Kconfig 53.8 KB
Newer Older
R
Roman Zippel 已提交
1 2 3 4 5 6 7 8
config ARCH
	string
	option env="ARCH"

config KERNELVERSION
	string
	option env="KERNELVERSION"

9 10
config DEFCONFIG_LIST
	string
11
	depends on !UML
12 13 14 15
	option defconfig_list
	default "/lib/modules/$UNAME_RELEASE/.config"
	default "/etc/kernel-config"
	default "/boot/config-$UNAME_RELEASE"
16
	default "$ARCH_DEFCONFIG"
17 18
	default "arch/$ARCH/defconfig"

19 20 21 22
config CONSTRUCTORS
	bool
	depends on !UML

23 24 25 26 27 28 29
config HAVE_IRQ_WORK
	bool

config IRQ_WORK
	bool
	depends on HAVE_IRQ_WORK

30 31 32
config BUILDTIME_EXTABLE_SORT
	bool

33
menu "General setup"
L
Linus Torvalds 已提交
34 35

config EXPERIMENTAL
36 37
	bool
	default y
L
Linus Torvalds 已提交
38 39 40 41 42 43 44 45 46 47 48

config BROKEN
	bool

config BROKEN_ON_SMP
	bool
	depends on BROKEN || !SMP
	default y

config INIT_ENV_ARG_LIMIT
	int
49 50
	default 32 if !UML
	default 128 if UML
L
Linus Torvalds 已提交
51
	help
52 53
	  Maximum of each of the number of arguments and environment
	  variables passed to init from the kernel command line.
L
Linus Torvalds 已提交
54 55


R
Roland McGrath 已提交
56 57 58 59 60 61 62 63
config CROSS_COMPILE
	string "Cross-compiler tool prefix"
	help
	  Same as running 'make CROSS_COMPILE=prefix-' but stored for
	  default make runs in this kernel build directory.  You don't
	  need to set this unless you want the configured kernel build
	  directory to select the cross-compiler automatically.

L
Linus Torvalds 已提交
64 65 66 67 68 69 70 71 72 73
config LOCALVERSION
	string "Local version - append to kernel release"
	help
	  Append an extra string to the end of your kernel version.
	  This will show up when you type uname, for example.
	  The string you set here will be appended after the contents of
	  any files with a filename matching localversion* in your
	  object and source tree, in that order.  Your total string can
	  be a maximum of 64 characters.

74 75 76 77 78
config LOCALVERSION_AUTO
	bool "Automatically append version information to the version string"
	default y
	help
	  This will try to automatically determine if the current tree is a
79 80
	  release tree by looking for git tags that belong to the current
	  top of tree revision.
81 82

	  A string of the format -gxxxxxxxx will be added to the localversion
83
	  if a git-based tree is found.  The string generated by this will be
84
	  appended after any matching localversion* files, and after the value
85
	  set in CONFIG_LOCALVERSION.
86

87 88 89 90 91 92
	  (The actual string used here is the first eight characters produced
	  by running the command:

	    $ git rev-parse --verify HEAD

	  which is done within the script "scripts/setlocalversion".)
93

94 95 96 97 98 99 100 101 102
config HAVE_KERNEL_GZIP
	bool

config HAVE_KERNEL_BZIP2
	bool

config HAVE_KERNEL_LZMA
	bool

103 104 105
config HAVE_KERNEL_XZ
	bool

106 107 108
config HAVE_KERNEL_LZO
	bool

109
choice
110 111
	prompt "Kernel compression mode"
	default KERNEL_GZIP
112
	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
113
	help
114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131
	  The linux kernel is a kind of self-extracting executable.
	  Several compression algorithms are available, which differ
	  in efficiency, compression and decompression speed.
	  Compression speed is only relevant when building a kernel.
	  Decompression speed is relevant at each boot.

	  If you have any problems with bzip2 or lzma compressed
	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
	  version of this functionality (bzip2 only), for 2.4, was
	  supplied by Christian Ludwig)

	  High compression options are mostly useful for users, who
	  are low on disk space (embedded systems), but for whom ram
	  size matters less.

	  If in doubt, select 'gzip'

config KERNEL_GZIP
132 133 134
	bool "Gzip"
	depends on HAVE_KERNEL_GZIP
	help
135 136
	  The old and tried gzip compression. It provides a good balance
	  between compression ratio and decompression speed.
137 138 139

config KERNEL_BZIP2
	bool "Bzip2"
140
	depends on HAVE_KERNEL_BZIP2
141 142
	help
	  Its compression ratio and speed is intermediate.
143
	  Decompression speed is slowest among the choices.  The kernel
144 145 146
	  size is about 10% smaller with bzip2, in comparison to gzip.
	  Bzip2 uses a large amount of memory. For modern kernels you
	  will need at least 8MB RAM or more for booting.
147 148

config KERNEL_LZMA
149 150 151
	bool "LZMA"
	depends on HAVE_KERNEL_LZMA
	help
152 153 154
	  This compression algorithm's ratio is best.  Decompression speed
	  is between gzip and bzip2.  Compression is slowest.
	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
155

156 157 158 159 160 161 162 163 164 165 166 167 168 169 170
config KERNEL_XZ
	bool "XZ"
	depends on HAVE_KERNEL_XZ
	help
	  XZ uses the LZMA2 algorithm and instruction set specific
	  BCJ filters which can improve compression ratio of executable
	  code. The size of the kernel is about 30% smaller with XZ in
	  comparison to gzip. On architectures for which there is a BCJ
	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
	  will create a few percent smaller kernel than plain LZMA.

	  The speed is about the same as with LZMA: The decompression
	  speed of XZ is better than that of bzip2 but worse than gzip
	  and LZO. Compression is slow.

171 172 173 174
config KERNEL_LZO
	bool "LZO"
	depends on HAVE_KERNEL_LZO
	help
175
	  Its compression ratio is the poorest among the choices. The kernel
S
Stephan Sperber 已提交
176
	  size is about 10% bigger than gzip; however its speed
177 178
	  (both compression and decompression) is the fastest.

179 180
endchoice

181 182 183 184 185 186 187 188 189
config DEFAULT_HOSTNAME
	string "Default hostname"
	default "(none)"
	help
	  This option determines the default system hostname before userspace
	  calls sethostname(2). The kernel traditionally uses "(none)" here,
	  but you may wish to use a different default here to make a minimal
	  system more usable with less configuration.

L
Linus Torvalds 已提交
190 191
config SWAP
	bool "Support for paging of anonymous memory (swap)"
192
	depends on MMU && BLOCK
L
Linus Torvalds 已提交
193 194 195
	default y
	help
	  This option allows you to choose whether you want to have support
196
	  for so called swap devices or swap files in your kernel that are
L
Linus Torvalds 已提交
197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214
	  used to provide more virtual memory than the actual RAM present
	  in your computer.  If unsure say Y.

config SYSVIPC
	bool "System V IPC"
	---help---
	  Inter Process Communication is a suite of library functions and
	  system calls which let processes (running programs) synchronize and
	  exchange information. It is generally considered to be a good thing,
	  and some programs won't run unless you say Y here. In particular, if
	  you want to run the DOS emulator dosemu under Linux (read the
	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
	  you'll need to say Y here.

	  You can find documentation about IPC with "info ipc" and also in
	  section 6.4 of the Linux Programmer's Guide, available from
	  <http://www.tldp.org/guides.html>.

215 216 217 218 219 220
config SYSVIPC_SYSCTL
	bool
	depends on SYSVIPC
	depends on SYSCTL
	default y

L
Linus Torvalds 已提交
221 222 223 224 225 226 227 228
config POSIX_MQUEUE
	bool "POSIX Message Queues"
	depends on NET && EXPERIMENTAL
	---help---
	  POSIX variant of message queues is a part of IPC. In POSIX message
	  queues every message has a priority which decides about succession
	  of receiving it by a process. If you want to compile and run
	  programs written e.g. for Solaris with use of its POSIX message
229
	  queues (functions mq_*) say Y here.
L
Linus Torvalds 已提交
230 231 232 233 234 235 236

	  POSIX message queues are visible as a filesystem called 'mqueue'
	  and can be mounted somewhere if you want to do filesystem
	  operations on message queues.

	  If unsure, say Y.

237 238 239 240 241 242
config POSIX_MQUEUE_SYSCTL
	bool
	depends on POSIX_MQUEUE
	depends on SYSCTL
	default y

243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301
config FHANDLE
	bool "open by fhandle syscalls"
	select EXPORTFS
	help
	  If you say Y here, a user level program will be able to map
	  file names to handle and then later use the handle for
	  different file system operations. This is useful in implementing
	  userspace file servers, which now track files using handles instead
	  of names. The handle would remain the same even if file names
	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
	  syscalls.

config AUDIT
	bool "Auditing support"
	depends on NET
	help
	  Enable auditing infrastructure that can be used with another
	  kernel subsystem, such as SELinux (which requires this for
	  logging of avc messages output).  Does not do system-call
	  auditing without CONFIG_AUDITSYSCALL.

config AUDITSYSCALL
	bool "Enable system-call auditing support"
	depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
	default y if SECURITY_SELINUX
	help
	  Enable low-overhead system-call auditing infrastructure that
	  can be used independently or with another kernel subsystem,
	  such as SELinux.

config AUDIT_WATCH
	def_bool y
	depends on AUDITSYSCALL
	select FSNOTIFY

config AUDIT_TREE
	def_bool y
	depends on AUDITSYSCALL
	select FSNOTIFY

config AUDIT_LOGINUID_IMMUTABLE
	bool "Make audit loginuid immutable"
	depends on AUDIT
	help
	  The config option toggles if a task setting its loginuid requires
	  CAP_SYS_AUDITCONTROL or if that task should require no special permissions
	  but should instead only allow setting its loginuid if it was never
	  previously set.  On systems which use systemd or a similar central
	  process to restart login services this should be set to true.  On older
	  systems in which an admin would typically have to directly stop and
	  start processes this should be set to false.  Setting this to true allows
	  one to drop potentially dangerous capabilites from the login tasks,
	  but may not be backwards compatible with older init systems.

source "kernel/irq/Kconfig"
source "kernel/time/Kconfig"

menu "CPU/Task time and stats accounting"

302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317
choice
	prompt "Cputime accounting"
	default TICK_CPU_ACCOUNTING if !PPC64
	default VIRT_CPU_ACCOUNTING if PPC64

# Kind of a stub config for the pure tick based cputime accounting
config TICK_CPU_ACCOUNTING
	bool "Simple tick based cputime accounting"
	depends on !S390
	help
	  This is the basic tick based cputime accounting that maintains
	  statistics about user, system and idle time spent on per jiffies
	  granularity.

	  If unsure, say Y.

318 319 320 321 322 323 324 325 326 327 328 329
config VIRT_CPU_ACCOUNTING
	bool "Deterministic task and CPU time accounting"
	depends on HAVE_VIRT_CPU_ACCOUNTING
	help
	  Select this option to enable more accurate task and CPU time
	  accounting.  This is done by reading a CPU counter on each
	  kernel entry and exit and on transitions within the kernel
	  between system, softirq and hardirq state, so there is a
	  small performance impact.  In the case of s390 or IBM POWER > 5,
	  this also enables accounting of stolen time on logically-partitioned
	  systems.

330 331 332 333 334 335 336 337 338 339 340 341 342
config IRQ_TIME_ACCOUNTING
	bool "Fine granularity task level IRQ time accounting"
	depends on HAVE_IRQ_TIME_ACCOUNTING
	help
	  Select this option to enable fine granularity task irq time
	  accounting. This is done by reading a timestamp on each
	  transitions between softirq and hardirq state, so there can be a
	  small performance impact.

	  If in doubt, say N here.

endchoice

L
Linus Torvalds 已提交
343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365
config BSD_PROCESS_ACCT
	bool "BSD Process Accounting"
	help
	  If you say Y here, a user level program will be able to instruct the
	  kernel (via a special system call) to write process accounting
	  information to a file: whenever a process exits, information about
	  that process will be appended to the file by the kernel.  The
	  information includes things such as creation time, owning user,
	  command name, memory usage, controlling terminal etc. (the complete
	  list is in the struct acct in <file:include/linux/acct.h>).  It is
	  up to the user level program to do useful things with this
	  information.  This is generally a good idea, so say Y.

config BSD_PROCESS_ACCT_V3
	bool "BSD Process Accounting version 3 file format"
	depends on BSD_PROCESS_ACCT
	default n
	help
	  If you say Y here, the process accounting information is written
	  in a new file format that also logs the process IDs of each
	  process and it's parent. Note that this file format is incompatible
	  with previous v0/v1/v2 file formats, so you will need updated tools
	  for processing it. A preliminary version of these tools is available
366
	  at <http://www.gnu.org/software/acct/>.
L
Linus Torvalds 已提交
367

368 369 370 371 372 373 374 375 376 377 378 379 380
config TASKSTATS
	bool "Export task/process statistics through netlink (EXPERIMENTAL)"
	depends on NET
	default n
	help
	  Export selected statistics for tasks/processes through the
	  generic netlink interface. Unlike BSD process accounting, the
	  statistics are available during the lifetime of tasks/processes as
	  responses to commands. Like BSD accounting, they are sent to user
	  space on task exit.

	  Say N if unsure.

381 382
config TASK_DELAY_ACCT
	bool "Enable per-task delay accounting (EXPERIMENTAL)"
383
	depends on TASKSTATS
384 385 386 387 388 389 390 391
	help
	  Collect information on time spent by a task waiting for system
	  resources like cpu, synchronous block I/O completion and swapping
	  in pages. Such statistics can help in setting a task's priorities
	  relative to other tasks for cpu, io, rss limits etc.

	  Say N if unsure.

392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409
config TASK_XACCT
	bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
	depends on TASKSTATS
	help
	  Collect extended task accounting data and send the data
	  to userland for processing over the taskstats interface.

	  Say N if unsure.

config TASK_IO_ACCOUNTING
	bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
	depends on TASK_XACCT
	help
	  Collect information on the number of bytes of storage I/O which this
	  task has caused.

	  Say N if unsure.

410
endmenu # "CPU/Task time and stats accounting"
T
Thomas Gleixner 已提交
411

M
Mike Travis 已提交
412 413 414 415
menu "RCU Subsystem"

choice
	prompt "RCU Implementation"
P
Paul E. McKenney 已提交
416
	default TREE_RCU
M
Mike Travis 已提交
417 418 419

config TREE_RCU
	bool "Tree-based hierarchical RCU"
420
	depends on !PREEMPT && SMP
M
Mike Travis 已提交
421 422 423
	help
	  This option selects the RCU implementation that is
	  designed for very large SMP system with hundreds or
P
Paul E. McKenney 已提交
424 425
	  thousands of CPUs.  It also scales down nicely to
	  smaller systems.
M
Mike Travis 已提交
426

427
config TREE_PREEMPT_RCU
P
Paul E. McKenney 已提交
428
	bool "Preemptible tree-based hierarchical RCU"
429
	depends on PREEMPT && SMP
430 431 432 433
	help
	  This option selects the RCU implementation that is
	  designed for very large SMP systems with hundreds or
	  thousands of CPUs, but for which real-time response
434 435
	  is also required.  It also scales down nicely to
	  smaller systems.
436

437 438
config TINY_RCU
	bool "UP-only small-memory-footprint RCU"
439
	depends on !PREEMPT && !SMP
440 441 442 443 444 445
	help
	  This option selects the RCU implementation that is
	  designed for UP systems from which real-time response
	  is not required.  This option greatly reduces the
	  memory footprint of RCU.

P
Paul E. McKenney 已提交
446 447
config TINY_PREEMPT_RCU
	bool "Preemptible UP-only small-memory-footprint RCU"
448
	depends on PREEMPT && !SMP
P
Paul E. McKenney 已提交
449 450 451 452 453
	help
	  This option selects the RCU implementation that is designed
	  for real-time UP systems.  This option greatly reduces the
	  memory footprint of RCU.

M
Mike Travis 已提交
454 455
endchoice

P
Paul E. McKenney 已提交
456 457 458 459 460 461
config PREEMPT_RCU
	def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
	help
	  This option enables preemptible-RCU code that is common between
	  the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.

462 463 464
config CONTEXT_TRACKING
       bool

465 466
config RCU_USER_QS
	bool "Consider userspace as in RCU extended quiescent state"
467 468
	depends on HAVE_CONTEXT_TRACKING && SMP
	select CONTEXT_TRACKING
469 470 471 472 473
	help
	  This option sets hooks on kernel / userspace boundaries and
	  puts RCU in extended quiescent state when the CPU runs in
	  userspace. It means that when a CPU runs in userspace, it is
	  excluded from the global RCU state machine and thus doesn't
474
	  try to keep the timer tick on for RCU.
475

476
	  Unless you want to hack and help the development of the full
477
	  dynticks mode, you shouldn't enable this option.  It also
478
	  adds unnecessary overhead.
479 480 481

	  If unsure say N

482 483 484
config CONTEXT_TRACKING_FORCE
	bool "Force context tracking"
	depends on CONTEXT_TRACKING
485
	help
486 487 488 489 490
	  Probe on user/kernel boundaries by default in order to
	  test the features that rely on it such as userspace RCU extended
	  quiescent states.
	  This test is there for debugging until we have a real user like the
	  full dynticks mode.
491

M
Mike Travis 已提交
492 493 494 495
config RCU_FANOUT
	int "Tree-based hierarchical RCU fanout value"
	range 2 64 if 64BIT
	range 2 32 if !64BIT
496
	depends on TREE_RCU || TREE_PREEMPT_RCU
M
Mike Travis 已提交
497 498 499 500 501
	default 64 if 64BIT
	default 32 if !64BIT
	help
	  This option controls the fanout of hierarchical implementations
	  of RCU, allowing RCU to work efficiently on machines with
502 503 504 505 506 507
	  large numbers of CPUs.  This value must be at least the fourth
	  root of NR_CPUS, which allows NR_CPUS to be insanely large.
	  The default value of RCU_FANOUT should be used for production
	  systems, but if you are stress-testing the RCU implementation
	  itself, small RCU_FANOUT values allow you to test large-system
	  code paths on small(er) systems.
M
Mike Travis 已提交
508 509 510 511

	  Select a specific number if testing RCU itself.
	  Take the default if unsure.

512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538
config RCU_FANOUT_LEAF
	int "Tree-based hierarchical RCU leaf-level fanout value"
	range 2 RCU_FANOUT if 64BIT
	range 2 RCU_FANOUT if !64BIT
	depends on TREE_RCU || TREE_PREEMPT_RCU
	default 16
	help
	  This option controls the leaf-level fanout of hierarchical
	  implementations of RCU, and allows trading off cache misses
	  against lock contention.  Systems that synchronize their
	  scheduling-clock interrupts for energy-efficiency reasons will
	  want the default because the smaller leaf-level fanout keeps
	  lock contention levels acceptably low.  Very large systems
	  (hundreds or thousands of CPUs) will instead want to set this
	  value to the maximum value possible in order to reduce the
	  number of cache misses incurred during RCU's grace-period
	  initialization.  These systems tend to run CPU-bound, and thus
	  are not helped by synchronized interrupts, and thus tend to
	  skew them, which reduces lock contention enough that large
	  leaf-level fanouts work well.

	  Select a specific number if testing RCU itself.

	  Select the maximum permissible value for large systems.

	  Take the default if unsure.

M
Mike Travis 已提交
539 540
config RCU_FANOUT_EXACT
	bool "Disable tree-based hierarchical RCU auto-balancing"
541
	depends on TREE_RCU || TREE_PREEMPT_RCU
M
Mike Travis 已提交
542 543 544 545 546 547 548 549 550 551 552
	default n
	help
	  This option forces use of the exact RCU_FANOUT value specified,
	  regardless of imbalances in the hierarchy.  This is useful for
	  testing RCU itself, and might one day be useful on systems with
	  strong NUMA behavior.

	  Without RCU_FANOUT_EXACT, the code will balance the hierarchy.

	  Say N if unsure.

553 554
config RCU_FAST_NO_HZ
	bool "Accelerate last non-dyntick-idle CPU's grace periods"
555
	depends on NO_HZ && SMP
556 557
	default n
	help
558 559 560 561 562 563 564
	  This option causes RCU to attempt to accelerate grace periods in
	  order to allow CPUs to enter dynticks-idle state more quickly.
	  On the other hand, this option increases the overhead of the
	  dynticks-idle checking, thus degrading scheduling latency.

	  Say Y if energy efficiency is critically important, and you don't
	  	care about real-time response.
565 566 567

	  Say N if you are unsure.

M
Mike Travis 已提交
568
config TREE_RCU_TRACE
569
	def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
M
Mike Travis 已提交
570 571
	select DEBUG_FS
	help
572 573 574
	  This option provides tracing for the TREE_RCU and
	  TREE_PREEMPT_RCU implementations, permitting Makefile to
	  trivially select kernel/rcutree_trace.c.
M
Mike Travis 已提交
575

576 577
config RCU_BOOST
	bool "Enable RCU priority boosting"
578
	depends on RT_MUTEXES && PREEMPT_RCU
579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594
	default n
	help
	  This option boosts the priority of preempted RCU readers that
	  block the current preemptible RCU grace period for too long.
	  This option also prevents heavy loads from blocking RCU
	  callback invocation for all flavors of RCU.

	  Say Y here if you are working with real-time apps or heavy loads
	  Say N here if you are unsure.

config RCU_BOOST_PRIO
	int "Real-time priority to boost RCU readers to"
	range 1 99
	depends on RCU_BOOST
	default 1
	help
595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613
	  This option specifies the real-time priority to which long-term
	  preempted RCU readers are to be boosted.  If you are working
	  with a real-time application that has one or more CPU-bound
	  threads running at a real-time priority level, you should set
	  RCU_BOOST_PRIO to a priority higher then the highest-priority
	  real-time CPU-bound thread.  The default RCU_BOOST_PRIO value
	  of 1 is appropriate in the common case, which is real-time
	  applications that do not have any CPU-bound threads.

	  Some real-time applications might not have a single real-time
	  thread that saturates a given CPU, but instead might have
	  multiple real-time threads that, taken together, fully utilize
	  that CPU.  In this case, you should set RCU_BOOST_PRIO to
	  a priority higher than the lowest-priority thread that is
	  conspiring to prevent the CPU from running any non-real-time
	  tasks.  For example, if one thread at priority 10 and another
	  thread at priority 5 are between themselves fully consuming
	  the CPU time on a given CPU, then RCU_BOOST_PRIO should be
	  set to priority 6 or higher.
614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629

	  Specify the real-time priority, or take the default if unsure.

config RCU_BOOST_DELAY
	int "Milliseconds to delay boosting after RCU grace-period start"
	range 0 3000
	depends on RCU_BOOST
	default 500
	help
	  This option specifies the time to wait after the beginning of
	  a given grace period before priority-boosting preempted RCU
	  readers blocking that grace period.  Note that any RCU reader
	  blocking an expedited RCU grace period is boosted immediately.

	  Accept the default if unsure.

P
Paul E. McKenney 已提交
630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651
config RCU_NOCB_CPU
	bool "Offload RCU callback processing from boot-selected CPUs"
	depends on TREE_RCU || TREE_PREEMPT_RCU
	default n
	help
	  Use this option to reduce OS jitter for aggressive HPC or
	  real-time workloads.	It can also be used to offload RCU
	  callback invocation to energy-efficient CPUs in battery-powered
	  asymmetric multiprocessors.

	  This option offloads callback invocation from the set of
	  CPUs specified at boot time by the rcu_nocbs parameter.
	  For each such CPU, a kthread ("rcuoN") will be created to
	  invoke callbacks, where the "N" is the CPU being offloaded.
	  Nothing prevents this kthread from running on the specified
	  CPUs, but (1) the kthreads may be preempted between each
	  callback, and (2) affinity or cgroups can be used to force
	  the kthreads to run on whatever set of CPUs is desired.

	  Say Y here if you want reduced OS jitter on selected CPUs.
	  Say N here if you are unsure.

M
Mike Travis 已提交
652 653
endmenu # "RCU Subsystem"

L
Linus Torvalds 已提交
654
config IKCONFIG
655
	tristate "Kernel .config support"
L
Linus Torvalds 已提交
656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672
	---help---
	  This option enables the complete Linux kernel ".config" file
	  contents to be saved in the kernel. It provides documentation
	  of which kernel options are used in a running kernel or in an
	  on-disk kernel.  This information can be extracted from the kernel
	  image file with the script scripts/extract-ikconfig and used as
	  input to rebuild the current kernel or to build another kernel.
	  It can also be extracted from a running kernel by reading
	  /proc/config.gz if enabled (below).

config IKCONFIG_PROC
	bool "Enable access to .config through /proc/config.gz"
	depends on IKCONFIG && PROC_FS
	---help---
	  This option enables access to the kernel configuration file
	  through /proc/config.gz.

673 674 675
config LOG_BUF_SHIFT
	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
	range 12 21
A
Adrian Bunk 已提交
676
	default 17
677 678
	help
	  Select kernel log buffer size as a power of 2.
A
Adrian Bunk 已提交
679 680 681 682 683
	  Examples:
	  	     17 => 128 KB
		     16 => 64 KB
	             15 => 32 KB
	             14 => 16 KB
684 685 686
		     13 =>  8 KB
		     12 =>  4 KB

687 688 689 690 691 692
#
# Architectures with an unreliable sched_clock() should select this:
#
config HAVE_UNSTABLE_SCHED_CLOCK
	bool

693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716
#
# For architectures that want to enable the support for NUMA-affine scheduler
# balancing logic:
#
config ARCH_SUPPORTS_NUMA_BALANCING
	bool

# For architectures that (ab)use NUMA to represent different memory regions
# all cpu-local but of different latencies, such as SuperH.
#
config ARCH_WANT_NUMA_VARIABLE_LOCALITY
	bool

#
# For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
config ARCH_WANTS_PROT_NUMA_PROT_NONE
	bool

config ARCH_USES_NUMA_PROT_NONE
	bool
	default y
	depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
	depends on NUMA_BALANCING

717 718 719 720 721 722 723 724
config NUMA_BALANCING_DEFAULT_ENABLED
	bool "Automatically enable NUMA aware memory/task placement"
	default y
	depends on NUMA_BALANCING
	help
	  If set, autonumic NUMA balancing will be enabled if running on a NUMA
	  machine.

725 726 727 728 729 730 731 732 733 734 735 736
config NUMA_BALANCING
	bool "Memory placement aware NUMA scheduler"
	depends on ARCH_SUPPORTS_NUMA_BALANCING
	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
	depends on SMP && NUMA && MIGRATION
	help
	  This option adds support for automatic NUMA aware memory/task placement.
	  The mechanism is quite primitive and is based on migrating memory when
	  it is references to the node the task is running on.

	  This system will be inactive on UMA systems.

L
Li Zefan 已提交
737 738
menuconfig CGROUPS
	boolean "Control Group support"
739
	depends on EVENTFD
740
	help
L
Li Zefan 已提交
741
	  This option adds support for grouping sets of processes together, for
742 743 744 745
	  use with process control subsystems such as Cpusets, CFS, memory
	  controls or device isolation.
	  See
		- Documentation/scheduler/sched-design-CFS.txt	(CFS)
L
Li Zefan 已提交
746 747
		- Documentation/cgroups/ (features for grouping, isolation
					  and resource control)
748 749 750

	  Say N if unsure.

L
Li Zefan 已提交
751 752
if CGROUPS

753 754 755 756 757 758
config CGROUP_DEBUG
	bool "Example debug cgroup subsystem"
	default n
	help
	  This option enables a simple cgroup subsystem that
	  exports useful debugging information about the cgroups
L
Li Zefan 已提交
759
	  framework.
760

L
Li Zefan 已提交
761
	  Say N if unsure.
762 763

config CGROUP_FREEZER
L
Li Zefan 已提交
764 765 766
	bool "Freezer cgroup subsystem"
	help
	  Provides a way to freeze and unfreeze all tasks in a
767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784
	  cgroup.

config CGROUP_DEVICE
	bool "Device controller for cgroups"
	help
	  Provides a cgroup implementing whitelists for devices which
	  a process in the cgroup can mknod or open.

config CPUSETS
	bool "Cpuset support"
	help
	  This option will let you create and manage CPUSETs which
	  allow dynamically partitioning a system into sets of CPUs and
	  Memory Nodes and assigning tasks to run only within those sets.
	  This is primarily useful on large SMP or NUMA systems.

	  Say N if unsure.

L
Li Zefan 已提交
785 786 787 788 789
config PROC_PID_CPUSET
	bool "Include legacy /proc/<pid>/cpuset file"
	depends on CPUSETS
	default y

790 791 792 793
config CGROUP_CPUACCT
	bool "Simple CPU accounting cgroup subsystem"
	help
	  Provides a simple Resource Controller for monitoring the
L
Li Zefan 已提交
794
	  total CPU consumed by the tasks in a cgroup.
795

796 797 798 799
config RESOURCE_COUNTERS
	bool "Resource counters"
	help
	  This option enables controller independent resource accounting
L
Li Zefan 已提交
800
	  infrastructure that works with cgroups.
801

A
Andrew Morton 已提交
802
config MEMCG
803
	bool "Memory Resource Controller for Control Groups"
804
	depends on RESOURCE_COUNTERS
805
	select MM_OWNER
806
	help
807
	  Provides a memory resource controller that manages both anonymous
808
	  memory and page cache. (See Documentation/cgroups/memory.txt)
809 810

	  Note that setting this option increases fixed memory overhead
811 812 813 814
	  associated with each page of memory in the system. By this,
	  20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
	  usage tracking struct at boot. Total amount of this is printed out
	  at boot.
815 816

	  Only enable when you're ok with these trade offs and really
817 818 819
	  sure you need the memory resource controller. Even when you enable
	  this, you can set "cgroup_disable=memory" at your boot option to
	  disable memory resource controller and you can avoid overheads.
L
Li Zefan 已提交
820
	  (and lose benefits of memory resource controller)
821

822 823 824
	  This config option also selects MM_OWNER config option, which
	  could in turn add some fork/exit overhead.

A
Andrew Morton 已提交
825
config MEMCG_SWAP
826
	bool "Memory Resource Controller Swap Extension"
A
Andrew Morton 已提交
827
	depends on MEMCG && SWAP
828 829 830 831 832 833 834 835 836 837 838
	help
	  Add swap management feature to memory resource controller. When you
	  enable this, you can limit mem+swap usage per cgroup. In other words,
	  when you disable this, memory resource controller has no cares to
	  usage of swap...a process can exhaust all of the swap. This extension
	  is useful when you want to avoid exhaustion swap but this itself
	  adds more overheads and consumes memory for remembering information.
	  Especially if you use 32bit system or small memory system, please
	  be careful about enabling this. When memory resource controller
	  is disabled by boot option, this will be automatically disabled and
	  there will be no overhead from this. Even when you set this config=y,
839
	  if boot option "swapaccount=0" is set, swap will not be accounted.
840 841
	  Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
	  size is 4096bytes, 512k per 1Gbytes of swap.
A
Andrew Morton 已提交
842
config MEMCG_SWAP_ENABLED
843
	bool "Memory Resource Controller Swap Extension enabled by default"
A
Andrew Morton 已提交
844
	depends on MEMCG_SWAP
845 846 847 848
	default y
	help
	  Memory Resource Controller Swap Extension comes with its price in
	  a bigger memory consumption. General purpose distribution kernels
J
Jim Cromie 已提交
849
	  which want to enable the feature but keep it disabled by default
850 851 852 853
	  and let the user enable it by swapaccount boot command line
	  parameter should have this option unselected.
	  For those who want to have the feature enabled by default should
	  select this option (if, for some reason, they need to disable it
854
	  then swapaccount=0 does the trick).
A
Andrew Morton 已提交
855
config MEMCG_KMEM
856
	bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
A
Andrew Morton 已提交
857
	depends on MEMCG && EXPERIMENTAL
858
	depends on SLUB || SLAB
859 860 861 862 863 864 865
	help
	  The Kernel Memory extension for Memory Resource Controller can limit
	  the amount of memory used by kernel objects in the system. Those are
	  fundamentally different from the entities handled by the standard
	  Memory Controller, which are page-based, and can be swapped. Users of
	  the kmem extension can use it to guarantee that no group of processes
	  will ever exhaust kernel resources alone.
866

867 868 869 870 871 872 873 874 875 876 877 878 879 880 881
config CGROUP_HUGETLB
	bool "HugeTLB Resource Controller for Control Groups"
	depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
	default n
	help
	  Provides a cgroup Resource Controller for HugeTLB pages.
	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
	  The limit is enforced during page fault. Since HugeTLB doesn't
	  support page reclaim, enforcing the limit at page fault time implies
	  that, the application will get SIGBUS signal if it tries to access
	  HugeTLB pages beyond its limit. This requires the application to know
	  beforehand how much HugeTLB pages it would require for its use. The
	  control group is tracked in the third page lru pointer. This means
	  that we cannot use the controller with huge page less than 3 pages.

S
Stephane Eranian 已提交
882 883 884 885 886
config CGROUP_PERF
	bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
	depends on PERF_EVENTS && CGROUPS
	help
	  This option extends the per-cpu mode to restrict monitoring to
887
	  threads which belong to the cgroup specified and run on the
S
Stephane Eranian 已提交
888 889 890 891
	  designated cpu.

	  Say N if unsure.

D
Dhaval Giani 已提交
892 893 894 895 896 897 898 899 900 901 902 903 904 905
menuconfig CGROUP_SCHED
	bool "Group CPU scheduler"
	default n
	help
	  This feature lets CPU scheduler recognize task groups and control CPU
	  bandwidth allocation to such task groups. It uses cgroups to group
	  tasks.

if CGROUP_SCHED
config FAIR_GROUP_SCHED
	bool "Group scheduling for SCHED_OTHER"
	depends on CGROUP_SCHED
	default CGROUP_SCHED

906 907 908 909 910 911 912 913 914 915 916 917
config CFS_BANDWIDTH
	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
	depends on EXPERIMENTAL
	depends on FAIR_GROUP_SCHED
	default n
	help
	  This option allows users to define CPU bandwidth rates (limits) for
	  tasks running within the fair group scheduler.  Groups with no limit
	  set are considered to be unconstrained and will run with no
	  restriction.
	  See tip/Documentation/scheduler/sched-bwc.txt for more information.

D
Dhaval Giani 已提交
918 919 920 921 922 923 924
config RT_GROUP_SCHED
	bool "Group scheduling for SCHED_RR/FIFO"
	depends on EXPERIMENTAL
	depends on CGROUP_SCHED
	default n
	help
	  This feature lets you explicitly allocate real CPU bandwidth
925
	  to task groups. If enabled, it will also make it impossible to
D
Dhaval Giani 已提交
926 927 928 929 930 931
	  schedule realtime tasks for non-root users until you allocate
	  realtime bandwidth for them.
	  See Documentation/scheduler/sched-rt-group.txt for more information.

endif #CGROUP_SCHED

932
config BLK_CGROUP
T
Tejun Heo 已提交
933
	bool "Block IO controller"
934
	depends on BLOCK
935 936 937 938 939 940 941 942
	default n
	---help---
	Generic block IO controller cgroup interface. This is the common
	cgroup interface which should be used by various IO controlling
	policies.

	Currently, CFQ IO scheduler uses it to recognize task groups and
	control disk bandwidth allocation (proportional time slice allocation)
943 944
	to such task groups. It is also used by bio throttling logic in
	block layer to implement upper limit in IO rates on a device.
945 946

	This option only enables generic Block IO controller infrastructure.
947
	One needs to also enable actual IO controlling logic/policy. For
M
Michael Witten 已提交
948 949
	enabling proportional weight division of disk bandwidth in CFQ, set
	CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
950
	CONFIG_BLK_DEV_THROTTLING=y.
951 952 953 954 955 956 957 958 959 960 961

	See Documentation/cgroups/blkio-controller.txt for more information.

config DEBUG_BLK_CGROUP
	bool "Enable Block IO controller debugging"
	depends on BLK_CGROUP
	default n
	---help---
	Enable some debugging help. Currently it exports additional stat
	files in a cgroup which can be useful for debugging.

L
Li Zefan 已提交
962
endif # CGROUPS
963

964 965 966 967 968 969 970 971 972 973 974
config CHECKPOINT_RESTORE
	bool "Checkpoint/restore support" if EXPERT
	default n
	help
	  Enables additional kernel features in a sake of checkpoint/restore.
	  In particular it adds auxiliary prctl codes to setup process text,
	  data and heap segment sizes, and a few additional /proc filesystem
	  entries.

	  If unsure, say N here.

975
menuconfig NAMESPACES
976 977
	bool "Namespaces support" if EXPERT
	default !EXPERT
978 979 980 981 982 983
	help
	  Provides the way to make tasks work with different objects using
	  the same id. For example same IPC id may refer to different objects
	  or same user id or pid may refer to different tasks when used in
	  different namespaces.

984 985
if NAMESPACES

986 987
config UTS_NS
	bool "UTS namespace"
988
	default y
989 990 991 992
	help
	  In this namespace tasks see different info provided with the
	  uname() system call

993 994
config IPC_NS
	bool "IPC namespace"
995
	depends on (SYSVIPC || POSIX_MQUEUE)
996
	default y
997 998
	help
	  In this namespace tasks work with IPC ids which correspond to
999
	  different IPC objects in different namespaces.
1000

1001 1002
config USER_NS
	bool "User namespace (EXPERIMENTAL)"
1003
	depends on EXPERIMENTAL
1004
	depends on UIDGID_CONVERTED
1005
	select UIDGID_STRICT_TYPE_CHECKS
1006

1007
	default n
1008 1009 1010 1011 1012
	help
	  This allows containers, i.e. vservers, to use user namespaces
	  to provide different user info for different servers.
	  If unsure, say N.

1013
config PID_NS
1014
	bool "PID Namespaces"
1015
	default y
1016
	help
1017
	  Support process id namespaces.  This allows having multiple
1018
	  processes with the same pid as long as they are in different
1019 1020
	  pid namespaces.  This is a building block of containers.

1021 1022
config NET_NS
	bool "Network namespace"
1023
	depends on NET
1024
	default y
1025 1026 1027 1028
	help
	  Allow user space to create what appear to be multiple instances
	  of the network stack.

1029 1030
endif # NAMESPACES

1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054
config UIDGID_CONVERTED
	# True if all of the selected software conmponents are known
	# to have uid_t and gid_t converted to kuid_t and kgid_t
	# where appropriate and are otherwise safe to use with
	# the user namespace.
	bool
	default y

	# Networking
	depends on NET_9P = n

	# Filesystems
	depends on 9P_FS = n
	depends on AFS_FS = n
	depends on CEPH_FS = n
	depends on CIFS = n
	depends on CODA_FS = n
	depends on GFS2_FS = n
	depends on NCP_FS = n
	depends on NFSD = n
	depends on NFS_FS = n
	depends on OCFS2_FS = n
	depends on XFS_FS = n

1055 1056
config UIDGID_STRICT_TYPE_CHECKS
	bool "Require conversions between uid/gids and their internal representation"
1057
	depends on UIDGID_CONVERTED
1058 1059 1060 1061 1062 1063 1064
	default n
	help
	 While the nececessary conversions are being added to all subsystems this option allows
	 the code to continue to build for unconverted subsystems.

	 Say Y here if you want the strict type checking enabled

1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077
config SCHED_AUTOGROUP
	bool "Automatic process group scheduling"
	select EVENTFD
	select CGROUPS
	select CGROUP_SCHED
	select FAIR_GROUP_SCHED
	help
	  This option optimizes the scheduler for common desktop workloads by
	  automatically creating and populating task groups.  This separation
	  of workloads isolates aggressive CPU burners (like build jobs) from
	  desktop applications.  Task group autogeneration is currently based
	  upon task session.

1078 1079 1080 1081
config MM_OWNER
	bool

config SYSFS_DEPRECATED
1082
	bool "Enable deprecated sysfs features to support old userspace tools"
1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104
	depends on SYSFS
	default n
	help
	  This option adds code that switches the layout of the "block" class
	  devices, to not show up in /sys/class/block/, but only in
	  /sys/block/.

	  This switch is only active when the sysfs.deprecated=1 boot option is
	  passed or the SYSFS_DEPRECATED_V2 option is set.

	  This option allows new kernels to run on old distributions and tools,
	  which might get confused by /sys/class/block/. Since 2007/2008 all
	  major distributions and tools handle this just fine.

	  Recent distributions and userspace tools after 2009/2010 depend on
	  the existence of /sys/class/block/, and will not work with this
	  option enabled.

	  Only if you are using a new kernel on an old distribution, you might
	  need to say Y here.

config SYSFS_DEPRECATED_V2
1105
	bool "Enable deprecated sysfs features by default"
1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129
	default n
	depends on SYSFS
	depends on SYSFS_DEPRECATED
	help
	  Enable deprecated sysfs by default.

	  See the CONFIG_SYSFS_DEPRECATED option for more details about this
	  option.

	  Only if you are using a new kernel on an old distribution, you might
	  need to say Y here. Even then, odds are you would not need it
	  enabled, you can always pass the boot option if absolutely necessary.

config RELAY
	bool "Kernel->user space relay support (formerly relayfs)"
	help
	  This option enables support for relay interface support in
	  certain file systems (such as debugfs).
	  It is designed to provide an efficient mechanism for tools and
	  facilities to relay large amounts of data from kernel space to
	  user space.

	  If unsure, say N.

1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145
config BLK_DEV_INITRD
	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
	depends on BROKEN || !FRV
	help
	  The initial RAM filesystem is a ramfs which is loaded by the
	  boot loader (loadlin or lilo) and that is mounted as root
	  before the normal boot procedure. It is typically used to
	  load modules needed to mount the "real" root file system,
	  etc. See <file:Documentation/initrd.txt> for details.

	  If RAM disk support (BLK_DEV_RAM) is also included, this
	  also enables initial RAM disk (initrd) support and adds
	  15 Kbytes (more on some other architectures) to the kernel size.

	  If unsure say Y.

1146 1147
if BLK_DEV_INITRD

1148 1149
source "usr/Kconfig"

1150 1151
endif

1152
config CC_OPTIMIZE_FOR_SIZE
1153
	bool "Optimize for size"
1154 1155 1156 1157
	help
	  Enabling this option will pass "-Os" instead of "-O2" to gcc
	  resulting in a smaller kernel.

1158
	  If unsure, say Y.
1159

R
Randy Dunlap 已提交
1160 1161 1162
config SYSCTL
	bool

R
Randy Dunlap 已提交
1163 1164 1165
config ANON_INODES
	bool

1166 1167
menuconfig EXPERT
	bool "Configure standard kernel features (expert users)"
1168 1169
	# Unhide debug options, to make the on-by-default options visible
	select DEBUG_KERNEL
L
Linus Torvalds 已提交
1170 1171 1172 1173 1174 1175
	help
	  This option allows certain base kernel options and settings
          to be disabled or tweaked. This is for specialized
          environments which can tolerate a "non-standard" kernel.
          Only use this if you really know what you are doing.

1176 1177 1178
config HAVE_UID16
	bool

1179
config UID16
1180
	bool "Enable 16-bit UID system calls" if EXPERT
1181
	depends on HAVE_UID16
1182 1183 1184 1185
	default y
	help
	  This enables the legacy 16-bit UID syscall wrappers.

1186
config SYSCTL_SYSCALL
1187
	bool "Sysctl syscall support" if EXPERT
1188
	depends on PROC_SYSCTL
1189
	default n
1190
	select SYSCTL
1191
	---help---
1192 1193 1194 1195
	  sys_sysctl uses binary paths that have been found challenging
	  to properly maintain and use.  The interface in /proc/sys
	  using paths with ascii names is now the primary path to this
	  information.
1196

1197 1198 1199
	  Almost nothing using the binary sysctl interface so if you are
	  trying to save some space it is probably safe to disable this,
	  making your kernel marginally smaller.
1200

1201
	  If unsure say N here.
1202

1203 1204 1205 1206 1207
config SYSCTL_EXCEPTION_TRACE
	bool
	help
	  Enable support for /proc/sys/debug/exception-trace.

L
Linus Torvalds 已提交
1208
config KALLSYMS
1209
	 bool "Load all symbols for debugging/ksymoops" if EXPERT
L
Linus Torvalds 已提交
1210 1211 1212 1213 1214 1215 1216 1217 1218 1219
	 default y
	 help
	   Say Y here to let the kernel print out symbolic crash information and
	   symbolic stack backtraces. This increases the size of the kernel
	   somewhat, as all symbols have to be loaded into the kernel image.

config KALLSYMS_ALL
	bool "Include all symbols in kallsyms"
	depends on DEBUG_KERNEL && KALLSYMS
	help
1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231
	   Normally kallsyms only contains the symbols of functions for nicer
	   OOPS messages and backtraces (i.e., symbols from the text and inittext
	   sections). This is sufficient for most cases. And only in very rare
	   cases (e.g., when a debugger is used) all symbols are required (e.g.,
	   names of variables from the data sections, etc).

	   This option makes sure that all symbols are loaded into the kernel
	   image (i.e., symbols from all sections) in cost of increased kernel
	   size (depending on the kernel configuration, it may be 300KiB or
	   something like this).

	   Say N unless you really need all symbols.
M
Matt Mackall 已提交
1232

1233
config HOTPLUG
1234
	def_bool y
1235

M
Matt Mackall 已提交
1236 1237
config PRINTK
	default y
1238
	bool "Enable support for printk" if EXPERT
M
Matt Mackall 已提交
1239 1240 1241 1242 1243 1244 1245
	help
	  This option enables normal printk support. Removing it
	  eliminates most of the message strings from the kernel image
	  and makes the kernel more or less silent. As this makes it
	  very difficult to diagnose system problems, saying N here is
	  strongly discouraged.

M
Matt Mackall 已提交
1246
config BUG
1247
	bool "BUG() support" if EXPERT
M
Matt Mackall 已提交
1248 1249 1250 1251 1252 1253 1254 1255
	default y
	help
          Disabling this option eliminates support for BUG and WARN, reducing
          the size of your kernel image and potentially quietly ignoring
          numerous fatal conditions. You should only consider disabling this
          option for embedded systems with no facilities for reporting errors.
          Just say Y.

1256
config ELF_CORE
1257
	depends on COREDUMP
1258
	default y
1259
	bool "Enable ELF core dumps" if EXPERT
1260 1261 1262
	help
	  Enable support for generating core dumps. Disabling saves about 4k.

1263

S
Stas Sergeev 已提交
1264
config PCSPKR_PLATFORM
1265
	bool "Enable PC-Speaker support" if EXPERT
1266
	depends on HAVE_PCSPKR_PLATFORM
1267
	select I8253_LOCK
S
Stas Sergeev 已提交
1268 1269 1270 1271 1272
	default y
	help
          This option allows to disable the internal PC-Speaker
          support, saving some memory.

1273 1274 1275
config HAVE_PCSPKR_PLATFORM
	bool

L
Linus Torvalds 已提交
1276 1277
config BASE_FULL
	default y
1278
	bool "Enable full-sized data structures for core" if EXPERT
L
Linus Torvalds 已提交
1279 1280 1281 1282 1283 1284
	help
	  Disabling this option reduces the size of miscellaneous core
	  kernel data structures. This saves memory on small machines,
	  but may reduce performance.

config FUTEX
1285
	bool "Enable futex support" if EXPERT
L
Linus Torvalds 已提交
1286
	default y
I
Ingo Molnar 已提交
1287
	select RT_MUTEXES
L
Linus Torvalds 已提交
1288 1289 1290 1291 1292 1293
	help
	  Disabling this option will cause the kernel to be built without
	  support for "fast userspace mutexes".  The resulting kernel may not
	  run glibc-based applications correctly.

config EPOLL
1294
	bool "Enable eventpoll support" if EXPERT
L
Linus Torvalds 已提交
1295
	default y
1296
	select ANON_INODES
L
Linus Torvalds 已提交
1297 1298 1299 1300
	help
	  Disabling this option will cause the kernel to be built without
	  support for epoll family of system calls.

1301
config SIGNALFD
1302
	bool "Enable signalfd() system call" if EXPERT
1303
	select ANON_INODES
1304 1305 1306 1307 1308 1309 1310
	default y
	help
	  Enable the signalfd() system call that allows to receive signals
	  on a file descriptor.

	  If unsure, say Y.

1311
config TIMERFD
1312
	bool "Enable timerfd() system call" if EXPERT
1313
	select ANON_INODES
1314 1315 1316 1317 1318 1319 1320
	default y
	help
	  Enable the timerfd() system call that allows to receive timer
	  events on a file descriptor.

	  If unsure, say Y.

1321
config EVENTFD
1322
	bool "Enable eventfd() system call" if EXPERT
1323
	select ANON_INODES
1324 1325 1326 1327 1328 1329 1330
	default y
	help
	  Enable the eventfd() system call that allows to receive both
	  kernel notification (ie. KAIO) or userspace notifications.

	  If unsure, say Y.

L
Linus Torvalds 已提交
1331
config SHMEM
1332
	bool "Use full shmem filesystem" if EXPERT
L
Linus Torvalds 已提交
1333 1334 1335 1336 1337 1338 1339 1340 1341
	default y
	depends on MMU
	help
	  The shmem is an internal filesystem used to manage shared memory.
	  It is backed by swap and manages resource limits. It is also exported
	  to userspace as tmpfs if TMPFS is enabled. Disabling this
	  option replaces shmem and tmpfs with the much simpler ramfs code,
	  which may be appropriate on small systems without swap.

T
Thomas Petazzoni 已提交
1342
config AIO
1343
	bool "Enable AIO support" if EXPERT
T
Thomas Petazzoni 已提交
1344 1345 1346 1347 1348 1349
	default y
	help
	  This option enables POSIX asynchronous I/O which may by used
          by some high performance threaded applications. Disabling
          this option saves about 7k.

1350 1351 1352 1353 1354 1355 1356 1357
config EMBEDDED
	bool "Embedded system"
	select EXPERT
	help
	  This option should be enabled if compiling the kernel for
	  an embedded system so certain expert options are available
	  for configuration.

1358
config HAVE_PERF_EVENTS
T
Thomas Gleixner 已提交
1359
	bool
1360 1361
	help
	  See tools/perf/design.txt for details.
T
Thomas Gleixner 已提交
1362

1363 1364 1365 1366 1367
config PERF_USE_VMALLOC
	bool
	help
	  See tools/perf/design.txt for details

I
Ingo Molnar 已提交
1368
menu "Kernel Performance Events And Counters"
T
Thomas Gleixner 已提交
1369

1370
config PERF_EVENTS
I
Ingo Molnar 已提交
1371
	bool "Kernel performance events and counters"
1372
	default y if PROFILING
1373
	depends on HAVE_PERF_EVENTS
I
Ingo Molnar 已提交
1374
	select ANON_INODES
1375
	select IRQ_WORK
T
Thomas Gleixner 已提交
1376
	help
I
Ingo Molnar 已提交
1377 1378
	  Enable kernel support for various performance events provided
	  by software and hardware.
T
Thomas Gleixner 已提交
1379

1380
	  Software events are supported either built-in or via the
I
Ingo Molnar 已提交
1381
	  use of generic tracepoints.
T
Thomas Gleixner 已提交
1382

I
Ingo Molnar 已提交
1383 1384
	  Most modern CPUs support performance events via performance
	  counter registers. These registers count the number of certain
T
Thomas Gleixner 已提交
1385 1386 1387 1388 1389 1390
	  types of hw events: such as instructions executed, cachemisses
	  suffered, or branches mis-predicted - without slowing down the
	  kernel or applications. These registers can also trigger interrupts
	  when a threshold number of events have passed - and can thus be
	  used to profile the code that runs on that CPU.

I
Ingo Molnar 已提交
1391
	  The Linux Performance Event subsystem provides an abstraction of
1392
	  these software and hardware event capabilities, available via a
I
Ingo Molnar 已提交
1393
	  system call and used by the "perf" utility in tools/perf/. It
T
Thomas Gleixner 已提交
1394 1395 1396 1397 1398
	  provides per task and per CPU counters, and it provides event
	  capabilities on top of those.

	  Say Y if unsure.

1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411
config DEBUG_PERF_USE_VMALLOC
	default n
	bool "Debug: use vmalloc to back perf mmap() buffers"
	depends on PERF_EVENTS && DEBUG_KERNEL
	select PERF_USE_VMALLOC
	help
	 Use vmalloc memory to back perf mmap() buffers.

	 Mostly useful for debugging the vmalloc code on platforms
	 that don't require it.

	 Say N if unsure.

T
Thomas Gleixner 已提交
1412 1413
endmenu

1414 1415
config VM_EVENT_COUNTERS
	default y
1416
	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1417
	help
1418 1419
	  VM event counters are needed for event counts to be shown.
	  This option allows the disabling of the VM event counters
1420
	  on EXPERT systems.  /proc/vmstat will only show page counts
1421
	  if VM event counters are disabled.
1422

1423 1424
config PCI_QUIRKS
	default y
1425
	bool "Enable PCI quirk workarounds" if EXPERT
1426
	depends on PCI
1427 1428 1429 1430 1431
	help
	  This enables workarounds for various PCI chipset
          bugs/quirks. Disable this only if your target machine is
          unaffected by PCI quirks.

C
Christoph Lameter 已提交
1432 1433
config SLUB_DEBUG
	default y
1434
	bool "Enable SLUB debugging support" if EXPERT
C
Christoph Lameter 已提交
1435
	depends on SLUB && SYSFS
C
Christoph Lameter 已提交
1436 1437 1438 1439 1440 1441
	help
	  SLUB has extensive debug support features. Disabling these can
	  result in significant savings in code size. This also disables
	  SLUB sysfs support. /sys/slab will not exist and there will be
	  no support for cache validation etc.

R
Randy Dunlap 已提交
1442 1443 1444 1445 1446 1447 1448
config COMPAT_BRK
	bool "Disable heap randomization"
	default y
	help
	  Randomizing heap placement makes heap exploits harder, but it
	  also breaks ancient binaries (including anything libc5 based).
	  This option changes the bootup default to heap randomization
1449
	  disabled, and can be overridden at runtime by setting
R
Randy Dunlap 已提交
1450 1451 1452 1453
	  /proc/sys/kernel/randomize_va_space to 2.

	  On non-ancient distros (post-2000 ones) N is usually a safe choice.

C
Christoph Lameter 已提交
1454 1455
choice
	prompt "Choose SLAB allocator"
1456
	default SLUB
C
Christoph Lameter 已提交
1457 1458 1459 1460 1461 1462 1463
	help
	   This option allows to select a slab allocator.

config SLAB
	bool "SLAB"
	help
	  The regular slab allocator that is established and known to work
1464
	  well in all environments. It organizes cache hot objects in
1465
	  per cpu and per node queues.
C
Christoph Lameter 已提交
1466 1467 1468 1469 1470 1471 1472 1473

config SLUB
	bool "SLUB (Unqueued Allocator)"
	help
	   SLUB is a slab allocator that minimizes cache line usage
	   instead of managing queues of cached objects (SLAB approach).
	   Per cpu caching is realized using slabs of objects instead
	   of queues of objects. SLUB can use memory efficiently
1474 1475
	   and has enhanced diagnostics. SLUB is the default choice for
	   a slab allocator.
C
Christoph Lameter 已提交
1476 1477

config SLOB
1478
	depends on EXPERT
C
Christoph Lameter 已提交
1479 1480
	bool "SLOB (Simple Allocator)"
	help
M
Matt Mackall 已提交
1481 1482 1483
	   SLOB replaces the stock allocator with a drastically simpler
	   allocator. SLOB is generally more space efficient but
	   does not perform as well on large systems.
C
Christoph Lameter 已提交
1484 1485 1486

endchoice

1487 1488
config MMAP_ALLOW_UNINITIALIZED
	bool "Allow mmapped anonymous memory to be uninitialized"
1489
	depends on EXPERT && !MMU
1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508
	default n
	help
	  Normally, and according to the Linux spec, anonymous memory obtained
	  from mmap() has it's contents cleared before it is passed to
	  userspace.  Enabling this config option allows you to request that
	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
	  providing a huge performance boost.  If this option is not enabled,
	  then the flag will be ignored.

	  This is taken advantage of by uClibc's malloc(), and also by
	  ELF-FDPIC binfmt's brk and stack allocator.

	  Because of the obvious security issues, this option should only be
	  enabled on embedded devices where you control what is run in
	  userspace.  Since that isn't generally a problem on no-MMU systems,
	  it is normally safe to say Y here.

	  See Documentation/nommu-mmap.txt for more information.

1509
config PROFILING
1510
	bool "Profiling support"
1511 1512 1513 1514
	help
	  Say Y here to enable the extended profiling support mechanisms used
	  by profilers such as OProfile.

1515 1516 1517 1518
#
# Place an empty function call at each tracepoint site. Can be
# dynamically changed for a probe function.
#
M
Mathieu Desnoyers 已提交
1519
config TRACEPOINTS
1520
	bool
M
Mathieu Desnoyers 已提交
1521

M
Mathieu Desnoyers 已提交
1522 1523
source "arch/Kconfig"

L
Linus Torvalds 已提交
1524 1525
endmenu		# General setup

1526 1527 1528 1529
config HAVE_GENERIC_DMA_COHERENT
	bool
	default n

1530 1531 1532
config SLABINFO
	bool
	depends on PROC_FS
1533
	depends on SLAB || SLUB_DEBUG
1534 1535
	default y

1536 1537 1538
config RT_MUTEXES
	boolean

L
Linus Torvalds 已提交
1539 1540 1541 1542 1543
config BASE_SMALL
	int
	default 0 if BASE_FULL
	default 1 if !BASE_FULL

1544
menuconfig MODULES
L
Linus Torvalds 已提交
1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563
	bool "Enable loadable module support"
	help
	  Kernel modules are small pieces of compiled code which can
	  be inserted in the running kernel, rather than being
	  permanently built into the kernel.  You use the "modprobe"
	  tool to add (and sometimes remove) them.  If you say Y here,
	  many parts of the kernel can be built as modules (by
	  answering M instead of Y where indicated): this is most
	  useful for infrequently used options which are not required
	  for booting.  For more information, see the man pages for
	  modprobe, lsmod, modinfo, insmod and rmmod.

	  If you say Y here, you will need to run "make
	  modules_install" to put the modules under /lib/modules/
	  where modprobe can find them (you may need to be root to do
	  this).

	  If unsure, say Y.

1564 1565
if MODULES

1566 1567 1568 1569
config MODULE_FORCE_LOAD
	bool "Forced module loading"
	default n
	help
1570 1571 1572
	  Allow loading of modules without version information (ie. modprobe
	  --force).  Forced module loading sets the 'F' (forced) taint flag and
	  is usually a really bad idea.
1573

L
Linus Torvalds 已提交
1574 1575 1576 1577 1578
config MODULE_UNLOAD
	bool "Module unloading"
	help
	  Without this option you will not be able to unload any
	  modules (note that some modules may not be unloadable
1579 1580
	  anyway), which makes your kernel smaller, faster
	  and simpler.  If unsure, say Y.
L
Linus Torvalds 已提交
1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592

config MODULE_FORCE_UNLOAD
	bool "Forced module unloading"
	depends on MODULE_UNLOAD && EXPERIMENTAL
	help
	  This option allows you to force a module to unload, even if the
	  kernel believes it is unsafe: the kernel will remove the module
	  without waiting for anyone to stop using it (using the -f option to
	  rmmod).  This is mainly for kernel developers and desperate users.
	  If unsure, say N.

config MODVERSIONS
1593
	bool "Module versioning support"
L
Linus Torvalds 已提交
1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612
	help
	  Usually, you have to use modules compiled with your kernel.
	  Saying Y here makes it sometimes possible to use modules
	  compiled for different kernels, by adding enough information
	  to the modules to (hopefully) spot any changes which would
	  make them incompatible with the kernel you are running.  If
	  unsure, say N.

config MODULE_SRCVERSION_ALL
	bool "Source checksum for all modules"
	help
	  Modules which contain a MODULE_VERSION get an extra "srcversion"
	  field inserted into their modinfo section, which contains a
    	  sum of the source files which made it.  This helps maintainers
	  see exactly which source was used to build a module (since
	  others sometimes change the module source without updating
	  the version).  With this option, such a "srcversion" field
	  will be created for all modules.  If unsure, say N.

R
Rusty Russell 已提交
1613 1614 1615
config MODULE_SIG
	bool "Module signature verification"
	depends on MODULES
1616 1617 1618 1619 1620 1621 1622 1623
	select KEYS
	select CRYPTO
	select ASYMMETRIC_KEY_TYPE
	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
	select PUBLIC_KEY_ALGO_RSA
	select ASN1
	select OID_REGISTRY
	select X509_CERTIFICATE_PARSER
R
Rusty Russell 已提交
1624 1625 1626 1627 1628
	help
	  Check modules for valid signatures upon load: the signature
	  is simply appended to the module. For more information see
	  Documentation/module-signing.txt.

D
David Howells 已提交
1629 1630 1631 1632 1633
	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
	  module DOES NOT get stripped after being signed.  This includes the
	  debuginfo strip done by some packagers (such as rpmbuild) and
	  inclusion into an initramfs that wants the module size reduced.

R
Rusty Russell 已提交
1634 1635 1636 1637 1638 1639
config MODULE_SIG_FORCE
	bool "Require modules to be validly signed"
	depends on MODULE_SIG
	help
	  Reject unsigned modules or signed modules for which we don't have a
	  key.  Without this, such modules will simply taint the kernel.
D
David Howells 已提交
1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672

choice
	prompt "Which hash algorithm should modules be signed with?"
	depends on MODULE_SIG
	help
	  This determines which sort of hashing algorithm will be used during
	  signature generation.  This algorithm _must_ be built into the kernel
	  directly so that signature verification can take place.  It is not
	  possible to load a signed module containing the algorithm to check
	  the signature on that module.

config MODULE_SIG_SHA1
	bool "Sign modules with SHA-1"
	select CRYPTO_SHA1

config MODULE_SIG_SHA224
	bool "Sign modules with SHA-224"
	select CRYPTO_SHA256

config MODULE_SIG_SHA256
	bool "Sign modules with SHA-256"
	select CRYPTO_SHA256

config MODULE_SIG_SHA384
	bool "Sign modules with SHA-384"
	select CRYPTO_SHA512

config MODULE_SIG_SHA512
	bool "Sign modules with SHA-512"
	select CRYPTO_SHA512

endchoice

1673 1674
endif # MODULES

1675 1676 1677
config INIT_ALL_POSSIBLE
	bool
	help
1678 1679
	  Back when each arch used to define their own cpu_online_mask and
	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1680 1681
	  with all 1s, and others with all 0s.  When they were centralised,
	  it was better to provide this option than to break all the archs
1682
	  and have several arch maintainers pursuing me down dark alleys.
1683

L
Linus Torvalds 已提交
1684 1685 1686 1687 1688 1689
config STOP_MACHINE
	bool
	default y
	depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
	help
	  Need stop_machine() primitive.
1690 1691

source "block/Kconfig"
1692 1693 1694

config PREEMPT_NOTIFIERS
	bool
P
Paul E. McKenney 已提交
1695

1696 1697 1698 1699
config PADATA
	depends on SMP
	bool

1700 1701 1702 1703 1704 1705
# Can be selected by architectures with broken toolchains
# that get confused by correct const<->read_only section
# mappings
config BROKEN_RODATA
	bool

1706 1707 1708 1709 1710 1711 1712 1713
config ASN1
	tristate
	help
	  Build a simple ASN.1 grammar compiler that produces a bytecode output
	  that can be interpreted by the ASN.1 stream decoder and used to
	  inform it as to what tags are to be expected in a stream and what
	  functions to call on what tags.

1714
source "kernel/Kconfig.locks"