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/$ARCH/defconfig"
  17
  18 menu "General setup"
  19
  20 config EXPERIMENTAL
  21         bool "Prompt for development and/or incomplete code/drivers"
  22         ---help---
  23           Some of the various things that Linux supports (such as network
  24           drivers, file systems, network protocols, etc.) can be in a state
  25           of development where the functionality, stability, or the level of
  26           testing is not yet high enough for general use. This is usually
  27           known as the "alpha-test" phase among developers. If a feature is
  28           currently in alpha-test, then the developers usually discourage
  29           uninformed widespread use of this feature by the general public to
  30           avoid "Why doesn't this work?" type mail messages. However, active
  31           testing and use of these systems is welcomed. Just be aware that it
  32           may not meet the normal level of reliability or it may fail to work
  33           in some special cases. Detailed bug reports from people familiar
  34           with the kernel internals are usually welcomed by the developers
  35           (before submitting bug reports, please read the documents
  36           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  37           <file:Documentation/BUG-HUNTING>, and
  38           <file:Documentation/oops-tracing.txt> in the kernel source).
  39
  40           This option will also make obsoleted drivers available. These are
  41           drivers that have been replaced by something else, and/or are
  42           scheduled to be removed in a future kernel release.
  43
  44           Unless you intend to help test and develop a feature or driver that
  45           falls into this category, or you have a situation that requires
  46           using these features, you should probably say N here, which will
  47           cause the configurator to present you with fewer choices. If
  48           you say Y here, you will be offered the choice of using features or
  49           drivers that are currently considered to be in the alpha-test phase.
  50
  51 config BROKEN
  52         bool
  53
  54 config BROKEN_ON_SMP
  55         bool
  56         depends on BROKEN || !SMP
  57         default y
  58
  59 config LOCK_KERNEL
  60         bool
  61         depends on SMP || PREEMPT
  62         default y
  63
  64 config INIT_ENV_ARG_LIMIT
  65         int
  66         default 32 if !UML
  67         default 128 if UML
  68         help
  69           Maximum of each of the number of arguments and environment
  70           variables passed to init from the kernel command line.
  71
  72
  73 config LOCALVERSION
  74         string "Local version - append to kernel release"
  75         help
  76           Append an extra string to the end of your kernel version.
  77           This will show up when you type uname, for example.
  78           The string you set here will be appended after the contents of
  79           any files with a filename matching localversion* in your
  80           object and source tree, in that order.  Your total string can
  81           be a maximum of 64 characters.
  82
  83 config LOCALVERSION_AUTO
  84         bool "Automatically append version information to the version string"
  85         default y
  86         help
  87           This will try to automatically determine if the current tree is a
  88           release tree by looking for git tags that belong to the current
  89           top of tree revision.
  90
  91           A string of the format -gxxxxxxxx will be added to the localversion
  92           if a git-based tree is found.  The string generated by this will be
  93           appended after any matching localversion* files, and after the value
  94           set in CONFIG_LOCALVERSION.
  95
  96           (The actual string used here is the first eight characters produced
  97           by running the command:
  98
  99             $ git rev-parse --verify HEAD
 100
 101           which is done within the script "scripts/setlocalversion".)
 102
 103 config SWAP
 104         bool "Support for paging of anonymous memory (swap)"
 105         depends on MMU && BLOCK
 106         default y
 107         help
 108           This option allows you to choose whether you want to have support
 109           for so called swap devices or swap files in your kernel that are
 110           used to provide more virtual memory than the actual RAM present
 111           in your computer.  If unsure say Y.
 112
 113 config SYSVIPC
 114         bool "System V IPC"
 115         ---help---
 116           Inter Process Communication is a suite of library functions and
 117           system calls which let processes (running programs) synchronize and
 118           exchange information. It is generally considered to be a good thing,
 119           and some programs won't run unless you say Y here. In particular, if
 120           you want to run the DOS emulator dosemu under Linux (read the
 121           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 122           you'll need to say Y here.
 123
 124           You can find documentation about IPC with "info ipc" and also in
 125           section 6.4 of the Linux Programmer's Guide, available from
 126           <http://www.tldp.org/guides.html>.
 127
 128 config SYSVIPC_SYSCTL
 129         bool
 130         depends on SYSVIPC
 131         depends on SYSCTL
 132         default y
 133
 134 config POSIX_MQUEUE
 135         bool "POSIX Message Queues"
 136         depends on NET && EXPERIMENTAL
 137         ---help---
 138           POSIX variant of message queues is a part of IPC. In POSIX message
 139           queues every message has a priority which decides about succession
 140           of receiving it by a process. If you want to compile and run
 141           programs written e.g. for Solaris with use of its POSIX message
 142           queues (functions mq_*) say Y here.
 143
 144           POSIX message queues are visible as a filesystem called 'mqueue'
 145           and can be mounted somewhere if you want to do filesystem
 146           operations on message queues.
 147
 148           If unsure, say Y.
 149
 150 config BSD_PROCESS_ACCT
 151         bool "BSD Process Accounting"
 152         help
 153           If you say Y here, a user level program will be able to instruct the
 154           kernel (via a special system call) to write process accounting
 155           information to a file: whenever a process exits, information about
 156           that process will be appended to the file by the kernel.  The
 157           information includes things such as creation time, owning user,
 158           command name, memory usage, controlling terminal etc. (the complete
 159           list is in the struct acct in <file:include/linux/acct.h>).  It is
 160           up to the user level program to do useful things with this
 161           information.  This is generally a good idea, so say Y.
 162
 163 config BSD_PROCESS_ACCT_V3
 164         bool "BSD Process Accounting version 3 file format"
 165         depends on BSD_PROCESS_ACCT
 166         default n
 167         help
 168           If you say Y here, the process accounting information is written
 169           in a new file format that also logs the process IDs of each
 170           process and it's parent. Note that this file format is incompatible
 171           with previous v0/v1/v2 file formats, so you will need updated tools
 172           for processing it. A preliminary version of these tools is available
 173           at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
 174
 175 config TASKSTATS
 176         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 177         depends on NET
 178         default n
 179         help
 180           Export selected statistics for tasks/processes through the
 181           generic netlink interface. Unlike BSD process accounting, the
 182           statistics are available during the lifetime of tasks/processes as
 183           responses to commands. Like BSD accounting, they are sent to user
 184           space on task exit.
 185
 186           Say N if unsure.
 187
 188 config TASK_DELAY_ACCT
 189         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 190         depends on TASKSTATS
 191         help
 192           Collect information on time spent by a task waiting for system
 193           resources like cpu, synchronous block I/O completion and swapping
 194           in pages. Such statistics can help in setting a task's priorities
 195           relative to other tasks for cpu, io, rss limits etc.
 196
 197           Say N if unsure.
 198
 199 config TASK_XACCT
 200         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 201         depends on TASKSTATS
 202         help
 203           Collect extended task accounting data and send the data
 204           to userland for processing over the taskstats interface.
 205
 206           Say N if unsure.
 207
 208 config TASK_IO_ACCOUNTING
 209         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 210         depends on TASK_XACCT
 211         help
 212           Collect information on the number of bytes of storage I/O which this
 213           task has caused.
 214
 215           Say N if unsure.
 216
 217 config AUDIT
 218         bool "Auditing support"
 219         depends on NET
 220         help
 221           Enable auditing infrastructure that can be used with another
 222           kernel subsystem, such as SELinux (which requires this for
 223           logging of avc messages output).  Does not do system-call
 224           auditing without CONFIG_AUDITSYSCALL.
 225
 226 config AUDITSYSCALL
 227         bool "Enable system-call auditing support"
 228         depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
 229         default y if SECURITY_SELINUX
 230         help
 231           Enable low-overhead system-call auditing infrastructure that
 232           can be used independently or with another kernel subsystem,
 233           such as SELinux.  To use audit's filesystem watch feature, please
 234           ensure that INOTIFY is configured.
 235
 236 config AUDIT_TREE
 237         def_bool y
 238         depends on AUDITSYSCALL && INOTIFY
 239
 240 config IKCONFIG
 241         tristate "Kernel .config support"
 242         ---help---
 243           This option enables the complete Linux kernel ".config" file
 244           contents to be saved in the kernel. It provides documentation
 245           of which kernel options are used in a running kernel or in an
 246           on-disk kernel.  This information can be extracted from the kernel
 247           image file with the script scripts/extract-ikconfig and used as
 248           input to rebuild the current kernel or to build another kernel.
 249           It can also be extracted from a running kernel by reading
 250           /proc/config.gz if enabled (below).
 251
 252 config IKCONFIG_PROC
 253         bool "Enable access to .config through /proc/config.gz"
 254         depends on IKCONFIG && PROC_FS
 255         ---help---
 256           This option enables access to the kernel configuration file
 257           through /proc/config.gz.
 258
 259 config LOG_BUF_SHIFT
 260         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 261         range 12 21
 262         default 17 if S390 || LOCKDEP
 263         default 16 if X86_NUMAQ || IA64
 264         default 15 if SMP
 265         default 14
 266         help
 267           Select kernel log buffer size as a power of 2.
 268           Defaults and Examples:
 269                      17 => 128 KB for S/390
 270                      16 => 64 KB for x86 NUMAQ or IA-64
 271                      15 => 32 KB for SMP
 272                      14 => 16 KB for uniprocessor
 273                      13 =>  8 KB
 274                      12 =>  4 KB
 275
 276 config CGROUPS
 277         bool "Control Group support"
 278         help
 279           This option will let you use process cgroup subsystems
 280           such as Cpusets
 281
 282           Say N if unsure.
 283
 284 config CGROUP_DEBUG
 285         bool "Example debug cgroup subsystem"
 286         depends on CGROUPS
 287         help
 288           This option enables a simple cgroup subsystem that
 289           exports useful debugging information about the cgroups
 290           framework
 291
 292           Say N if unsure
 293
 294 config CGROUP_NS
 295         bool "Namespace cgroup subsystem"
 296         depends on CGROUPS
 297         help
 298           Provides a simple namespace cgroup subsystem to
 299           provide hierarchical naming of sets of namespaces,
 300           for instance virtual servers and checkpoint/restart
 301           jobs.
 302
 303 config CPUSETS
 304         bool "Cpuset support"
 305         depends on SMP && CGROUPS
 306         help
 307           This option will let you create and manage CPUSETs which
 308           allow dynamically partitioning a system into sets of CPUs and
 309           Memory Nodes and assigning tasks to run only within those sets.
 310           This is primarily useful on large SMP or NUMA systems.
 311
 312           Say N if unsure.
 313
 314 config FAIR_GROUP_SCHED
 315         bool "Fair group CPU scheduler"
 316         default y
 317         help
 318           This feature lets CPU scheduler recognize task groups and control CPU
 319           bandwidth allocation to such task groups.
 320
 321 choice
 322         depends on FAIR_GROUP_SCHED
 323         prompt "Basis for grouping tasks"
 324         default FAIR_USER_SCHED
 325
 326 config FAIR_USER_SCHED
 327         bool "user id"
 328         help
 329           This option will choose userid as the basis for grouping
 330           tasks, thus providing equal CPU bandwidth to each user.
 331
 332 config FAIR_CGROUP_SCHED
 333         bool "Control groups"
 334         depends on CGROUPS
 335         help
 336           This option allows you to create arbitrary task groups
 337           using the "cgroup" pseudo filesystem and control
 338           the cpu bandwidth allocated to each such task group.
 339           Refer to Documentation/cgroups.txt for more information
 340           on "cgroup" pseudo filesystem.
 341
 342 endchoice
 343
 344 config CGROUP_CPUACCT
 345         bool "Simple CPU accounting cgroup subsystem"
 346         depends on CGROUPS
 347         help
 348           Provides a simple Resource Controller for monitoring the
 349           total CPU consumed by the tasks in a cgroup
 350
 351 config RESOURCE_COUNTERS
 352         bool "Resource counters"
 353         help
 354           This option enables controller independent resource accounting
 355           infrastructure that works with cgroups
 356         depends on CGROUPS
 357
 358 config SYSFS_DEPRECATED
 359         bool "Create deprecated sysfs files"
 360         depends on SYSFS
 361         default y
 362         help
 363           This option creates deprecated symlinks such as the
 364           "device"-link, the <subsystem>:<name>-link, and the
 365           "bus"-link. It may also add deprecated key in the
 366           uevent environment.
 367           None of these features or values should be used today, as
 368           they export driver core implementation details to userspace
 369           or export properties which can't be kept stable across kernel
 370           releases.
 371
 372           If enabled, this option will also move any device structures
 373           that belong to a class, back into the /sys/class hierarchy, in
 374           order to support older versions of udev.
 375
 376           If you are using a distro that was released in 2006 or later,
 377           it should be safe to say N here.
 378
 379 config CGROUP_MEM_CONT
 380         bool "Memory controller for cgroups"
 381         depends on CGROUPS && RESOURCE_COUNTERS
 382         help
 383           Provides a memory controller that manages both page cache and
 384           RSS memory.
 385
 386 config PROC_PID_CPUSET
 387         bool "Include legacy /proc/<pid>/cpuset file"
 388         depends on CPUSETS
 389         default y
 390
 391 config RELAY
 392         bool "Kernel->user space relay support (formerly relayfs)"
 393         help
 394           This option enables support for relay interface support in
 395           certain file systems (such as debugfs).
 396           It is designed to provide an efficient mechanism for tools and
 397           facilities to relay large amounts of data from kernel space to
 398           user space.
 399
 400           If unsure, say N.
 401
 402 config NAMESPACES
 403         bool "Namespaces support" if EMBEDDED
 404         default !EMBEDDED
 405         help
 406           Provides the way to make tasks work with different objects using
 407           the same id. For example same IPC id may refer to different objects
 408           or same user id or pid may refer to different tasks when used in
 409           different namespaces.
 410
 411 config UTS_NS
 412         bool "UTS namespace"
 413         depends on NAMESPACES
 414         help
 415           In this namespace tasks see different info provided with the
 416           uname() system call
 417
 418 config IPC_NS
 419         bool "IPC namespace"
 420         depends on NAMESPACES && SYSVIPC
 421         help
 422           In this namespace tasks work with IPC ids which correspond to
 423           different IPC objects in different namespaces
 424
 425 config USER_NS
 426         bool "User namespace (EXPERIMENTAL)"
 427         depends on NAMESPACES && EXPERIMENTAL
 428         help
 429           This allows containers, i.e. vservers, to use user namespaces
 430           to provide different user info for different servers.
 431           If unsure, say N.
 432
 433 config PID_NS
 434         bool "PID Namespaces (EXPERIMENTAL)"
 435         default n
 436         depends on NAMESPACES && EXPERIMENTAL
 437         help
 438           Suport process id namespaces.  This allows having multiple
 439           process with the same pid as long as they are in different
 440           pid namespaces.  This is a building block of containers.
 441
 442           Unless you want to work with an experimental feature
 443           say N here.
 444
 445 config BLK_DEV_INITRD
 446         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 447         depends on BROKEN || !FRV
 448         help
 449           The initial RAM filesystem is a ramfs which is loaded by the
 450           boot loader (loadlin or lilo) and that is mounted as root
 451           before the normal boot procedure. It is typically used to
 452           load modules needed to mount the "real" root file system,
 453           etc. See <file:Documentation/initrd.txt> for details.
 454
 455           If RAM disk support (BLK_DEV_RAM) is also included, this
 456           also enables initial RAM disk (initrd) support and adds
 457           15 Kbytes (more on some other architectures) to the kernel size.
 458
 459           If unsure say Y.
 460
 461 if BLK_DEV_INITRD
 462
 463 source "usr/Kconfig"
 464
 465 endif
 466
 467 config CC_OPTIMIZE_FOR_SIZE
 468         bool "Optimize for size (Look out for broken compilers!)"
 469         default y
 470         depends on ARM || H8300 || SUPERH || EXPERIMENTAL
 471         help
 472           Enabling this option will pass "-Os" instead of "-O2" to gcc
 473           resulting in a smaller kernel.
 474
 475           WARNING: some versions of gcc may generate incorrect code with this
 476           option.  If problems are observed, a gcc upgrade may be needed.
 477
 478           If unsure, say N.
 479
 480 config SYSCTL
 481         bool
 482
 483 menuconfig EMBEDDED
 484         bool "Configure standard kernel features (for small systems)"
 485         help
 486           This option allows certain base kernel options and settings
 487           to be disabled or tweaked. This is for specialized
 488           environments which can tolerate a "non-standard" kernel.
 489           Only use this if you really know what you are doing.
 490
 491 config UID16
 492         bool "Enable 16-bit UID system calls" if EMBEDDED
 493         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
 494         default y
 495         help
 496           This enables the legacy 16-bit UID syscall wrappers.
 497
 498 config SYSCTL_SYSCALL
 499         bool "Sysctl syscall support" if EMBEDDED
 500         default y
 501         select SYSCTL
 502         ---help---
 503           sys_sysctl uses binary paths that have been found challenging
 504           to properly maintain and use.  The interface in /proc/sys
 505           using paths with ascii names is now the primary path to this
 506           information.
 507
 508           Almost nothing using the binary sysctl interface so if you are
 509           trying to save some space it is probably safe to disable this,
 510           making your kernel marginally smaller.
 511
 512           If unsure say Y here.
 513
 514 config KALLSYMS
 515          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 516          default y
 517          help
 518            Say Y here to let the kernel print out symbolic crash information and
 519            symbolic stack backtraces. This increases the size of the kernel
 520            somewhat, as all symbols have to be loaded into the kernel image.
 521
 522 config KALLSYMS_ALL
 523         bool "Include all symbols in kallsyms"
 524         depends on DEBUG_KERNEL && KALLSYMS
 525         help
 526            Normally kallsyms only contains the symbols of functions, for nicer
 527            OOPS messages.  Some debuggers can use kallsyms for other
 528            symbols too: say Y here to include all symbols, if you need them
 529            and you don't care about adding 300k to the size of your kernel.
 530
 531            Say N.
 532
 533 config KALLSYMS_EXTRA_PASS
 534         bool "Do an extra kallsyms pass"
 535         depends on KALLSYMS
 536         help
 537            If kallsyms is not working correctly, the build will fail with
 538            inconsistent kallsyms data.  If that occurs, log a bug report and
 539            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 540            Always say N here unless you find a bug in kallsyms, which must be
 541            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 542            you wait for kallsyms to be fixed.
 543
 544
 545 config HOTPLUG
 546         bool "Support for hot-pluggable devices" if EMBEDDED
 547         default y
 548         help
 549           This option is provided for the case where no hotplug or uevent
 550           capabilities is wanted by the kernel.  You should only consider
 551           disabling this option for embedded systems that do not use modules, a
 552           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 553
 554 config PRINTK
 555         default y
 556         bool "Enable support for printk" if EMBEDDED
 557         help
 558           This option enables normal printk support. Removing it
 559           eliminates most of the message strings from the kernel image
 560           and makes the kernel more or less silent. As this makes it
 561           very difficult to diagnose system problems, saying N here is
 562           strongly discouraged.
 563
 564 config BUG
 565         bool "BUG() support" if EMBEDDED
 566         default y
 567         help
 568           Disabling this option eliminates support for BUG and WARN, reducing
 569           the size of your kernel image and potentially quietly ignoring
 570           numerous fatal conditions. You should only consider disabling this
 571           option for embedded systems with no facilities for reporting errors.
 572           Just say Y.
 573
 574 config ELF_CORE
 575         default y
 576         bool "Enable ELF core dumps" if EMBEDDED
 577         help
 578           Enable support for generating core dumps. Disabling saves about 4k.
 579
 580 config COMPAT_BRK
 581         bool "Disable heap randomization"
 582         default y
 583         help
 584           Randomizing heap placement makes heap exploits harder, but it
 585           also breaks ancient binaries (including anything libc5 based).
 586           This option changes the bootup default to heap randomization
 587           disabled, and can be overriden runtime by setting
 588           /proc/sys/kernel/randomize_va_space to 2.
 589
 590           On non-ancient distros (post-2000 ones) Y is usually a safe choice.
 591
 592 config BASE_FULL
 593         default y
 594         bool "Enable full-sized data structures for core" if EMBEDDED
 595         help
 596           Disabling this option reduces the size of miscellaneous core
 597           kernel data structures. This saves memory on small machines,
 598           but may reduce performance.
 599
 600 config FUTEX
 601         bool "Enable futex support" if EMBEDDED
 602         default y
 603         select RT_MUTEXES
 604         help
 605           Disabling this option will cause the kernel to be built without
 606           support for "fast userspace mutexes".  The resulting kernel may not
 607           run glibc-based applications correctly.
 608
 609 config ANON_INODES
 610         bool
 611
 612 config EPOLL
 613         bool "Enable eventpoll support" if EMBEDDED
 614         default y
 615         select ANON_INODES
 616         help
 617           Disabling this option will cause the kernel to be built without
 618           support for epoll family of system calls.
 619
 620 config SIGNALFD
 621         bool "Enable signalfd() system call" if EMBEDDED
 622         select ANON_INODES
 623         default y
 624         help
 625           Enable the signalfd() system call that allows to receive signals
 626           on a file descriptor.
 627
 628           If unsure, say Y.
 629
 630 config TIMERFD
 631         bool "Enable timerfd() system call" if EMBEDDED
 632         select ANON_INODES
 633         default y
 634         help
 635           Enable the timerfd() system call that allows to receive timer
 636           events on a file descriptor.
 637
 638           If unsure, say Y.
 639
 640 config EVENTFD
 641         bool "Enable eventfd() system call" if EMBEDDED
 642         select ANON_INODES
 643         default y
 644         help
 645           Enable the eventfd() system call that allows to receive both
 646           kernel notification (ie. KAIO) or userspace notifications.
 647
 648           If unsure, say Y.
 649
 650 config SHMEM
 651         bool "Use full shmem filesystem" if EMBEDDED
 652         default y
 653         depends on MMU
 654         help
 655           The shmem is an internal filesystem used to manage shared memory.
 656           It is backed by swap and manages resource limits. It is also exported
 657           to userspace as tmpfs if TMPFS is enabled. Disabling this
 658           option replaces shmem and tmpfs with the much simpler ramfs code,
 659           which may be appropriate on small systems without swap.
 660
 661 config VM_EVENT_COUNTERS
 662         default y
 663         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 664         help
 665           VM event counters are needed for event counts to be shown.
 666           This option allows the disabling of the VM event counters
 667           on EMBEDDED systems.  /proc/vmstat will only show page counts
 668           if VM event counters are disabled.
 669
 670 config SLUB_DEBUG
 671         default y
 672         bool "Enable SLUB debugging support" if EMBEDDED
 673         depends on SLUB
 674         help
 675           SLUB has extensive debug support features. Disabling these can
 676           result in significant savings in code size. This also disables
 677           SLUB sysfs support. /sys/slab will not exist and there will be
 678           no support for cache validation etc.
 679
 680 choice
 681         prompt "Choose SLAB allocator"
 682         default SLUB
 683         help
 684            This option allows to select a slab allocator.
 685
 686 config SLAB
 687         bool "SLAB"
 688         help
 689           The regular slab allocator that is established and known to work
 690           well in all environments. It organizes cache hot objects in
 691           per cpu and per node queues. SLAB is the default choice for
 692           a slab allocator.
 693
 694 config SLUB
 695         bool "SLUB (Unqueued Allocator)"
 696         help
 697            SLUB is a slab allocator that minimizes cache line usage
 698            instead of managing queues of cached objects (SLAB approach).
 699            Per cpu caching is realized using slabs of objects instead
 700            of queues of objects. SLUB can use memory efficiently
 701            and has enhanced diagnostics.
 702
 703 config SLOB
 704         depends on EMBEDDED
 705         bool "SLOB (Simple Allocator)"
 706         help
 707            SLOB replaces the stock allocator with a drastically simpler
 708            allocator. SLOB is generally more space efficient but
 709            does not perform as well on large systems.
 710
 711 endchoice
 712
 713 config PROFILING
 714         bool "Profiling support (EXPERIMENTAL)"
 715         help
 716           Say Y here to enable the extended profiling support mechanisms used
 717           by profilers such as OProfile.
 718
 719 config MARKERS
 720         bool "Activate markers"
 721         help
 722           Place an empty function call at each marker site. Can be
 723           dynamically changed for a probe function.
 724
 725 source "arch/Kconfig"
 726
 727 config PROC_PAGE_MONITOR
 728         default y
 729         depends on PROC_FS && MMU
 730         bool "Enable /proc page monitoring" if EMBEDDED
 731         help
 732           Various /proc files exist to monitor process memory utilization:
 733           /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
 734           /proc/kpagecount, and /proc/kpageflags. Disabling these
 735           interfaces will reduce the size of the kernel by approximately 4kb.
 736
 737 endmenu         # General setup
 738
 739 config SLABINFO
 740         bool
 741         depends on PROC_FS
 742         depends on SLAB || SLUB
 743         default y
 744
 745 config RT_MUTEXES
 746         boolean
 747         select PLIST
 748
 749 config TINY_SHMEM
 750         default !SHMEM
 751         bool
 752
 753 config BASE_SMALL
 754         int
 755         default 0 if BASE_FULL
 756         default 1 if !BASE_FULL
 757
 758 menuconfig MODULES
 759         bool "Enable loadable module support"
 760         help
 761           Kernel modules are small pieces of compiled code which can
 762           be inserted in the running kernel, rather than being
 763           permanently built into the kernel.  You use the "modprobe"
 764           tool to add (and sometimes remove) them.  If you say Y here,
 765           many parts of the kernel can be built as modules (by
 766           answering M instead of Y where indicated): this is most
 767           useful for infrequently used options which are not required
 768           for booting.  For more information, see the man pages for
 769           modprobe, lsmod, modinfo, insmod and rmmod.
 770
 771           If you say Y here, you will need to run "make
 772           modules_install" to put the modules under /lib/modules/
 773           where modprobe can find them (you may need to be root to do
 774           this).
 775
 776           If unsure, say Y.
 777
 778 config MODULE_UNLOAD
 779         bool "Module unloading"
 780         depends on MODULES
 781         help
 782           Without this option you will not be able to unload any
 783           modules (note that some modules may not be unloadable
 784           anyway), which makes your kernel slightly smaller and
 785           simpler.  If unsure, say Y.
 786
 787 config MODULE_FORCE_UNLOAD
 788         bool "Forced module unloading"
 789         depends on MODULE_UNLOAD && EXPERIMENTAL
 790         help
 791           This option allows you to force a module to unload, even if the
 792           kernel believes it is unsafe: the kernel will remove the module
 793           without waiting for anyone to stop using it (using the -f option to
 794           rmmod).  This is mainly for kernel developers and desperate users.
 795           If unsure, say N.
 796
 797 config MODVERSIONS
 798         bool "Module versioning support"
 799         depends on MODULES
 800         help
 801           Usually, you have to use modules compiled with your kernel.
 802           Saying Y here makes it sometimes possible to use modules
 803           compiled for different kernels, by adding enough information
 804           to the modules to (hopefully) spot any changes which would
 805           make them incompatible with the kernel you are running.  If
 806           unsure, say N.
 807
 808 config MODULE_SRCVERSION_ALL
 809         bool "Source checksum for all modules"
 810         depends on MODULES
 811         help
 812           Modules which contain a MODULE_VERSION get an extra "srcversion"
 813           field inserted into their modinfo section, which contains a
 814           sum of the source files which made it.  This helps maintainers
 815           see exactly which source was used to build a module (since
 816           others sometimes change the module source without updating
 817           the version).  With this option, such a "srcversion" field
 818           will be created for all modules.  If unsure, say N.
 819
 820 config KMOD
 821         bool "Automatic kernel module loading"
 822         depends on MODULES
 823         help
 824           Normally when you have selected some parts of the kernel to
 825           be created as kernel modules, you must load them (using the
 826           "modprobe" command) before you can use them. If you say Y
 827           here, some parts of the kernel will be able to load modules
 828           automatically: when a part of the kernel needs a module, it
 829           runs modprobe with the appropriate arguments, thereby
 830           loading the module if it is available.  If unsure, say Y.
 831
 832 config STOP_MACHINE
 833         bool
 834         default y
 835         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 836         help
 837           Need stop_machine() primitive.
 838
 839 source "block/Kconfig"
 840
 841 config PREEMPT_NOTIFIERS
 842         bool
 843
 844 choice
 845         prompt "RCU implementation type:"
 846         default CLASSIC_RCU
 847         help
 848           This allows you to choose either the classic RCU implementation
 849           that is designed for best read-side performance on non-realtime
 850           systems, or the preemptible RCU implementation for best latency
 851           on realtime systems.  Note that some kernel preemption modes
 852           will restrict your choice.
 853
 854           Select the default if you are unsure.
 855
 856 config CLASSIC_RCU
 857         bool "Classic RCU"
 858         help
 859           This option selects the classic RCU implementation that is
 860           designed for best read-side performance on non-realtime
 861           systems.
 862
 863           Say Y if you are unsure.
 864
 865 config PREEMPT_RCU
 866         bool "Preemptible RCU"
 867         depends on PREEMPT
 868         help
 869           This option reduces the latency of the kernel by making certain
 870           RCU sections preemptible. Normally RCU code is non-preemptible, if
 871           this option is selected then read-only RCU sections become
 872           preemptible. This helps latency, but may expose bugs due to
 873           now-naive assumptions about each RCU read-side critical section
 874           remaining on a given CPU through its execution.
 875
 876           Say N if you are unsure.
 877
 878 endchoice