system or small memory system, please
740 be careful about enabling this. When memory resource controller
741 is disabled by boot option, this will be automatically disabled and
742 there will be no overhead from this. Even when you set this config=y,
00a66d29 743 if boot option "swapaccount=0" is set, swap will not be accounted.
627991a2
KH
744 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
745 size is 4096bytes, 512k per 1Gbytes of swap.
c255a458 746config MEMCG_SWAP_ENABLED
a42c390c 747 bool "Memory Resource Controller Swap Extension enabled by default"
c255a458 748 depends on MEMCG_SWAP
a42c390c
MH
749 default y
750 help
751 Memory Resource Controller Swap Extension comes with its price in
752 a bigger memory consumption. General purpose distribution kernels
43d547f9 753 which want to enable the feature but keep it disabled by default
a42c390c
MH
754 and let the user enable it by swapaccount boot command line
755 parameter should have this option unselected.
756 For those who want to have the feature enabled by default should
757 select this option (if, for some reason, they need to disable it
00a66d29 758 then swapaccount=0 does the trick).
c255a458 759config MEMCG_KMEM
e5671dfa 760 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
c255a458 761 depends on MEMCG && EXPERIMENTAL
e5671dfa
GC
762 default n
763 help
764 The Kernel Memory extension for Memory Resource Controller can limit
765 the amount of memory used by kernel objects in the system. Those are
766 fundamentally different from the entities handled by the standard
767 Memory Controller, which are page-based, and can be swapped. Users of
768 the kmem extension can use it to guarantee that no group of processes
769 will ever exhaust kernel resources alone.
c077719b 770
2bc64a20
AK
771config CGROUP_HUGETLB
772 bool "HugeTLB Resource Controller for Control Groups"
773 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
774 default n
775 help
776 Provides a cgroup Resource Controller for HugeTLB pages.
777 When you enable this, you can put a per cgroup limit on HugeTLB usage.
778 The limit is enforced during page fault. Since HugeTLB doesn't
779 support page reclaim, enforcing the limit at page fault time implies
780 that, the application will get SIGBUS signal if it tries to access
781 HugeTLB pages beyond its limit. This requires the application to know
782 beforehand how much HugeTLB pages it would require for its use. The
783 control group is tracked in the third page lru pointer. This means
784 that we cannot use the controller with huge page less than 3 pages.
785
e5d1367f
SE
786config CGROUP_PERF
787 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
788 depends on PERF_EVENTS && CGROUPS
789 help
790 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 791 threads which belong to the cgroup specified and run on the
e5d1367f
SE
792 designated cpu.
793
794 Say N if unsure.
795
7c941438
DG
796menuconfig CGROUP_SCHED
797 bool "Group CPU scheduler"
7c941438
DG
798 default n
799 help
800 This feature lets CPU scheduler recognize task groups and control CPU
801 bandwidth allocation to such task groups. It uses cgroups to group
802 tasks.
803
804if CGROUP_SCHED
805config FAIR_GROUP_SCHED
806 bool "Group scheduling for SCHED_OTHER"
807 depends on CGROUP_SCHED
808 default CGROUP_SCHED
809
ab84d31e
PT
810config CFS_BANDWIDTH
811 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
812 depends on EXPERIMENTAL
813 depends on FAIR_GROUP_SCHED
814 default n
815 help
816 This option allows users to define CPU bandwidth rates (limits) for
817 tasks running within the fair group scheduler. Groups with no limit
818 set are considered to be unconstrained and will run with no
819 restriction.
820 See tip/Documentation/scheduler/sched-bwc.txt for more information.
821
7c941438
DG
822config RT_GROUP_SCHED
823 bool "Group scheduling for SCHED_RR/FIFO"
824 depends on EXPERIMENTAL
825 depends on CGROUP_SCHED
826 default n
827 help
828 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 829 to task groups. If enabled, it will also make it impossible to
7c941438
DG
830 schedule realtime tasks for non-root users until you allocate
831 realtime bandwidth for them.
832 See Documentation/scheduler/sched-rt-group.txt for more information.
833
834endif #CGROUP_SCHED
835
afc24d49 836config BLK_CGROUP
32e380ae 837 bool "Block IO controller"
79ae9c29 838 depends on BLOCK
afc24d49
VG
839 default n
840 ---help---
841 Generic block IO controller cgroup interface. This is the common
842 cgroup interface which should be used by various IO controlling
843 policies.
844
845 Currently, CFQ IO scheduler uses it to recognize task groups and
846 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
847 to such task groups. It is also used by bio throttling logic in
848 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
849
850 This option only enables generic Block IO controller infrastructure.
e43473b7 851 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
852 enabling proportional weight division of disk bandwidth in CFQ, set
853 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 854 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
855
856 See Documentation/cgroups/blkio-controller.txt for more information.
857
858config DEBUG_BLK_CGROUP
859 bool "Enable Block IO controller debugging"
860 depends on BLK_CGROUP
861 default n
862 ---help---
863 Enable some debugging help. Currently it exports additional stat
864 files in a cgroup which can be useful for debugging.
865
23964d2d 866endif # CGROUPS
c077719b 867
067bce1a
CG
868config CHECKPOINT_RESTORE
869 bool "Checkpoint/restore support" if EXPERT
870 default n
871 help
872 Enables additional kernel features in a sake of checkpoint/restore.
873 In particular it adds auxiliary prctl codes to setup process text,
874 data and heap segment sizes, and a few additional /proc filesystem
875 entries.
876
877 If unsure, say N here.
878
8dd2a82c 879menuconfig NAMESPACES
6a108a14
DR
880 bool "Namespaces support" if EXPERT
881 default !EXPERT
c5289a69
PE
882 help
883 Provides the way to make tasks work with different objects using
884 the same id. For example same IPC id may refer to different objects
885 or same user id or pid may refer to different tasks when used in
886 different namespaces.
887
8dd2a82c
DL
888if NAMESPACES
889
58bfdd6d
PE
890config UTS_NS
891 bool "UTS namespace"
17a6d441 892 default y
58bfdd6d
PE
893 help
894 In this namespace tasks see different info provided with the
895 uname() system call
896
ae5e1b22
PE
897config IPC_NS
898 bool "IPC namespace"
8dd2a82c 899 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 900 default y
ae5e1b22
PE
901 help
902 In this namespace tasks work with IPC ids which correspond to
614b84cf 903 different IPC objects in different namespaces.
ae5e1b22 904
aee16ce7
PE
905config USER_NS
906 bool "User namespace (EXPERIMENTAL)"
8dd2a82c 907 depends on EXPERIMENTAL
e1c972b6 908 depends on UIDGID_CONVERTED
5673a94c 909 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 910
5673a94c 911 default n
aee16ce7
PE
912 help
913 This allows containers, i.e. vservers, to use user namespaces
914 to provide different user info for different servers.
915 If unsure, say N.
916
74bd59bb 917config PID_NS
9bd38c2c 918 bool "PID Namespaces"
17a6d441 919 default y
74bd59bb 920 help
12d2b8f9 921 Support process id namespaces. This allows having multiple
692105b8 922 processes with the same pid as long as they are in different
74bd59bb
PE
923 pid namespaces. This is a building block of containers.
924
d6eb633f
MH
925config NET_NS
926 bool "Network namespace"
8dd2a82c 927 depends on NET
17a6d441 928 default y
d6eb633f
MH
929 help
930 Allow user space to create what appear to be multiple instances
931 of the network stack.
932
8dd2a82c
DL
933endif # NAMESPACES
934
e1c972b6
EB
935config UIDGID_CONVERTED
936 # True if all of the selected software conmponents are known
937 # to have uid_t and gid_t converted to kuid_t and kgid_t
938 # where appropriate and are otherwise safe to use with
939 # the user namespace.
940 bool
941 default y
942
943 # List of kernel pieces that need user namespace work
944 # Features
e1c972b6
EB
945 depends on SYSVIPC = n
946 depends on IMA = n
947 depends on EVM = n
948 depends on KEYS = n
949 depends on AUDIT = n
950 depends on AUDITSYSCALL = n
951 depends on TASKSTATS = n
952 depends on TRACING = n
953 depends on FS_POSIX_ACL = n
954 depends on QUOTA = n
955 depends on QUOTACTL = n
956 depends on DEBUG_CREDENTIALS = n
957 depends on BSD_PROCESS_ACCT = n
958 depends on DRM = n
959 depends on PROC_EVENTS = n
960
961 # Networking
962 depends on NET = n
963 depends on NET_9P = n
964 depends on IPX = n
965 depends on PHONET = n
966 depends on NET_CLS_FLOW = n
967 depends on NETFILTER_XT_MATCH_OWNER = n
968 depends on NETFILTER_XT_MATCH_RECENT = n
969 depends on NETFILTER_XT_TARGET_LOG = n
970 depends on NETFILTER_NETLINK_LOG = n
971 depends on INET = n
972 depends on IPV6 = n
973 depends on IP_SCTP = n
974 depends on AF_RXRPC = n
975 depends on LLC2 = n
976 depends on NET_KEY = n
977 depends on INET_DIAG = n
978 depends on DNS_RESOLVER = n
979 depends on AX25 = n
980 depends on ATALK = n
981
982 # Filesystems
983 depends on USB_DEVICEFS = n
984 depends on USB_GADGETFS = n
985 depends on USB_FUNCTIONFS = n
986 depends on DEVTMPFS = n
987 depends on XENFS = n
988
989 depends on 9P_FS = n
990 depends on ADFS_FS = n
991 depends on AFFS_FS = n
992 depends on AFS_FS = n
993 depends on AUTOFS4_FS = n
994 depends on BEFS_FS = n
995 depends on BFS_FS = n
996 depends on BTRFS_FS = n
997 depends on CEPH_FS = n
998 depends on CIFS = n
999 depends on CODA_FS = n
1000 depends on CONFIGFS_FS = n
1001 depends on CRAMFS = n
1002 depends on DEBUG_FS = n
1003 depends on ECRYPT_FS = n
1004 depends on EFS_FS = n
1005 depends on EXOFS_FS = n
e1c972b6
EB
1006 depends on FAT_FS = n
1007 depends on FUSE_FS = n
1008 depends on GFS2_FS = n
1009 depends on HFS_FS = n
1010 depends on HFSPLUS_FS = n
1011 depends on HPFS_FS = n
1012 depends on HUGETLBFS = n
1013 depends on ISO9660_FS = n
1014 depends on JFFS2_FS = n
1015 depends on JFS_FS = n
1016 depends on LOGFS = n
1017 depends on MINIX_FS = n
1018 depends on NCP_FS = n
1019 depends on NFSD = n
1020 depends on NFS_FS = n
1021 depends on NILFS2_FS = n
1022 depends on NTFS_FS = n
1023 depends on OCFS2_FS = n
1024 depends on OMFS_FS = n
e1c972b6
EB
1025 depends on QNX4FS_FS = n
1026 depends on QNX6FS_FS = n
1027 depends on REISERFS_FS = n
1028 depends on SQUASHFS = n
e1c972b6 1029 depends on SYSV_FS = n
e1c972b6
EB
1030 depends on UBIFS_FS = n
1031 depends on UDF_FS = n
1032 depends on UFS_FS = n
1033 depends on VXFS_FS = n
1034 depends on XFS_FS = n
1035
1036 depends on !UML || HOSTFS = n
1037
1038 # The rare drivers that won't build
1039 depends on AIRO = n
1040 depends on AIRO_CS = n
1041 depends on TUN = n
1042 depends on INFINIBAND_QIB = n
1043 depends on BLK_DEV_LOOP = n
1044 depends on ANDROID_BINDER_IPC = n
1045
1046 # Security modules
1047 depends on SECURITY_TOMOYO = n
1048 depends on SECURITY_APPARMOR = n
1049
5673a94c
EB
1050config UIDGID_STRICT_TYPE_CHECKS
1051 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1052 depends on UIDGID_CONVERTED
5673a94c
EB
1053 default n
1054 help
1055 While the nececessary conversions are being added to all subsystems this option allows
1056 the code to continue to build for unconverted subsystems.
1057
1058 Say Y here if you want the strict type checking enabled
1059
5091faa4
MG
1060config SCHED_AUTOGROUP
1061 bool "Automatic process group scheduling"
1062 select EVENTFD
1063 select CGROUPS
1064 select CGROUP_SCHED
1065 select FAIR_GROUP_SCHED
1066 help
1067 This option optimizes the scheduler for common desktop workloads by
1068 automatically creating and populating task groups. This separation
1069 of workloads isolates aggressive CPU burners (like build jobs) from
1070 desktop applications. Task group autogeneration is currently based
1071 upon task session.
1072
7af37bec
DL
1073config MM_OWNER
1074 bool
1075
1076config SYSFS_DEPRECATED
5d6a4ea5 1077 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1078 depends on SYSFS
1079 default n
1080 help
1081 This option adds code that switches the layout of the "block" class
1082 devices, to not show up in /sys/class/block/, but only in
1083 /sys/block/.
1084
1085 This switch is only active when the sysfs.deprecated=1 boot option is
1086 passed or the SYSFS_DEPRECATED_V2 option is set.
1087
1088 This option allows new kernels to run on old distributions and tools,
1089 which might get confused by /sys/class/block/. Since 2007/2008 all
1090 major distributions and tools handle this just fine.
1091
1092 Recent distributions and userspace tools after 2009/2010 depend on
1093 the existence of /sys/class/block/, and will not work with this
1094 option enabled.
1095
1096 Only if you are using a new kernel on an old distribution, you might
1097 need to say Y here.
1098
1099config SYSFS_DEPRECATED_V2
5d6a4ea5 1100 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1101 default n
1102 depends on SYSFS
1103 depends on SYSFS_DEPRECATED
1104 help
1105 Enable deprecated sysfs by default.
1106
1107 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1108 option.
1109
1110 Only if you are using a new kernel on an old distribution, you might
1111 need to say Y here. Even then, odds are you would not need it
1112 enabled, you can always pass the boot option if absolutely necessary.
1113
1114config RELAY
1115 bool "Kernel->user space relay support (formerly relayfs)"
1116 help
1117 This option enables support for relay interface support in
1118 certain file systems (such as debugfs).
1119 It is designed to provide an efficient mechanism for tools and
1120 facilities to relay large amounts of data from kernel space to
1121 user space.
1122
1123 If unsure, say N.
1124
f991633d
DG
1125config BLK_DEV_INITRD
1126 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1127 depends on BROKEN || !FRV
1128 help
1129 The initial RAM filesystem is a ramfs which is loaded by the
1130 boot loader (loadlin or lilo) and that is mounted as root
1131 before the normal boot procedure. It is typically used to
1132 load modules needed to mount the "real" root file system,
1133 etc. See <file:Documentation/initrd.txt> for details.
1134
1135 If RAM disk support (BLK_DEV_RAM) is also included, this
1136 also enables initial RAM disk (initrd) support and adds
1137 15 Kbytes (more on some other architectures) to the kernel size.
1138
1139 If unsure say Y.
1140
c33df4ea
JPS
1141if BLK_DEV_INITRD
1142
dbec4866
SR
1143source "usr/Kconfig"
1144
c33df4ea
JPS
1145endif
1146
c45b4f1f 1147config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1148 bool "Optimize for size"
c45b4f1f
LT
1149 help
1150 Enabling this option will pass "-Os" instead of "-O2" to gcc
1151 resulting in a smaller kernel.
1152
775a7229 1153 If unsure, say Y.
c45b4f1f 1154
0847062a
RD
1155config SYSCTL
1156 bool
1157
b943c460
RD
1158config ANON_INODES
1159 bool
1160
6a108a14
DR
1161menuconfig EXPERT
1162 bool "Configure standard kernel features (expert users)"
f505c553
JT
1163 # Unhide debug options, to make the on-by-default options visible
1164 select DEBUG_KERNEL
1da177e4
LT
1165 help
1166 This option allows certain base kernel options and settings
1167 to be disabled or tweaked. This is for specialized
1168 environments which can tolerate a "non-standard" kernel.
1169 Only use this if you really know what you are doing.
1170
ae81f9e3 1171config UID16
6a108a14 1172 bool "Enable 16-bit UID system calls" if EXPERT
09337f50 1173 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
ae81f9e3
CE
1174 default y
1175 help
1176 This enables the legacy 16-bit UID syscall wrappers.
1177
b89a8171 1178config SYSCTL_SYSCALL
6a108a14 1179 bool "Sysctl syscall support" if EXPERT
26a7034b 1180 depends on PROC_SYSCTL
c736de60 1181 default n
b89a8171 1182 select SYSCTL
ae81f9e3 1183 ---help---
13bb7e37
EB
1184 sys_sysctl uses binary paths that have been found challenging
1185 to properly maintain and use. The interface in /proc/sys
1186 using paths with ascii names is now the primary path to this
1187 information.
b89a8171 1188
13bb7e37
EB
1189 Almost nothing using the binary sysctl interface so if you are
1190 trying to save some space it is probably safe to disable this,
1191 making your kernel marginally smaller.
b89a8171 1192
c736de60 1193 If unsure say N here.
ae81f9e3 1194
1da177e4 1195config KALLSYMS
6a108a14 1196 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1197 default y
1198 help
1199 Say Y here to let the kernel print out symbolic crash information and
1200 symbolic stack backtraces. This increases the size of the kernel
1201 somewhat, as all symbols have to be loaded into the kernel image.
1202
1203config KALLSYMS_ALL
1204 bool "Include all symbols in kallsyms"
1205 depends on DEBUG_KERNEL && KALLSYMS
1206 help
71a83ec7
AB
1207 Normally kallsyms only contains the symbols of functions for nicer
1208 OOPS messages and backtraces (i.e., symbols from the text and inittext
1209 sections). This is sufficient for most cases. And only in very rare
1210 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1211 names of variables from the data sections, etc).
1212
1213 This option makes sure that all symbols are loaded into the kernel
1214 image (i.e., symbols from all sections) in cost of increased kernel
1215 size (depending on the kernel configuration, it may be 300KiB or
1216 something like this).
1217
1218 Say N unless you really need all symbols.
d59745ce 1219
712f47ce 1220config HOTPLUG
6a108a14 1221 bool "Support for hot-pluggable devices" if EXPERT
712f47ce
GKH
1222 default y
1223 help
1224 This option is provided for the case where no hotplug or uevent
1225 capabilities is wanted by the kernel. You should only consider
1226 disabling this option for embedded systems that do not use modules, a
1227 dynamic /dev tree, or dynamic device discovery. Just say Y.
1228
d59745ce
MM
1229config PRINTK
1230 default y
6a108a14 1231 bool "Enable support for printk" if EXPERT
d59745ce
MM
1232 help
1233 This option enables normal printk support. Removing it
1234 eliminates most of the message strings from the kernel image
1235 and makes the kernel more or less silent. As this makes it
1236 very difficult to diagnose system problems, saying N here is
1237 strongly discouraged.
1238
c8538a7a 1239config BUG
6a108a14 1240 bool "BUG() support" if EXPERT
c8538a7a
MM
1241 default y
1242 help
1243 Disabling this option eliminates support for BUG and WARN, reducing
1244 the size of your kernel image and potentially quietly ignoring
1245 numerous fatal conditions. You should only consider disabling this
1246 option for embedded systems with no facilities for reporting errors.
1247 Just say Y.
1248
708e9a79
MM
1249config ELF_CORE
1250 default y
6a108a14 1251 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1252 help
1253 Enable support for generating core dumps. Disabling saves about 4k.
1254
8761f1ab 1255
e5e1d3cb 1256config PCSPKR_PLATFORM
6a108a14 1257 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1258 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1259 select I8253_LOCK
e5e1d3cb
SS
1260 default y
1261 help
1262 This option allows to disable the internal PC-Speaker
1263 support, saving some memory.
1264
8761f1ab
RB
1265config HAVE_PCSPKR_PLATFORM
1266 bool
1267
1da177e4
LT
1268config BASE_FULL
1269 default y
6a108a14 1270 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1271 help
1272 Disabling this option reduces the size of miscellaneous core
1273 kernel data structures. This saves memory on small machines,
1274 but may reduce performance.
1275
1276config FUTEX
6a108a14 1277 bool "Enable futex support" if EXPERT
1da177e4 1278 default y
23f78d4a 1279 select RT_MUTEXES
1da177e4
LT
1280 help
1281 Disabling this option will cause the kernel to be built without
1282 support for "fast userspace mutexes". The resulting kernel may not
1283 run glibc-based applications correctly.
1284
1285config EPOLL
6a108a14 1286 bool "Enable eventpoll support" if EXPERT
1da177e4 1287 default y
448e3cee 1288 select ANON_INODES
1da177e4
LT
1289 help
1290 Disabling this option will cause the kernel to be built without
1291 support for epoll family of system calls.
1292
fba2afaa 1293config SIGNALFD
6a108a14 1294 bool "Enable signalfd() system call" if EXPERT
448e3cee 1295 select ANON_INODES
fba2afaa
DL
1296 default y
1297 help
1298 Enable the signalfd() system call that allows to receive signals
1299 on a file descriptor.
1300
1301 If unsure, say Y.
1302
b215e283 1303config TIMERFD
6a108a14 1304 bool "Enable timerfd() system call" if EXPERT
448e3cee 1305 select ANON_INODES
b215e283
DL
1306 default y
1307 help
1308 Enable the timerfd() system call that allows to receive timer
1309 events on a file descriptor.
1310
1311 If unsure, say Y.
1312
e1ad7468 1313config EVENTFD
6a108a14 1314 bool "Enable eventfd() system call" if EXPERT
448e3cee 1315 select ANON_INODES
e1ad7468
DL
1316 default y
1317 help
1318 Enable the eventfd() system call that allows to receive both
1319 kernel notification (ie. KAIO) or userspace notifications.
1320
1321 If unsure, say Y.
1322
1da177e4 1323config SHMEM
6a108a14 1324 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1325 default y
1326 depends on MMU
1327 help
1328 The shmem is an internal filesystem used to manage shared memory.
1329 It is backed by swap and manages resource limits. It is also exported
1330 to userspace as tmpfs if TMPFS is enabled. Disabling this
1331 option replaces shmem and tmpfs with the much simpler ramfs code,
1332 which may be appropriate on small systems without swap.
1333
ebf3f09c 1334config AIO
6a108a14 1335 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1336 default y
1337 help
1338 This option enables POSIX asynchronous I/O which may by used
1339 by some high performance threaded applications. Disabling
1340 this option saves about 7k.
1341
6befe5f6
RD
1342config EMBEDDED
1343 bool "Embedded system"
1344 select EXPERT
1345 help
1346 This option should be enabled if compiling the kernel for
1347 an embedded system so certain expert options are available
1348 for configuration.
1349
cdd6c482 1350config HAVE_PERF_EVENTS
0793a61d 1351 bool
018df72d
MF
1352 help
1353 See tools/perf/design.txt for details.
0793a61d 1354
906010b2
PZ
1355config PERF_USE_VMALLOC
1356 bool
1357 help
1358 See tools/perf/design.txt for details
1359
57c0c15b 1360menu "Kernel Performance Events And Counters"
0793a61d 1361
cdd6c482 1362config PERF_EVENTS
57c0c15b 1363 bool "Kernel performance events and counters"
392d65a9 1364 default y if PROFILING
cdd6c482 1365 depends on HAVE_PERF_EVENTS
4c59e467 1366 select ANON_INODES
e360adbe 1367 select IRQ_WORK
0793a61d 1368 help
57c0c15b
IM
1369 Enable kernel support for various performance events provided
1370 by software and hardware.
0793a61d 1371
dd77038d 1372 Software events are supported either built-in or via the
57c0c15b 1373 use of generic tracepoints.
0793a61d 1374
57c0c15b
IM
1375 Most modern CPUs support performance events via performance
1376 counter registers. These registers count the number of certain
0793a61d
TG
1377 types of hw events: such as instructions executed, cachemisses
1378 suffered, or branches mis-predicted - without slowing down the
1379 kernel or applications. These registers can also trigger interrupts
1380 when a threshold number of events have passed - and can thus be
1381 used to profile the code that runs on that CPU.
1382
57c0c15b 1383 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1384 these software and hardware event capabilities, available via a
57c0c15b 1385 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1386 provides per task and per CPU counters, and it provides event
1387 capabilities on top of those.
1388
1389 Say Y if unsure.
1390
906010b2
PZ
1391config DEBUG_PERF_USE_VMALLOC
1392 default n
1393 bool "Debug: use vmalloc to back perf mmap() buffers"
1394 depends on PERF_EVENTS && DEBUG_KERNEL
1395 select PERF_USE_VMALLOC
1396 help
1397 Use vmalloc memory to back perf mmap() buffers.
1398
1399 Mostly useful for debugging the vmalloc code on platforms
1400 that don't require it.
1401
1402 Say N if unsure.
1403
0793a61d
TG
1404endmenu
1405
f8891e5e
CL
1406config VM_EVENT_COUNTERS
1407 default y
6a108a14 1408 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1409 help
2aea4fb6
PJ
1410 VM event counters are needed for event counts to be shown.
1411 This option allows the disabling of the VM event counters
6a108a14 1412 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1413 if VM event counters are disabled.
f8891e5e 1414
3d137310
TP
1415config PCI_QUIRKS
1416 default y
6a108a14 1417 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1418 depends on PCI
3d137310
TP
1419 help
1420 This enables workarounds for various PCI chipset
1421 bugs/quirks. Disable this only if your target machine is
1422 unaffected by PCI quirks.
1423
41ecc55b
CL
1424config SLUB_DEBUG
1425 default y
6a108a14 1426 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1427 depends on SLUB && SYSFS
41ecc55b
CL
1428 help
1429 SLUB has extensive debug support features. Disabling these can
1430 result in significant savings in code size. This also disables
1431 SLUB sysfs support. /sys/slab will not exist and there will be
1432 no support for cache validation etc.
1433
b943c460
RD
1434config COMPAT_BRK
1435 bool "Disable heap randomization"
1436 default y
1437 help
1438 Randomizing heap placement makes heap exploits harder, but it
1439 also breaks ancient binaries (including anything libc5 based).
1440 This option changes the bootup default to heap randomization
692105b8 1441 disabled, and can be overridden at runtime by setting
b943c460
RD
1442 /proc/sys/kernel/randomize_va_space to 2.
1443
1444 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1445
81819f0f
CL
1446choice
1447 prompt "Choose SLAB allocator"
a0acd820 1448 default SLUB
81819f0f
CL
1449 help
1450 This option allows to select a slab allocator.
1451
1452config SLAB
1453 bool "SLAB"
1454 help
1455 The regular slab allocator that is established and known to work
34013886 1456 well in all environments. It organizes cache hot objects in
02f56210 1457 per cpu and per node queues.
81819f0f
CL
1458
1459config SLUB
81819f0f
CL
1460 bool "SLUB (Unqueued Allocator)"
1461 help
1462 SLUB is a slab allocator that minimizes cache line usage
1463 instead of managing queues of cached objects (SLAB approach).
1464 Per cpu caching is realized using slabs of objects instead
1465 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1466 and has enhanced diagnostics. SLUB is the default choice for
1467 a slab allocator.
81819f0f
CL
1468
1469config SLOB
6a108a14 1470 depends on EXPERT
81819f0f
CL
1471 bool "SLOB (Simple Allocator)"
1472 help
37291458
MM
1473 SLOB replaces the stock allocator with a drastically simpler
1474 allocator. SLOB is generally more space efficient but
1475 does not perform as well on large systems.
81819f0f
CL
1476
1477endchoice
1478
ea637639
JZ
1479config MMAP_ALLOW_UNINITIALIZED
1480 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1481 depends on EXPERT && !MMU
ea637639
JZ
1482 default n
1483 help
1484 Normally, and according to the Linux spec, anonymous memory obtained
1485 from mmap() has it's contents cleared before it is passed to
1486 userspace. Enabling this config option allows you to request that
1487 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1488 providing a huge performance boost. If this option is not enabled,
1489 then the flag will be ignored.
1490
1491 This is taken advantage of by uClibc's malloc(), and also by
1492 ELF-FDPIC binfmt's brk and stack allocator.
1493
1494 Because of the obvious security issues, this option should only be
1495 enabled on embedded devices where you control what is run in
1496 userspace. Since that isn't generally a problem on no-MMU systems,
1497 it is normally safe to say Y here.
1498
1499 See Documentation/nommu-mmap.txt for more information.
1500
125e5645 1501config PROFILING
b309a294 1502 bool "Profiling support"
125e5645
MD
1503 help
1504 Say Y here to enable the extended profiling support mechanisms used
1505 by profilers such as OProfile.
1506
5f87f112
IM
1507#
1508# Place an empty function call at each tracepoint site. Can be
1509# dynamically changed for a probe function.
1510#
97e1c18e 1511config TRACEPOINTS
5f87f112 1512 bool
97e1c18e 1513
fb32e03f
MD
1514source "arch/Kconfig"
1515
1da177e4
LT
1516endmenu # General setup
1517
ee7e5516
DES
1518config HAVE_GENERIC_DMA_COHERENT
1519 bool
1520 default n
1521
158a9624
LT
1522config SLABINFO
1523 bool
1524 depends on PROC_FS
0f389ec6 1525 depends on SLAB || SLUB_DEBUG
158a9624
LT
1526 default y
1527
ae81f9e3
CE
1528config RT_MUTEXES
1529 boolean
ae81f9e3 1530
1da177e4
LT
1531config BASE_SMALL
1532 int
1533 default 0 if BASE_FULL
1534 default 1 if !BASE_FULL
1535
66da5733 1536menuconfig MODULES
1da177e4
LT
1537 bool "Enable loadable module support"
1538 help
1539 Kernel modules are small pieces of compiled code which can
1540 be inserted in the running kernel, rather than being
1541 permanently built into the kernel. You use the "modprobe"
1542 tool to add (and sometimes remove) them. If you say Y here,
1543 many parts of the kernel can be built as modules (by
1544 answering M instead of Y where indicated): this is most
1545 useful for infrequently used options which are not required
1546 for booting. For more information, see the man pages for
1547 modprobe, lsmod, modinfo, insmod and rmmod.
1548
1549 If you say Y here, you will need to run "make
1550 modules_install" to put the modules under /lib/modules/
1551 where modprobe can find them (you may need to be root to do
1552 this).
1553
1554 If unsure, say Y.
1555
0b0de144
RD
1556if MODULES
1557
826e4506
LT
1558config MODULE_FORCE_LOAD
1559 bool "Forced module loading"
826e4506
LT
1560 default n
1561 help
91e37a79
RR
1562 Allow loading of modules without version information (ie. modprobe
1563 --force). Forced module loading sets the 'F' (forced) taint flag and
1564 is usually a really bad idea.
826e4506 1565
1da177e4
LT
1566config MODULE_UNLOAD
1567 bool "Module unloading"
1da177e4
LT
1568 help
1569 Without this option you will not be able to unload any
1570 modules (note that some modules may not be unloadable
f7f5b675
DV
1571 anyway), which makes your kernel smaller, faster
1572 and simpler. If unsure, say Y.
1da177e4
LT
1573
1574config MODULE_FORCE_UNLOAD
1575 bool "Forced module unloading"
1576 depends on MODULE_UNLOAD && EXPERIMENTAL
1577 help
1578 This option allows you to force a module to unload, even if the
1579 kernel believes it is unsafe: the kernel will remove the module
1580 without waiting for anyone to stop using it (using the -f option to
1581 rmmod). This is mainly for kernel developers and desperate users.
1582 If unsure, say N.
1583
1da177e4 1584config MODVERSIONS
0d541643 1585 bool "Module versioning support"
1da177e4
LT
1586 help
1587 Usually, you have to use modules compiled with your kernel.
1588 Saying Y here makes it sometimes possible to use modules
1589 compiled for different kernels, by adding enough information
1590 to the modules to (hopefully) spot any changes which would
1591 make them incompatible with the kernel you are running. If
1592 unsure, say N.
1593
1594config MODULE_SRCVERSION_ALL
1595 bool "Source checksum for all modules"
1da177e4
LT
1596 help
1597 Modules which contain a MODULE_VERSION get an extra "srcversion"
1598 field inserted into their modinfo section, which contains a
1599 sum of the source files which made it. This helps maintainers
1600 see exactly which source was used to build a module (since
1601 others sometimes change the module source without updating
1602 the version). With this option, such a "srcversion" field
1603 will be created for all modules. If unsure, say N.
1604
0b0de144
RD
1605endif # MODULES
1606
98a79d6a
RR
1607config INIT_ALL_POSSIBLE
1608 bool
1609 help
5f054e31
RR
1610 Back when each arch used to define their own cpu_online_mask and
1611 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1612 with all 1s, and others with all 0s. When they were centralised,
1613 it was better to provide this option than to break all the archs
692105b8 1614 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1615
1da177e4
LT
1616config STOP_MACHINE
1617 bool
1618 default y
1619 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1620 help
1621 Need stop_machine() primitive.
3a65dfe8 1622
3a65dfe8 1623source "block/Kconfig"
e98c3202
AK
1624
1625config PREEMPT_NOTIFIERS
1626 bool
e260be67 1627
16295bec
SK
1628config PADATA
1629 depends on SMP
1630 bool
1631
6beb0009 1632source "kernel/Kconfig.locks"