wireless: remove conflicting version of print_hex_dump_bytes
[deliverable/linux.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
5a958db3
KC
36 bool
37 default y
1da177e4 38
1da177e4
LT
39config BROKEN
40 bool
1da177e4
LT
41
42config BROKEN_ON_SMP
43 bool
44 depends on BROKEN || !SMP
45 default y
46
1da177e4
LT
47config INIT_ENV_ARG_LIMIT
48 int
dd673bca
AB
49 default 32 if !UML
50 default 128 if UML
1da177e4 51 help
34ad92c2
RD
52 Maximum of each of the number of arguments and environment
53 variables passed to init from the kernel command line.
1da177e4 54
1da177e4 55
84336466
RM
56config CROSS_COMPILE
57 string "Cross-compiler tool prefix"
58 help
59 Same as running 'make CROSS_COMPILE=prefix-' but stored for
60 default make runs in this kernel build directory. You don't
61 need to set this unless you want the configured kernel build
62 directory to select the cross-compiler automatically.
63
1da177e4
LT
64config LOCALVERSION
65 string "Local version - append to kernel release"
66 help
67 Append an extra string to the end of your kernel version.
68 This will show up when you type uname, for example.
69 The string you set here will be appended after the contents of
70 any files with a filename matching localversion* in your
71 object and source tree, in that order. Your total string can
72 be a maximum of 64 characters.
73
aaebf433
RA
74config LOCALVERSION_AUTO
75 bool "Automatically append version information to the version string"
76 default y
77 help
78 This will try to automatically determine if the current tree is a
6e5a5420
RD
79 release tree by looking for git tags that belong to the current
80 top of tree revision.
aaebf433
RA
81
82 A string of the format -gxxxxxxxx will be added to the localversion
6e5a5420 83 if a git-based tree is found. The string generated by this will be
aaebf433 84 appended after any matching localversion* files, and after the value
6e5a5420 85 set in CONFIG_LOCALVERSION.
aaebf433 86
6e5a5420
RD
87 (The actual string used here is the first eight characters produced
88 by running the command:
89
90 $ git rev-parse --verify HEAD
91
92 which is done within the script "scripts/setlocalversion".)
aaebf433 93
2e9f3bdd
PA
94config HAVE_KERNEL_GZIP
95 bool
96
97config HAVE_KERNEL_BZIP2
98 bool
99
100config HAVE_KERNEL_LZMA
101 bool
102
3ebe1243
LC
103config HAVE_KERNEL_XZ
104 bool
105
7dd65feb
AT
106config HAVE_KERNEL_LZO
107 bool
108
30d65dbf 109choice
2e9f3bdd
PA
110 prompt "Kernel compression mode"
111 default KERNEL_GZIP
3ebe1243 112 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
2e9f3bdd 113 help
30d65dbf
AK
114 The linux kernel is a kind of self-extracting executable.
115 Several compression algorithms are available, which differ
116 in efficiency, compression and decompression speed.
117 Compression speed is only relevant when building a kernel.
118 Decompression speed is relevant at each boot.
119
120 If you have any problems with bzip2 or lzma compressed
121 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
122 version of this functionality (bzip2 only), for 2.4, was
123 supplied by Christian Ludwig)
124
125 High compression options are mostly useful for users, who
126 are low on disk space (embedded systems), but for whom ram
127 size matters less.
128
129 If in doubt, select 'gzip'
130
131config KERNEL_GZIP
2e9f3bdd
PA
132 bool "Gzip"
133 depends on HAVE_KERNEL_GZIP
134 help
7dd65feb
AT
135 The old and tried gzip compression. It provides a good balance
136 between compression ratio and decompression speed.
30d65dbf
AK
137
138config KERNEL_BZIP2
139 bool "Bzip2"
2e9f3bdd 140 depends on HAVE_KERNEL_BZIP2
30d65dbf
AK
141 help
142 Its compression ratio and speed is intermediate.
0a4dd35c 143 Decompression speed is slowest among the choices. The kernel
2e9f3bdd
PA
144 size is about 10% smaller with bzip2, in comparison to gzip.
145 Bzip2 uses a large amount of memory. For modern kernels you
146 will need at least 8MB RAM or more for booting.
30d65dbf
AK
147
148config KERNEL_LZMA
2e9f3bdd
PA
149 bool "LZMA"
150 depends on HAVE_KERNEL_LZMA
151 help
0a4dd35c
RD
152 This compression algorithm's ratio is best. Decompression speed
153 is between gzip and bzip2. Compression is slowest.
154 The kernel size is about 33% smaller with LZMA in comparison to gzip.
30d65dbf 155
3ebe1243
LC
156config KERNEL_XZ
157 bool "XZ"
158 depends on HAVE_KERNEL_XZ
159 help
160 XZ uses the LZMA2 algorithm and instruction set specific
161 BCJ filters which can improve compression ratio of executable
162 code. The size of the kernel is about 30% smaller with XZ in
163 comparison to gzip. On architectures for which there is a BCJ
164 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
165 will create a few percent smaller kernel than plain LZMA.
166
167 The speed is about the same as with LZMA: The decompression
168 speed of XZ is better than that of bzip2 but worse than gzip
169 and LZO. Compression is slow.
170
7dd65feb
AT
171config KERNEL_LZO
172 bool "LZO"
173 depends on HAVE_KERNEL_LZO
174 help
0a4dd35c 175 Its compression ratio is the poorest among the choices. The kernel
681b3049 176 size is about 10% bigger than gzip; however its speed
7dd65feb
AT
177 (both compression and decompression) is the fastest.
178
30d65dbf
AK
179endchoice
180
bd5dc17b
JT
181config DEFAULT_HOSTNAME
182 string "Default hostname"
183 default "(none)"
184 help
185 This option determines the default system hostname before userspace
186 calls sethostname(2). The kernel traditionally uses "(none)" here,
187 but you may wish to use a different default here to make a minimal
188 system more usable with less configuration.
189
1da177e4
LT
190config SWAP
191 bool "Support for paging of anonymous memory (swap)"
9361401e 192 depends on MMU && BLOCK
1da177e4
LT
193 default y
194 help
195 This option allows you to choose whether you want to have support
92c3504e 196 for so called swap devices or swap files in your kernel that are
1da177e4
LT
197 used to provide more virtual memory than the actual RAM present
198 in your computer. If unsure say Y.
199
200config SYSVIPC
201 bool "System V IPC"
1da177e4
LT
202 ---help---
203 Inter Process Communication is a suite of library functions and
204 system calls which let processes (running programs) synchronize and
205 exchange information. It is generally considered to be a good thing,
206 and some programs won't run unless you say Y here. In particular, if
207 you want to run the DOS emulator dosemu under Linux (read the
208 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
209 you'll need to say Y here.
210
211 You can find documentation about IPC with "info ipc" and also in
212 section 6.4 of the Linux Programmer's Guide, available from
213 <http://www.tldp.org/guides.html>.
214
a5494dcd
EB
215config SYSVIPC_SYSCTL
216 bool
217 depends on SYSVIPC
218 depends on SYSCTL
219 default y
220
1da177e4
LT
221config POSIX_MQUEUE
222 bool "POSIX Message Queues"
19c92399 223 depends on NET
1da177e4
LT
224 ---help---
225 POSIX variant of message queues is a part of IPC. In POSIX message
226 queues every message has a priority which decides about succession
227 of receiving it by a process. If you want to compile and run
228 programs written e.g. for Solaris with use of its POSIX message
b0e37650 229 queues (functions mq_*) say Y here.
1da177e4
LT
230
231 POSIX message queues are visible as a filesystem called 'mqueue'
232 and can be mounted somewhere if you want to do filesystem
233 operations on message queues.
234
235 If unsure, say Y.
236
bdc8e5f8
SH
237config POSIX_MQUEUE_SYSCTL
238 bool
239 depends on POSIX_MQUEUE
240 depends on SYSCTL
241 default y
242
391dc69c
FW
243config FHANDLE
244 bool "open by fhandle syscalls"
245 select EXPORTFS
246 help
247 If you say Y here, a user level program will be able to map
248 file names to handle and then later use the handle for
249 different file system operations. This is useful in implementing
250 userspace file servers, which now track files using handles instead
251 of names. The handle would remain the same even if file names
252 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
253 syscalls.
254
255config AUDIT
256 bool "Auditing support"
257 depends on NET
258 help
259 Enable auditing infrastructure that can be used with another
260 kernel subsystem, such as SELinux (which requires this for
261 logging of avc messages output). Does not do system-call
262 auditing without CONFIG_AUDITSYSCALL.
263
264config AUDITSYSCALL
265 bool "Enable system-call auditing support"
266 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
267 default y if SECURITY_SELINUX
268 help
269 Enable low-overhead system-call auditing infrastructure that
270 can be used independently or with another kernel subsystem,
271 such as SELinux.
272
273config AUDIT_WATCH
274 def_bool y
275 depends on AUDITSYSCALL
276 select FSNOTIFY
277
278config AUDIT_TREE
279 def_bool y
280 depends on AUDITSYSCALL
281 select FSNOTIFY
282
283config AUDIT_LOGINUID_IMMUTABLE
284 bool "Make audit loginuid immutable"
285 depends on AUDIT
286 help
287 The config option toggles if a task setting its loginuid requires
288 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
289 but should instead only allow setting its loginuid if it was never
290 previously set. On systems which use systemd or a similar central
291 process to restart login services this should be set to true. On older
292 systems in which an admin would typically have to directly stop and
293 start processes this should be set to false. Setting this to true allows
294 one to drop potentially dangerous capabilites from the login tasks,
295 but may not be backwards compatible with older init systems.
296
297source "kernel/irq/Kconfig"
298source "kernel/time/Kconfig"
299
300menu "CPU/Task time and stats accounting"
301
fdf9c356
FW
302choice
303 prompt "Cputime accounting"
304 default TICK_CPU_ACCOUNTING if !PPC64
305 default VIRT_CPU_ACCOUNTING if PPC64
306
307# Kind of a stub config for the pure tick based cputime accounting
308config TICK_CPU_ACCOUNTING
309 bool "Simple tick based cputime accounting"
310 depends on !S390
311 help
312 This is the basic tick based cputime accounting that maintains
313 statistics about user, system and idle time spent on per jiffies
314 granularity.
315
316 If unsure, say Y.
317
b952741c
FW
318config VIRT_CPU_ACCOUNTING
319 bool "Deterministic task and CPU time accounting"
320 depends on HAVE_VIRT_CPU_ACCOUNTING
b952741c
FW
321 help
322 Select this option to enable more accurate task and CPU time
323 accounting. This is done by reading a CPU counter on each
324 kernel entry and exit and on transitions within the kernel
325 between system, softirq and hardirq state, so there is a
326 small performance impact. In the case of s390 or IBM POWER > 5,
327 this also enables accounting of stolen time on logically-partitioned
328 systems.
329
fdf9c356
FW
330config IRQ_TIME_ACCOUNTING
331 bool "Fine granularity task level IRQ time accounting"
332 depends on HAVE_IRQ_TIME_ACCOUNTING
333 help
334 Select this option to enable fine granularity task irq time
335 accounting. This is done by reading a timestamp on each
336 transitions between softirq and hardirq state, so there can be a
337 small performance impact.
338
339 If in doubt, say N here.
340
341endchoice
342
1da177e4
LT
343config BSD_PROCESS_ACCT
344 bool "BSD Process Accounting"
345 help
346 If you say Y here, a user level program will be able to instruct the
347 kernel (via a special system call) to write process accounting
348 information to a file: whenever a process exits, information about
349 that process will be appended to the file by the kernel. The
350 information includes things such as creation time, owning user,
351 command name, memory usage, controlling terminal etc. (the complete
352 list is in the struct acct in <file:include/linux/acct.h>). It is
353 up to the user level program to do useful things with this
354 information. This is generally a good idea, so say Y.
355
356config BSD_PROCESS_ACCT_V3
357 bool "BSD Process Accounting version 3 file format"
358 depends on BSD_PROCESS_ACCT
359 default n
360 help
361 If you say Y here, the process accounting information is written
362 in a new file format that also logs the process IDs of each
363 process and it's parent. Note that this file format is incompatible
364 with previous v0/v1/v2 file formats, so you will need updated tools
365 for processing it. A preliminary version of these tools is available
37a4c940 366 at <http://www.gnu.org/software/acct/>.
1da177e4 367
c757249a 368config TASKSTATS
19c92399 369 bool "Export task/process statistics through netlink"
c757249a
SN
370 depends on NET
371 default n
372 help
373 Export selected statistics for tasks/processes through the
374 generic netlink interface. Unlike BSD process accounting, the
375 statistics are available during the lifetime of tasks/processes as
376 responses to commands. Like BSD accounting, they are sent to user
377 space on task exit.
378
379 Say N if unsure.
380
ca74e92b 381config TASK_DELAY_ACCT
19c92399 382 bool "Enable per-task delay accounting"
6f44993f 383 depends on TASKSTATS
ca74e92b
SN
384 help
385 Collect information on time spent by a task waiting for system
386 resources like cpu, synchronous block I/O completion and swapping
387 in pages. Such statistics can help in setting a task's priorities
388 relative to other tasks for cpu, io, rss limits etc.
389
390 Say N if unsure.
391
18f705f4 392config TASK_XACCT
19c92399 393 bool "Enable extended accounting over taskstats"
18f705f4
AD
394 depends on TASKSTATS
395 help
396 Collect extended task accounting data and send the data
397 to userland for processing over the taskstats interface.
398
399 Say N if unsure.
400
401config TASK_IO_ACCOUNTING
19c92399 402 bool "Enable per-task storage I/O accounting"
18f705f4
AD
403 depends on TASK_XACCT
404 help
405 Collect information on the number of bytes of storage I/O which this
406 task has caused.
407
408 Say N if unsure.
409
391dc69c 410endmenu # "CPU/Task time and stats accounting"
d9817ebe 411
c903ff83
MT
412menu "RCU Subsystem"
413
414choice
415 prompt "RCU Implementation"
31c9a24e 416 default TREE_RCU
c903ff83 417
c903ff83
MT
418config TREE_RCU
419 bool "Tree-based hierarchical RCU"
687d7a96 420 depends on !PREEMPT && SMP
c903ff83
MT
421 help
422 This option selects the RCU implementation that is
423 designed for very large SMP system with hundreds or
c17ef453
PM
424 thousands of CPUs. It also scales down nicely to
425 smaller systems.
c903ff83 426
f41d911f 427config TREE_PREEMPT_RCU
a57eb940 428 bool "Preemptible tree-based hierarchical RCU"
8008e129 429 depends on PREEMPT && SMP
f41d911f
PM
430 help
431 This option selects the RCU implementation that is
432 designed for very large SMP systems with hundreds or
433 thousands of CPUs, but for which real-time response
bbe3eae8
PM
434 is also required. It also scales down nicely to
435 smaller systems.
f41d911f 436
9b1d82fa
PM
437config TINY_RCU
438 bool "UP-only small-memory-footprint RCU"
8008e129 439 depends on !PREEMPT && !SMP
9b1d82fa
PM
440 help
441 This option selects the RCU implementation that is
442 designed for UP systems from which real-time response
443 is not required. This option greatly reduces the
444 memory footprint of RCU.
445
a57eb940
PM
446config TINY_PREEMPT_RCU
447 bool "Preemptible UP-only small-memory-footprint RCU"
8008e129 448 depends on PREEMPT && !SMP
a57eb940
PM
449 help
450 This option selects the RCU implementation that is designed
451 for real-time UP systems. This option greatly reduces the
452 memory footprint of RCU.
453
c903ff83
MT
454endchoice
455
a57eb940
PM
456config PREEMPT_RCU
457 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
458 help
459 This option enables preemptible-RCU code that is common between
460 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
461
91d1aa43
FW
462config CONTEXT_TRACKING
463 bool
464
2b1d5024
FW
465config RCU_USER_QS
466 bool "Consider userspace as in RCU extended quiescent state"
91d1aa43
FW
467 depends on HAVE_CONTEXT_TRACKING && SMP
468 select CONTEXT_TRACKING
2b1d5024
FW
469 help
470 This option sets hooks on kernel / userspace boundaries and
471 puts RCU in extended quiescent state when the CPU runs in
472 userspace. It means that when a CPU runs in userspace, it is
473 excluded from the global RCU state machine and thus doesn't
af71befa 474 try to keep the timer tick on for RCU.
2b1d5024 475
d677124b 476 Unless you want to hack and help the development of the full
91d1aa43 477 dynticks mode, you shouldn't enable this option. It also
af71befa 478 adds unnecessary overhead.
d677124b
FW
479
480 If unsure say N
481
91d1aa43
FW
482config CONTEXT_TRACKING_FORCE
483 bool "Force context tracking"
484 depends on CONTEXT_TRACKING
1fd2b442 485 help
91d1aa43
FW
486 Probe on user/kernel boundaries by default in order to
487 test the features that rely on it such as userspace RCU extended
488 quiescent states.
489 This test is there for debugging until we have a real user like the
490 full dynticks mode.
d677124b 491
c903ff83
MT
492config RCU_FANOUT
493 int "Tree-based hierarchical RCU fanout value"
494 range 2 64 if 64BIT
495 range 2 32 if !64BIT
f41d911f 496 depends on TREE_RCU || TREE_PREEMPT_RCU
c903ff83
MT
497 default 64 if 64BIT
498 default 32 if !64BIT
499 help
500 This option controls the fanout of hierarchical implementations
501 of RCU, allowing RCU to work efficiently on machines with
4d87ffad
PM
502 large numbers of CPUs. This value must be at least the fourth
503 root of NR_CPUS, which allows NR_CPUS to be insanely large.
504 The default value of RCU_FANOUT should be used for production
505 systems, but if you are stress-testing the RCU implementation
506 itself, small RCU_FANOUT values allow you to test large-system
507 code paths on small(er) systems.
c903ff83
MT
508
509 Select a specific number if testing RCU itself.
510 Take the default if unsure.
511
8932a63d
PM
512config RCU_FANOUT_LEAF
513 int "Tree-based hierarchical RCU leaf-level fanout value"
514 range 2 RCU_FANOUT if 64BIT
515 range 2 RCU_FANOUT if !64BIT
516 depends on TREE_RCU || TREE_PREEMPT_RCU
517 default 16
518 help
519 This option controls the leaf-level fanout of hierarchical
520 implementations of RCU, and allows trading off cache misses
521 against lock contention. Systems that synchronize their
522 scheduling-clock interrupts for energy-efficiency reasons will
523 want the default because the smaller leaf-level fanout keeps
524 lock contention levels acceptably low. Very large systems
525 (hundreds or thousands of CPUs) will instead want to set this
526 value to the maximum value possible in order to reduce the
527 number of cache misses incurred during RCU's grace-period
528 initialization. These systems tend to run CPU-bound, and thus
529 are not helped by synchronized interrupts, and thus tend to
530 skew them, which reduces lock contention enough that large
531 leaf-level fanouts work well.
532
533 Select a specific number if testing RCU itself.
534
535 Select the maximum permissible value for large systems.
536
537 Take the default if unsure.
538
c903ff83
MT
539config RCU_FANOUT_EXACT
540 bool "Disable tree-based hierarchical RCU auto-balancing"
f41d911f 541 depends on TREE_RCU || TREE_PREEMPT_RCU
c903ff83
MT
542 default n
543 help
544 This option forces use of the exact RCU_FANOUT value specified,
545 regardless of imbalances in the hierarchy. This is useful for
546 testing RCU itself, and might one day be useful on systems with
547 strong NUMA behavior.
548
549 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
550
551 Say N if unsure.
552
8bd93a2c
PM
553config RCU_FAST_NO_HZ
554 bool "Accelerate last non-dyntick-idle CPU's grace periods"
b807fbff 555 depends on NO_HZ && SMP
8bd93a2c
PM
556 default n
557 help
ba49df47
PM
558 This option causes RCU to attempt to accelerate grace periods in
559 order to allow CPUs to enter dynticks-idle state more quickly.
560 On the other hand, this option increases the overhead of the
561 dynticks-idle checking, thus degrading scheduling latency.
562
563 Say Y if energy efficiency is critically important, and you don't
564 care about real-time response.
8bd93a2c
PM
565
566 Say N if you are unsure.
567
c903ff83 568config TREE_RCU_TRACE
f41d911f 569 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
c903ff83
MT
570 select DEBUG_FS
571 help
f41d911f
PM
572 This option provides tracing for the TREE_RCU and
573 TREE_PREEMPT_RCU implementations, permitting Makefile to
574 trivially select kernel/rcutree_trace.c.
c903ff83 575
24278d14
PM
576config RCU_BOOST
577 bool "Enable RCU priority boosting"
27f4d280 578 depends on RT_MUTEXES && PREEMPT_RCU
24278d14
PM
579 default n
580 help
581 This option boosts the priority of preempted RCU readers that
582 block the current preemptible RCU grace period for too long.
583 This option also prevents heavy loads from blocking RCU
584 callback invocation for all flavors of RCU.
585
586 Say Y here if you are working with real-time apps or heavy loads
587 Say N here if you are unsure.
588
589config RCU_BOOST_PRIO
590 int "Real-time priority to boost RCU readers to"
591 range 1 99
592 depends on RCU_BOOST
593 default 1
594 help
c9336643
PM
595 This option specifies the real-time priority to which long-term
596 preempted RCU readers are to be boosted. If you are working
597 with a real-time application that has one or more CPU-bound
598 threads running at a real-time priority level, you should set
599 RCU_BOOST_PRIO to a priority higher then the highest-priority
600 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
601 of 1 is appropriate in the common case, which is real-time
602 applications that do not have any CPU-bound threads.
603
604 Some real-time applications might not have a single real-time
605 thread that saturates a given CPU, but instead might have
606 multiple real-time threads that, taken together, fully utilize
607 that CPU. In this case, you should set RCU_BOOST_PRIO to
608 a priority higher than the lowest-priority thread that is
609 conspiring to prevent the CPU from running any non-real-time
610 tasks. For example, if one thread at priority 10 and another
611 thread at priority 5 are between themselves fully consuming
612 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
613 set to priority 6 or higher.
24278d14
PM
614
615 Specify the real-time priority, or take the default if unsure.
616
617config RCU_BOOST_DELAY
618 int "Milliseconds to delay boosting after RCU grace-period start"
619 range 0 3000
620 depends on RCU_BOOST
621 default 500
622 help
623 This option specifies the time to wait after the beginning of
624 a given grace period before priority-boosting preempted RCU
625 readers blocking that grace period. Note that any RCU reader
626 blocking an expedited RCU grace period is boosted immediately.
627
628 Accept the default if unsure.
629
3fbfbf7a
PM
630config RCU_NOCB_CPU
631 bool "Offload RCU callback processing from boot-selected CPUs"
632 depends on TREE_RCU || TREE_PREEMPT_RCU
633 default n
634 help
635 Use this option to reduce OS jitter for aggressive HPC or
636 real-time workloads. It can also be used to offload RCU
637 callback invocation to energy-efficient CPUs in battery-powered
638 asymmetric multiprocessors.
639
640 This option offloads callback invocation from the set of
641 CPUs specified at boot time by the rcu_nocbs parameter.
642 For each such CPU, a kthread ("rcuoN") will be created to
643 invoke callbacks, where the "N" is the CPU being offloaded.
644 Nothing prevents this kthread from running on the specified
645 CPUs, but (1) the kthreads may be preempted between each
646 callback, and (2) affinity or cgroups can be used to force
647 the kthreads to run on whatever set of CPUs is desired.
648
649 Say Y here if you want reduced OS jitter on selected CPUs.
650 Say N here if you are unsure.
651
c903ff83
MT
652endmenu # "RCU Subsystem"
653
1da177e4 654config IKCONFIG
f2443ab6 655 tristate "Kernel .config support"
1da177e4
LT
656 ---help---
657 This option enables the complete Linux kernel ".config" file
658 contents to be saved in the kernel. It provides documentation
659 of which kernel options are used in a running kernel or in an
660 on-disk kernel. This information can be extracted from the kernel
661 image file with the script scripts/extract-ikconfig and used as
662 input to rebuild the current kernel or to build another kernel.
663 It can also be extracted from a running kernel by reading
664 /proc/config.gz if enabled (below).
665
666config IKCONFIG_PROC
667 bool "Enable access to .config through /proc/config.gz"
668 depends on IKCONFIG && PROC_FS
669 ---help---
670 This option enables access to the kernel configuration file
671 through /proc/config.gz.
672
794543a2
AJS
673config LOG_BUF_SHIFT
674 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
675 range 12 21
f17a32e9 676 default 17
794543a2
AJS
677 help
678 Select kernel log buffer size as a power of 2.
f17a32e9
AB
679 Examples:
680 17 => 128 KB
681 16 => 64 KB
682 15 => 32 KB
683 14 => 16 KB
794543a2
AJS
684 13 => 8 KB
685 12 => 4 KB
686
a5574cf6
IM
687#
688# Architectures with an unreliable sched_clock() should select this:
689#
690config HAVE_UNSTABLE_SCHED_CLOCK
691 bool
692
be3a7284
AA
693#
694# For architectures that want to enable the support for NUMA-affine scheduler
695# balancing logic:
696#
697config ARCH_SUPPORTS_NUMA_BALANCING
698 bool
699
700# For architectures that (ab)use NUMA to represent different memory regions
701# all cpu-local but of different latencies, such as SuperH.
702#
703config ARCH_WANT_NUMA_VARIABLE_LOCALITY
704 bool
705
706#
707# For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
708config ARCH_WANTS_PROT_NUMA_PROT_NONE
709 bool
710
711config ARCH_USES_NUMA_PROT_NONE
712 bool
713 default y
714 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
715 depends on NUMA_BALANCING
716
1a687c2e
MG
717config NUMA_BALANCING_DEFAULT_ENABLED
718 bool "Automatically enable NUMA aware memory/task placement"
719 default y
720 depends on NUMA_BALANCING
721 help
722 If set, autonumic NUMA balancing will be enabled if running on a NUMA
723 machine.
724
be3a7284
AA
725config NUMA_BALANCING
726 bool "Memory placement aware NUMA scheduler"
be3a7284
AA
727 depends on ARCH_SUPPORTS_NUMA_BALANCING
728 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
729 depends on SMP && NUMA && MIGRATION
730 help
731 This option adds support for automatic NUMA aware memory/task placement.
732 The mechanism is quite primitive and is based on migrating memory when
733 it is references to the node the task is running on.
734
735 This system will be inactive on UMA systems.
736
23964d2d
LZ
737menuconfig CGROUPS
738 boolean "Control Group support"
0dea1168 739 depends on EVENTFD
5cdc38f9 740 help
23964d2d 741 This option adds support for grouping sets of processes together, for
5cdc38f9
KH
742 use with process control subsystems such as Cpusets, CFS, memory
743 controls or device isolation.
744 See
5cdc38f9 745 - Documentation/scheduler/sched-design-CFS.txt (CFS)
45ce80fb
LZ
746 - Documentation/cgroups/ (features for grouping, isolation
747 and resource control)
5cdc38f9
KH
748
749 Say N if unsure.
750
23964d2d
LZ
751if CGROUPS
752
5cdc38f9
KH
753config CGROUP_DEBUG
754 bool "Example debug cgroup subsystem"
5cdc38f9
KH
755 default n
756 help
757 This option enables a simple cgroup subsystem that
758 exports useful debugging information about the cgroups
23964d2d 759 framework.
5cdc38f9 760
23964d2d 761 Say N if unsure.
5cdc38f9 762
5cdc38f9 763config CGROUP_FREEZER
23964d2d 764 bool "Freezer cgroup subsystem"
23964d2d
LZ
765 help
766 Provides a way to freeze and unfreeze all tasks in a
5cdc38f9
KH
767 cgroup.
768
769config CGROUP_DEVICE
770 bool "Device controller for cgroups"
5cdc38f9
KH
771 help
772 Provides a cgroup implementing whitelists for devices which
773 a process in the cgroup can mknod or open.
774
775config CPUSETS
776 bool "Cpuset support"
5cdc38f9
KH
777 help
778 This option will let you create and manage CPUSETs which
779 allow dynamically partitioning a system into sets of CPUs and
780 Memory Nodes and assigning tasks to run only within those sets.
781 This is primarily useful on large SMP or NUMA systems.
782
783 Say N if unsure.
784
23964d2d
LZ
785config PROC_PID_CPUSET
786 bool "Include legacy /proc/<pid>/cpuset file"
787 depends on CPUSETS
788 default y
789
d842de87
SV
790config CGROUP_CPUACCT
791 bool "Simple CPU accounting cgroup subsystem"
d842de87
SV
792 help
793 Provides a simple Resource Controller for monitoring the
23964d2d 794 total CPU consumed by the tasks in a cgroup.
d842de87 795
e552b661
PE
796config RESOURCE_COUNTERS
797 bool "Resource counters"
798 help
799 This option enables controller independent resource accounting
23964d2d 800 infrastructure that works with cgroups.
e552b661 801
c255a458 802config MEMCG
00f0b825 803 bool "Memory Resource Controller for Control Groups"
79ae9c29 804 depends on RESOURCE_COUNTERS
cf475ad2 805 select MM_OWNER
00f0b825 806 help
84ad6d70 807 Provides a memory resource controller that manages both anonymous
21acb9ca 808 memory and page cache. (See Documentation/cgroups/memory.txt)
00f0b825
BS
809
810 Note that setting this option increases fixed memory overhead
84ad6d70
KH
811 associated with each page of memory in the system. By this,
812 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
813 usage tracking struct at boot. Total amount of this is printed out
814 at boot.
00f0b825
BS
815
816 Only enable when you're ok with these trade offs and really
84ad6d70
KH
817 sure you need the memory resource controller. Even when you enable
818 this, you can set "cgroup_disable=memory" at your boot option to
819 disable memory resource controller and you can avoid overheads.
c9d5409f 820 (and lose benefits of memory resource controller)
00f0b825 821
cf475ad2
BS
822 This config option also selects MM_OWNER config option, which
823 could in turn add some fork/exit overhead.
824
c255a458 825config MEMCG_SWAP
65e0e811 826 bool "Memory Resource Controller Swap Extension"
c255a458 827 depends on MEMCG && SWAP
c077719b
KH
828 help
829 Add swap management feature to memory resource controller. When you
830 enable this, you can limit mem+swap usage per cgroup. In other words,
831 when you disable this, memory resource controller has no cares to
832 usage of swap...a process can exhaust all of the swap. This extension
833 is useful when you want to avoid exhaustion swap but this itself
834 adds more overheads and consumes memory for remembering information.
835 Especially if you use 32bit system or small memory system, please
836 be careful about enabling this. When memory resource controller
837 is disabled by boot option, this will be automatically disabled and
838 there will be no overhead from this. Even when you set this config=y,
00a66d29 839 if boot option "swapaccount=0" is set, swap will not be accounted.
627991a2
KH
840 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
841 size is 4096bytes, 512k per 1Gbytes of swap.
c255a458 842config MEMCG_SWAP_ENABLED
a42c390c 843 bool "Memory Resource Controller Swap Extension enabled by default"
c255a458 844 depends on MEMCG_SWAP
a42c390c
MH
845 default y
846 help
847 Memory Resource Controller Swap Extension comes with its price in
848 a bigger memory consumption. General purpose distribution kernels
43d547f9 849 which want to enable the feature but keep it disabled by default
a42c390c
MH
850 and let the user enable it by swapaccount boot command line
851 parameter should have this option unselected.
852 For those who want to have the feature enabled by default should
853 select this option (if, for some reason, they need to disable it
00a66d29 854 then swapaccount=0 does the trick).
c255a458 855config MEMCG_KMEM
19c92399
KC
856 bool "Memory Resource Controller Kernel Memory accounting"
857 depends on MEMCG
510fc4e1 858 depends on SLUB || SLAB
e5671dfa
GC
859 help
860 The Kernel Memory extension for Memory Resource Controller can limit
861 the amount of memory used by kernel objects in the system. Those are
862 fundamentally different from the entities handled by the standard
863 Memory Controller, which are page-based, and can be swapped. Users of
864 the kmem extension can use it to guarantee that no group of processes
865 will ever exhaust kernel resources alone.
c077719b 866
2bc64a20
AK
867config CGROUP_HUGETLB
868 bool "HugeTLB Resource Controller for Control Groups"
19c92399 869 depends on RESOURCE_COUNTERS && HUGETLB_PAGE
2bc64a20
AK
870 default n
871 help
872 Provides a cgroup Resource Controller for HugeTLB pages.
873 When you enable this, you can put a per cgroup limit on HugeTLB usage.
874 The limit is enforced during page fault. Since HugeTLB doesn't
875 support page reclaim, enforcing the limit at page fault time implies
876 that, the application will get SIGBUS signal if it tries to access
877 HugeTLB pages beyond its limit. This requires the application to know
878 beforehand how much HugeTLB pages it would require for its use. The
879 control group is tracked in the third page lru pointer. This means
880 that we cannot use the controller with huge page less than 3 pages.
881
e5d1367f
SE
882config CGROUP_PERF
883 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
884 depends on PERF_EVENTS && CGROUPS
885 help
886 This option extends the per-cpu mode to restrict monitoring to
2d0f2520 887 threads which belong to the cgroup specified and run on the
e5d1367f
SE
888 designated cpu.
889
890 Say N if unsure.
891
7c941438
DG
892menuconfig CGROUP_SCHED
893 bool "Group CPU scheduler"
7c941438
DG
894 default n
895 help
896 This feature lets CPU scheduler recognize task groups and control CPU
897 bandwidth allocation to such task groups. It uses cgroups to group
898 tasks.
899
900if CGROUP_SCHED
901config FAIR_GROUP_SCHED
902 bool "Group scheduling for SCHED_OTHER"
903 depends on CGROUP_SCHED
904 default CGROUP_SCHED
905
ab84d31e
PT
906config CFS_BANDWIDTH
907 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
ab84d31e
PT
908 depends on FAIR_GROUP_SCHED
909 default n
910 help
911 This option allows users to define CPU bandwidth rates (limits) for
912 tasks running within the fair group scheduler. Groups with no limit
913 set are considered to be unconstrained and will run with no
914 restriction.
915 See tip/Documentation/scheduler/sched-bwc.txt for more information.
916
7c941438
DG
917config RT_GROUP_SCHED
918 bool "Group scheduling for SCHED_RR/FIFO"
7c941438
DG
919 depends on CGROUP_SCHED
920 default n
921 help
922 This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5 923 to task groups. If enabled, it will also make it impossible to
7c941438
DG
924 schedule realtime tasks for non-root users until you allocate
925 realtime bandwidth for them.
926 See Documentation/scheduler/sched-rt-group.txt for more information.
927
928endif #CGROUP_SCHED
929
afc24d49 930config BLK_CGROUP
32e380ae 931 bool "Block IO controller"
79ae9c29 932 depends on BLOCK
afc24d49
VG
933 default n
934 ---help---
935 Generic block IO controller cgroup interface. This is the common
936 cgroup interface which should be used by various IO controlling
937 policies.
938
939 Currently, CFQ IO scheduler uses it to recognize task groups and
940 control disk bandwidth allocation (proportional time slice allocation)
e43473b7
VG
941 to such task groups. It is also used by bio throttling logic in
942 block layer to implement upper limit in IO rates on a device.
afc24d49
VG
943
944 This option only enables generic Block IO controller infrastructure.
e43473b7 945 One needs to also enable actual IO controlling logic/policy. For
79e2e759
MW
946 enabling proportional weight division of disk bandwidth in CFQ, set
947 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
c5e0591a 948 CONFIG_BLK_DEV_THROTTLING=y.
afc24d49
VG
949
950 See Documentation/cgroups/blkio-controller.txt for more information.
951
952config DEBUG_BLK_CGROUP
953 bool "Enable Block IO controller debugging"
954 depends on BLK_CGROUP
955 default n
956 ---help---
957 Enable some debugging help. Currently it exports additional stat
958 files in a cgroup which can be useful for debugging.
959
23964d2d 960endif # CGROUPS
c077719b 961
067bce1a
CG
962config CHECKPOINT_RESTORE
963 bool "Checkpoint/restore support" if EXPERT
964 default n
965 help
966 Enables additional kernel features in a sake of checkpoint/restore.
967 In particular it adds auxiliary prctl codes to setup process text,
968 data and heap segment sizes, and a few additional /proc filesystem
969 entries.
970
971 If unsure, say N here.
972
8dd2a82c 973menuconfig NAMESPACES
6a108a14
DR
974 bool "Namespaces support" if EXPERT
975 default !EXPERT
c5289a69
PE
976 help
977 Provides the way to make tasks work with different objects using
978 the same id. For example same IPC id may refer to different objects
979 or same user id or pid may refer to different tasks when used in
980 different namespaces.
981
8dd2a82c
DL
982if NAMESPACES
983
58bfdd6d
PE
984config UTS_NS
985 bool "UTS namespace"
17a6d441 986 default y
58bfdd6d
PE
987 help
988 In this namespace tasks see different info provided with the
989 uname() system call
990
ae5e1b22
PE
991config IPC_NS
992 bool "IPC namespace"
8dd2a82c 993 depends on (SYSVIPC || POSIX_MQUEUE)
17a6d441 994 default y
ae5e1b22
PE
995 help
996 In this namespace tasks work with IPC ids which correspond to
614b84cf 997 different IPC objects in different namespaces.
ae5e1b22 998
aee16ce7 999config USER_NS
19c92399 1000 bool "User namespace"
e1c972b6 1001 depends on UIDGID_CONVERTED
5673a94c 1002 select UIDGID_STRICT_TYPE_CHECKS
e1c972b6 1003
5673a94c 1004 default n
aee16ce7
PE
1005 help
1006 This allows containers, i.e. vservers, to use user namespaces
1007 to provide different user info for different servers.
1008 If unsure, say N.
1009
74bd59bb 1010config PID_NS
9bd38c2c 1011 bool "PID Namespaces"
17a6d441 1012 default y
74bd59bb 1013 help
12d2b8f9 1014 Support process id namespaces. This allows having multiple
692105b8 1015 processes with the same pid as long as they are in different
74bd59bb
PE
1016 pid namespaces. This is a building block of containers.
1017
d6eb633f
MH
1018config NET_NS
1019 bool "Network namespace"
8dd2a82c 1020 depends on NET
17a6d441 1021 default y
d6eb633f
MH
1022 help
1023 Allow user space to create what appear to be multiple instances
1024 of the network stack.
1025
8dd2a82c
DL
1026endif # NAMESPACES
1027
e1c972b6
EB
1028config UIDGID_CONVERTED
1029 # True if all of the selected software conmponents are known
1030 # to have uid_t and gid_t converted to kuid_t and kgid_t
1031 # where appropriate and are otherwise safe to use with
1032 # the user namespace.
1033 bool
1034 default y
1035
e1c972b6 1036 # Networking
e1c972b6 1037 depends on NET_9P = n
e1c972b6
EB
1038
1039 # Filesystems
e1c972b6 1040 depends on 9P_FS = n
e1c972b6 1041 depends on AFS_FS = n
e1c972b6
EB
1042 depends on CEPH_FS = n
1043 depends on CIFS = n
1044 depends on CODA_FS = n
e1c972b6 1045 depends on GFS2_FS = n
e1c972b6
EB
1046 depends on NCP_FS = n
1047 depends on NFSD = n
1048 depends on NFS_FS = n
e1c972b6 1049 depends on OCFS2_FS = n
e1c972b6
EB
1050 depends on XFS_FS = n
1051
5673a94c
EB
1052config UIDGID_STRICT_TYPE_CHECKS
1053 bool "Require conversions between uid/gids and their internal representation"
e1c972b6 1054 depends on UIDGID_CONVERTED
5673a94c
EB
1055 default n
1056 help
1057 While the nececessary conversions are being added to all subsystems this option allows
1058 the code to continue to build for unconverted subsystems.
1059
1060 Say Y here if you want the strict type checking enabled
1061
5091faa4
MG
1062config SCHED_AUTOGROUP
1063 bool "Automatic process group scheduling"
1064 select EVENTFD
1065 select CGROUPS
1066 select CGROUP_SCHED
1067 select FAIR_GROUP_SCHED
1068 help
1069 This option optimizes the scheduler for common desktop workloads by
1070 automatically creating and populating task groups. This separation
1071 of workloads isolates aggressive CPU burners (like build jobs) from
1072 desktop applications. Task group autogeneration is currently based
1073 upon task session.
1074
7af37bec
DL
1075config MM_OWNER
1076 bool
1077
1078config SYSFS_DEPRECATED
5d6a4ea5 1079 bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec
DL
1080 depends on SYSFS
1081 default n
1082 help
1083 This option adds code that switches the layout of the "block" class
1084 devices, to not show up in /sys/class/block/, but only in
1085 /sys/block/.
1086
1087 This switch is only active when the sysfs.deprecated=1 boot option is
1088 passed or the SYSFS_DEPRECATED_V2 option is set.
1089
1090 This option allows new kernels to run on old distributions and tools,
1091 which might get confused by /sys/class/block/. Since 2007/2008 all
1092 major distributions and tools handle this just fine.
1093
1094 Recent distributions and userspace tools after 2009/2010 depend on
1095 the existence of /sys/class/block/, and will not work with this
1096 option enabled.
1097
1098 Only if you are using a new kernel on an old distribution, you might
1099 need to say Y here.
1100
1101config SYSFS_DEPRECATED_V2
5d6a4ea5 1102 bool "Enable deprecated sysfs features by default"
7af37bec
DL
1103 default n
1104 depends on SYSFS
1105 depends on SYSFS_DEPRECATED
1106 help
1107 Enable deprecated sysfs by default.
1108
1109 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1110 option.
1111
1112 Only if you are using a new kernel on an old distribution, you might
1113 need to say Y here. Even then, odds are you would not need it
1114 enabled, you can always pass the boot option if absolutely necessary.
1115
1116config RELAY
1117 bool "Kernel->user space relay support (formerly relayfs)"
1118 help
1119 This option enables support for relay interface support in
1120 certain file systems (such as debugfs).
1121 It is designed to provide an efficient mechanism for tools and
1122 facilities to relay large amounts of data from kernel space to
1123 user space.
1124
1125 If unsure, say N.
1126
f991633d
DG
1127config BLK_DEV_INITRD
1128 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1129 depends on BROKEN || !FRV
1130 help
1131 The initial RAM filesystem is a ramfs which is loaded by the
1132 boot loader (loadlin or lilo) and that is mounted as root
1133 before the normal boot procedure. It is typically used to
1134 load modules needed to mount the "real" root file system,
1135 etc. See <file:Documentation/initrd.txt> for details.
1136
1137 If RAM disk support (BLK_DEV_RAM) is also included, this
1138 also enables initial RAM disk (initrd) support and adds
1139 15 Kbytes (more on some other architectures) to the kernel size.
1140
1141 If unsure say Y.
1142
c33df4ea
JPS
1143if BLK_DEV_INITRD
1144
dbec4866
SR
1145source "usr/Kconfig"
1146
c33df4ea
JPS
1147endif
1148
c45b4f1f 1149config CC_OPTIMIZE_FOR_SIZE
96fffeb4 1150 bool "Optimize for size"
c45b4f1f
LT
1151 help
1152 Enabling this option will pass "-Os" instead of "-O2" to gcc
1153 resulting in a smaller kernel.
1154
3a55fb0d 1155 If unsure, say N.
c45b4f1f 1156
0847062a
RD
1157config SYSCTL
1158 bool
1159
b943c460
RD
1160config ANON_INODES
1161 bool
1162
6a108a14
DR
1163menuconfig EXPERT
1164 bool "Configure standard kernel features (expert users)"
f505c553
JT
1165 # Unhide debug options, to make the on-by-default options visible
1166 select DEBUG_KERNEL
1da177e4
LT
1167 help
1168 This option allows certain base kernel options and settings
1169 to be disabled or tweaked. This is for specialized
1170 environments which can tolerate a "non-standard" kernel.
1171 Only use this if you really know what you are doing.
1172
af1839eb
CM
1173config HAVE_UID16
1174 bool
1175
ae81f9e3 1176config UID16
6a108a14 1177 bool "Enable 16-bit UID system calls" if EXPERT
af1839eb 1178 depends on HAVE_UID16
ae81f9e3
CE
1179 default y
1180 help
1181 This enables the legacy 16-bit UID syscall wrappers.
1182
b89a8171 1183config SYSCTL_SYSCALL
6a108a14 1184 bool "Sysctl syscall support" if EXPERT
26a7034b 1185 depends on PROC_SYSCTL
c736de60 1186 default n
b89a8171 1187 select SYSCTL
ae81f9e3 1188 ---help---
13bb7e37
EB
1189 sys_sysctl uses binary paths that have been found challenging
1190 to properly maintain and use. The interface in /proc/sys
1191 using paths with ascii names is now the primary path to this
1192 information.
b89a8171 1193
13bb7e37
EB
1194 Almost nothing using the binary sysctl interface so if you are
1195 trying to save some space it is probably safe to disable this,
1196 making your kernel marginally smaller.
b89a8171 1197
c736de60 1198 If unsure say N here.
ae81f9e3 1199
7ac57a89
CM
1200config SYSCTL_EXCEPTION_TRACE
1201 bool
1202 help
1203 Enable support for /proc/sys/debug/exception-trace.
1204
1da177e4 1205config KALLSYMS
6a108a14 1206 bool "Load all symbols for debugging/ksymoops" if EXPERT
1da177e4
LT
1207 default y
1208 help
1209 Say Y here to let the kernel print out symbolic crash information and
1210 symbolic stack backtraces. This increases the size of the kernel
1211 somewhat, as all symbols have to be loaded into the kernel image.
1212
1213config KALLSYMS_ALL
1214 bool "Include all symbols in kallsyms"
1215 depends on DEBUG_KERNEL && KALLSYMS
1216 help
71a83ec7
AB
1217 Normally kallsyms only contains the symbols of functions for nicer
1218 OOPS messages and backtraces (i.e., symbols from the text and inittext
1219 sections). This is sufficient for most cases. And only in very rare
1220 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1221 names of variables from the data sections, etc).
1222
1223 This option makes sure that all symbols are loaded into the kernel
1224 image (i.e., symbols from all sections) in cost of increased kernel
1225 size (depending on the kernel configuration, it may be 300KiB or
1226 something like this).
1227
1228 Say N unless you really need all symbols.
d59745ce 1229
712f47ce 1230config HOTPLUG
45f035ab 1231 def_bool y
712f47ce 1232
d59745ce
MM
1233config PRINTK
1234 default y
6a108a14 1235 bool "Enable support for printk" if EXPERT
d59745ce
MM
1236 help
1237 This option enables normal printk support. Removing it
1238 eliminates most of the message strings from the kernel image
1239 and makes the kernel more or less silent. As this makes it
1240 very difficult to diagnose system problems, saying N here is
1241 strongly discouraged.
1242
c8538a7a 1243config BUG
6a108a14 1244 bool "BUG() support" if EXPERT
c8538a7a
MM
1245 default y
1246 help
1247 Disabling this option eliminates support for BUG and WARN, reducing
1248 the size of your kernel image and potentially quietly ignoring
1249 numerous fatal conditions. You should only consider disabling this
1250 option for embedded systems with no facilities for reporting errors.
1251 Just say Y.
1252
708e9a79 1253config ELF_CORE
046d662f 1254 depends on COREDUMP
708e9a79 1255 default y
6a108a14 1256 bool "Enable ELF core dumps" if EXPERT
708e9a79
MM
1257 help
1258 Enable support for generating core dumps. Disabling saves about 4k.
1259
8761f1ab 1260
e5e1d3cb 1261config PCSPKR_PLATFORM
6a108a14 1262 bool "Enable PC-Speaker support" if EXPERT
8761f1ab 1263 depends on HAVE_PCSPKR_PLATFORM
15f304b6 1264 select I8253_LOCK
e5e1d3cb
SS
1265 default y
1266 help
1267 This option allows to disable the internal PC-Speaker
1268 support, saving some memory.
1269
8761f1ab
RB
1270config HAVE_PCSPKR_PLATFORM
1271 bool
1272
1da177e4
LT
1273config BASE_FULL
1274 default y
6a108a14 1275 bool "Enable full-sized data structures for core" if EXPERT
1da177e4
LT
1276 help
1277 Disabling this option reduces the size of miscellaneous core
1278 kernel data structures. This saves memory on small machines,
1279 but may reduce performance.
1280
1281config FUTEX
6a108a14 1282 bool "Enable futex support" if EXPERT
1da177e4 1283 default y
23f78d4a 1284 select RT_MUTEXES
1da177e4
LT
1285 help
1286 Disabling this option will cause the kernel to be built without
1287 support for "fast userspace mutexes". The resulting kernel may not
1288 run glibc-based applications correctly.
1289
1290config EPOLL
6a108a14 1291 bool "Enable eventpoll support" if EXPERT
1da177e4 1292 default y
448e3cee 1293 select ANON_INODES
1da177e4
LT
1294 help
1295 Disabling this option will cause the kernel to be built without
1296 support for epoll family of system calls.
1297
fba2afaa 1298config SIGNALFD
6a108a14 1299 bool "Enable signalfd() system call" if EXPERT
448e3cee 1300 select ANON_INODES
fba2afaa
DL
1301 default y
1302 help
1303 Enable the signalfd() system call that allows to receive signals
1304 on a file descriptor.
1305
1306 If unsure, say Y.
1307
b215e283 1308config TIMERFD
6a108a14 1309 bool "Enable timerfd() system call" if EXPERT
448e3cee 1310 select ANON_INODES
b215e283
DL
1311 default y
1312 help
1313 Enable the timerfd() system call that allows to receive timer
1314 events on a file descriptor.
1315
1316 If unsure, say Y.
1317
e1ad7468 1318config EVENTFD
6a108a14 1319 bool "Enable eventfd() system call" if EXPERT
448e3cee 1320 select ANON_INODES
e1ad7468
DL
1321 default y
1322 help
1323 Enable the eventfd() system call that allows to receive both
1324 kernel notification (ie. KAIO) or userspace notifications.
1325
1326 If unsure, say Y.
1327
1da177e4 1328config SHMEM
6a108a14 1329 bool "Use full shmem filesystem" if EXPERT
1da177e4
LT
1330 default y
1331 depends on MMU
1332 help
1333 The shmem is an internal filesystem used to manage shared memory.
1334 It is backed by swap and manages resource limits. It is also exported
1335 to userspace as tmpfs if TMPFS is enabled. Disabling this
1336 option replaces shmem and tmpfs with the much simpler ramfs code,
1337 which may be appropriate on small systems without swap.
1338
ebf3f09c 1339config AIO
6a108a14 1340 bool "Enable AIO support" if EXPERT
ebf3f09c
TP
1341 default y
1342 help
1343 This option enables POSIX asynchronous I/O which may by used
1344 by some high performance threaded applications. Disabling
1345 this option saves about 7k.
1346
6befe5f6
RD
1347config EMBEDDED
1348 bool "Embedded system"
1349 select EXPERT
1350 help
1351 This option should be enabled if compiling the kernel for
1352 an embedded system so certain expert options are available
1353 for configuration.
1354
cdd6c482 1355config HAVE_PERF_EVENTS
0793a61d 1356 bool
018df72d
MF
1357 help
1358 See tools/perf/design.txt for details.
0793a61d 1359
906010b2
PZ
1360config PERF_USE_VMALLOC
1361 bool
1362 help
1363 See tools/perf/design.txt for details
1364
57c0c15b 1365menu "Kernel Performance Events And Counters"
0793a61d 1366
cdd6c482 1367config PERF_EVENTS
57c0c15b 1368 bool "Kernel performance events and counters"
392d65a9 1369 default y if PROFILING
cdd6c482 1370 depends on HAVE_PERF_EVENTS
4c59e467 1371 select ANON_INODES
e360adbe 1372 select IRQ_WORK
0793a61d 1373 help
57c0c15b
IM
1374 Enable kernel support for various performance events provided
1375 by software and hardware.
0793a61d 1376
dd77038d 1377 Software events are supported either built-in or via the
57c0c15b 1378 use of generic tracepoints.
0793a61d 1379
57c0c15b
IM
1380 Most modern CPUs support performance events via performance
1381 counter registers. These registers count the number of certain
0793a61d
TG
1382 types of hw events: such as instructions executed, cachemisses
1383 suffered, or branches mis-predicted - without slowing down the
1384 kernel or applications. These registers can also trigger interrupts
1385 when a threshold number of events have passed - and can thus be
1386 used to profile the code that runs on that CPU.
1387
57c0c15b 1388 The Linux Performance Event subsystem provides an abstraction of
dd77038d 1389 these software and hardware event capabilities, available via a
57c0c15b 1390 system call and used by the "perf" utility in tools/perf/. It
0793a61d
TG
1391 provides per task and per CPU counters, and it provides event
1392 capabilities on top of those.
1393
1394 Say Y if unsure.
1395
906010b2
PZ
1396config DEBUG_PERF_USE_VMALLOC
1397 default n
1398 bool "Debug: use vmalloc to back perf mmap() buffers"
1399 depends on PERF_EVENTS && DEBUG_KERNEL
1400 select PERF_USE_VMALLOC
1401 help
1402 Use vmalloc memory to back perf mmap() buffers.
1403
1404 Mostly useful for debugging the vmalloc code on platforms
1405 that don't require it.
1406
1407 Say N if unsure.
1408
0793a61d
TG
1409endmenu
1410
f8891e5e
CL
1411config VM_EVENT_COUNTERS
1412 default y
6a108a14 1413 bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e 1414 help
2aea4fb6
PJ
1415 VM event counters are needed for event counts to be shown.
1416 This option allows the disabling of the VM event counters
6a108a14 1417 on EXPERT systems. /proc/vmstat will only show page counts
2aea4fb6 1418 if VM event counters are disabled.
f8891e5e 1419
3d137310
TP
1420config PCI_QUIRKS
1421 default y
6a108a14 1422 bool "Enable PCI quirk workarounds" if EXPERT
61cfc7e4 1423 depends on PCI
3d137310
TP
1424 help
1425 This enables workarounds for various PCI chipset
1426 bugs/quirks. Disable this only if your target machine is
1427 unaffected by PCI quirks.
1428
41ecc55b
CL
1429config SLUB_DEBUG
1430 default y
6a108a14 1431 bool "Enable SLUB debugging support" if EXPERT
f6acb635 1432 depends on SLUB && SYSFS
41ecc55b
CL
1433 help
1434 SLUB has extensive debug support features. Disabling these can
1435 result in significant savings in code size. This also disables
1436 SLUB sysfs support. /sys/slab will not exist and there will be
1437 no support for cache validation etc.
1438
b943c460
RD
1439config COMPAT_BRK
1440 bool "Disable heap randomization"
1441 default y
1442 help
1443 Randomizing heap placement makes heap exploits harder, but it
1444 also breaks ancient binaries (including anything libc5 based).
1445 This option changes the bootup default to heap randomization
692105b8 1446 disabled, and can be overridden at runtime by setting
b943c460
RD
1447 /proc/sys/kernel/randomize_va_space to 2.
1448
1449 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1450
81819f0f
CL
1451choice
1452 prompt "Choose SLAB allocator"
a0acd820 1453 default SLUB
81819f0f
CL
1454 help
1455 This option allows to select a slab allocator.
1456
1457config SLAB
1458 bool "SLAB"
1459 help
1460 The regular slab allocator that is established and known to work
34013886 1461 well in all environments. It organizes cache hot objects in
02f56210 1462 per cpu and per node queues.
81819f0f
CL
1463
1464config SLUB
81819f0f
CL
1465 bool "SLUB (Unqueued Allocator)"
1466 help
1467 SLUB is a slab allocator that minimizes cache line usage
1468 instead of managing queues of cached objects (SLAB approach).
1469 Per cpu caching is realized using slabs of objects instead
1470 of queues of objects. SLUB can use memory efficiently
02f56210
SA
1471 and has enhanced diagnostics. SLUB is the default choice for
1472 a slab allocator.
81819f0f
CL
1473
1474config SLOB
6a108a14 1475 depends on EXPERT
81819f0f
CL
1476 bool "SLOB (Simple Allocator)"
1477 help
37291458
MM
1478 SLOB replaces the stock allocator with a drastically simpler
1479 allocator. SLOB is generally more space efficient but
1480 does not perform as well on large systems.
81819f0f
CL
1481
1482endchoice
1483
ea637639
JZ
1484config MMAP_ALLOW_UNINITIALIZED
1485 bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14 1486 depends on EXPERT && !MMU
ea637639
JZ
1487 default n
1488 help
1489 Normally, and according to the Linux spec, anonymous memory obtained
1490 from mmap() has it's contents cleared before it is passed to
1491 userspace. Enabling this config option allows you to request that
1492 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1493 providing a huge performance boost. If this option is not enabled,
1494 then the flag will be ignored.
1495
1496 This is taken advantage of by uClibc's malloc(), and also by
1497 ELF-FDPIC binfmt's brk and stack allocator.
1498
1499 Because of the obvious security issues, this option should only be
1500 enabled on embedded devices where you control what is run in
1501 userspace. Since that isn't generally a problem on no-MMU systems,
1502 it is normally safe to say Y here.
1503
1504 See Documentation/nommu-mmap.txt for more information.
1505
125e5645 1506config PROFILING
b309a294 1507 bool "Profiling support"
125e5645
MD
1508 help
1509 Say Y here to enable the extended profiling support mechanisms used
1510 by profilers such as OProfile.
1511
5f87f112
IM
1512#
1513# Place an empty function call at each tracepoint site. Can be
1514# dynamically changed for a probe function.
1515#
97e1c18e 1516config TRACEPOINTS
5f87f112 1517 bool
97e1c18e 1518
fb32e03f
MD
1519source "arch/Kconfig"
1520
1da177e4
LT
1521endmenu # General setup
1522
ee7e5516
DB
1523config HAVE_GENERIC_DMA_COHERENT
1524 bool
1525 default n
1526
158a9624
LT
1527config SLABINFO
1528 bool
1529 depends on PROC_FS
0f389ec6 1530 depends on SLAB || SLUB_DEBUG
158a9624
LT
1531 default y
1532
ae81f9e3
CE
1533config RT_MUTEXES
1534 boolean
ae81f9e3 1535
1da177e4
LT
1536config BASE_SMALL
1537 int
1538 default 0 if BASE_FULL
1539 default 1 if !BASE_FULL
1540
66da5733 1541menuconfig MODULES
1da177e4
LT
1542 bool "Enable loadable module support"
1543 help
1544 Kernel modules are small pieces of compiled code which can
1545 be inserted in the running kernel, rather than being
1546 permanently built into the kernel. You use the "modprobe"
1547 tool to add (and sometimes remove) them. If you say Y here,
1548 many parts of the kernel can be built as modules (by
1549 answering M instead of Y where indicated): this is most
1550 useful for infrequently used options which are not required
1551 for booting. For more information, see the man pages for
1552 modprobe, lsmod, modinfo, insmod and rmmod.
1553
1554 If you say Y here, you will need to run "make
1555 modules_install" to put the modules under /lib/modules/
1556 where modprobe can find them (you may need to be root to do
1557 this).
1558
1559 If unsure, say Y.
1560
0b0de144
RD
1561if MODULES
1562
826e4506
LT
1563config MODULE_FORCE_LOAD
1564 bool "Forced module loading"
826e4506
LT
1565 default n
1566 help
91e37a79
RR
1567 Allow loading of modules without version information (ie. modprobe
1568 --force). Forced module loading sets the 'F' (forced) taint flag and
1569 is usually a really bad idea.
826e4506 1570
1da177e4
LT
1571config MODULE_UNLOAD
1572 bool "Module unloading"
1da177e4
LT
1573 help
1574 Without this option you will not be able to unload any
1575 modules (note that some modules may not be unloadable
f7f5b675
DV
1576 anyway), which makes your kernel smaller, faster
1577 and simpler. If unsure, say Y.
1da177e4
LT
1578
1579config MODULE_FORCE_UNLOAD
1580 bool "Forced module unloading"
19c92399 1581 depends on MODULE_UNLOAD
1da177e4
LT
1582 help
1583 This option allows you to force a module to unload, even if the
1584 kernel believes it is unsafe: the kernel will remove the module
1585 without waiting for anyone to stop using it (using the -f option to
1586 rmmod). This is mainly for kernel developers and desperate users.
1587 If unsure, say N.
1588
1da177e4 1589config MODVERSIONS
0d541643 1590 bool "Module versioning support"
1da177e4
LT
1591 help
1592 Usually, you have to use modules compiled with your kernel.
1593 Saying Y here makes it sometimes possible to use modules
1594 compiled for different kernels, by adding enough information
1595 to the modules to (hopefully) spot any changes which would
1596 make them incompatible with the kernel you are running. If
1597 unsure, say N.
1598
1599config MODULE_SRCVERSION_ALL
1600 bool "Source checksum for all modules"
1da177e4
LT
1601 help
1602 Modules which contain a MODULE_VERSION get an extra "srcversion"
1603 field inserted into their modinfo section, which contains a
1604 sum of the source files which made it. This helps maintainers
1605 see exactly which source was used to build a module (since
1606 others sometimes change the module source without updating
1607 the version). With this option, such a "srcversion" field
1608 will be created for all modules. If unsure, say N.
1609
106a4ee2
RR
1610config MODULE_SIG
1611 bool "Module signature verification"
1612 depends on MODULES
48ba2462
DH
1613 select KEYS
1614 select CRYPTO
1615 select ASYMMETRIC_KEY_TYPE
1616 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1617 select PUBLIC_KEY_ALGO_RSA
1618 select ASN1
1619 select OID_REGISTRY
1620 select X509_CERTIFICATE_PARSER
106a4ee2
RR
1621 help
1622 Check modules for valid signatures upon load: the signature
1623 is simply appended to the module. For more information see
1624 Documentation/module-signing.txt.
1625
ea0b6dcf
DH
1626 !!!WARNING!!! If you enable this option, you MUST make sure that the
1627 module DOES NOT get stripped after being signed. This includes the
1628 debuginfo strip done by some packagers (such as rpmbuild) and
1629 inclusion into an initramfs that wants the module size reduced.
1630
106a4ee2
RR
1631config MODULE_SIG_FORCE
1632 bool "Require modules to be validly signed"
1633 depends on MODULE_SIG
1634 help
1635 Reject unsigned modules or signed modules for which we don't have a
1636 key. Without this, such modules will simply taint the kernel.
ea0b6dcf
DH
1637
1638choice
1639 prompt "Which hash algorithm should modules be signed with?"
1640 depends on MODULE_SIG
1641 help
1642 This determines which sort of hashing algorithm will be used during
1643 signature generation. This algorithm _must_ be built into the kernel
1644 directly so that signature verification can take place. It is not
1645 possible to load a signed module containing the algorithm to check
1646 the signature on that module.
1647
1648config MODULE_SIG_SHA1
1649 bool "Sign modules with SHA-1"
1650 select CRYPTO_SHA1
1651
1652config MODULE_SIG_SHA224
1653 bool "Sign modules with SHA-224"
1654 select CRYPTO_SHA256
1655
1656config MODULE_SIG_SHA256
1657 bool "Sign modules with SHA-256"
1658 select CRYPTO_SHA256
1659
1660config MODULE_SIG_SHA384
1661 bool "Sign modules with SHA-384"
1662 select CRYPTO_SHA512
1663
1664config MODULE_SIG_SHA512
1665 bool "Sign modules with SHA-512"
1666 select CRYPTO_SHA512
1667
1668endchoice
1669
0b0de144
RD
1670endif # MODULES
1671
98a79d6a
RR
1672config INIT_ALL_POSSIBLE
1673 bool
1674 help
5f054e31
RR
1675 Back when each arch used to define their own cpu_online_mask and
1676 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a
RR
1677 with all 1s, and others with all 0s. When they were centralised,
1678 it was better to provide this option than to break all the archs
692105b8 1679 and have several arch maintainers pursuing me down dark alleys.
98a79d6a 1680
1da177e4
LT
1681config STOP_MACHINE
1682 bool
1683 default y
1684 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1685 help
1686 Need stop_machine() primitive.
3a65dfe8 1687
3a65dfe8 1688source "block/Kconfig"
e98c3202
AK
1689
1690config PREEMPT_NOTIFIERS
1691 bool
e260be67 1692
16295bec
SK
1693config PADATA
1694 depends on SMP
1695 bool
1696
754b7b63
AK
1697# Can be selected by architectures with broken toolchains
1698# that get confused by correct const<->read_only section
1699# mappings
1700config BROKEN_RODATA
1701 bool
1702
4520c6a4
DH
1703config ASN1
1704 tristate
1705 help
1706 Build a simple ASN.1 grammar compiler that produces a bytecode output
1707 that can be interpreted by the ASN.1 stream decoder and used to
1708 inform it as to what tags are to be expected in a stream and what
1709 functions to call on what tags.
1710
6beb0009 1711source "kernel/Kconfig.locks"
This page took 1.237264 seconds and 5 git commands to generate.