Kconfig 49.3 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 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75

config EXPERIMENTAL
	bool "Prompt for development and/or incomplete code/drivers"
	---help---
	  Some of the various things that Linux supports (such as network
	  drivers, file systems, network protocols, etc.) can be in a state
	  of development where the functionality, stability, or the level of
	  testing is not yet high enough for general use. This is usually
	  known as the "alpha-test" phase among developers. If a feature is
	  currently in alpha-test, then the developers usually discourage
	  uninformed widespread use of this feature by the general public to
	  avoid "Why doesn't this work?" type mail messages. However, active
	  testing and use of these systems is welcomed. Just be aware that it
	  may not meet the normal level of reliability or it may fail to work
	  in some special cases. Detailed bug reports from people familiar
	  with the kernel internals are usually welcomed by the developers
	  (before submitting bug reports, please read the documents
	  <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
	  <file:Documentation/BUG-HUNTING>, and
	  <file:Documentation/oops-tracing.txt> in the kernel source).

	  This option will also make obsoleted drivers available. These are
	  drivers that have been replaced by something else, and/or are
	  scheduled to be removed in a future kernel release.

	  Unless you intend to help test and develop a feature or driver that
	  falls into this category, or you have a situation that requires
	  using these features, you should probably say N here, which will
	  cause the configurator to present you with fewer choices. If
	  you say Y here, you will be offered the choice of using features or
	  drivers that are currently considered to be in the alpha-test phase.

config BROKEN
	bool

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

config INIT_ENV_ARG_LIMIT
	int
76 77
	default 32 if !UML
	default 128 if UML
L
Linus Torvalds 已提交
78
	help
79 80
	  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
81 82


R
Roland McGrath 已提交
83 84 85 86 87 88 89 90
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
91 92 93 94 95 96 97 98 99 100
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.

101 102 103 104 105
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
106 107
	  release tree by looking for git tags that belong to the current
	  top of tree revision.
108 109

	  A string of the format -gxxxxxxxx will be added to the localversion
110
	  if a git-based tree is found.  The string generated by this will be
111
	  appended after any matching localversion* files, and after the value
112
	  set in CONFIG_LOCALVERSION.
113

114 115 116 117 118 119
	  (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".)
120

121 122 123 124 125 126 127 128 129
config HAVE_KERNEL_GZIP
	bool

config HAVE_KERNEL_BZIP2
	bool

config HAVE_KERNEL_LZMA
	bool

130 131 132
config HAVE_KERNEL_XZ
	bool

133 134 135
config HAVE_KERNEL_LZO
	bool

136
choice
137 138
	prompt "Kernel compression mode"
	default KERNEL_GZIP
139
	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
140
	help
141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158
	  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
159 160 161
	bool "Gzip"
	depends on HAVE_KERNEL_GZIP
	help
162 163
	  The old and tried gzip compression. It provides a good balance
	  between compression ratio and decompression speed.
164 165 166

config KERNEL_BZIP2
	bool "Bzip2"
167
	depends on HAVE_KERNEL_BZIP2
168 169
	help
	  Its compression ratio and speed is intermediate.
170
	  Decompression speed is slowest among the choices.  The kernel
171 172 173
	  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.
174 175

config KERNEL_LZMA
176 177 178
	bool "LZMA"
	depends on HAVE_KERNEL_LZMA
	help
179 180 181
	  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.
182

183 184 185 186 187 188 189 190 191 192 193 194 195 196 197
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.

198 199 200 201
config KERNEL_LZO
	bool "LZO"
	depends on HAVE_KERNEL_LZO
	help
202
	  Its compression ratio is the poorest among the choices. The kernel
S
Stephan Sperber 已提交
203
	  size is about 10% bigger than gzip; however its speed
204 205
	  (both compression and decompression) is the fastest.

206 207
endchoice

208 209 210 211 212 213 214 215 216
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
217 218
config SWAP
	bool "Support for paging of anonymous memory (swap)"
219
	depends on MMU && BLOCK
L
Linus Torvalds 已提交
220 221 222
	default y
	help
	  This option allows you to choose whether you want to have support
223
	  for so called swap devices or swap files in your kernel that are
L
Linus Torvalds 已提交
224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241
	  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>.

242 243 244 245 246 247
config SYSVIPC_SYSCTL
	bool
	depends on SYSVIPC
	depends on SYSCTL
	default y

L
Linus Torvalds 已提交
248 249 250 251 252 253 254 255
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
256
	  queues (functions mq_*) say Y here.
L
Linus Torvalds 已提交
257 258 259 260 261 262 263

	  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.

264 265 266 267 268 269
config POSIX_MQUEUE_SYSCTL
	bool
	depends on POSIX_MQUEUE
	depends on SYSCTL
	default y

L
Linus Torvalds 已提交
270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292
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
293
	  at <http://www.gnu.org/software/acct/>.
L
Linus Torvalds 已提交
294

295 296 297 298 299 300 301 302 303 304 305 306
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.

307 308 309 310 311 312 313 314 315 316 317 318 319
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.

320 321
config TASK_DELAY_ACCT
	bool "Enable per-task delay accounting (EXPERIMENTAL)"
322
	depends on TASKSTATS
323 324 325 326 327 328 329 330
	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.

331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348
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.

L
Linus Torvalds 已提交
349 350
config AUDIT
	bool "Auditing support"
C
Chris Wright 已提交
351
	depends on NET
L
Linus Torvalds 已提交
352 353 354 355 356 357 358 359
	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"
360
	depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
L
Linus Torvalds 已提交
361 362 363 364
	default y if SECURITY_SELINUX
	help
	  Enable low-overhead system-call auditing infrastructure that
	  can be used independently or with another kernel subsystem,
365
	  such as SELinux.
L
Linus Torvalds 已提交
366

E
Eric Paris 已提交
367 368 369 370
config AUDIT_WATCH
	def_bool y
	depends on AUDITSYSCALL
	select FSNOTIFY
L
Linus Torvalds 已提交
371

A
Al Viro 已提交
372 373
config AUDIT_TREE
	def_bool y
374
	depends on AUDITSYSCALL
375
	select FSNOTIFY
A
Al Viro 已提交
376

377 378 379 380
config AUDIT_LOGINUID_IMMUTABLE
	bool "Make audit loginuid immutable"
	depends on AUDIT
	help
381
	  The config option toggles if a task setting its loginuid requires
382 383 384 385 386 387 388 389 390
	  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.

T
Thomas Gleixner 已提交
391
source "kernel/irq/Kconfig"
392
source "kernel/time/Kconfig"
T
Thomas Gleixner 已提交
393

M
Mike Travis 已提交
394 395 396 397
menu "RCU Subsystem"

choice
	prompt "RCU Implementation"
P
Paul E. McKenney 已提交
398
	default TREE_RCU
M
Mike Travis 已提交
399 400 401

config TREE_RCU
	bool "Tree-based hierarchical RCU"
402
	depends on !PREEMPT && SMP
M
Mike Travis 已提交
403 404 405
	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
406 407
	  thousands of CPUs.  It also scales down nicely to
	  smaller systems.
M
Mike Travis 已提交
408

409
config TREE_PREEMPT_RCU
P
Paul E. McKenney 已提交
410
	bool "Preemptible tree-based hierarchical RCU"
411
	depends on PREEMPT && SMP
412 413 414 415
	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
416 417
	  is also required.  It also scales down nicely to
	  smaller systems.
418

419 420
config TINY_RCU
	bool "UP-only small-memory-footprint RCU"
421
	depends on !PREEMPT && !SMP
422 423 424 425 426 427
	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
428 429
config TINY_PREEMPT_RCU
	bool "Preemptible UP-only small-memory-footprint RCU"
430
	depends on PREEMPT && !SMP
P
Paul E. McKenney 已提交
431 432 433 434 435
	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
436 437
endchoice

P
Paul E. McKenney 已提交
438 439 440 441 442 443
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.

M
Mike Travis 已提交
444 445 446 447
config RCU_FANOUT
	int "Tree-based hierarchical RCU fanout value"
	range 2 64 if 64BIT
	range 2 32 if !64BIT
448
	depends on TREE_RCU || TREE_PREEMPT_RCU
M
Mike Travis 已提交
449 450 451 452 453
	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
454 455 456 457 458 459
	  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
460 461 462 463

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

464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490
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
491 492
config RCU_FANOUT_EXACT
	bool "Disable tree-based hierarchical RCU auto-balancing"
493
	depends on TREE_RCU || TREE_PREEMPT_RCU
M
Mike Travis 已提交
494 495 496 497 498 499 500 501 502 503 504
	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.

505 506
config RCU_FAST_NO_HZ
	bool "Accelerate last non-dyntick-idle CPU's grace periods"
507
	depends on NO_HZ && SMP
508 509 510
	default n
	help
	  This option causes RCU to attempt to accelerate grace periods
511 512 513 514
	  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, particularly on systems with
	  large numbers of CPUs.
515 516 517 518 519 520

	  Say Y if energy efficiency is critically important, particularly
	  	if you have relatively few CPUs.

	  Say N if you are unsure.

M
Mike Travis 已提交
521
config TREE_RCU_TRACE
522
	def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
M
Mike Travis 已提交
523 524
	select DEBUG_FS
	help
525 526 527
	  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
528

529 530
config RCU_BOOST
	bool "Enable RCU priority boosting"
531
	depends on RT_MUTEXES && PREEMPT_RCU
532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547
	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
548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566
	  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.
567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582

	  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.

M
Mike Travis 已提交
583 584
endmenu # "RCU Subsystem"

L
Linus Torvalds 已提交
585
config IKCONFIG
586
	tristate "Kernel .config support"
L
Linus Torvalds 已提交
587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603
	---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.

604 605 606
config LOG_BUF_SHIFT
	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
	range 12 21
A
Adrian Bunk 已提交
607
	default 17
608 609
	help
	  Select kernel log buffer size as a power of 2.
A
Adrian Bunk 已提交
610 611 612 613 614
	  Examples:
	  	     17 => 128 KB
		     16 => 64 KB
	             15 => 32 KB
	             14 => 16 KB
615 616 617
		     13 =>  8 KB
		     12 =>  4 KB

618 619 620 621 622 623
#
# Architectures with an unreliable sched_clock() should select this:
#
config HAVE_UNSTABLE_SCHED_CLOCK
	bool

L
Li Zefan 已提交
624 625
menuconfig CGROUPS
	boolean "Control Group support"
626
	depends on EVENTFD
627
	help
L
Li Zefan 已提交
628
	  This option adds support for grouping sets of processes together, for
629 630 631 632
	  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
633 634
		- Documentation/cgroups/ (features for grouping, isolation
					  and resource control)
635 636 637

	  Say N if unsure.

L
Li Zefan 已提交
638 639
if CGROUPS

640 641 642 643 644 645
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
646
	  framework.
647

L
Li Zefan 已提交
648
	  Say N if unsure.
649 650

config CGROUP_FREEZER
L
Li Zefan 已提交
651 652 653
	bool "Freezer cgroup subsystem"
	help
	  Provides a way to freeze and unfreeze all tasks in a
654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671
	  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
672 673 674 675 676
config PROC_PID_CPUSET
	bool "Include legacy /proc/<pid>/cpuset file"
	depends on CPUSETS
	default y

677 678 679 680
config CGROUP_CPUACCT
	bool "Simple CPU accounting cgroup subsystem"
	help
	  Provides a simple Resource Controller for monitoring the
L
Li Zefan 已提交
681
	  total CPU consumed by the tasks in a cgroup.
682

683 684 685 686
config RESOURCE_COUNTERS
	bool "Resource counters"
	help
	  This option enables controller independent resource accounting
L
Li Zefan 已提交
687
	  infrastructure that works with cgroups.
688

A
Andrew Morton 已提交
689
config MEMCG
690
	bool "Memory Resource Controller for Control Groups"
691
	depends on RESOURCE_COUNTERS
692
	select MM_OWNER
693
	help
694
	  Provides a memory resource controller that manages both anonymous
695
	  memory and page cache. (See Documentation/cgroups/memory.txt)
696 697

	  Note that setting this option increases fixed memory overhead
698 699 700 701
	  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.
702 703

	  Only enable when you're ok with these trade offs and really
704 705 706
	  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
707
	  (and lose benefits of memory resource controller)
708

709 710 711
	  This config option also selects MM_OWNER config option, which
	  could in turn add some fork/exit overhead.

A
Andrew Morton 已提交
712
config MEMCG_SWAP
713
	bool "Memory Resource Controller Swap Extension"
A
Andrew Morton 已提交
714
	depends on MEMCG && SWAP
715 716 717 718 719 720 721 722 723 724 725
	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,
726
	  if boot option "swapaccount=0" is set, swap will not be accounted.
727 728
	  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
729
config MEMCG_SWAP_ENABLED
730
	bool "Memory Resource Controller Swap Extension enabled by default"
A
Andrew Morton 已提交
731
	depends on MEMCG_SWAP
732 733 734 735
	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
736
	  which want to enable the feature but keep it disabled by default
737 738 739 740
	  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
741
	  then swapaccount=0 does the trick).
A
Andrew Morton 已提交
742
config MEMCG_KMEM
743
	bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
A
Andrew Morton 已提交
744
	depends on MEMCG && EXPERIMENTAL
745 746 747 748 749 750 751 752
	default n
	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.
753

754 755 756 757 758 759 760 761 762 763 764 765 766 767 768
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
769 770 771 772 773
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
774
	  threads which belong to the cgroup specified and run on the
S
Stephane Eranian 已提交
775 776 777 778
	  designated cpu.

	  Say N if unsure.

D
Dhaval Giani 已提交
779 780 781 782 783 784 785 786 787 788 789 790 791 792
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

793 794 795 796 797 798 799 800 801 802 803 804
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
805 806 807 808 809 810 811
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
812
	  to task groups. If enabled, it will also make it impossible to
D
Dhaval Giani 已提交
813 814 815 816 817 818
	  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

819
config BLK_CGROUP
T
Tejun Heo 已提交
820
	bool "Block IO controller"
821
	depends on BLOCK
822 823 824 825 826 827 828 829
	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)
830 831
	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.
832 833

	This option only enables generic Block IO controller infrastructure.
834
	One needs to also enable actual IO controlling logic/policy. For
M
Michael Witten 已提交
835 836
	enabling proportional weight division of disk bandwidth in CFQ, set
	CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
837
	CONFIG_BLK_DEV_THROTTLING=y.
838 839 840 841 842 843 844 845 846 847 848

	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
849
endif # CGROUPS
850

851 852 853 854 855 856 857 858 859 860 861
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.

862
menuconfig NAMESPACES
863 864
	bool "Namespaces support" if EXPERT
	default !EXPERT
865 866 867 868 869 870
	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.

871 872
if NAMESPACES

873 874
config UTS_NS
	bool "UTS namespace"
875
	default y
876 877 878 879
	help
	  In this namespace tasks see different info provided with the
	  uname() system call

880 881
config IPC_NS
	bool "IPC namespace"
882
	depends on (SYSVIPC || POSIX_MQUEUE)
883
	default y
884 885
	help
	  In this namespace tasks work with IPC ids which correspond to
886
	  different IPC objects in different namespaces.
887

888 889
config USER_NS
	bool "User namespace (EXPERIMENTAL)"
890
	depends on EXPERIMENTAL
891
	depends on UIDGID_CONVERTED
892
	select UIDGID_STRICT_TYPE_CHECKS
893

894
	default n
895 896 897 898 899
	help
	  This allows containers, i.e. vservers, to use user namespaces
	  to provide different user info for different servers.
	  If unsure, say N.

900
config PID_NS
901
	bool "PID Namespaces"
902
	default y
903
	help
904
	  Support process id namespaces.  This allows having multiple
905
	  processes with the same pid as long as they are in different
906 907
	  pid namespaces.  This is a building block of containers.

908 909
config NET_NS
	bool "Network namespace"
910
	depends on NET
911
	default y
912 913 914 915
	help
	  Allow user space to create what appear to be multiple instances
	  of the network stack.

916 917
endif # NAMESPACES

918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948
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 AUTOFS4_FS = n
	depends on CEPH_FS = n
	depends on CIFS = n
	depends on CODA_FS = n
	depends on FUSE_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 REISERFS_FS = n
	depends on SQUASHFS = n
	depends on UBIFS_FS = n
	depends on UDF_FS = n
	depends on UFS_FS = n
	depends on XFS_FS = n

949 950
config UIDGID_STRICT_TYPE_CHECKS
	bool "Require conversions between uid/gids and their internal representation"
951
	depends on UIDGID_CONVERTED
952 953 954 955 956 957 958
	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

959 960 961 962 963 964 965 966 967 968 969 970 971
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.

972 973 974 975
config MM_OWNER
	bool

config SYSFS_DEPRECATED
976
	bool "Enable deprecated sysfs features to support old userspace tools"
977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998
	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
999
	bool "Enable deprecated sysfs features by default"
1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023
	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.

1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039
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.

1040 1041
if BLK_DEV_INITRD

1042 1043
source "usr/Kconfig"

1044 1045
endif

1046
config CC_OPTIMIZE_FOR_SIZE
1047
	bool "Optimize for size"
1048 1049 1050 1051
	help
	  Enabling this option will pass "-Os" instead of "-O2" to gcc
	  resulting in a smaller kernel.

1052
	  If unsure, say Y.
1053

R
Randy Dunlap 已提交
1054 1055 1056
config SYSCTL
	bool

R
Randy Dunlap 已提交
1057 1058 1059
config ANON_INODES
	bool

1060 1061
menuconfig EXPERT
	bool "Configure standard kernel features (expert users)"
1062 1063
	# Unhide debug options, to make the on-by-default options visible
	select DEBUG_KERNEL
L
Linus Torvalds 已提交
1064 1065 1066 1067 1068 1069
	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.

1070
config UID16
1071
	bool "Enable 16-bit UID system calls" if EXPERT
1072
	depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
1073 1074 1075 1076
	default y
	help
	  This enables the legacy 16-bit UID syscall wrappers.

1077
config SYSCTL_SYSCALL
1078
	bool "Sysctl syscall support" if EXPERT
1079
	depends on PROC_SYSCTL
1080
	default n
1081
	select SYSCTL
1082
	---help---
1083 1084 1085 1086
	  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.
1087

1088 1089 1090
	  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.
1091

1092
	  If unsure say N here.
1093

L
Linus Torvalds 已提交
1094
config KALLSYMS
1095
	 bool "Load all symbols for debugging/ksymoops" if EXPERT
L
Linus Torvalds 已提交
1096 1097 1098 1099 1100 1101 1102 1103 1104 1105
	 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
1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117
	   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
1118

1119
config HOTPLUG
1120
	bool "Support for hot-pluggable devices" if EXPERT
1121 1122 1123 1124 1125 1126 1127
	default y
	help
	  This option is provided for the case where no hotplug or uevent
	  capabilities is wanted by the kernel.  You should only consider
	  disabling this option for embedded systems that do not use modules, a
	  dynamic /dev tree, or dynamic device discovery.  Just say Y.

M
Matt Mackall 已提交
1128 1129
config PRINTK
	default y
1130
	bool "Enable support for printk" if EXPERT
M
Matt Mackall 已提交
1131 1132 1133 1134 1135 1136 1137
	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
1138
config BUG
1139
	bool "BUG() support" if EXPERT
M
Matt Mackall 已提交
1140 1141 1142 1143 1144 1145 1146 1147
	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.

1148 1149
config ELF_CORE
	default y
1150
	bool "Enable ELF core dumps" if EXPERT
1151 1152 1153
	help
	  Enable support for generating core dumps. Disabling saves about 4k.

1154

S
Stas Sergeev 已提交
1155
config PCSPKR_PLATFORM
1156
	bool "Enable PC-Speaker support" if EXPERT
1157
	depends on HAVE_PCSPKR_PLATFORM
1158
	select I8253_LOCK
S
Stas Sergeev 已提交
1159 1160 1161 1162 1163
	default y
	help
          This option allows to disable the internal PC-Speaker
          support, saving some memory.

1164 1165 1166
config HAVE_PCSPKR_PLATFORM
	bool

L
Linus Torvalds 已提交
1167 1168
config BASE_FULL
	default y
1169
	bool "Enable full-sized data structures for core" if EXPERT
L
Linus Torvalds 已提交
1170 1171 1172 1173 1174 1175
	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
1176
	bool "Enable futex support" if EXPERT
L
Linus Torvalds 已提交
1177
	default y
I
Ingo Molnar 已提交
1178
	select RT_MUTEXES
L
Linus Torvalds 已提交
1179 1180 1181 1182 1183 1184
	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
1185
	bool "Enable eventpoll support" if EXPERT
L
Linus Torvalds 已提交
1186
	default y
1187
	select ANON_INODES
L
Linus Torvalds 已提交
1188 1189 1190 1191
	help
	  Disabling this option will cause the kernel to be built without
	  support for epoll family of system calls.

1192
config SIGNALFD
1193
	bool "Enable signalfd() system call" if EXPERT
1194
	select ANON_INODES
1195 1196 1197 1198 1199 1200 1201
	default y
	help
	  Enable the signalfd() system call that allows to receive signals
	  on a file descriptor.

	  If unsure, say Y.

1202
config TIMERFD
1203
	bool "Enable timerfd() system call" if EXPERT
1204
	select ANON_INODES
1205 1206 1207 1208 1209 1210 1211
	default y
	help
	  Enable the timerfd() system call that allows to receive timer
	  events on a file descriptor.

	  If unsure, say Y.

1212
config EVENTFD
1213
	bool "Enable eventfd() system call" if EXPERT
1214
	select ANON_INODES
1215 1216 1217 1218 1219 1220 1221
	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
1222
config SHMEM
1223
	bool "Use full shmem filesystem" if EXPERT
L
Linus Torvalds 已提交
1224 1225 1226 1227 1228 1229 1230 1231 1232
	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
1233
config AIO
1234
	bool "Enable AIO support" if EXPERT
T
Thomas Petazzoni 已提交
1235 1236 1237 1238 1239 1240
	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.

1241 1242 1243 1244 1245 1246 1247 1248
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.

1249
config HAVE_PERF_EVENTS
T
Thomas Gleixner 已提交
1250
	bool
1251 1252
	help
	  See tools/perf/design.txt for details.
T
Thomas Gleixner 已提交
1253

1254 1255 1256 1257 1258
config PERF_USE_VMALLOC
	bool
	help
	  See tools/perf/design.txt for details

I
Ingo Molnar 已提交
1259
menu "Kernel Performance Events And Counters"
T
Thomas Gleixner 已提交
1260

1261
config PERF_EVENTS
I
Ingo Molnar 已提交
1262
	bool "Kernel performance events and counters"
1263
	default y if PROFILING
1264
	depends on HAVE_PERF_EVENTS
I
Ingo Molnar 已提交
1265
	select ANON_INODES
1266
	select IRQ_WORK
T
Thomas Gleixner 已提交
1267
	help
I
Ingo Molnar 已提交
1268 1269
	  Enable kernel support for various performance events provided
	  by software and hardware.
T
Thomas Gleixner 已提交
1270

1271
	  Software events are supported either built-in or via the
I
Ingo Molnar 已提交
1272
	  use of generic tracepoints.
T
Thomas Gleixner 已提交
1273

I
Ingo Molnar 已提交
1274 1275
	  Most modern CPUs support performance events via performance
	  counter registers. These registers count the number of certain
T
Thomas Gleixner 已提交
1276 1277 1278 1279 1280 1281
	  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
1282
	  The Linux Performance Event subsystem provides an abstraction of
1283
	  these software and hardware event capabilities, available via a
I
Ingo Molnar 已提交
1284
	  system call and used by the "perf" utility in tools/perf/. It
T
Thomas Gleixner 已提交
1285 1286 1287 1288 1289
	  provides per task and per CPU counters, and it provides event
	  capabilities on top of those.

	  Say Y if unsure.

1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302
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
1303 1304
endmenu

1305 1306
config VM_EVENT_COUNTERS
	default y
1307
	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1308
	help
1309 1310
	  VM event counters are needed for event counts to be shown.
	  This option allows the disabling of the VM event counters
1311
	  on EXPERT systems.  /proc/vmstat will only show page counts
1312
	  if VM event counters are disabled.
1313

1314 1315
config PCI_QUIRKS
	default y
1316
	bool "Enable PCI quirk workarounds" if EXPERT
1317
	depends on PCI
1318 1319 1320 1321 1322
	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
1323 1324
config SLUB_DEBUG
	default y
1325
	bool "Enable SLUB debugging support" if EXPERT
C
Christoph Lameter 已提交
1326
	depends on SLUB && SYSFS
C
Christoph Lameter 已提交
1327 1328 1329 1330 1331 1332
	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
1333 1334 1335 1336 1337 1338 1339
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
1340
	  disabled, and can be overridden at runtime by setting
R
Randy Dunlap 已提交
1341 1342 1343 1344
	  /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
1345 1346
choice
	prompt "Choose SLAB allocator"
1347
	default SLUB
C
Christoph Lameter 已提交
1348 1349 1350 1351 1352 1353 1354
	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
1355
	  well in all environments. It organizes cache hot objects in
1356
	  per cpu and per node queues.
C
Christoph Lameter 已提交
1357 1358 1359 1360 1361 1362 1363 1364

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
1365 1366
	   and has enhanced diagnostics. SLUB is the default choice for
	   a slab allocator.
C
Christoph Lameter 已提交
1367 1368

config SLOB
1369
	depends on EXPERT
C
Christoph Lameter 已提交
1370 1371
	bool "SLOB (Simple Allocator)"
	help
M
Matt Mackall 已提交
1372 1373 1374
	   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
1375 1376 1377

endchoice

1378 1379
config MMAP_ALLOW_UNINITIALIZED
	bool "Allow mmapped anonymous memory to be uninitialized"
1380
	depends on EXPERT && !MMU
1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399
	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.

1400
config PROFILING
1401
	bool "Profiling support"
1402 1403 1404 1405
	help
	  Say Y here to enable the extended profiling support mechanisms used
	  by profilers such as OProfile.

1406 1407 1408 1409
#
# Place an empty function call at each tracepoint site. Can be
# dynamically changed for a probe function.
#
M
Mathieu Desnoyers 已提交
1410
config TRACEPOINTS
1411
	bool
M
Mathieu Desnoyers 已提交
1412

M
Mathieu Desnoyers 已提交
1413 1414
source "arch/Kconfig"

L
Linus Torvalds 已提交
1415 1416
endmenu		# General setup

1417 1418 1419 1420
config HAVE_GENERIC_DMA_COHERENT
	bool
	default n

1421 1422 1423
config SLABINFO
	bool
	depends on PROC_FS
1424
	depends on SLAB || SLUB_DEBUG
1425 1426
	default y

1427 1428 1429
config RT_MUTEXES
	boolean

L
Linus Torvalds 已提交
1430 1431 1432 1433 1434
config BASE_SMALL
	int
	default 0 if BASE_FULL
	default 1 if !BASE_FULL

1435
menuconfig MODULES
L
Linus Torvalds 已提交
1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454
	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.

1455 1456
if MODULES

1457 1458 1459 1460
config MODULE_FORCE_LOAD
	bool "Forced module loading"
	default n
	help
1461 1462 1463
	  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.
1464

L
Linus Torvalds 已提交
1465 1466 1467 1468 1469
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
1470 1471
	  anyway), which makes your kernel smaller, faster
	  and simpler.  If unsure, say Y.
L
Linus Torvalds 已提交
1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483

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
1484
	bool "Module versioning support"
L
Linus Torvalds 已提交
1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503
	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.

1504 1505
endif # MODULES

1506 1507 1508
config INIT_ALL_POSSIBLE
	bool
	help
1509 1510
	  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
1511 1512
	  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
1513
	  and have several arch maintainers pursuing me down dark alleys.
1514

L
Linus Torvalds 已提交
1515 1516 1517 1518 1519 1520
config STOP_MACHINE
	bool
	default y
	depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
	help
	  Need stop_machine() primitive.
1521 1522

source "block/Kconfig"
1523 1524 1525

config PREEMPT_NOTIFIERS
	bool
P
Paul E. McKenney 已提交
1526

1527 1528 1529 1530
config PADATA
	depends on SMP
	bool

1531
source "kernel/Kconfig.locks"