Kconfig 47.8 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
menu "General setup"
L
Linus Torvalds 已提交
31 32 33 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

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	  drivers that have been replaced by something else, and/or are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
73 74
	default 32 if !UML
	default 128 if UML
L
Linus Torvalds 已提交
75
	help
76 77
	  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
78 79


R
Roland McGrath 已提交
80 81 82 83 84 85 86 87
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
88 89 90 91 92 93 94 95 96 97
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.

98 99 100 101 102
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
103 104
	  release tree by looking for git tags that belong to the current
	  top of tree revision.
105 106

	  A string of the format -gxxxxxxxx will be added to the localversion
107
	  if a git-based tree is found.  The string generated by this will be
108
	  appended after any matching localversion* files, and after the value
109
	  set in CONFIG_LOCALVERSION.
110

111 112 113 114 115 116
	  (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".)
117

118 119 120 121 122 123 124 125 126
config HAVE_KERNEL_GZIP
	bool

config HAVE_KERNEL_BZIP2
	bool

config HAVE_KERNEL_LZMA
	bool

127 128 129
config HAVE_KERNEL_XZ
	bool

130 131 132
config HAVE_KERNEL_LZO
	bool

133
choice
134 135
	prompt "Kernel compression mode"
	default KERNEL_GZIP
136
	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
137
	help
138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155
	  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
156 157 158
	bool "Gzip"
	depends on HAVE_KERNEL_GZIP
	help
159 160
	  The old and tried gzip compression. It provides a good balance
	  between compression ratio and decompression speed.
161 162 163

config KERNEL_BZIP2
	bool "Bzip2"
164
	depends on HAVE_KERNEL_BZIP2
165 166
	help
	  Its compression ratio and speed is intermediate.
167 168 169 170
	  Decompression speed is slowest among the three.  The kernel
	  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.
171 172

config KERNEL_LZMA
173 174 175 176 177 178 179
	bool "LZMA"
	depends on HAVE_KERNEL_LZMA
	help
	  The most recent compression algorithm.
	  Its ratio is best, decompression speed is between the other
	  two. Compression is slowest.	The kernel size is about 33%
	  smaller with LZMA in comparison to gzip.
180

181 182 183 184 185 186 187 188 189 190 191 192 193 194 195
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.

196 197 198 199 200
config KERNEL_LZO
	bool "LZO"
	depends on HAVE_KERNEL_LZO
	help
	  Its compression ratio is the poorest among the 4. The kernel
S
Stephan Sperber 已提交
201
	  size is about 10% bigger than gzip; however its speed
202 203
	  (both compression and decompression) is the fastest.

204 205
endchoice

206 207 208 209 210 211 212 213 214
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
215 216
config SWAP
	bool "Support for paging of anonymous memory (swap)"
217
	depends on MMU && BLOCK
L
Linus Torvalds 已提交
218 219 220
	default y
	help
	  This option allows you to choose whether you want to have support
221
	  for so called swap devices or swap files in your kernel that are
L
Linus Torvalds 已提交
222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239
	  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>.

240 241 242 243 244 245
config SYSVIPC_SYSCTL
	bool
	depends on SYSVIPC
	depends on SYSCTL
	default y

L
Linus Torvalds 已提交
246 247 248 249 250 251 252 253
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
254
	  queues (functions mq_*) say Y here.
L
Linus Torvalds 已提交
255 256 257 258 259 260 261

	  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.

262 263 264 265 266 267
config POSIX_MQUEUE_SYSCTL
	bool
	depends on POSIX_MQUEUE
	depends on SYSCTL
	default y

L
Linus Torvalds 已提交
268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290
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
291
	  at <http://www.gnu.org/software/acct/>.
L
Linus Torvalds 已提交
292

293 294 295 296 297 298 299 300 301 302 303 304
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.

305 306 307 308 309 310 311 312 313 314 315 316 317
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.

318 319
config TASK_DELAY_ACCT
	bool "Enable per-task delay accounting (EXPERIMENTAL)"
320
	depends on TASKSTATS
321 322 323 324 325 326 327 328
	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.

329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346
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
347 348
config AUDIT
	bool "Auditing support"
C
Chris Wright 已提交
349
	depends on NET
L
Linus Torvalds 已提交
350 351 352 353 354 355 356 357
	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"
358
	depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM)
L
Linus Torvalds 已提交
359 360 361 362
	default y if SECURITY_SELINUX
	help
	  Enable low-overhead system-call auditing infrastructure that
	  can be used independently or with another kernel subsystem,
363
	  such as SELinux.
L
Linus Torvalds 已提交
364

E
Eric Paris 已提交
365 366 367 368
config AUDIT_WATCH
	def_bool y
	depends on AUDITSYSCALL
	select FSNOTIFY
L
Linus Torvalds 已提交
369

A
Al Viro 已提交
370 371
config AUDIT_TREE
	def_bool y
372
	depends on AUDITSYSCALL
373
	select FSNOTIFY
A
Al Viro 已提交
374

375 376 377 378
config AUDIT_LOGINUID_IMMUTABLE
	bool "Make audit loginuid immutable"
	depends on AUDIT
	help
379
	  The config option toggles if a task setting its loginuid requires
380 381 382 383 384 385 386 387 388
	  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
389 390
source "kernel/irq/Kconfig"

M
Mike Travis 已提交
391 392 393 394
menu "RCU Subsystem"

choice
	prompt "RCU Implementation"
P
Paul E. McKenney 已提交
395
	default TREE_RCU
M
Mike Travis 已提交
396 397 398

config TREE_RCU
	bool "Tree-based hierarchical RCU"
399
	depends on !PREEMPT && SMP
M
Mike Travis 已提交
400 401 402
	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
403 404
	  thousands of CPUs.  It also scales down nicely to
	  smaller systems.
M
Mike Travis 已提交
405

406
config TREE_PREEMPT_RCU
P
Paul E. McKenney 已提交
407
	bool "Preemptible tree-based hierarchical RCU"
408
	depends on PREEMPT && SMP
409 410 411 412
	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
413 414
	  is also required.  It also scales down nicely to
	  smaller systems.
415

416 417
config TINY_RCU
	bool "UP-only small-memory-footprint RCU"
418
	depends on !PREEMPT && !SMP
419 420 421 422 423 424
	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
425 426
config TINY_PREEMPT_RCU
	bool "Preemptible UP-only small-memory-footprint RCU"
427
	depends on PREEMPT && !SMP
P
Paul E. McKenney 已提交
428 429 430 431 432
	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
433 434
endchoice

P
Paul E. McKenney 已提交
435 436 437 438 439 440
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
441 442 443 444
config RCU_FANOUT
	int "Tree-based hierarchical RCU fanout value"
	range 2 64 if 64BIT
	range 2 32 if !64BIT
445
	depends on TREE_RCU || TREE_PREEMPT_RCU
M
Mike Travis 已提交
446 447 448 449 450
	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
451 452 453 454 455 456
	  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
457 458 459 460

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

461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487
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
488 489
config RCU_FANOUT_EXACT
	bool "Disable tree-based hierarchical RCU auto-balancing"
490
	depends on TREE_RCU || TREE_PREEMPT_RCU
M
Mike Travis 已提交
491 492 493 494 495 496 497 498 499 500 501
	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.

502 503
config RCU_FAST_NO_HZ
	bool "Accelerate last non-dyntick-idle CPU's grace periods"
504
	depends on NO_HZ && SMP
505 506 507
	default n
	help
	  This option causes RCU to attempt to accelerate grace periods
508 509 510 511
	  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.
512 513 514 515 516 517

	  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
518
config TREE_RCU_TRACE
519
	def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
M
Mike Travis 已提交
520 521
	select DEBUG_FS
	help
522 523 524
	  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
525

526 527
config RCU_BOOST
	bool "Enable RCU priority boosting"
528
	depends on RT_MUTEXES && PREEMPT_RCU
529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544
	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
545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563
	  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.
564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579

	  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
580 581
endmenu # "RCU Subsystem"

L
Linus Torvalds 已提交
582
config IKCONFIG
583
	tristate "Kernel .config support"
L
Linus Torvalds 已提交
584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600
	---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.

601 602 603
config LOG_BUF_SHIFT
	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
	range 12 21
A
Adrian Bunk 已提交
604
	default 17
605 606
	help
	  Select kernel log buffer size as a power of 2.
A
Adrian Bunk 已提交
607 608 609 610 611
	  Examples:
	  	     17 => 128 KB
		     16 => 64 KB
	             15 => 32 KB
	             14 => 16 KB
612 613 614
		     13 =>  8 KB
		     12 =>  4 KB

615 616 617 618 619 620
#
# Architectures with an unreliable sched_clock() should select this:
#
config HAVE_UNSTABLE_SCHED_CLOCK
	bool

L
Li Zefan 已提交
621 622
menuconfig CGROUPS
	boolean "Control Group support"
623
	depends on EVENTFD
624
	help
L
Li Zefan 已提交
625
	  This option adds support for grouping sets of processes together, for
626 627 628 629
	  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
630 631
		- Documentation/cgroups/ (features for grouping, isolation
					  and resource control)
632 633 634

	  Say N if unsure.

L
Li Zefan 已提交
635 636
if CGROUPS

637 638 639 640 641 642
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
643
	  framework.
644

L
Li Zefan 已提交
645
	  Say N if unsure.
646 647

config CGROUP_FREEZER
L
Li Zefan 已提交
648 649 650
	bool "Freezer cgroup subsystem"
	help
	  Provides a way to freeze and unfreeze all tasks in a
651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668
	  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
669 670 671 672 673
config PROC_PID_CPUSET
	bool "Include legacy /proc/<pid>/cpuset file"
	depends on CPUSETS
	default y

674 675 676 677
config CGROUP_CPUACCT
	bool "Simple CPU accounting cgroup subsystem"
	help
	  Provides a simple Resource Controller for monitoring the
L
Li Zefan 已提交
678
	  total CPU consumed by the tasks in a cgroup.
679

680 681 682 683
config RESOURCE_COUNTERS
	bool "Resource counters"
	help
	  This option enables controller independent resource accounting
L
Li Zefan 已提交
684
	  infrastructure that works with cgroups.
685

686 687
config CGROUP_MEM_RES_CTLR
	bool "Memory Resource Controller for Control Groups"
688
	depends on RESOURCE_COUNTERS
689
	select MM_OWNER
690
	help
691
	  Provides a memory resource controller that manages both anonymous
692
	  memory and page cache. (See Documentation/cgroups/memory.txt)
693 694

	  Note that setting this option increases fixed memory overhead
695 696 697 698
	  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.
699 700

	  Only enable when you're ok with these trade offs and really
701 702 703
	  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
704
	  (and lose benefits of memory resource controller)
705

706 707 708
	  This config option also selects MM_OWNER config option, which
	  could in turn add some fork/exit overhead.

709
config CGROUP_MEM_RES_CTLR_SWAP
710 711
	bool "Memory Resource Controller Swap Extension"
	depends on CGROUP_MEM_RES_CTLR && SWAP
712 713 714 715 716 717 718 719 720 721 722
	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,
723
	  if boot option "swapaccount=0" is set, swap will not be accounted.
724 725
	  Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
	  size is 4096bytes, 512k per 1Gbytes of swap.
726 727 728 729 730 731 732
config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
	bool "Memory Resource Controller Swap Extension enabled by default"
	depends on CGROUP_MEM_RES_CTLR_SWAP
	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
733
	  which want to enable the feature but keep it disabled by default
734 735 736 737
	  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
738
	  then swapaccount=0 does the trick).
739 740 741 742 743 744 745 746 747 748 749
config CGROUP_MEM_RES_CTLR_KMEM
	bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
	depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL
	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.
750

S
Stephane Eranian 已提交
751 752 753 754 755
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
756
	  threads which belong to the cgroup specified and run on the
S
Stephane Eranian 已提交
757 758 759 760
	  designated cpu.

	  Say N if unsure.

D
Dhaval Giani 已提交
761 762 763 764 765 766 767 768 769 770 771 772 773 774
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

775 776 777 778 779 780 781 782 783 784 785 786
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
787 788 789 790 791 792 793
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
794
	  to task groups. If enabled, it will also make it impossible to
D
Dhaval Giani 已提交
795 796 797 798 799 800
	  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

801 802
config BLK_CGROUP
	tristate "Block IO controller"
803
	depends on BLOCK
804 805 806 807 808 809 810 811
	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)
812 813
	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.
814 815

	This option only enables generic Block IO controller infrastructure.
816
	One needs to also enable actual IO controlling logic/policy. For
M
Michael Witten 已提交
817 818
	enabling proportional weight division of disk bandwidth in CFQ, set
	CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
819
	CONFIG_BLK_DEV_THROTTLING=y.
820 821 822 823 824 825 826 827 828 829 830

	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
831
endif # CGROUPS
832

833 834 835 836 837 838 839 840 841 842 843
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.

844
menuconfig NAMESPACES
845 846
	bool "Namespaces support" if EXPERT
	default !EXPERT
847 848 849 850 851 852
	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.

853 854
if NAMESPACES

855 856
config UTS_NS
	bool "UTS namespace"
857
	default y
858 859 860 861
	help
	  In this namespace tasks see different info provided with the
	  uname() system call

862 863
config IPC_NS
	bool "IPC namespace"
864
	depends on (SYSVIPC || POSIX_MQUEUE)
865
	default y
866 867
	help
	  In this namespace tasks work with IPC ids which correspond to
868
	  different IPC objects in different namespaces.
869

870 871
config USER_NS
	bool "User namespace (EXPERIMENTAL)"
872
	depends on EXPERIMENTAL
873
	default y
874 875 876 877 878
	help
	  This allows containers, i.e. vservers, to use user namespaces
	  to provide different user info for different servers.
	  If unsure, say N.

879
config PID_NS
880
	bool "PID Namespaces"
881
	default y
882
	help
883
	  Support process id namespaces.  This allows having multiple
884
	  processes with the same pid as long as they are in different
885 886
	  pid namespaces.  This is a building block of containers.

887 888
config NET_NS
	bool "Network namespace"
889
	depends on NET
890
	default y
891 892 893 894
	help
	  Allow user space to create what appear to be multiple instances
	  of the network stack.

895 896
endif # NAMESPACES

897 898 899 900 901 902 903 904 905 906 907 908 909
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.

910 911 912 913
config MM_OWNER
	bool

config SYSFS_DEPRECATED
914
	bool "Enable deprecated sysfs features to support old userspace tools"
915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
	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
937
	bool "Enable deprecated sysfs features by default"
938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961
	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.

962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977
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.

978 979
if BLK_DEV_INITRD

980 981
source "usr/Kconfig"

982 983
endif

984
config CC_OPTIMIZE_FOR_SIZE
985
	bool "Optimize for size"
986 987 988 989
	help
	  Enabling this option will pass "-Os" instead of "-O2" to gcc
	  resulting in a smaller kernel.

990
	  If unsure, say Y.
991

R
Randy Dunlap 已提交
992 993 994
config SYSCTL
	bool

R
Randy Dunlap 已提交
995 996 997
config ANON_INODES
	bool

998 999
menuconfig EXPERT
	bool "Configure standard kernel features (expert users)"
1000 1001
	# Unhide debug options, to make the on-by-default options visible
	select DEBUG_KERNEL
L
Linus Torvalds 已提交
1002 1003 1004 1005 1006 1007
	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.

1008
config UID16
1009
	bool "Enable 16-bit UID system calls" if EXPERT
1010
	depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
1011 1012 1013 1014
	default y
	help
	  This enables the legacy 16-bit UID syscall wrappers.

1015
config SYSCTL_SYSCALL
1016
	bool "Sysctl syscall support" if EXPERT
1017
	depends on PROC_SYSCTL
1018
	default n
1019
	select SYSCTL
1020
	---help---
1021 1022 1023 1024
	  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.
1025

1026 1027 1028
	  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.
1029

1030
	  If unsure say N here.
1031

L
Linus Torvalds 已提交
1032
config KALLSYMS
1033
	 bool "Load all symbols for debugging/ksymoops" if EXPERT
L
Linus Torvalds 已提交
1034 1035 1036 1037 1038 1039 1040 1041 1042 1043
	 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
1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
	   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
1056

1057
config HOTPLUG
1058
	bool "Support for hot-pluggable devices" if EXPERT
1059 1060 1061 1062 1063 1064 1065
	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
1066 1067
config PRINTK
	default y
1068
	bool "Enable support for printk" if EXPERT
M
Matt Mackall 已提交
1069 1070 1071 1072 1073 1074 1075
	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
1076
config BUG
1077
	bool "BUG() support" if EXPERT
M
Matt Mackall 已提交
1078 1079 1080 1081 1082 1083 1084 1085
	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.

1086 1087
config ELF_CORE
	default y
1088
	bool "Enable ELF core dumps" if EXPERT
1089 1090 1091
	help
	  Enable support for generating core dumps. Disabling saves about 4k.

1092

S
Stas Sergeev 已提交
1093
config PCSPKR_PLATFORM
1094
	bool "Enable PC-Speaker support" if EXPERT
1095
	depends on HAVE_PCSPKR_PLATFORM
1096
	select I8253_LOCK
S
Stas Sergeev 已提交
1097 1098 1099 1100 1101
	default y
	help
          This option allows to disable the internal PC-Speaker
          support, saving some memory.

1102 1103 1104
config HAVE_PCSPKR_PLATFORM
	bool

L
Linus Torvalds 已提交
1105 1106
config BASE_FULL
	default y
1107
	bool "Enable full-sized data structures for core" if EXPERT
L
Linus Torvalds 已提交
1108 1109 1110 1111 1112 1113
	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
1114
	bool "Enable futex support" if EXPERT
L
Linus Torvalds 已提交
1115
	default y
I
Ingo Molnar 已提交
1116
	select RT_MUTEXES
L
Linus Torvalds 已提交
1117 1118 1119 1120 1121 1122
	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
1123
	bool "Enable eventpoll support" if EXPERT
L
Linus Torvalds 已提交
1124
	default y
1125
	select ANON_INODES
L
Linus Torvalds 已提交
1126 1127 1128 1129
	help
	  Disabling this option will cause the kernel to be built without
	  support for epoll family of system calls.

1130
config SIGNALFD
1131
	bool "Enable signalfd() system call" if EXPERT
1132
	select ANON_INODES
1133 1134 1135 1136 1137 1138 1139
	default y
	help
	  Enable the signalfd() system call that allows to receive signals
	  on a file descriptor.

	  If unsure, say Y.

1140
config TIMERFD
1141
	bool "Enable timerfd() system call" if EXPERT
1142
	select ANON_INODES
1143 1144 1145 1146 1147 1148 1149
	default y
	help
	  Enable the timerfd() system call that allows to receive timer
	  events on a file descriptor.

	  If unsure, say Y.

1150
config EVENTFD
1151
	bool "Enable eventfd() system call" if EXPERT
1152
	select ANON_INODES
1153 1154 1155 1156 1157 1158 1159
	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
1160
config SHMEM
1161
	bool "Use full shmem filesystem" if EXPERT
L
Linus Torvalds 已提交
1162 1163 1164 1165 1166 1167 1168 1169 1170
	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
1171
config AIO
1172
	bool "Enable AIO support" if EXPERT
T
Thomas Petazzoni 已提交
1173 1174 1175 1176 1177 1178
	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.

1179 1180 1181 1182 1183 1184 1185 1186
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.

1187
config HAVE_PERF_EVENTS
T
Thomas Gleixner 已提交
1188
	bool
1189 1190
	help
	  See tools/perf/design.txt for details.
T
Thomas Gleixner 已提交
1191

1192 1193 1194 1195 1196
config PERF_USE_VMALLOC
	bool
	help
	  See tools/perf/design.txt for details

I
Ingo Molnar 已提交
1197
menu "Kernel Performance Events And Counters"
T
Thomas Gleixner 已提交
1198

1199
config PERF_EVENTS
I
Ingo Molnar 已提交
1200 1201
	bool "Kernel performance events and counters"
	default y if (PROFILING || PERF_COUNTERS)
1202
	depends on HAVE_PERF_EVENTS
I
Ingo Molnar 已提交
1203
	select ANON_INODES
1204
	select IRQ_WORK
T
Thomas Gleixner 已提交
1205
	help
I
Ingo Molnar 已提交
1206 1207
	  Enable kernel support for various performance events provided
	  by software and hardware.
T
Thomas Gleixner 已提交
1208

1209
	  Software events are supported either built-in or via the
I
Ingo Molnar 已提交
1210
	  use of generic tracepoints.
T
Thomas Gleixner 已提交
1211

I
Ingo Molnar 已提交
1212 1213
	  Most modern CPUs support performance events via performance
	  counter registers. These registers count the number of certain
T
Thomas Gleixner 已提交
1214 1215 1216 1217 1218 1219
	  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
1220
	  The Linux Performance Event subsystem provides an abstraction of
1221
	  these software and hardware event capabilities, available via a
I
Ingo Molnar 已提交
1222
	  system call and used by the "perf" utility in tools/perf/. It
T
Thomas Gleixner 已提交
1223 1224 1225 1226 1227
	  provides per task and per CPU counters, and it provides event
	  capabilities on top of those.

	  Say Y if unsure.

I
Ingo Molnar 已提交
1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239
config PERF_COUNTERS
	bool "Kernel performance counters (old config option)"
	depends on HAVE_PERF_EVENTS
	help
	  This config has been obsoleted by the PERF_EVENTS
	  config option - please see that one for details.

	  It has no effect on the kernel whether you enable
	  it or not, it is a compatibility placeholder.

	  Say N if unsure.

1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252
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
1253 1254
endmenu

1255 1256
config VM_EVENT_COUNTERS
	default y
1257
	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1258
	help
1259 1260
	  VM event counters are needed for event counts to be shown.
	  This option allows the disabling of the VM event counters
1261
	  on EXPERT systems.  /proc/vmstat will only show page counts
1262
	  if VM event counters are disabled.
1263

1264 1265
config PCI_QUIRKS
	default y
1266
	bool "Enable PCI quirk workarounds" if EXPERT
1267
	depends on PCI
1268 1269 1270 1271 1272
	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
1273 1274
config SLUB_DEBUG
	default y
1275
	bool "Enable SLUB debugging support" if EXPERT
C
Christoph Lameter 已提交
1276
	depends on SLUB && SYSFS
C
Christoph Lameter 已提交
1277 1278 1279 1280 1281 1282
	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
1283 1284 1285 1286 1287 1288 1289
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
1290
	  disabled, and can be overridden at runtime by setting
R
Randy Dunlap 已提交
1291 1292 1293 1294
	  /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
1295 1296
choice
	prompt "Choose SLAB allocator"
1297
	default SLUB
C
Christoph Lameter 已提交
1298 1299 1300 1301 1302 1303 1304
	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
1305
	  well in all environments. It organizes cache hot objects in
1306
	  per cpu and per node queues.
C
Christoph Lameter 已提交
1307 1308 1309 1310 1311 1312 1313 1314

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
1315 1316
	   and has enhanced diagnostics. SLUB is the default choice for
	   a slab allocator.
C
Christoph Lameter 已提交
1317 1318

config SLOB
1319
	depends on EXPERT
C
Christoph Lameter 已提交
1320 1321
	bool "SLOB (Simple Allocator)"
	help
M
Matt Mackall 已提交
1322 1323 1324
	   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
1325 1326 1327

endchoice

1328 1329
config MMAP_ALLOW_UNINITIALIZED
	bool "Allow mmapped anonymous memory to be uninitialized"
1330
	depends on EXPERT && !MMU
1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349
	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.

1350
config PROFILING
1351
	bool "Profiling support"
1352 1353 1354 1355
	help
	  Say Y here to enable the extended profiling support mechanisms used
	  by profilers such as OProfile.

1356 1357 1358 1359
#
# Place an empty function call at each tracepoint site. Can be
# dynamically changed for a probe function.
#
M
Mathieu Desnoyers 已提交
1360
config TRACEPOINTS
1361
	bool
M
Mathieu Desnoyers 已提交
1362

M
Mathieu Desnoyers 已提交
1363 1364
source "arch/Kconfig"

L
Linus Torvalds 已提交
1365 1366
endmenu		# General setup

1367 1368 1369 1370
config HAVE_GENERIC_DMA_COHERENT
	bool
	default n

1371 1372 1373
config SLABINFO
	bool
	depends on PROC_FS
1374
	depends on SLAB || SLUB_DEBUG
1375 1376
	default y

1377 1378 1379
config RT_MUTEXES
	boolean

L
Linus Torvalds 已提交
1380 1381 1382 1383 1384
config BASE_SMALL
	int
	default 0 if BASE_FULL
	default 1 if !BASE_FULL

1385
menuconfig MODULES
L
Linus Torvalds 已提交
1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404
	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.

1405 1406
if MODULES

1407 1408 1409 1410
config MODULE_FORCE_LOAD
	bool "Forced module loading"
	default n
	help
1411 1412 1413
	  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.
1414

L
Linus Torvalds 已提交
1415 1416 1417 1418 1419
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
1420 1421
	  anyway), which makes your kernel smaller, faster
	  and simpler.  If unsure, say Y.
L
Linus Torvalds 已提交
1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433

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
1434
	bool "Module versioning support"
L
Linus Torvalds 已提交
1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453
	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.

1454 1455
endif # MODULES

1456 1457 1458
config INIT_ALL_POSSIBLE
	bool
	help
1459 1460
	  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
1461 1462
	  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
1463
	  and have several arch maintainers pursuing me down dark alleys.
1464

L
Linus Torvalds 已提交
1465 1466 1467 1468 1469 1470
config STOP_MACHINE
	bool
	default y
	depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
	help
	  Need stop_machine() primitive.
1471 1472

source "block/Kconfig"
1473 1474 1475

config PREEMPT_NOTIFIERS
	bool
P
Paul E. McKenney 已提交
1476

1477 1478 1479 1480
config PADATA
	depends on SMP
	bool

1481
source "kernel/Kconfig.locks"