init/Kconfig

   1 config DEFCONFIG_LIST
   2         string
   3         depends on !UML
   4         option defconfig_list
   5         default "/lib/modules/$UNAME_RELEASE/.config"
   6         default "/etc/kernel-config"
   7         default "/boot/config-$UNAME_RELEASE"
   8         default "arch/$ARCH/defconfig"
   9
  10 menu "General setup"
  11
  12 config EXPERIMENTAL
  13         bool "Prompt for development and/or incomplete code/drivers"
  14         ---help---
  15           Some of the various things that Linux supports (such as network
  16           drivers, file systems, network protocols, etc.) can be in a state
  17           of development where the functionality, stability, or the level of
  18           testing is not yet high enough for general use. This is usually
  19           known as the "alpha-test" phase among developers. If a feature is
  20           currently in alpha-test, then the developers usually discourage
  21           uninformed widespread use of this feature by the general public to
  22           avoid "Why doesn't this work?" type mail messages. However, active
  23           testing and use of these systems is welcomed. Just be aware that it
  24           may not meet the normal level of reliability or it may fail to work
  25           in some special cases. Detailed bug reports from people familiar
  26           with the kernel internals are usually welcomed by the developers
  27           (before submitting bug reports, please read the documents
  28           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  29           <file:Documentation/BUG-HUNTING>, and
  30           <file:Documentation/oops-tracing.txt> in the kernel source).
  31
  32           This option will also make obsoleted drivers available. These are
  33           drivers that have been replaced by something else, and/or are
  34           scheduled to be removed in a future kernel release.
  35
  36           Unless you intend to help test and develop a feature or driver that
  37           falls into this category, or you have a situation that requires
  38           using these features, you should probably say N here, which will
  39           cause the configurator to present you with fewer choices. If
  40           you say Y here, you will be offered the choice of using features or
  41           drivers that are currently considered to be in the alpha-test phase.
  42
  43 config BROKEN
  44         bool
  45
  46 config BROKEN_ON_SMP
  47         bool
  48         depends on BROKEN || !SMP
  49         default y
  50
  51 config LOCK_KERNEL
  52         bool
  53         depends on SMP || PREEMPT
  54         default y
  55
  56 config INIT_ENV_ARG_LIMIT
  57         int
  58         default 32 if !UML
  59         default 128 if UML
  60         help
  61           Maximum of each of the number of arguments and environment
  62           variables passed to init from the kernel command line.
  63
  64
  65 config LOCALVERSION
  66         string "Local version - append to kernel release"
  67         help
  68           Append an extra string to the end of your kernel version.
  69           This will show up when you type uname, for example.
  70           The string you set here will be appended after the contents of
  71           any files with a filename matching localversion* in your
  72           object and source tree, in that order.  Your total string can
  73           be a maximum of 64 characters.
  74
  75 config LOCALVERSION_AUTO
  76         bool "Automatically append version information to the version string"
  77         default y
  78         help
  79           This will try to automatically determine if the current tree is a
  80           release tree by looking for git tags that belong to the current
  81           top of tree revision.
  82
  83           A string of the format -gxxxxxxxx will be added to the localversion
  84           if a git-based tree is found.  The string generated by this will be
  85           appended after any matching localversion* files, and after the value
  86           set in CONFIG_LOCALVERSION.
  87
  88           (The actual string used here is the first eight characters produced
  89           by running the command:
  90
  91             $ git rev-parse --verify HEAD
  92
  93           which is done within the script "scripts/setlocalversion".)
  94
  95 config SWAP
  96         bool "Support for paging of anonymous memory (swap)"
  97         depends on MMU && BLOCK
  98         default y
  99         help
 100           This option allows you to choose whether you want to have support
 101           for so called swap devices or swap files in your kernel that are
 102           used to provide more virtual memory than the actual RAM present
 103           in your computer.  If unsure say Y.
 104
 105 config SYSVIPC
 106         bool "System V IPC"
 107         ---help---
 108           Inter Process Communication is a suite of library functions and
 109           system calls which let processes (running programs) synchronize and
 110           exchange information. It is generally considered to be a good thing,
 111           and some programs won't run unless you say Y here. In particular, if
 112           you want to run the DOS emulator dosemu under Linux (read the
 113           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 114           you'll need to say Y here.
 115
 116           You can find documentation about IPC with "info ipc" and also in
 117           section 6.4 of the Linux Programmer's Guide, available from
 118           <http://www.tldp.org/guides.html>.
 119
 120 config SYSVIPC_SYSCTL
 121         bool
 122         depends on SYSVIPC
 123         depends on SYSCTL
 124         default y
 125
 126 config POSIX_MQUEUE
 127         bool "POSIX Message Queues"
 128         depends on NET && EXPERIMENTAL
 129         ---help---
 130           POSIX variant of message queues is a part of IPC. In POSIX message
 131           queues every message has a priority which decides about succession
 132           of receiving it by a process. If you want to compile and run
 133           programs written e.g. for Solaris with use of its POSIX message
 134           queues (functions mq_*) say Y here.
 135
 136           POSIX message queues are visible as a filesystem called 'mqueue'
 137           and can be mounted somewhere if you want to do filesystem
 138           operations on message queues.
 139
 140           If unsure, say Y.
 141
 142 config BSD_PROCESS_ACCT
 143         bool "BSD Process Accounting"
 144         help
 145           If you say Y here, a user level program will be able to instruct the
 146           kernel (via a special system call) to write process accounting
 147           information to a file: whenever a process exits, information about
 148           that process will be appended to the file by the kernel.  The
 149           information includes things such as creation time, owning user,
 150           command name, memory usage, controlling terminal etc. (the complete
 151           list is in the struct acct in <file:include/linux/acct.h>).  It is
 152           up to the user level program to do useful things with this
 153           information.  This is generally a good idea, so say Y.
 154
 155 config BSD_PROCESS_ACCT_V3
 156         bool "BSD Process Accounting version 3 file format"
 157         depends on BSD_PROCESS_ACCT
 158         default n
 159         help
 160           If you say Y here, the process accounting information is written
 161           in a new file format that also logs the process IDs of each
 162           process and it's parent. Note that this file format is incompatible
 163           with previous v0/v1/v2 file formats, so you will need updated tools
 164           for processing it. A preliminary version of these tools is available
 165           at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
 166
 167 config TASKSTATS
 168         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 169         depends on NET
 170         default n
 171         help
 172           Export selected statistics for tasks/processes through the
 173           generic netlink interface. Unlike BSD process accounting, the
 174           statistics are available during the lifetime of tasks/processes as
 175           responses to commands. Like BSD accounting, they are sent to user
 176           space on task exit.
 177
 178           Say N if unsure.
 179
 180 config TASK_DELAY_ACCT
 181         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 182         depends on TASKSTATS
 183         help
 184           Collect information on time spent by a task waiting for system
 185           resources like cpu, synchronous block I/O completion and swapping
 186           in pages. Such statistics can help in setting a task's priorities
 187           relative to other tasks for cpu, io, rss limits etc.
 188
 189           Say N if unsure.
 190
 191 config TASK_XACCT
 192         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 193         depends on TASKSTATS
 194         help
 195           Collect extended task accounting data and send the data
 196           to userland for processing over the taskstats interface.
 197
 198           Say N if unsure.
 199
 200 config TASK_IO_ACCOUNTING
 201         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 202         depends on TASK_XACCT
 203         help
 204           Collect information on the number of bytes of storage I/O which this
 205           task has caused.
 206
 207           Say N if unsure.
 208
 209 config USER_NS
 210         bool "User Namespaces (EXPERIMENTAL)"
 211         default n
 212         depends on EXPERIMENTAL
 213         help
 214           Support user namespaces.  This allows containers, i.e.
 215           vservers, to use user namespaces to provide different
 216           user info for different servers.  If unsure, say N.
 217
 218 config AUDIT
 219         bool "Auditing support"
 220         depends on NET
 221         help
 222           Enable auditing infrastructure that can be used with another
 223           kernel subsystem, such as SELinux (which requires this for
 224           logging of avc messages output).  Does not do system-call
 225           auditing without CONFIG_AUDITSYSCALL.
 226
 227 config AUDITSYSCALL
 228         bool "Enable system-call auditing support"
 229         depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
 230         default y if SECURITY_SELINUX
 231         help
 232           Enable low-overhead system-call auditing infrastructure that
 233           can be used independently or with another kernel subsystem,
 234           such as SELinux.  To use audit's filesystem watch feature, please
 235           ensure that INOTIFY is configured.
 236
 237 config IKCONFIG
 238         tristate "Kernel .config support"
 239         ---help---
 240           This option enables the complete Linux kernel ".config" file
 241           contents to be saved in the kernel. It provides documentation
 242           of which kernel options are used in a running kernel or in an
 243           on-disk kernel.  This information can be extracted from the kernel
 244           image file with the script scripts/extract-ikconfig and used as
 245           input to rebuild the current kernel or to build another kernel.
 246           It can also be extracted from a running kernel by reading
 247           /proc/config.gz if enabled (below).
 248
 249 config IKCONFIG_PROC
 250         bool "Enable access to .config through /proc/config.gz"
 251         depends on IKCONFIG && PROC_FS
 252         ---help---
 253           This option enables access to the kernel configuration file
 254           through /proc/config.gz.
 255
 256 config LOG_BUF_SHIFT
 257         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 258         range 12 21
 259         default 17 if S390 || LOCKDEP
 260         default 16 if X86_NUMAQ || IA64
 261         default 15 if SMP
 262         default 14
 263         help
 264           Select kernel log buffer size as a power of 2.
 265           Defaults and Examples:
 266                      17 => 128 KB for S/390
 267                      16 => 64 KB for x86 NUMAQ or IA-64
 268                      15 => 32 KB for SMP
 269                      14 => 16 KB for uniprocessor
 270                      13 =>  8 KB
 271                      12 =>  4 KB
 272
 273 config CGROUPS
 274         bool "Control Group support"
 275         help
 276           This option will let you use process cgroup subsystems
 277           such as Cpusets
 278
 279           Say N if unsure.
 280
 281 config CGROUP_DEBUG
 282         bool "Example debug cgroup subsystem"
 283         depends on CGROUPS
 284         help
 285           This option enables a simple cgroup subsystem that
 286           exports useful debugging information about the cgroups
 287           framework
 288
 289           Say N if unsure
 290
 291 config CGROUP_NS
 292         bool "Namespace cgroup subsystem"
 293         depends on CGROUPS
 294         help
 295           Provides a simple namespace cgroup subsystem to
 296           provide hierarchical naming of sets of namespaces,
 297           for instance virtual servers and checkpoint/restart
 298           jobs.
 299
 300 config CGROUP_CPUACCT
 301         bool "Simple CPU accounting cgroup subsystem"
 302         depends on CGROUPS
 303         help
 304           Provides a simple Resource Controller for monitoring the
 305           total CPU consumed by the tasks in a cgroup
 306
 307 config CPUSETS
 308         bool "Cpuset support"
 309         depends on SMP && CGROUPS
 310         help
 311           This option will let you create and manage CPUSETs which
 312           allow dynamically partitioning a system into sets of CPUs and
 313           Memory Nodes and assigning tasks to run only within those sets.
 314           This is primarily useful on large SMP or NUMA systems.
 315
 316           Say N if unsure.
 317
 318 config FAIR_GROUP_SCHED
 319         bool "Fair group CPU scheduler"
 320         default y
 321         depends on EXPERIMENTAL
 322         help
 323           This feature lets CPU scheduler recognize task groups and control CPU
 324           bandwidth allocation to such task groups.
 325
 326 choice
 327         depends on FAIR_GROUP_SCHED
 328         prompt "Basis for grouping tasks"
 329         default FAIR_USER_SCHED
 330
 331 config FAIR_USER_SCHED
 332         bool "user id"
 333         help
 334           This option will choose userid as the basis for grouping
 335           tasks, thus providing equal CPU bandwidth to each user.
 336
 337 config FAIR_CGROUP_SCHED
 338         bool "Control groups"
 339         depends on CGROUPS
 340         help
 341           This option allows you to create arbitrary task groups
 342           using the "cgroup" pseudo filesystem and control
 343           the cpu bandwidth allocated to each such task group.
 344           Refer to Documentation/cgroups.txt for more information
 345           on "cgroup" pseudo filesystem.
 346
 347 endchoice
 348
 349 config SYSFS_DEPRECATED
 350         bool "Create deprecated sysfs files"
 351         default y
 352         help
 353           This option creates deprecated symlinks such as the
 354           "device"-link, the <subsystem>:<name>-link, and the
 355           "bus"-link. It may also add deprecated key in the
 356           uevent environment.
 357           None of these features or values should be used today, as
 358           they export driver core implementation details to userspace
 359           or export properties which can't be kept stable across kernel
 360           releases.
 361
 362           If enabled, this option will also move any device structures
 363           that belong to a class, back into the /sys/class hierarchy, in
 364           order to support older versions of udev.
 365
 366           If you are using a distro that was released in 2006 or later,
 367           it should be safe to say N here.
 368
 369 config PROC_PID_CPUSET
 370         bool "Include legacy /proc/<pid>/cpuset file"
 371         depends on CPUSETS
 372         default y
 373
 374 config RELAY
 375         bool "Kernel->user space relay support (formerly relayfs)"
 376         help
 377           This option enables support for relay interface support in
 378           certain file systems (such as debugfs).
 379           It is designed to provide an efficient mechanism for tools and
 380           facilities to relay large amounts of data from kernel space to
 381           user space.
 382
 383           If unsure, say N.
 384
 385 config BLK_DEV_INITRD
 386         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 387         depends on BROKEN || !FRV
 388         help
 389           The initial RAM filesystem is a ramfs which is loaded by the
 390           boot loader (loadlin or lilo) and that is mounted as root
 391           before the normal boot procedure. It is typically used to
 392           load modules needed to mount the "real" root file system,
 393           etc. See <file:Documentation/initrd.txt> for details.
 394
 395           If RAM disk support (BLK_DEV_RAM) is also included, this
 396           also enables initial RAM disk (initrd) support and adds
 397           15 Kbytes (more on some other architectures) to the kernel size.
 398
 399           If unsure say Y.
 400
 401 if BLK_DEV_INITRD
 402
 403 source "usr/Kconfig"
 404
 405 endif
 406
 407 config CC_OPTIMIZE_FOR_SIZE
 408         bool "Optimize for size (Look out for broken compilers!)"
 409         default y
 410         depends on ARM || H8300 || SUPERH || EXPERIMENTAL
 411         help
 412           Enabling this option will pass "-Os" instead of "-O2" to gcc
 413           resulting in a smaller kernel.
 414
 415           WARNING: some versions of gcc may generate incorrect code with this
 416           option.  If problems are observed, a gcc upgrade may be needed.
 417
 418           If unsure, say N.
 419
 420 config SYSCTL
 421         bool
 422
 423 menuconfig EMBEDDED
 424         bool "Configure standard kernel features (for small systems)"
 425         help
 426           This option allows certain base kernel options and settings
 427           to be disabled or tweaked. This is for specialized
 428           environments which can tolerate a "non-standard" kernel.
 429           Only use this if you really know what you are doing.
 430
 431 config UID16
 432         bool "Enable 16-bit UID system calls" if EMBEDDED
 433         depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
 434         default y
 435         help
 436           This enables the legacy 16-bit UID syscall wrappers.
 437
 438 config SYSCTL_SYSCALL
 439         bool "Sysctl syscall support" if EMBEDDED
 440         default y
 441         select SYSCTL
 442         ---help---
 443           sys_sysctl uses binary paths that have been found challenging
 444           to properly maintain and use.  The interface in /proc/sys
 445           using paths with ascii names is now the primary path to this
 446           information.
 447
 448           Almost nothing using the binary sysctl interface so if you are
 449           trying to save some space it is probably safe to disable this,
 450           making your kernel marginally smaller.
 451
 452           If unsure say Y here.
 453
 454 config KALLSYMS
 455          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 456          default y
 457          help
 458            Say Y here to let the kernel print out symbolic crash information and
 459            symbolic stack backtraces. This increases the size of the kernel
 460            somewhat, as all symbols have to be loaded into the kernel image.
 461
 462 config KALLSYMS_ALL
 463         bool "Include all symbols in kallsyms"
 464         depends on DEBUG_KERNEL && KALLSYMS
 465         help
 466            Normally kallsyms only contains the symbols of functions, for nicer
 467            OOPS messages.  Some debuggers can use kallsyms for other
 468            symbols too: say Y here to include all symbols, if you need them
 469            and you don't care about adding 300k to the size of your kernel.
 470
 471            Say N.
 472
 473 config KALLSYMS_EXTRA_PASS
 474         bool "Do an extra kallsyms pass"
 475         depends on KALLSYMS
 476         help
 477            If kallsyms is not working correctly, the build will fail with
 478            inconsistent kallsyms data.  If that occurs, log a bug report and
 479            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 480            Always say N here unless you find a bug in kallsyms, which must be
 481            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 482            you wait for kallsyms to be fixed.
 483
 484
 485 config HOTPLUG
 486         bool "Support for hot-pluggable devices" if EMBEDDED
 487         default y
 488         help
 489           This option is provided for the case where no hotplug or uevent
 490           capabilities is wanted by the kernel.  You should only consider
 491           disabling this option for embedded systems that do not use modules, a
 492           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 493
 494 config PRINTK
 495         default y
 496         bool "Enable support for printk" if EMBEDDED
 497         help
 498           This option enables normal printk support. Removing it
 499           eliminates most of the message strings from the kernel image
 500           and makes the kernel more or less silent. As this makes it
 501           very difficult to diagnose system problems, saying N here is
 502           strongly discouraged.
 503
 504 config BUG
 505         bool "BUG() support" if EMBEDDED
 506         default y
 507         help
 508           Disabling this option eliminates support for BUG and WARN, reducing
 509           the size of your kernel image and potentially quietly ignoring
 510           numerous fatal conditions. You should only consider disabling this
 511           option for embedded systems with no facilities for reporting errors.
 512           Just say Y.
 513
 514 config ELF_CORE
 515         default y
 516         bool "Enable ELF core dumps" if EMBEDDED
 517         help
 518           Enable support for generating core dumps. Disabling saves about 4k.
 519
 520 config BASE_FULL
 521         default y
 522         bool "Enable full-sized data structures for core" if EMBEDDED
 523         help
 524           Disabling this option reduces the size of miscellaneous core
 525           kernel data structures. This saves memory on small machines,
 526           but may reduce performance.
 527
 528 config FUTEX
 529         bool "Enable futex support" if EMBEDDED
 530         default y
 531         select RT_MUTEXES
 532         help
 533           Disabling this option will cause the kernel to be built without
 534           support for "fast userspace mutexes".  The resulting kernel may not
 535           run glibc-based applications correctly.
 536
 537 config ANON_INODES
 538         bool
 539
 540 config EPOLL
 541         bool "Enable eventpoll support" if EMBEDDED
 542         default y
 543         select ANON_INODES
 544         help
 545           Disabling this option will cause the kernel to be built without
 546           support for epoll family of system calls.
 547
 548 config SIGNALFD
 549         bool "Enable signalfd() system call" if EMBEDDED
 550         select ANON_INODES
 551         default y
 552         help
 553           Enable the signalfd() system call that allows to receive signals
 554           on a file descriptor.
 555
 556           If unsure, say Y.
 557
 558 config TIMERFD
 559         bool "Enable timerfd() system call" if EMBEDDED
 560         select ANON_INODES
 561         depends on BROKEN
 562         default y
 563         help
 564           Enable the timerfd() system call that allows to receive timer
 565           events on a file descriptor.
 566
 567           If unsure, say Y.
 568
 569 config EVENTFD
 570         bool "Enable eventfd() system call" if EMBEDDED
 571         select ANON_INODES
 572         default y
 573         help
 574           Enable the eventfd() system call that allows to receive both
 575           kernel notification (ie. KAIO) or userspace notifications.
 576
 577           If unsure, say Y.
 578
 579 config SHMEM
 580         bool "Use full shmem filesystem" if EMBEDDED
 581         default y
 582         depends on MMU
 583         help
 584           The shmem is an internal filesystem used to manage shared memory.
 585           It is backed by swap and manages resource limits. It is also exported
 586           to userspace as tmpfs if TMPFS is enabled. Disabling this
 587           option replaces shmem and tmpfs with the much simpler ramfs code,
 588           which may be appropriate on small systems without swap.
 589
 590 config VM_EVENT_COUNTERS
 591         default y
 592         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 593         help
 594           VM event counters are needed for event counts to be shown.
 595           This option allows the disabling of the VM event counters
 596           on EMBEDDED systems.  /proc/vmstat will only show page counts
 597           if VM event counters are disabled.
 598
 599 config SLUB_DEBUG
 600         default y
 601         bool "Enable SLUB debugging support" if EMBEDDED
 602         depends on SLUB
 603         help
 604           SLUB has extensive debug support features. Disabling these can
 605           result in significant savings in code size. This also disables
 606           SLUB sysfs support. /sys/slab will not exist and there will be
 607           no support for cache validation etc.
 608
 609 choice
 610         prompt "Choose SLAB allocator"
 611         default SLUB
 612         help
 613            This option allows to select a slab allocator.
 614
 615 config SLAB
 616         bool "SLAB"
 617         help
 618           The regular slab allocator that is established and known to work
 619           well in all environments. It organizes cache hot objects in
 620           per cpu and per node queues. SLAB is the default choice for
 621           a slab allocator.
 622
 623 config SLUB
 624         bool "SLUB (Unqueued Allocator)"
 625         help
 626            SLUB is a slab allocator that minimizes cache line usage
 627            instead of managing queues of cached objects (SLAB approach).
 628            Per cpu caching is realized using slabs of objects instead
 629            of queues of objects. SLUB can use memory efficiently
 630            and has enhanced diagnostics.
 631
 632 config SLOB
 633         depends on EMBEDDED
 634         bool "SLOB (Simple Allocator)"
 635         help
 636            SLOB replaces the SLAB allocator with a drastically simpler
 637            allocator.  SLOB is more space efficient than SLAB but does not
 638            scale well (single lock for all operations) and is also highly
 639            susceptible to fragmentation. SLUB can accomplish a higher object
 640            density. It is usually better to use SLUB instead of SLOB.
 641
 642 endchoice
 643
 644 endmenu         # General setup
 645
 646 config RT_MUTEXES
 647         boolean
 648         select PLIST
 649
 650 config TINY_SHMEM
 651         default !SHMEM
 652         bool
 653
 654 config BASE_SMALL
 655         int
 656         default 0 if BASE_FULL
 657         default 1 if !BASE_FULL
 658
 659 menuconfig MODULES
 660         bool "Enable loadable module support"
 661         help
 662           Kernel modules are small pieces of compiled code which can
 663           be inserted in the running kernel, rather than being
 664           permanently built into the kernel.  You use the "modprobe"
 665           tool to add (and sometimes remove) them.  If you say Y here,
 666           many parts of the kernel can be built as modules (by
 667           answering M instead of Y where indicated): this is most
 668           useful for infrequently used options which are not required
 669           for booting.  For more information, see the man pages for
 670           modprobe, lsmod, modinfo, insmod and rmmod.
 671
 672           If you say Y here, you will need to run "make
 673           modules_install" to put the modules under /lib/modules/
 674           where modprobe can find them (you may need to be root to do
 675           this).
 676
 677           If unsure, say Y.
 678
 679 config MODULE_UNLOAD
 680         bool "Module unloading"
 681         depends on MODULES
 682         help
 683           Without this option you will not be able to unload any
 684           modules (note that some modules may not be unloadable
 685           anyway), which makes your kernel slightly smaller and
 686           simpler.  If unsure, say Y.
 687
 688 config MODULE_FORCE_UNLOAD
 689         bool "Forced module unloading"
 690         depends on MODULE_UNLOAD && EXPERIMENTAL
 691         help
 692           This option allows you to force a module to unload, even if the
 693           kernel believes it is unsafe: the kernel will remove the module
 694           without waiting for anyone to stop using it (using the -f option to
 695           rmmod).  This is mainly for kernel developers and desperate users.
 696           If unsure, say N.
 697
 698 config MODVERSIONS
 699         bool "Module versioning support"
 700         depends on MODULES
 701         help
 702           Usually, you have to use modules compiled with your kernel.
 703           Saying Y here makes it sometimes possible to use modules
 704           compiled for different kernels, by adding enough information
 705           to the modules to (hopefully) spot any changes which would
 706           make them incompatible with the kernel you are running.  If
 707           unsure, say N.
 708
 709 config MODULE_SRCVERSION_ALL
 710         bool "Source checksum for all modules"
 711         depends on MODULES
 712         help
 713           Modules which contain a MODULE_VERSION get an extra "srcversion"
 714           field inserted into their modinfo section, which contains a
 715           sum of the source files which made it.  This helps maintainers
 716           see exactly which source was used to build a module (since
 717           others sometimes change the module source without updating
 718           the version).  With this option, such a "srcversion" field
 719           will be created for all modules.  If unsure, say N.
 720
 721 config KMOD
 722         bool "Automatic kernel module loading"
 723         depends on MODULES
 724         help
 725           Normally when you have selected some parts of the kernel to
 726           be created as kernel modules, you must load them (using the
 727           "modprobe" command) before you can use them. If you say Y
 728           here, some parts of the kernel will be able to load modules
 729           automatically: when a part of the kernel needs a module, it
 730           runs modprobe with the appropriate arguments, thereby
 731           loading the module if it is available.  If unsure, say Y.
 732
 733 config STOP_MACHINE
 734         bool
 735         default y
 736         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 737         help
 738           Need stop_machine() primitive.
 739
 740 source "block/Kconfig"
 741
 742 config PREEMPT_NOTIFIERS
 743         bool