init/Kconfig

   1 config ARCH
   2         string
   3         option env="ARCH"
   4
   5 config KERNELVERSION
   6         string
   7         option env="KERNELVERSION"
   8
   9 config DEFCONFIG_LIST
  10         string
  11         depends on !UML
  12         option defconfig_list
  13         default "/lib/modules/$UNAME_RELEASE/.config"
  14         default "/etc/kernel-config"
  15         default "/boot/config-$UNAME_RELEASE"
  16         default "$ARCH_DEFCONFIG"
  17         default "arch/$ARCH/defconfig"
  18
  19 config CONSTRUCTORS
  20         bool
  21         depends on !UML
  22         default y
  23
  24 config HAVE_IRQ_WORK
  25         bool
  26
  27 config IRQ_WORK
  28         bool
  29         depends on HAVE_IRQ_WORK
  30
  31 menu "General setup"
  32
  33 config EXPERIMENTAL
  34         bool "Prompt for development and/or incomplete code/drivers"
  35         ---help---
  36           Some of the various things that Linux supports (such as network
  37           drivers, file systems, network protocols, etc.) can be in a state
  38           of development where the functionality, stability, or the level of
  39           testing is not yet high enough for general use. This is usually
  40           known as the "alpha-test" phase among developers. If a feature is
  41           currently in alpha-test, then the developers usually discourage
  42           uninformed widespread use of this feature by the general public to
  43           avoid "Why doesn't this work?" type mail messages. However, active
  44           testing and use of these systems is welcomed. Just be aware that it
  45           may not meet the normal level of reliability or it may fail to work
  46           in some special cases. Detailed bug reports from people familiar
  47           with the kernel internals are usually welcomed by the developers
  48           (before submitting bug reports, please read the documents
  49           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  50           <file:Documentation/BUG-HUNTING>, and
  51           <file:Documentation/oops-tracing.txt> in the kernel source).
  52
  53           This option will also make obsoleted drivers available. These are
  54           drivers that have been replaced by something else, and/or are
  55           scheduled to be removed in a future kernel release.
  56
  57           Unless you intend to help test and develop a feature or driver that
  58           falls into this category, or you have a situation that requires
  59           using these features, you should probably say N here, which will
  60           cause the configurator to present you with fewer choices. If
  61           you say Y here, you will be offered the choice of using features or
  62           drivers that are currently considered to be in the alpha-test phase.
  63
  64 config BROKEN
  65         bool
  66
  67 config BROKEN_ON_SMP
  68         bool
  69         depends on BROKEN || !SMP
  70         default y
  71
  72 config INIT_ENV_ARG_LIMIT
  73         int
  74         default 32 if !UML
  75         default 128 if UML
  76         help
  77           Maximum of each of the number of arguments and environment
  78           variables passed to init from the kernel command line.
  79
  80
  81 config CROSS_COMPILE
  82         string "Cross-compiler tool prefix"
  83         help
  84           Same as running 'make CROSS_COMPILE=prefix-' but stored for
  85           default make runs in this kernel build directory.  You don't
  86           need to set this unless you want the configured kernel build
  87           directory to select the cross-compiler automatically.
  88
  89 config LOCALVERSION
  90         string "Local version - append to kernel release"
  91         help
  92           Append an extra string to the end of your kernel version.
  93           This will show up when you type uname, for example.
  94           The string you set here will be appended after the contents of
  95           any files with a filename matching localversion* in your
  96           object and source tree, in that order.  Your total string can
  97           be a maximum of 64 characters.
  98
  99 config LOCALVERSION_AUTO
 100         bool "Automatically append version information to the version string"
 101         default y
 102         help
 103           This will try to automatically determine if the current tree is a
 104           release tree by looking for git tags that belong to the current
 105           top of tree revision.
 106
 107           A string of the format -gxxxxxxxx will be added to the localversion
 108           if a git-based tree is found.  The string generated by this will be
 109           appended after any matching localversion* files, and after the value
 110           set in CONFIG_LOCALVERSION.
 111
 112           (The actual string used here is the first eight characters produced
 113           by running the command:
 114
 115             $ git rev-parse --verify HEAD
 116
 117           which is done within the script "scripts/setlocalversion".)
 118
 119 config HAVE_KERNEL_GZIP
 120         bool
 121
 122 config HAVE_KERNEL_BZIP2
 123         bool
 124
 125 config HAVE_KERNEL_LZMA
 126         bool
 127
 128 config HAVE_KERNEL_XZ
 129         bool
 130
 131 config HAVE_KERNEL_LZO
 132         bool
 133
 134 choice
 135         prompt "Kernel compression mode"
 136         default KERNEL_GZIP
 137         depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
 138         help
 139           The linux kernel is a kind of self-extracting executable.
 140           Several compression algorithms are available, which differ
 141           in efficiency, compression and decompression speed.
 142           Compression speed is only relevant when building a kernel.
 143           Decompression speed is relevant at each boot.
 144
 145           If you have any problems with bzip2 or lzma compressed
 146           kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 147           version of this functionality (bzip2 only), for 2.4, was
 148           supplied by Christian Ludwig)
 149
 150           High compression options are mostly useful for users, who
 151           are low on disk space (embedded systems), but for whom ram
 152           size matters less.
 153
 154           If in doubt, select 'gzip'
 155
 156 config KERNEL_GZIP
 157         bool "Gzip"
 158         depends on HAVE_KERNEL_GZIP
 159         help
 160           The old and tried gzip compression. It provides a good balance
 161           between compression ratio and decompression speed.
 162
 163 config KERNEL_BZIP2
 164         bool "Bzip2"
 165         depends on HAVE_KERNEL_BZIP2
 166         help
 167           Its compression ratio and speed is intermediate.
 168           Decompression speed is slowest among the three.  The kernel
 169           size is about 10% smaller with bzip2, in comparison to gzip.
 170           Bzip2 uses a large amount of memory. For modern kernels you
 171           will need at least 8MB RAM or more for booting.
 172
 173 config KERNEL_LZMA
 174         bool "LZMA"
 175         depends on HAVE_KERNEL_LZMA
 176         help
 177           The most recent compression algorithm.
 178           Its ratio is best, decompression speed is between the other
 179           two. Compression is slowest.  The kernel size is about 33%
 180           smaller with LZMA in comparison to gzip.
 181
 182 config KERNEL_XZ
 183         bool "XZ"
 184         depends on HAVE_KERNEL_XZ
 185         help
 186           XZ uses the LZMA2 algorithm and instruction set specific
 187           BCJ filters which can improve compression ratio of executable
 188           code. The size of the kernel is about 30% smaller with XZ in
 189           comparison to gzip. On architectures for which there is a BCJ
 190           filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
 191           will create a few percent smaller kernel than plain LZMA.
 192
 193           The speed is about the same as with LZMA: The decompression
 194           speed of XZ is better than that of bzip2 but worse than gzip
 195           and LZO. Compression is slow.
 196
 197 config KERNEL_LZO
 198         bool "LZO"
 199         depends on HAVE_KERNEL_LZO
 200         help
 201           Its compression ratio is the poorest among the 4. The kernel
 202           size is about 10% bigger than gzip; however its speed
 203           (both compression and decompression) is the fastest.
 204
 205 endchoice
 206
 207 config SWAP
 208         bool "Support for paging of anonymous memory (swap)"
 209         depends on MMU && BLOCK
 210         default y
 211         help
 212           This option allows you to choose whether you want to have support
 213           for so called swap devices or swap files in your kernel that are
 214           used to provide more virtual memory than the actual RAM present
 215           in your computer.  If unsure say Y.
 216
 217 config SYSVIPC
 218         bool "System V IPC"
 219         ---help---
 220           Inter Process Communication is a suite of library functions and
 221           system calls which let processes (running programs) synchronize and
 222           exchange information. It is generally considered to be a good thing,
 223           and some programs won't run unless you say Y here. In particular, if
 224           you want to run the DOS emulator dosemu under Linux (read the
 225           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 226           you'll need to say Y here.
 227
 228           You can find documentation about IPC with "info ipc" and also in
 229           section 6.4 of the Linux Programmer's Guide, available from
 230           <http://www.tldp.org/guides.html>.
 231
 232 config SYSVIPC_SYSCTL
 233         bool
 234         depends on SYSVIPC
 235         depends on SYSCTL
 236         default y
 237
 238 config POSIX_MQUEUE
 239         bool "POSIX Message Queues"
 240         depends on NET && EXPERIMENTAL
 241         ---help---
 242           POSIX variant of message queues is a part of IPC. In POSIX message
 243           queues every message has a priority which decides about succession
 244           of receiving it by a process. If you want to compile and run
 245           programs written e.g. for Solaris with use of its POSIX message
 246           queues (functions mq_*) say Y here.
 247
 248           POSIX message queues are visible as a filesystem called 'mqueue'
 249           and can be mounted somewhere if you want to do filesystem
 250           operations on message queues.
 251
 252           If unsure, say Y.
 253
 254 config POSIX_MQUEUE_SYSCTL
 255         bool
 256         depends on POSIX_MQUEUE
 257         depends on SYSCTL
 258         default y
 259
 260 config BSD_PROCESS_ACCT
 261         bool "BSD Process Accounting"
 262         help
 263           If you say Y here, a user level program will be able to instruct the
 264           kernel (via a special system call) to write process accounting
 265           information to a file: whenever a process exits, information about
 266           that process will be appended to the file by the kernel.  The
 267           information includes things such as creation time, owning user,
 268           command name, memory usage, controlling terminal etc. (the complete
 269           list is in the struct acct in <file:include/linux/acct.h>).  It is
 270           up to the user level program to do useful things with this
 271           information.  This is generally a good idea, so say Y.
 272
 273 config BSD_PROCESS_ACCT_V3
 274         bool "BSD Process Accounting version 3 file format"
 275         depends on BSD_PROCESS_ACCT
 276         default n
 277         help
 278           If you say Y here, the process accounting information is written
 279           in a new file format that also logs the process IDs of each
 280           process and it's parent. Note that this file format is incompatible
 281           with previous v0/v1/v2 file formats, so you will need updated tools
 282           for processing it. A preliminary version of these tools is available
 283           at <http://www.gnu.org/software/acct/>.
 284
 285 config FHANDLE
 286         bool "open by fhandle syscalls"
 287         select EXPORTFS
 288         help
 289           If you say Y here, a user level program will be able to map
 290           file names to handle and then later use the handle for
 291           different file system operations. This is useful in implementing
 292           userspace file servers, which now track files using handles instead
 293           of names. The handle would remain the same even if file names
 294           get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
 295           syscalls.
 296
 297 config TASKSTATS
 298         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 299         depends on NET
 300         default n
 301         help
 302           Export selected statistics for tasks/processes through the
 303           generic netlink interface. Unlike BSD process accounting, the
 304           statistics are available during the lifetime of tasks/processes as
 305           responses to commands. Like BSD accounting, they are sent to user
 306           space on task exit.
 307
 308           Say N if unsure.
 309
 310 config TASK_DELAY_ACCT
 311         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 312         depends on TASKSTATS
 313         help
 314           Collect information on time spent by a task waiting for system
 315           resources like cpu, synchronous block I/O completion and swapping
 316           in pages. Such statistics can help in setting a task's priorities
 317           relative to other tasks for cpu, io, rss limits etc.
 318
 319           Say N if unsure.
 320
 321 config TASK_XACCT
 322         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 323         depends on TASKSTATS
 324         help
 325           Collect extended task accounting data and send the data
 326           to userland for processing over the taskstats interface.
 327
 328           Say N if unsure.
 329
 330 config TASK_IO_ACCOUNTING
 331         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 332         depends on TASK_XACCT
 333         help
 334           Collect information on the number of bytes of storage I/O which this
 335           task has caused.
 336
 337           Say N if unsure.
 338
 339 config AUDIT
 340         bool "Auditing support"
 341         depends on NET
 342         help
 343           Enable auditing infrastructure that can be used with another
 344           kernel subsystem, such as SELinux (which requires this for
 345           logging of avc messages output).  Does not do system-call
 346           auditing without CONFIG_AUDITSYSCALL.
 347
 348 config AUDITSYSCALL
 349         bool "Enable system-call auditing support"
 350         depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
 351         default y if SECURITY_SELINUX
 352         help
 353           Enable low-overhead system-call auditing infrastructure that
 354           can be used independently or with another kernel subsystem,
 355           such as SELinux.
 356
 357 config AUDIT_WATCH
 358         def_bool y
 359         depends on AUDITSYSCALL
 360         select FSNOTIFY
 361
 362 config AUDIT_TREE
 363         def_bool y
 364         depends on AUDITSYSCALL
 365         select FSNOTIFY
 366
 367 source "kernel/irq/Kconfig"
 368
 369 menu "RCU Subsystem"
 370
 371 choice
 372         prompt "RCU Implementation"
 373         default TREE_RCU
 374
 375 config TREE_RCU
 376         bool "Tree-based hierarchical RCU"
 377         depends on !PREEMPT && SMP
 378         help
 379           This option selects the RCU implementation that is
 380           designed for very large SMP system with hundreds or
 381           thousands of CPUs.  It also scales down nicely to
 382           smaller systems.
 383
 384 config TREE_PREEMPT_RCU
 385         bool "Preemptible tree-based hierarchical RCU"
 386         depends on PREEMPT
 387         help
 388           This option selects the RCU implementation that is
 389           designed for very large SMP systems with hundreds or
 390           thousands of CPUs, but for which real-time response
 391           is also required.  It also scales down nicely to
 392           smaller systems.
 393
 394 config TINY_RCU
 395         bool "UP-only small-memory-footprint RCU"
 396         depends on !SMP
 397         help
 398           This option selects the RCU implementation that is
 399           designed for UP systems from which real-time response
 400           is not required.  This option greatly reduces the
 401           memory footprint of RCU.
 402
 403 config TINY_PREEMPT_RCU
 404         bool "Preemptible UP-only small-memory-footprint RCU"
 405         depends on !SMP && PREEMPT
 406         help
 407           This option selects the RCU implementation that is designed
 408           for real-time UP systems.  This option greatly reduces the
 409           memory footprint of RCU.
 410
 411 endchoice
 412
 413 config PREEMPT_RCU
 414         def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
 415         help
 416           This option enables preemptible-RCU code that is common between
 417           the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
 418
 419 config RCU_TRACE
 420         bool "Enable tracing for RCU"
 421         help
 422           This option provides tracing in RCU which presents stats
 423           in debugfs for debugging RCU implementation.
 424
 425           Say Y here if you want to enable RCU tracing
 426           Say N if you are unsure.
 427
 428 config RCU_FANOUT
 429         int "Tree-based hierarchical RCU fanout value"
 430         range 2 64 if 64BIT
 431         range 2 32 if !64BIT
 432         depends on TREE_RCU || TREE_PREEMPT_RCU
 433         default 64 if 64BIT
 434         default 32 if !64BIT
 435         help
 436           This option controls the fanout of hierarchical implementations
 437           of RCU, allowing RCU to work efficiently on machines with
 438           large numbers of CPUs.  This value must be at least the fourth
 439           root of NR_CPUS, which allows NR_CPUS to be insanely large.
 440           The default value of RCU_FANOUT should be used for production
 441           systems, but if you are stress-testing the RCU implementation
 442           itself, small RCU_FANOUT values allow you to test large-system
 443           code paths on small(er) systems.
 444
 445           Select a specific number if testing RCU itself.
 446           Take the default if unsure.
 447
 448 config RCU_FANOUT_EXACT
 449         bool "Disable tree-based hierarchical RCU auto-balancing"
 450         depends on TREE_RCU || TREE_PREEMPT_RCU
 451         default n
 452         help
 453           This option forces use of the exact RCU_FANOUT value specified,
 454           regardless of imbalances in the hierarchy.  This is useful for
 455           testing RCU itself, and might one day be useful on systems with
 456           strong NUMA behavior.
 457
 458           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 459
 460           Say N if unsure.
 461
 462 config RCU_FAST_NO_HZ
 463         bool "Accelerate last non-dyntick-idle CPU's grace periods"
 464         depends on TREE_RCU && NO_HZ && SMP
 465         default n
 466         help
 467           This option causes RCU to attempt to accelerate grace periods
 468           in order to allow the final CPU to enter dynticks-idle state
 469           more quickly.  On the other hand, this option increases the
 470           overhead of the dynticks-idle checking, particularly on systems
 471           with large numbers of CPUs.
 472
 473           Say Y if energy efficiency is critically important, particularly
 474                 if you have relatively few CPUs.
 475
 476           Say N if you are unsure.
 477
 478 config TREE_RCU_TRACE
 479         def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 480         select DEBUG_FS
 481         help
 482           This option provides tracing for the TREE_RCU and
 483           TREE_PREEMPT_RCU implementations, permitting Makefile to
 484           trivially select kernel/rcutree_trace.c.
 485
 486 config RCU_BOOST
 487         bool "Enable RCU priority boosting"
 488         depends on RT_MUTEXES && TINY_PREEMPT_RCU
 489         default n
 490         help
 491           This option boosts the priority of preempted RCU readers that
 492           block the current preemptible RCU grace period for too long.
 493           This option also prevents heavy loads from blocking RCU
 494           callback invocation for all flavors of RCU.
 495
 496           Say Y here if you are working with real-time apps or heavy loads
 497           Say N here if you are unsure.
 498
 499 config RCU_BOOST_PRIO
 500         int "Real-time priority to boost RCU readers to"
 501         range 1 99
 502         depends on RCU_BOOST
 503         default 1
 504         help
 505           This option specifies the real-time priority to which preempted
 506           RCU readers are to be boosted.  If you are working with CPU-bound
 507           real-time applications, you should specify a priority higher then
 508           the highest-priority CPU-bound application.
 509
 510           Specify the real-time priority, or take the default if unsure.
 511
 512 config RCU_BOOST_DELAY
 513         int "Milliseconds to delay boosting after RCU grace-period start"
 514         range 0 3000
 515         depends on RCU_BOOST
 516         default 500
 517         help
 518           This option specifies the time to wait after the beginning of
 519           a given grace period before priority-boosting preempted RCU
 520           readers blocking that grace period.  Note that any RCU reader
 521           blocking an expedited RCU grace period is boosted immediately.
 522
 523           Accept the default if unsure.
 524
 525 endmenu # "RCU Subsystem"
 526
 527 config IKCONFIG
 528         tristate "Kernel .config support"
 529         ---help---
 530           This option enables the complete Linux kernel ".config" file
 531           contents to be saved in the kernel. It provides documentation
 532           of which kernel options are used in a running kernel or in an
 533           on-disk kernel.  This information can be extracted from the kernel
 534           image file with the script scripts/extract-ikconfig and used as
 535           input to rebuild the current kernel or to build another kernel.
 536           It can also be extracted from a running kernel by reading
 537           /proc/config.gz if enabled (below).
 538
 539 config IKCONFIG_PROC
 540         bool "Enable access to .config through /proc/config.gz"
 541         depends on IKCONFIG && PROC_FS
 542         ---help---
 543           This option enables access to the kernel configuration file
 544           through /proc/config.gz.
 545
 546 config LOG_BUF_SHIFT
 547         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 548         range 12 21
 549         default 17
 550         help
 551           Select kernel log buffer size as a power of 2.
 552           Examples:
 553                      17 => 128 KB
 554                      16 => 64 KB
 555                      15 => 32 KB
 556                      14 => 16 KB
 557                      13 =>  8 KB
 558                      12 =>  4 KB
 559
 560 #
 561 # Architectures with an unreliable sched_clock() should select this:
 562 #
 563 config HAVE_UNSTABLE_SCHED_CLOCK
 564         bool
 565
 566 menuconfig CGROUPS
 567         boolean "Control Group support"
 568         depends on EVENTFD
 569         help
 570           This option adds support for grouping sets of processes together, for
 571           use with process control subsystems such as Cpusets, CFS, memory
 572           controls or device isolation.
 573           See
 574                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 575                 - Documentation/cgroups/ (features for grouping, isolation
 576                                           and resource control)
 577
 578           Say N if unsure.
 579
 580 if CGROUPS
 581
 582 config CGROUP_DEBUG
 583         bool "Example debug cgroup subsystem"
 584         default n
 585         help
 586           This option enables a simple cgroup subsystem that
 587           exports useful debugging information about the cgroups
 588           framework.
 589
 590           Say N if unsure.
 591
 592 config CGROUP_NS
 593         bool "Namespace cgroup subsystem"
 594         help
 595           Provides a simple namespace cgroup subsystem to
 596           provide hierarchical naming of sets of namespaces,
 597           for instance virtual servers and checkpoint/restart
 598           jobs.
 599
 600 config CGROUP_FREEZER
 601         bool "Freezer cgroup subsystem"
 602         help
 603           Provides a way to freeze and unfreeze all tasks in a
 604           cgroup.
 605
 606 config CGROUP_DEVICE
 607         bool "Device controller for cgroups"
 608         help
 609           Provides a cgroup implementing whitelists for devices which
 610           a process in the cgroup can mknod or open.
 611
 612 config CPUSETS
 613         bool "Cpuset support"
 614         help
 615           This option will let you create and manage CPUSETs which
 616           allow dynamically partitioning a system into sets of CPUs and
 617           Memory Nodes and assigning tasks to run only within those sets.
 618           This is primarily useful on large SMP or NUMA systems.
 619
 620           Say N if unsure.
 621
 622 config PROC_PID_CPUSET
 623         bool "Include legacy /proc/<pid>/cpuset file"
 624         depends on CPUSETS
 625         default y
 626
 627 config CGROUP_CPUACCT
 628         bool "Simple CPU accounting cgroup subsystem"
 629         help
 630           Provides a simple Resource Controller for monitoring the
 631           total CPU consumed by the tasks in a cgroup.
 632
 633 config RESOURCE_COUNTERS
 634         bool "Resource counters"
 635         help
 636           This option enables controller independent resource accounting
 637           infrastructure that works with cgroups.
 638
 639 config CGROUP_MEM_RES_CTLR
 640         bool "Memory Resource Controller for Control Groups"
 641         depends on RESOURCE_COUNTERS
 642         select MM_OWNER
 643         help
 644           Provides a memory resource controller that manages both anonymous
 645           memory and page cache. (See Documentation/cgroups/memory.txt)
 646
 647           Note that setting this option increases fixed memory overhead
 648           associated with each page of memory in the system. By this,
 649           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 650           usage tracking struct at boot. Total amount of this is printed out
 651           at boot.
 652
 653           Only enable when you're ok with these trade offs and really
 654           sure you need the memory resource controller. Even when you enable
 655           this, you can set "cgroup_disable=memory" at your boot option to
 656           disable memory resource controller and you can avoid overheads.
 657           (and lose benefits of memory resource controller)
 658
 659           This config option also selects MM_OWNER config option, which
 660           could in turn add some fork/exit overhead.
 661
 662 config CGROUP_MEM_RES_CTLR_SWAP
 663         bool "Memory Resource Controller Swap Extension"
 664         depends on CGROUP_MEM_RES_CTLR && SWAP
 665         help
 666           Add swap management feature to memory resource controller. When you
 667           enable this, you can limit mem+swap usage per cgroup. In other words,
 668           when you disable this, memory resource controller has no cares to
 669           usage of swap...a process can exhaust all of the swap. This extension
 670           is useful when you want to avoid exhaustion swap but this itself
 671           adds more overheads and consumes memory for remembering information.
 672           Especially if you use 32bit system or small memory system, please
 673           be careful about enabling this. When memory resource controller
 674           is disabled by boot option, this will be automatically disabled and
 675           there will be no overhead from this. Even when you set this config=y,
 676           if boot option "noswapaccount" is set, swap will not be accounted.
 677           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 678           size is 4096bytes, 512k per 1Gbytes of swap.
 679 config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
 680         bool "Memory Resource Controller Swap Extension enabled by default"
 681         depends on CGROUP_MEM_RES_CTLR_SWAP
 682         default y
 683         help
 684           Memory Resource Controller Swap Extension comes with its price in
 685           a bigger memory consumption. General purpose distribution kernels
 686           which want to enable the feature but keep it disabled by default
 687           and let the user enable it by swapaccount boot command line
 688           parameter should have this option unselected.
 689           For those who want to have the feature enabled by default should
 690           select this option (if, for some reason, they need to disable it
 691           then noswapaccount does the trick).
 692
 693 config CGROUP_PERF
 694         bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
 695         depends on PERF_EVENTS && CGROUPS
 696         help
 697           This option extends the per-cpu mode to restrict monitoring to
 698           threads which belong to the cgroup specified and run on the
 699           designated cpu.
 700
 701           Say N if unsure.
 702
 703 menuconfig CGROUP_SCHED
 704         bool "Group CPU scheduler"
 705         depends on EXPERIMENTAL
 706         default n
 707         help
 708           This feature lets CPU scheduler recognize task groups and control CPU
 709           bandwidth allocation to such task groups. It uses cgroups to group
 710           tasks.
 711
 712 if CGROUP_SCHED
 713 config FAIR_GROUP_SCHED
 714         bool "Group scheduling for SCHED_OTHER"
 715         depends on CGROUP_SCHED
 716         default CGROUP_SCHED
 717
 718 config RT_GROUP_SCHED
 719         bool "Group scheduling for SCHED_RR/FIFO"
 720         depends on EXPERIMENTAL
 721         depends on CGROUP_SCHED
 722         default n
 723         help
 724           This feature lets you explicitly allocate real CPU bandwidth
 725           to task groups. If enabled, it will also make it impossible to
 726           schedule realtime tasks for non-root users until you allocate
 727           realtime bandwidth for them.
 728           See Documentation/scheduler/sched-rt-group.txt for more information.
 729
 730 endif #CGROUP_SCHED
 731
 732 config BLK_CGROUP
 733         tristate "Block IO controller"
 734         depends on BLOCK
 735         default n
 736         ---help---
 737         Generic block IO controller cgroup interface. This is the common
 738         cgroup interface which should be used by various IO controlling
 739         policies.
 740
 741         Currently, CFQ IO scheduler uses it to recognize task groups and
 742         control disk bandwidth allocation (proportional time slice allocation)
 743         to such task groups. It is also used by bio throttling logic in
 744         block layer to implement upper limit in IO rates on a device.
 745
 746         This option only enables generic Block IO controller infrastructure.
 747         One needs to also enable actual IO controlling logic/policy. For
 748         enabling proportional weight division of disk bandwidth in CFQ, set
 749         CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 750         CONFIG_BLK_DEV_THROTTLING=y.
 751
 752         See Documentation/cgroups/blkio-controller.txt for more information.
 753
 754 config DEBUG_BLK_CGROUP
 755         bool "Enable Block IO controller debugging"
 756         depends on BLK_CGROUP
 757         default n
 758         ---help---
 759         Enable some debugging help. Currently it exports additional stat
 760         files in a cgroup which can be useful for debugging.
 761
 762 endif # CGROUPS
 763
 764 menuconfig NAMESPACES
 765         bool "Namespaces support" if EXPERT
 766         default !EXPERT
 767         help
 768           Provides the way to make tasks work with different objects using
 769           the same id. For example same IPC id may refer to different objects
 770           or same user id or pid may refer to different tasks when used in
 771           different namespaces.
 772
 773 if NAMESPACES
 774
 775 config UTS_NS
 776         bool "UTS namespace"
 777         default y
 778         help
 779           In this namespace tasks see different info provided with the
 780           uname() system call
 781
 782 config IPC_NS
 783         bool "IPC namespace"
 784         depends on (SYSVIPC || POSIX_MQUEUE)
 785         default y
 786         help
 787           In this namespace tasks work with IPC ids which correspond to
 788           different IPC objects in different namespaces.
 789
 790 config USER_NS
 791         bool "User namespace (EXPERIMENTAL)"
 792         depends on EXPERIMENTAL
 793         default y
 794         help
 795           This allows containers, i.e. vservers, to use user namespaces
 796           to provide different user info for different servers.
 797           If unsure, say N.
 798
 799 config PID_NS
 800         bool "PID Namespaces"
 801         default y
 802         help
 803           Support process id namespaces.  This allows having multiple
 804           processes with the same pid as long as they are in different
 805           pid namespaces.  This is a building block of containers.
 806
 807 config NET_NS
 808         bool "Network namespace"
 809         depends on NET
 810         default y
 811         help
 812           Allow user space to create what appear to be multiple instances
 813           of the network stack.
 814
 815 endif # NAMESPACES
 816
 817 config SCHED_AUTOGROUP
 818         bool "Automatic process group scheduling"
 819         select EVENTFD
 820         select CGROUPS
 821         select CGROUP_SCHED
 822         select FAIR_GROUP_SCHED
 823         help
 824           This option optimizes the scheduler for common desktop workloads by
 825           automatically creating and populating task groups.  This separation
 826           of workloads isolates aggressive CPU burners (like build jobs) from
 827           desktop applications.  Task group autogeneration is currently based
 828           upon task session.
 829
 830 config MM_OWNER
 831         bool
 832
 833 config SYSFS_DEPRECATED
 834         bool "Enable deprecated sysfs features to support old userspace tools"
 835         depends on SYSFS
 836         default n
 837         help
 838           This option adds code that switches the layout of the "block" class
 839           devices, to not show up in /sys/class/block/, but only in
 840           /sys/block/.
 841
 842           This switch is only active when the sysfs.deprecated=1 boot option is
 843           passed or the SYSFS_DEPRECATED_V2 option is set.
 844
 845           This option allows new kernels to run on old distributions and tools,
 846           which might get confused by /sys/class/block/. Since 2007/2008 all
 847           major distributions and tools handle this just fine.
 848
 849           Recent distributions and userspace tools after 2009/2010 depend on
 850           the existence of /sys/class/block/, and will not work with this
 851           option enabled.
 852
 853           Only if you are using a new kernel on an old distribution, you might
 854           need to say Y here.
 855
 856 config SYSFS_DEPRECATED_V2
 857         bool "Enable deprecated sysfs features by default"
 858         default n
 859         depends on SYSFS
 860         depends on SYSFS_DEPRECATED
 861         help
 862           Enable deprecated sysfs by default.
 863
 864           See the CONFIG_SYSFS_DEPRECATED option for more details about this
 865           option.
 866
 867           Only if you are using a new kernel on an old distribution, you might
 868           need to say Y here. Even then, odds are you would not need it
 869           enabled, you can always pass the boot option if absolutely necessary.
 870
 871 config RELAY
 872         bool "Kernel->user space relay support (formerly relayfs)"
 873         help
 874           This option enables support for relay interface support in
 875           certain file systems (such as debugfs).
 876           It is designed to provide an efficient mechanism for tools and
 877           facilities to relay large amounts of data from kernel space to
 878           user space.
 879
 880           If unsure, say N.
 881
 882 config BLK_DEV_INITRD
 883         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 884         depends on BROKEN || !FRV
 885         help
 886           The initial RAM filesystem is a ramfs which is loaded by the
 887           boot loader (loadlin or lilo) and that is mounted as root
 888           before the normal boot procedure. It is typically used to
 889           load modules needed to mount the "real" root file system,
 890           etc. See <file:Documentation/initrd.txt> for details.
 891
 892           If RAM disk support (BLK_DEV_RAM) is also included, this
 893           also enables initial RAM disk (initrd) support and adds
 894           15 Kbytes (more on some other architectures) to the kernel size.
 895
 896           If unsure say Y.
 897
 898 if BLK_DEV_INITRD
 899
 900 source "usr/Kconfig"
 901
 902 endif
 903
 904 config CC_OPTIMIZE_FOR_SIZE
 905         bool "Optimize for size"
 906         default y
 907         help
 908           Enabling this option will pass "-Os" instead of "-O2" to gcc
 909           resulting in a smaller kernel.
 910
 911           If unsure, say Y.
 912
 913 config SYSCTL
 914         bool
 915
 916 config ANON_INODES
 917         bool
 918
 919 menuconfig EXPERT
 920         bool "Configure standard kernel features (expert users)"
 921         help
 922           This option allows certain base kernel options and settings
 923           to be disabled or tweaked. This is for specialized
 924           environments which can tolerate a "non-standard" kernel.
 925           Only use this if you really know what you are doing.
 926
 927 config EMBEDDED
 928         bool "Embedded system"
 929         select EXPERT
 930         help
 931           This option should be enabled if compiling the kernel for
 932           an embedded system so certain expert options are available
 933           for configuration.
 934
 935 config UID16
 936         bool "Enable 16-bit UID system calls" if EXPERT
 937         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 938         default y
 939         help
 940           This enables the legacy 16-bit UID syscall wrappers.
 941
 942 config SYSCTL_SYSCALL
 943         bool "Sysctl syscall support" if EXPERT
 944         depends on PROC_SYSCTL
 945         default y
 946         select SYSCTL
 947         ---help---
 948           sys_sysctl uses binary paths that have been found challenging
 949           to properly maintain and use.  The interface in /proc/sys
 950           using paths with ascii names is now the primary path to this
 951           information.
 952
 953           Almost nothing using the binary sysctl interface so if you are
 954           trying to save some space it is probably safe to disable this,
 955           making your kernel marginally smaller.
 956
 957           If unsure say Y here.
 958
 959 config KALLSYMS
 960          bool "Load all symbols for debugging/ksymoops" if EXPERT
 961          default y
 962          help
 963            Say Y here to let the kernel print out symbolic crash information and
 964            symbolic stack backtraces. This increases the size of the kernel
 965            somewhat, as all symbols have to be loaded into the kernel image.
 966
 967 config KALLSYMS_ALL
 968         bool "Include all symbols in kallsyms"
 969         depends on DEBUG_KERNEL && KALLSYMS
 970         help
 971            Normally kallsyms only contains the symbols of functions, for nicer
 972            OOPS messages.  Some debuggers can use kallsyms for other
 973            symbols too: say Y here to include all symbols, if you need them
 974            and you don't care about adding 300k to the size of your kernel.
 975
 976            Say N.
 977
 978 config KALLSYMS_EXTRA_PASS
 979         bool "Do an extra kallsyms pass"
 980         depends on KALLSYMS
 981         help
 982            If kallsyms is not working correctly, the build will fail with
 983            inconsistent kallsyms data.  If that occurs, log a bug report and
 984            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 985            Always say N here unless you find a bug in kallsyms, which must be
 986            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 987            you wait for kallsyms to be fixed.
 988
 989
 990 config HOTPLUG
 991         bool "Support for hot-pluggable devices" if EXPERT
 992         default y
 993         help
 994           This option is provided for the case where no hotplug or uevent
 995           capabilities is wanted by the kernel.  You should only consider
 996           disabling this option for embedded systems that do not use modules, a
 997           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 998
 999 config PRINTK
1000         default y
1001         bool "Enable support for printk" if EXPERT
1002         help
1003           This option enables normal printk support. Removing it
1004           eliminates most of the message strings from the kernel image
1005           and makes the kernel more or less silent. As this makes it
1006           very difficult to diagnose system problems, saying N here is
1007           strongly discouraged.
1008
1009 config BUG
1010         bool "BUG() support" if EXPERT
1011         default y
1012         help
1013           Disabling this option eliminates support for BUG and WARN, reducing
1014           the size of your kernel image and potentially quietly ignoring
1015           numerous fatal conditions. You should only consider disabling this
1016           option for embedded systems with no facilities for reporting errors.
1017           Just say Y.
1018
1019 config ELF_CORE
1020         default y
1021         bool "Enable ELF core dumps" if EXPERT
1022         help
1023           Enable support for generating core dumps. Disabling saves about 4k.
1024
1025 config PCSPKR_PLATFORM
1026         bool "Enable PC-Speaker support" if EXPERT
1027         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1028         default y
1029         help
1030           This option allows to disable the internal PC-Speaker
1031           support, saving some memory.
1032
1033 config BASE_FULL
1034         default y
1035         bool "Enable full-sized data structures for core" if EXPERT
1036         help
1037           Disabling this option reduces the size of miscellaneous core
1038           kernel data structures. This saves memory on small machines,
1039           but may reduce performance.
1040
1041 config FUTEX
1042         bool "Enable futex support" if EXPERT
1043         default y
1044         select RT_MUTEXES
1045         help
1046           Disabling this option will cause the kernel to be built without
1047           support for "fast userspace mutexes".  The resulting kernel may not
1048           run glibc-based applications correctly.
1049
1050 config EPOLL
1051         bool "Enable eventpoll support" if EXPERT
1052         default y
1053         select ANON_INODES
1054         help
1055           Disabling this option will cause the kernel to be built without
1056           support for epoll family of system calls.
1057
1058 config SIGNALFD
1059         bool "Enable signalfd() system call" if EXPERT
1060         select ANON_INODES
1061         default y
1062         help
1063           Enable the signalfd() system call that allows to receive signals
1064           on a file descriptor.
1065
1066           If unsure, say Y.
1067
1068 config TIMERFD
1069         bool "Enable timerfd() system call" if EXPERT
1070         select ANON_INODES
1071         default y
1072         help
1073           Enable the timerfd() system call that allows to receive timer
1074           events on a file descriptor.
1075
1076           If unsure, say Y.
1077
1078 config EVENTFD
1079         bool "Enable eventfd() system call" if EXPERT
1080         select ANON_INODES
1081         default y
1082         help
1083           Enable the eventfd() system call that allows to receive both
1084           kernel notification (ie. KAIO) or userspace notifications.
1085
1086           If unsure, say Y.
1087
1088 config SHMEM
1089         bool "Use full shmem filesystem" if EXPERT
1090         default y
1091         depends on MMU
1092         help
1093           The shmem is an internal filesystem used to manage shared memory.
1094           It is backed by swap and manages resource limits. It is also exported
1095           to userspace as tmpfs if TMPFS is enabled. Disabling this
1096           option replaces shmem and tmpfs with the much simpler ramfs code,
1097           which may be appropriate on small systems without swap.
1098
1099 config AIO
1100         bool "Enable AIO support" if EXPERT
1101         default y
1102         help
1103           This option enables POSIX asynchronous I/O which may by used
1104           by some high performance threaded applications. Disabling
1105           this option saves about 7k.
1106
1107 config HAVE_PERF_EVENTS
1108         bool
1109         help
1110           See tools/perf/design.txt for details.
1111
1112 config PERF_USE_VMALLOC
1113         bool
1114         help
1115           See tools/perf/design.txt for details
1116
1117 menu "Kernel Performance Events And Counters"
1118
1119 config PERF_EVENTS
1120         bool "Kernel performance events and counters"
1121         default y if (PROFILING || PERF_COUNTERS)
1122         depends on HAVE_PERF_EVENTS
1123         select ANON_INODES
1124         select IRQ_WORK
1125         help
1126           Enable kernel support for various performance events provided
1127           by software and hardware.
1128
1129           Software events are supported either built-in or via the
1130           use of generic tracepoints.
1131
1132           Most modern CPUs support performance events via performance
1133           counter registers. These registers count the number of certain
1134           types of hw events: such as instructions executed, cachemisses
1135           suffered, or branches mis-predicted - without slowing down the
1136           kernel or applications. These registers can also trigger interrupts
1137           when a threshold number of events have passed - and can thus be
1138           used to profile the code that runs on that CPU.
1139
1140           The Linux Performance Event subsystem provides an abstraction of
1141           these software and hardware event capabilities, available via a
1142           system call and used by the "perf" utility in tools/perf/. It
1143           provides per task and per CPU counters, and it provides event
1144           capabilities on top of those.
1145
1146           Say Y if unsure.
1147
1148 config PERF_COUNTERS
1149         bool "Kernel performance counters (old config option)"
1150         depends on HAVE_PERF_EVENTS
1151         help
1152           This config has been obsoleted by the PERF_EVENTS
1153           config option - please see that one for details.
1154
1155           It has no effect on the kernel whether you enable
1156           it or not, it is a compatibility placeholder.
1157
1158           Say N if unsure.
1159
1160 config DEBUG_PERF_USE_VMALLOC
1161         default n
1162         bool "Debug: use vmalloc to back perf mmap() buffers"
1163         depends on PERF_EVENTS && DEBUG_KERNEL
1164         select PERF_USE_VMALLOC
1165         help
1166          Use vmalloc memory to back perf mmap() buffers.
1167
1168          Mostly useful for debugging the vmalloc code on platforms
1169          that don't require it.
1170
1171          Say N if unsure.
1172
1173 endmenu
1174
1175 config VM_EVENT_COUNTERS
1176         default y
1177         bool "Enable VM event counters for /proc/vmstat" if EXPERT
1178         help
1179           VM event counters are needed for event counts to be shown.
1180           This option allows the disabling of the VM event counters
1181           on EXPERT systems.  /proc/vmstat will only show page counts
1182           if VM event counters are disabled.
1183
1184 config PCI_QUIRKS
1185         default y
1186         bool "Enable PCI quirk workarounds" if EXPERT
1187         depends on PCI
1188         help
1189           This enables workarounds for various PCI chipset
1190           bugs/quirks. Disable this only if your target machine is
1191           unaffected by PCI quirks.
1192
1193 config SLUB_DEBUG
1194         default y
1195         bool "Enable SLUB debugging support" if EXPERT
1196         depends on SLUB && SYSFS
1197         help
1198           SLUB has extensive debug support features. Disabling these can
1199           result in significant savings in code size. This also disables
1200           SLUB sysfs support. /sys/slab will not exist and there will be
1201           no support for cache validation etc.
1202
1203 config COMPAT_BRK
1204         bool "Disable heap randomization"
1205         default y
1206         help
1207           Randomizing heap placement makes heap exploits harder, but it
1208           also breaks ancient binaries (including anything libc5 based).
1209           This option changes the bootup default to heap randomization
1210           disabled, and can be overridden at runtime by setting
1211           /proc/sys/kernel/randomize_va_space to 2.
1212
1213           On non-ancient distros (post-2000 ones) N is usually a safe choice.
1214
1215 choice
1216         prompt "Choose SLAB allocator"
1217         default SLUB
1218         help
1219            This option allows to select a slab allocator.
1220
1221 config SLAB
1222         bool "SLAB"
1223         help
1224           The regular slab allocator that is established and known to work
1225           well in all environments. It organizes cache hot objects in
1226           per cpu and per node queues.
1227
1228 config SLUB
1229         bool "SLUB (Unqueued Allocator)"
1230         help
1231            SLUB is a slab allocator that minimizes cache line usage
1232            instead of managing queues of cached objects (SLAB approach).
1233            Per cpu caching is realized using slabs of objects instead
1234            of queues of objects. SLUB can use memory efficiently
1235            and has enhanced diagnostics. SLUB is the default choice for
1236            a slab allocator.
1237
1238 config SLOB
1239         depends on EXPERT
1240         bool "SLOB (Simple Allocator)"
1241         help
1242            SLOB replaces the stock allocator with a drastically simpler
1243            allocator. SLOB is generally more space efficient but
1244            does not perform as well on large systems.
1245
1246 endchoice
1247
1248 config MMAP_ALLOW_UNINITIALIZED
1249         bool "Allow mmapped anonymous memory to be uninitialized"
1250         depends on EXPERT && !MMU
1251         default n
1252         help
1253           Normally, and according to the Linux spec, anonymous memory obtained
1254           from mmap() has it's contents cleared before it is passed to
1255           userspace.  Enabling this config option allows you to request that
1256           mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1257           providing a huge performance boost.  If this option is not enabled,
1258           then the flag will be ignored.
1259
1260           This is taken advantage of by uClibc's malloc(), and also by
1261           ELF-FDPIC binfmt's brk and stack allocator.
1262
1263           Because of the obvious security issues, this option should only be
1264           enabled on embedded devices where you control what is run in
1265           userspace.  Since that isn't generally a problem on no-MMU systems,
1266           it is normally safe to say Y here.
1267
1268           See Documentation/nommu-mmap.txt for more information.
1269
1270 config PROFILING
1271         bool "Profiling support"
1272         help
1273           Say Y here to enable the extended profiling support mechanisms used
1274           by profilers such as OProfile.
1275
1276 #
1277 # Place an empty function call at each tracepoint site. Can be
1278 # dynamically changed for a probe function.
1279 #
1280 config TRACEPOINTS
1281         bool
1282
1283 source "arch/Kconfig"
1284
1285 endmenu         # General setup
1286
1287 config HAVE_GENERIC_DMA_COHERENT
1288         bool
1289         default n
1290
1291 config SLABINFO
1292         bool
1293         depends on PROC_FS
1294         depends on SLAB || SLUB_DEBUG
1295         default y
1296
1297 config RT_MUTEXES
1298         boolean
1299
1300 config BASE_SMALL
1301         int
1302         default 0 if BASE_FULL
1303         default 1 if !BASE_FULL
1304
1305 menuconfig MODULES
1306         bool "Enable loadable module support"
1307         help
1308           Kernel modules are small pieces of compiled code which can
1309           be inserted in the running kernel, rather than being
1310           permanently built into the kernel.  You use the "modprobe"
1311           tool to add (and sometimes remove) them.  If you say Y here,
1312           many parts of the kernel can be built as modules (by
1313           answering M instead of Y where indicated): this is most
1314           useful for infrequently used options which are not required
1315           for booting.  For more information, see the man pages for
1316           modprobe, lsmod, modinfo, insmod and rmmod.
1317
1318           If you say Y here, you will need to run "make
1319           modules_install" to put the modules under /lib/modules/
1320           where modprobe can find them (you may need to be root to do
1321           this).
1322
1323           If unsure, say Y.
1324
1325 if MODULES
1326
1327 config MODULE_FORCE_LOAD
1328         bool "Forced module loading"
1329         default n
1330         help
1331           Allow loading of modules without version information (ie. modprobe
1332           --force).  Forced module loading sets the 'F' (forced) taint flag and
1333           is usually a really bad idea.
1334
1335 config MODULE_UNLOAD
1336         bool "Module unloading"
1337         help
1338           Without this option you will not be able to unload any
1339           modules (note that some modules may not be unloadable
1340           anyway), which makes your kernel smaller, faster
1341           and simpler.  If unsure, say Y.
1342
1343 config MODULE_FORCE_UNLOAD
1344         bool "Forced module unloading"
1345         depends on MODULE_UNLOAD && EXPERIMENTAL
1346         help
1347           This option allows you to force a module to unload, even if the
1348           kernel believes it is unsafe: the kernel will remove the module
1349           without waiting for anyone to stop using it (using the -f option to
1350           rmmod).  This is mainly for kernel developers and desperate users.
1351           If unsure, say N.
1352
1353 config MODVERSIONS
1354         bool "Module versioning support"
1355         help
1356           Usually, you have to use modules compiled with your kernel.
1357           Saying Y here makes it sometimes possible to use modules
1358           compiled for different kernels, by adding enough information
1359           to the modules to (hopefully) spot any changes which would
1360           make them incompatible with the kernel you are running.  If
1361           unsure, say N.
1362
1363 config MODULE_SRCVERSION_ALL
1364         bool "Source checksum for all modules"
1365         help
1366           Modules which contain a MODULE_VERSION get an extra "srcversion"
1367           field inserted into their modinfo section, which contains a
1368           sum of the source files which made it.  This helps maintainers
1369           see exactly which source was used to build a module (since
1370           others sometimes change the module source without updating
1371           the version).  With this option, such a "srcversion" field
1372           will be created for all modules.  If unsure, say N.
1373
1374 endif # MODULES
1375
1376 config INIT_ALL_POSSIBLE
1377         bool
1378         help
1379           Back when each arch used to define their own cpu_online_map and
1380           cpu_possible_map, some of them chose to initialize cpu_possible_map
1381           with all 1s, and others with all 0s.  When they were centralised,
1382           it was better to provide this option than to break all the archs
1383           and have several arch maintainers pursuing me down dark alleys.
1384
1385 config STOP_MACHINE
1386         bool
1387         default y
1388         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1389         help
1390           Need stop_machine() primitive.
1391
1392 source "block/Kconfig"
1393
1394 config PREEMPT_NOTIFIERS
1395         bool
1396
1397 config PADATA
1398         depends on SMP
1399         bool
1400
1401 source "kernel/Kconfig.locks"