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  41           drivers that have been replaced by something else, and/or are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
 263         help
 264           Select kernel log buffer size as a power of 2.
 265           Examples:
 266                      17 => 128 KB
 267                      16 => 64 KB
 268                      15 => 32 KB
 269                      14 => 16 KB
 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         default n
 285         help
 286           This option enables a simple cgroup subsystem that
 287           exports useful debugging information about the cgroups
 288           framework
 289
 290           Say N if unsure
 291
 292 config CGROUP_NS
 293         bool "Namespace cgroup subsystem"
 294         depends on CGROUPS
 295         help
 296           Provides a simple namespace cgroup subsystem to
 297           provide hierarchical naming of sets of namespaces,
 298           for instance virtual servers and checkpoint/restart
 299           jobs.
 300
 301 config CGROUP_DEVICE
 302         bool "Device controller for cgroups"
 303         depends on CGROUPS && EXPERIMENTAL
 304         help
 305           Provides a cgroup implementing whitelists for devices which
 306           a process in the cgroup can mknod or open.
 307
 308 config CPUSETS
 309         bool "Cpuset support"
 310         depends on SMP && CGROUPS
 311         help
 312           This option will let you create and manage CPUSETs which
 313           allow dynamically partitioning a system into sets of CPUs and
 314           Memory Nodes and assigning tasks to run only within those sets.
 315           This is primarily useful on large SMP or NUMA systems.
 316
 317           Say N if unsure.
 318
 319 config GROUP_SCHED
 320         bool "Group CPU scheduler"
 321         default y
 322         help
 323           This feature lets CPU scheduler recognize task groups and control CPU
 324           bandwidth allocation to such task groups.
 325
 326 config FAIR_GROUP_SCHED
 327         bool "Group scheduling for SCHED_OTHER"
 328         depends on GROUP_SCHED
 329         default y
 330
 331 config RT_GROUP_SCHED
 332         bool "Group scheduling for SCHED_RR/FIFO"
 333         depends on EXPERIMENTAL
 334         depends on GROUP_SCHED
 335         default n
 336         help
 337           This feature lets you explicitly allocate real CPU bandwidth
 338           to users or control groups (depending on the "Basis for grouping tasks"
 339           setting below. If enabled, it will also make it impossible to
 340           schedule realtime tasks for non-root users until you allocate
 341           realtime bandwidth for them.
 342           See Documentation/sched-rt-group.txt for more information.
 343
 344 choice
 345         depends on GROUP_SCHED
 346         prompt "Basis for grouping tasks"
 347         default USER_SCHED
 348
 349 config USER_SCHED
 350         bool "user id"
 351         help
 352           This option will choose userid as the basis for grouping
 353           tasks, thus providing equal CPU bandwidth to each user.
 354
 355 config CGROUP_SCHED
 356         bool "Control groups"
 357         depends on CGROUPS
 358         help
 359           This option allows you to create arbitrary task groups
 360           using the "cgroup" pseudo filesystem and control
 361           the cpu bandwidth allocated to each such task group.
 362           Refer to Documentation/cgroups.txt for more information
 363           on "cgroup" pseudo filesystem.
 364
 365 endchoice
 366
 367 config CGROUP_CPUACCT
 368         bool "Simple CPU accounting cgroup subsystem"
 369         depends on CGROUPS
 370         help
 371           Provides a simple Resource Controller for monitoring the
 372           total CPU consumed by the tasks in a cgroup
 373
 374 config RESOURCE_COUNTERS
 375         bool "Resource counters"
 376         help
 377           This option enables controller independent resource accounting
 378           infrastructure that works with cgroups
 379         depends on CGROUPS
 380
 381 config MM_OWNER
 382         bool
 383
 384 config CGROUP_MEM_RES_CTLR
 385         bool "Memory Resource Controller for Control Groups"
 386         depends on CGROUPS && RESOURCE_COUNTERS
 387         select MM_OWNER
 388         help
 389           Provides a memory resource controller that manages both page cache and
 390           RSS memory.
 391
 392           Note that setting this option increases fixed memory overhead
 393           associated with each page of memory in the system by 4/8 bytes
 394           and also increases cache misses because struct page on many 64bit
 395           systems will not fit into a single cache line anymore.
 396
 397           Only enable when you're ok with these trade offs and really
 398           sure you need the memory resource controller.
 399
 400           This config option also selects MM_OWNER config option, which
 401           could in turn add some fork/exit overhead.
 402
 403 config SYSFS_DEPRECATED
 404         bool
 405
 406 config SYSFS_DEPRECATED_V2
 407         bool "Create deprecated sysfs files"
 408         depends on SYSFS
 409         default y
 410         select SYSFS_DEPRECATED
 411         help
 412           This option creates deprecated symlinks such as the
 413           "device"-link, the <subsystem>:<name>-link, and the
 414           "bus"-link. It may also add deprecated key in the
 415           uevent environment.
 416           None of these features or values should be used today, as
 417           they export driver core implementation details to userspace
 418           or export properties which can't be kept stable across kernel
 419           releases.
 420
 421           If enabled, this option will also move any device structures
 422           that belong to a class, back into the /sys/class hierarchy, in
 423           order to support older versions of udev and some userspace
 424           programs.
 425
 426           If you are using a distro with the most recent userspace
 427           packages, it should be safe to say N here.
 428
 429 config PROC_PID_CPUSET
 430         bool "Include legacy /proc/<pid>/cpuset file"
 431         depends on CPUSETS
 432         default y
 433
 434 config RELAY
 435         bool "Kernel->user space relay support (formerly relayfs)"
 436         help
 437           This option enables support for relay interface support in
 438           certain file systems (such as debugfs).
 439           It is designed to provide an efficient mechanism for tools and
 440           facilities to relay large amounts of data from kernel space to
 441           user space.
 442
 443           If unsure, say N.
 444
 445 config NAMESPACES
 446         bool "Namespaces support" if EMBEDDED
 447         default !EMBEDDED
 448         help
 449           Provides the way to make tasks work with different objects using
 450           the same id. For example same IPC id may refer to different objects
 451           or same user id or pid may refer to different tasks when used in
 452           different namespaces.
 453
 454 config UTS_NS
 455         bool "UTS namespace"
 456         depends on NAMESPACES
 457         help
 458           In this namespace tasks see different info provided with the
 459           uname() system call
 460
 461 config IPC_NS
 462         bool "IPC namespace"
 463         depends on NAMESPACES && SYSVIPC
 464         help
 465           In this namespace tasks work with IPC ids which correspond to
 466           different IPC objects in different namespaces
 467
 468 config USER_NS
 469         bool "User namespace (EXPERIMENTAL)"
 470         depends on NAMESPACES && EXPERIMENTAL
 471         help
 472           This allows containers, i.e. vservers, to use user namespaces
 473           to provide different user info for different servers.
 474           If unsure, say N.
 475
 476 config PID_NS
 477         bool "PID Namespaces (EXPERIMENTAL)"
 478         default n
 479         depends on NAMESPACES && EXPERIMENTAL
 480         help
 481           Suport process id namespaces.  This allows having multiple
 482           process with the same pid as long as they are in different
 483           pid namespaces.  This is a building block of containers.
 484
 485           Unless you want to work with an experimental feature
 486           say N here.
 487
 488 config BLK_DEV_INITRD
 489         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 490         depends on BROKEN || !FRV
 491         help
 492           The initial RAM filesystem is a ramfs which is loaded by the
 493           boot loader (loadlin or lilo) and that is mounted as root
 494           before the normal boot procedure. It is typically used to
 495           load modules needed to mount the "real" root file system,
 496           etc. See <file:Documentation/initrd.txt> for details.
 497
 498           If RAM disk support (BLK_DEV_RAM) is also included, this
 499           also enables initial RAM disk (initrd) support and adds
 500           15 Kbytes (more on some other architectures) to the kernel size.
 501
 502           If unsure say Y.
 503
 504 if BLK_DEV_INITRD
 505
 506 source "usr/Kconfig"
 507
 508 endif
 509
 510 config CC_OPTIMIZE_FOR_SIZE
 511         bool "Optimize for size"
 512         default y
 513         help
 514           Enabling this option will pass "-Os" instead of "-O2" to gcc
 515           resulting in a smaller kernel.
 516
 517           If unsure, say N.
 518
 519 config SYSCTL
 520         bool
 521
 522 menuconfig EMBEDDED
 523         bool "Configure standard kernel features (for small systems)"
 524         help
 525           This option allows certain base kernel options and settings
 526           to be disabled or tweaked. This is for specialized
 527           environments which can tolerate a "non-standard" kernel.
 528           Only use this if you really know what you are doing.
 529
 530 config UID16
 531         bool "Enable 16-bit UID system calls" if EMBEDDED
 532         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 533         default y
 534         help
 535           This enables the legacy 16-bit UID syscall wrappers.
 536
 537 config SYSCTL_SYSCALL
 538         bool "Sysctl syscall support" if EMBEDDED
 539         default y
 540         select SYSCTL
 541         ---help---
 542           sys_sysctl uses binary paths that have been found challenging
 543           to properly maintain and use.  The interface in /proc/sys
 544           using paths with ascii names is now the primary path to this
 545           information.
 546
 547           Almost nothing using the binary sysctl interface so if you are
 548           trying to save some space it is probably safe to disable this,
 549           making your kernel marginally smaller.
 550
 551           If unsure say Y here.
 552
 553 config KALLSYMS
 554          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 555          default y
 556          help
 557            Say Y here to let the kernel print out symbolic crash information and
 558            symbolic stack backtraces. This increases the size of the kernel
 559            somewhat, as all symbols have to be loaded into the kernel image.
 560
 561 config KALLSYMS_ALL
 562         bool "Include all symbols in kallsyms"
 563         depends on DEBUG_KERNEL && KALLSYMS
 564         help
 565            Normally kallsyms only contains the symbols of functions, for nicer
 566            OOPS messages.  Some debuggers can use kallsyms for other
 567            symbols too: say Y here to include all symbols, if you need them
 568            and you don't care about adding 300k to the size of your kernel.
 569
 570            Say N.
 571
 572 config KALLSYMS_EXTRA_PASS
 573         bool "Do an extra kallsyms pass"
 574         depends on KALLSYMS
 575         help
 576            If kallsyms is not working correctly, the build will fail with
 577            inconsistent kallsyms data.  If that occurs, log a bug report and
 578            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 579            Always say N here unless you find a bug in kallsyms, which must be
 580            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 581            you wait for kallsyms to be fixed.
 582
 583
 584 config HOTPLUG
 585         bool "Support for hot-pluggable devices" if EMBEDDED
 586         default y
 587         help
 588           This option is provided for the case where no hotplug or uevent
 589           capabilities is wanted by the kernel.  You should only consider
 590           disabling this option for embedded systems that do not use modules, a
 591           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 592
 593 config PRINTK
 594         default y
 595         bool "Enable support for printk" if EMBEDDED
 596         help
 597           This option enables normal printk support. Removing it
 598           eliminates most of the message strings from the kernel image
 599           and makes the kernel more or less silent. As this makes it
 600           very difficult to diagnose system problems, saying N here is
 601           strongly discouraged.
 602
 603 config BUG
 604         bool "BUG() support" if EMBEDDED
 605         default y
 606         help
 607           Disabling this option eliminates support for BUG and WARN, reducing
 608           the size of your kernel image and potentially quietly ignoring
 609           numerous fatal conditions. You should only consider disabling this
 610           option for embedded systems with no facilities for reporting errors.
 611           Just say Y.
 612
 613 config ELF_CORE
 614         default y
 615         bool "Enable ELF core dumps" if EMBEDDED
 616         help
 617           Enable support for generating core dumps. Disabling saves about 4k.
 618
 619 config COMPAT_BRK
 620         bool "Disable heap randomization"
 621         default y
 622         help
 623           Randomizing heap placement makes heap exploits harder, but it
 624           also breaks ancient binaries (including anything libc5 based).
 625           This option changes the bootup default to heap randomization
 626           disabled, and can be overriden runtime by setting
 627           /proc/sys/kernel/randomize_va_space to 2.
 628
 629           On non-ancient distros (post-2000 ones) N is usually a safe choice.
 630
 631 config BASE_FULL
 632         default y
 633         bool "Enable full-sized data structures for core" if EMBEDDED
 634         help
 635           Disabling this option reduces the size of miscellaneous core
 636           kernel data structures. This saves memory on small machines,
 637           but may reduce performance.
 638
 639 config FUTEX
 640         bool "Enable futex support" if EMBEDDED
 641         default y
 642         select RT_MUTEXES
 643         help
 644           Disabling this option will cause the kernel to be built without
 645           support for "fast userspace mutexes".  The resulting kernel may not
 646           run glibc-based applications correctly.
 647
 648 config ANON_INODES
 649         bool
 650
 651 config EPOLL
 652         bool "Enable eventpoll support" if EMBEDDED
 653         default y
 654         select ANON_INODES
 655         help
 656           Disabling this option will cause the kernel to be built without
 657           support for epoll family of system calls.
 658
 659 config SIGNALFD
 660         bool "Enable signalfd() system call" if EMBEDDED
 661         select ANON_INODES
 662         default y
 663         help
 664           Enable the signalfd() system call that allows to receive signals
 665           on a file descriptor.
 666
 667           If unsure, say Y.
 668
 669 config TIMERFD
 670         bool "Enable timerfd() system call" if EMBEDDED
 671         select ANON_INODES
 672         default y
 673         help
 674           Enable the timerfd() system call that allows to receive timer
 675           events on a file descriptor.
 676
 677           If unsure, say Y.
 678
 679 config EVENTFD
 680         bool "Enable eventfd() system call" if EMBEDDED
 681         select ANON_INODES
 682         default y
 683         help
 684           Enable the eventfd() system call that allows to receive both
 685           kernel notification (ie. KAIO) or userspace notifications.
 686
 687           If unsure, say Y.
 688
 689 config SHMEM
 690         bool "Use full shmem filesystem" if EMBEDDED
 691         default y
 692         depends on MMU
 693         help
 694           The shmem is an internal filesystem used to manage shared memory.
 695           It is backed by swap and manages resource limits. It is also exported
 696           to userspace as tmpfs if TMPFS is enabled. Disabling this
 697           option replaces shmem and tmpfs with the much simpler ramfs code,
 698           which may be appropriate on small systems without swap.
 699
 700 config VM_EVENT_COUNTERS
 701         default y
 702         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 703         help
 704           VM event counters are needed for event counts to be shown.
 705           This option allows the disabling of the VM event counters
 706           on EMBEDDED systems.  /proc/vmstat will only show page counts
 707           if VM event counters are disabled.
 708
 709 config SLUB_DEBUG
 710         default y
 711         bool "Enable SLUB debugging support" if EMBEDDED
 712         depends on SLUB
 713         help
 714           SLUB has extensive debug support features. Disabling these can
 715           result in significant savings in code size. This also disables
 716           SLUB sysfs support. /sys/slab will not exist and there will be
 717           no support for cache validation etc.
 718
 719 choice
 720         prompt "Choose SLAB allocator"
 721         default SLUB
 722         help
 723            This option allows to select a slab allocator.
 724
 725 config SLAB
 726         bool "SLAB"
 727         help
 728           The regular slab allocator that is established and known to work
 729           well in all environments. It organizes cache hot objects in
 730           per cpu and per node queues. SLAB is the default choice for
 731           a slab allocator.
 732
 733 config SLUB
 734         bool "SLUB (Unqueued Allocator)"
 735         help
 736            SLUB is a slab allocator that minimizes cache line usage
 737            instead of managing queues of cached objects (SLAB approach).
 738            Per cpu caching is realized using slabs of objects instead
 739            of queues of objects. SLUB can use memory efficiently
 740            and has enhanced diagnostics.
 741
 742 config SLOB
 743         depends on EMBEDDED
 744         bool "SLOB (Simple Allocator)"
 745         help
 746            SLOB replaces the stock allocator with a drastically simpler
 747            allocator. SLOB is generally more space efficient but
 748            does not perform as well on large systems.
 749
 750 endchoice
 751
 752 config PROFILING
 753         bool "Profiling support (EXPERIMENTAL)"
 754         help
 755           Say Y here to enable the extended profiling support mechanisms used
 756           by profilers such as OProfile.
 757
 758 config MARKERS
 759         bool "Activate markers"
 760         help
 761           Place an empty function call at each marker site. Can be
 762           dynamically changed for a probe function.
 763
 764 source "arch/Kconfig"
 765
 766 config PROC_PAGE_MONITOR
 767         default y
 768         depends on PROC_FS && MMU
 769         bool "Enable /proc page monitoring" if EMBEDDED
 770         help
 771           Various /proc files exist to monitor process memory utilization:
 772           /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
 773           /proc/kpagecount, and /proc/kpageflags. Disabling these
 774           interfaces will reduce the size of the kernel by approximately 4kb.
 775
 776 endmenu         # General setup
 777
 778 config SLABINFO
 779         bool
 780         depends on PROC_FS
 781         depends on SLAB || SLUB_DEBUG
 782         default y
 783
 784 config RT_MUTEXES
 785         boolean
 786         select PLIST
 787
 788 config TINY_SHMEM
 789         default !SHMEM
 790         bool
 791
 792 config BASE_SMALL
 793         int
 794         default 0 if BASE_FULL
 795         default 1 if !BASE_FULL
 796
 797 menuconfig MODULES
 798         bool "Enable loadable module support"
 799         help
 800           Kernel modules are small pieces of compiled code which can
 801           be inserted in the running kernel, rather than being
 802           permanently built into the kernel.  You use the "modprobe"
 803           tool to add (and sometimes remove) them.  If you say Y here,
 804           many parts of the kernel can be built as modules (by
 805           answering M instead of Y where indicated): this is most
 806           useful for infrequently used options which are not required
 807           for booting.  For more information, see the man pages for
 808           modprobe, lsmod, modinfo, insmod and rmmod.
 809
 810           If you say Y here, you will need to run "make
 811           modules_install" to put the modules under /lib/modules/
 812           where modprobe can find them (you may need to be root to do
 813           this).
 814
 815           If unsure, say Y.
 816
 817 config MODULE_UNLOAD
 818         bool "Module unloading"
 819         depends on MODULES
 820         help
 821           Without this option you will not be able to unload any
 822           modules (note that some modules may not be unloadable
 823           anyway), which makes your kernel slightly smaller and
 824           simpler.  If unsure, say Y.
 825
 826 config MODULE_FORCE_UNLOAD
 827         bool "Forced module unloading"
 828         depends on MODULE_UNLOAD && EXPERIMENTAL
 829         help
 830           This option allows you to force a module to unload, even if the
 831           kernel believes it is unsafe: the kernel will remove the module
 832           without waiting for anyone to stop using it (using the -f option to
 833           rmmod).  This is mainly for kernel developers and desperate users.
 834           If unsure, say N.
 835
 836 config MODVERSIONS
 837         bool "Module versioning support"
 838         depends on MODULES
 839         help
 840           Usually, you have to use modules compiled with your kernel.
 841           Saying Y here makes it sometimes possible to use modules
 842           compiled for different kernels, by adding enough information
 843           to the modules to (hopefully) spot any changes which would
 844           make them incompatible with the kernel you are running.  If
 845           unsure, say N.
 846
 847 config MODULE_SRCVERSION_ALL
 848         bool "Source checksum for all modules"
 849         depends on MODULES
 850         help
 851           Modules which contain a MODULE_VERSION get an extra "srcversion"
 852           field inserted into their modinfo section, which contains a
 853           sum of the source files which made it.  This helps maintainers
 854           see exactly which source was used to build a module (since
 855           others sometimes change the module source without updating
 856           the version).  With this option, such a "srcversion" field
 857           will be created for all modules.  If unsure, say N.
 858
 859 config KMOD
 860         bool "Automatic kernel module loading"
 861         depends on MODULES
 862         help
 863           Normally when you have selected some parts of the kernel to
 864           be created as kernel modules, you must load them (using the
 865           "modprobe" command) before you can use them. If you say Y
 866           here, some parts of the kernel will be able to load modules
 867           automatically: when a part of the kernel needs a module, it
 868           runs modprobe with the appropriate arguments, thereby
 869           loading the module if it is available.  If unsure, say Y.
 870
 871 config STOP_MACHINE
 872         bool
 873         default y
 874         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 875         help
 876           Need stop_machine() primitive.
 877
 878 source "block/Kconfig"
 879
 880 config PREEMPT_NOTIFIERS
 881         bool
 882
 883 config CLASSIC_RCU
 884         def_bool !PREEMPT_RCU
 885         help
 886           This option selects the classic RCU implementation that is
 887           designed for best read-side performance on non-realtime
 888           systems.  Classic RCU is the default.  Note that the
 889           PREEMPT_RCU symbol is used to select/deselect this option.