init/Kconfig

   1 config ARCH
   2         string
   3         option env="ARCH"
   4
   5 config KERNELVERSION
   6         string
   7         option env="KERNELVERSION"
   8
   9 config DEFCONFIG_LIST
  10         string
  11         depends on !UML
  12         option defconfig_list
  13         default "/lib/modules/$UNAME_RELEASE/.config"
  14         default "/etc/kernel-config"
  15         default "/boot/config-$UNAME_RELEASE"
  16         default "$ARCH_DEFCONFIG"
  17         default "arch/$ARCH/defconfig"
  18
  19 menu "General setup"
  20
  21 config EXPERIMENTAL
  22         bool "Prompt for development and/or incomplete code/drivers"
  23         ---help---
  24           Some of the various things that Linux supports (such as network
  25           drivers, file systems, network protocols, etc.) can be in a state
  26           of development where the functionality, stability, or the level of
  27           testing is not yet high enough for general use. This is usually
  28           known as the "alpha-test" phase among developers. If a feature is
  29           currently in alpha-test, then the developers usually discourage
  30           uninformed widespread use of this feature by the general public to
  31           avoid "Why doesn't this work?" type mail messages. However, active
  32           testing and use of these systems is welcomed. Just be aware that it
  33           may not meet the normal level of reliability or it may fail to work
  34           in some special cases. Detailed bug reports from people familiar
  35           with the kernel internals are usually welcomed by the developers
  36           (before submitting bug reports, please read the documents
  37           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  38           <file:Documentation/BUG-HUNTING>, and
  39           <file:Documentation/oops-tracing.txt> in the kernel source).
  40
  41           This option will also make obsoleted drivers available. These are
  42           drivers that have been replaced by something else, and/or are
  43           scheduled to be removed in a future kernel release.
  44
  45           Unless you intend to help test and develop a feature or driver that
  46           falls into this category, or you have a situation that requires
  47           using these features, you should probably say N here, which will
  48           cause the configurator to present you with fewer choices. If
  49           you say Y here, you will be offered the choice of using features or
  50           drivers that are currently considered to be in the alpha-test phase.
  51
  52 config BROKEN
  53         bool
  54
  55 config BROKEN_ON_SMP
  56         bool
  57         depends on BROKEN || !SMP
  58         default y
  59
  60 config LOCK_KERNEL
  61         bool
  62         depends on SMP || PREEMPT
  63         default y
  64
  65 config INIT_ENV_ARG_LIMIT
  66         int
  67         default 32 if !UML
  68         default 128 if UML
  69         help
  70           Maximum of each of the number of arguments and environment
  71           variables passed to init from the kernel command line.
  72
  73
  74 config LOCALVERSION
  75         string "Local version - append to kernel release"
  76         help
  77           Append an extra string to the end of your kernel version.
  78           This will show up when you type uname, for example.
  79           The string you set here will be appended after the contents of
  80           any files with a filename matching localversion* in your
  81           object and source tree, in that order.  Your total string can
  82           be a maximum of 64 characters.
  83
  84 config LOCALVERSION_AUTO
  85         bool "Automatically append version information to the version string"
  86         default y
  87         help
  88           This will try to automatically determine if the current tree is a
  89           release tree by looking for git tags that belong to the current
  90           top of tree revision.
  91
  92           A string of the format -gxxxxxxxx will be added to the localversion
  93           if a git-based tree is found.  The string generated by this will be
  94           appended after any matching localversion* files, and after the value
  95           set in CONFIG_LOCALVERSION.
  96
  97           (The actual string used here is the first eight characters produced
  98           by running the command:
  99
 100             $ git rev-parse --verify HEAD
 101
 102           which is done within the script "scripts/setlocalversion".)
 103
 104 config SWAP
 105         bool "Support for paging of anonymous memory (swap)"
 106         depends on MMU && BLOCK
 107         default y
 108         help
 109           This option allows you to choose whether you want to have support
 110           for so called swap devices or swap files in your kernel that are
 111           used to provide more virtual memory than the actual RAM present
 112           in your computer.  If unsure say Y.
 113
 114 config SYSVIPC
 115         bool "System V IPC"
 116         ---help---
 117           Inter Process Communication is a suite of library functions and
 118           system calls which let processes (running programs) synchronize and
 119           exchange information. It is generally considered to be a good thing,
 120           and some programs won't run unless you say Y here. In particular, if
 121           you want to run the DOS emulator dosemu under Linux (read the
 122           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 123           you'll need to say Y here.
 124
 125           You can find documentation about IPC with "info ipc" and also in
 126           section 6.4 of the Linux Programmer's Guide, available from
 127           <http://www.tldp.org/guides.html>.
 128
 129 config SYSVIPC_SYSCTL
 130         bool
 131         depends on SYSVIPC
 132         depends on SYSCTL
 133         default y
 134
 135 config POSIX_MQUEUE
 136         bool "POSIX Message Queues"
 137         depends on NET && EXPERIMENTAL
 138         ---help---
 139           POSIX variant of message queues is a part of IPC. In POSIX message
 140           queues every message has a priority which decides about succession
 141           of receiving it by a process. If you want to compile and run
 142           programs written e.g. for Solaris with use of its POSIX message
 143           queues (functions mq_*) say Y here.
 144
 145           POSIX message queues are visible as a filesystem called 'mqueue'
 146           and can be mounted somewhere if you want to do filesystem
 147           operations on message queues.
 148
 149           If unsure, say Y.
 150
 151 config BSD_PROCESS_ACCT
 152         bool "BSD Process Accounting"
 153         help
 154           If you say Y here, a user level program will be able to instruct the
 155           kernel (via a special system call) to write process accounting
 156           information to a file: whenever a process exits, information about
 157           that process will be appended to the file by the kernel.  The
 158           information includes things such as creation time, owning user,
 159           command name, memory usage, controlling terminal etc. (the complete
 160           list is in the struct acct in <file:include/linux/acct.h>).  It is
 161           up to the user level program to do useful things with this
 162           information.  This is generally a good idea, so say Y.
 163
 164 config BSD_PROCESS_ACCT_V3
 165         bool "BSD Process Accounting version 3 file format"
 166         depends on BSD_PROCESS_ACCT
 167         default n
 168         help
 169           If you say Y here, the process accounting information is written
 170           in a new file format that also logs the process IDs of each
 171           process and it's parent. Note that this file format is incompatible
 172           with previous v0/v1/v2 file formats, so you will need updated tools
 173           for processing it. A preliminary version of these tools is available
 174           at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
 175
 176 config TASKSTATS
 177         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 178         depends on NET
 179         default n
 180         help
 181           Export selected statistics for tasks/processes through the
 182           generic netlink interface. Unlike BSD process accounting, the
 183           statistics are available during the lifetime of tasks/processes as
 184           responses to commands. Like BSD accounting, they are sent to user
 185           space on task exit.
 186
 187           Say N if unsure.
 188
 189 config TASK_DELAY_ACCT
 190         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 191         depends on TASKSTATS
 192         help
 193           Collect information on time spent by a task waiting for system
 194           resources like cpu, synchronous block I/O completion and swapping
 195           in pages. Such statistics can help in setting a task's priorities
 196           relative to other tasks for cpu, io, rss limits etc.
 197
 198           Say N if unsure.
 199
 200 config TASK_XACCT
 201         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 202         depends on TASKSTATS
 203         help
 204           Collect extended task accounting data and send the data
 205           to userland for processing over the taskstats interface.
 206
 207           Say N if unsure.
 208
 209 config TASK_IO_ACCOUNTING
 210         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 211         depends on TASK_XACCT
 212         help
 213           Collect information on the number of bytes of storage I/O which this
 214           task has caused.
 215
 216           Say N if unsure.
 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|| SUPERH)
 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 AUDIT_TREE
 238         def_bool y
 239         depends on AUDITSYSCALL && INOTIFY
 240
 241 config IKCONFIG
 242         tristate "Kernel .config support"
 243         ---help---
 244           This option enables the complete Linux kernel ".config" file
 245           contents to be saved in the kernel. It provides documentation
 246           of which kernel options are used in a running kernel or in an
 247           on-disk kernel.  This information can be extracted from the kernel
 248           image file with the script scripts/extract-ikconfig and used as
 249           input to rebuild the current kernel or to build another kernel.
 250           It can also be extracted from a running kernel by reading
 251           /proc/config.gz if enabled (below).
 252
 253 config IKCONFIG_PROC
 254         bool "Enable access to .config through /proc/config.gz"
 255         depends on IKCONFIG && PROC_FS
 256         ---help---
 257           This option enables access to the kernel configuration file
 258           through /proc/config.gz.
 259
 260 config LOG_BUF_SHIFT
 261         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 262         range 12 21
 263         default 17
 264         help
 265           Select kernel log buffer size as a power of 2.
 266           Examples:
 267                      17 => 128 KB
 268                      16 => 64 KB
 269                      15 => 32 KB
 270                      14 => 16 KB
 271                      13 =>  8 KB
 272                      12 =>  4 KB
 273
 274 config CGROUPS
 275         bool "Control Group support"
 276         help
 277           This option will let you use process cgroup subsystems
 278           such as Cpusets
 279
 280           Say N if unsure.
 281
 282 config CGROUP_DEBUG
 283         bool "Example debug cgroup subsystem"
 284         depends on CGROUPS
 285         default n
 286         help
 287           This option enables a simple cgroup subsystem that
 288           exports useful debugging information about the cgroups
 289           framework
 290
 291           Say N if unsure
 292
 293 config CGROUP_NS
 294         bool "Namespace cgroup subsystem"
 295         depends on CGROUPS
 296         help
 297           Provides a simple namespace cgroup subsystem to
 298           provide hierarchical naming of sets of namespaces,
 299           for instance virtual servers and checkpoint/restart
 300           jobs.
 301
 302 config CGROUP_DEVICE
 303         bool "Device controller for cgroups"
 304         depends on CGROUPS && EXPERIMENTAL
 305         help
 306           Provides a cgroup implementing whitelists for devices which
 307           a process in the cgroup can mknod or open.
 308
 309 config CPUSETS
 310         bool "Cpuset support"
 311         depends on SMP && CGROUPS
 312         help
 313           This option will let you create and manage CPUSETs which
 314           allow dynamically partitioning a system into sets of CPUs and
 315           Memory Nodes and assigning tasks to run only within those sets.
 316           This is primarily useful on large SMP or NUMA systems.
 317
 318           Say N if unsure.
 319
 320 #
 321 # Architectures with an unreliable sched_clock() should select this:
 322 #
 323 config HAVE_UNSTABLE_SCHED_CLOCK
 324         bool
 325
 326 config GROUP_SCHED
 327         bool "Group CPU scheduler"
 328         depends on EXPERIMENTAL
 329         default n
 330         help
 331           This feature lets CPU scheduler recognize task groups and control CPU
 332           bandwidth allocation to such task groups.
 333
 334 config FAIR_GROUP_SCHED
 335         bool "Group scheduling for SCHED_OTHER"
 336         depends on GROUP_SCHED
 337         default GROUP_SCHED
 338
 339 config RT_GROUP_SCHED
 340         bool "Group scheduling for SCHED_RR/FIFO"
 341         depends on EXPERIMENTAL
 342         depends on GROUP_SCHED
 343         default n
 344         help
 345           This feature lets you explicitly allocate real CPU bandwidth
 346           to users or control groups (depending on the "Basis for grouping tasks"
 347           setting below. If enabled, it will also make it impossible to
 348           schedule realtime tasks for non-root users until you allocate
 349           realtime bandwidth for them.
 350           See Documentation/sched-rt-group.txt for more information.
 351
 352 choice
 353         depends on GROUP_SCHED
 354         prompt "Basis for grouping tasks"
 355         default USER_SCHED
 356
 357 config USER_SCHED
 358         bool "user id"
 359         help
 360           This option will choose userid as the basis for grouping
 361           tasks, thus providing equal CPU bandwidth to each user.
 362
 363 config CGROUP_SCHED
 364         bool "Control groups"
 365         depends on CGROUPS
 366         help
 367           This option allows you to create arbitrary task groups
 368           using the "cgroup" pseudo filesystem and control
 369           the cpu bandwidth allocated to each such task group.
 370           Refer to Documentation/cgroups.txt for more information
 371           on "cgroup" pseudo filesystem.
 372
 373 endchoice
 374
 375 config CGROUP_CPUACCT
 376         bool "Simple CPU accounting cgroup subsystem"
 377         depends on CGROUPS
 378         help
 379           Provides a simple Resource Controller for monitoring the
 380           total CPU consumed by the tasks in a cgroup
 381
 382 config RESOURCE_COUNTERS
 383         bool "Resource counters"
 384         help
 385           This option enables controller independent resource accounting
 386           infrastructure that works with cgroups
 387         depends on CGROUPS
 388
 389 config MM_OWNER
 390         bool
 391
 392 config CGROUP_MEM_RES_CTLR
 393         bool "Memory Resource Controller for Control Groups"
 394         depends on CGROUPS && RESOURCE_COUNTERS
 395         select MM_OWNER
 396         help
 397           Provides a memory resource controller that manages both page cache and
 398           RSS memory.
 399
 400           Note that setting this option increases fixed memory overhead
 401           associated with each page of memory in the system by 4/8 bytes
 402           and also increases cache misses because struct page on many 64bit
 403           systems will not fit into a single cache line anymore.
 404
 405           Only enable when you're ok with these trade offs and really
 406           sure you need the memory resource controller.
 407
 408           This config option also selects MM_OWNER config option, which
 409           could in turn add some fork/exit overhead.
 410
 411 config SYSFS_DEPRECATED
 412         bool
 413
 414 config SYSFS_DEPRECATED_V2
 415         bool "Create deprecated sysfs files"
 416         depends on SYSFS
 417         default y
 418         select SYSFS_DEPRECATED
 419         help
 420           This option creates deprecated symlinks such as the
 421           "device"-link, the <subsystem>:<name>-link, and the
 422           "bus"-link. It may also add deprecated key in the
 423           uevent environment.
 424           None of these features or values should be used today, as
 425           they export driver core implementation details to userspace
 426           or export properties which can't be kept stable across kernel
 427           releases.
 428
 429           If enabled, this option will also move any device structures
 430           that belong to a class, back into the /sys/class hierarchy, in
 431           order to support older versions of udev and some userspace
 432           programs.
 433
 434           If you are using a distro with the most recent userspace
 435           packages, it should be safe to say N here.
 436
 437 config PROC_PID_CPUSET
 438         bool "Include legacy /proc/<pid>/cpuset file"
 439         depends on CPUSETS
 440         default y
 441
 442 config RELAY
 443         bool "Kernel->user space relay support (formerly relayfs)"
 444         help
 445           This option enables support for relay interface support in
 446           certain file systems (such as debugfs).
 447           It is designed to provide an efficient mechanism for tools and
 448           facilities to relay large amounts of data from kernel space to
 449           user space.
 450
 451           If unsure, say N.
 452
 453 config NAMESPACES
 454         bool "Namespaces support" if EMBEDDED
 455         default !EMBEDDED
 456         help
 457           Provides the way to make tasks work with different objects using
 458           the same id. For example same IPC id may refer to different objects
 459           or same user id or pid may refer to different tasks when used in
 460           different namespaces.
 461
 462 config UTS_NS
 463         bool "UTS namespace"
 464         depends on NAMESPACES
 465         help
 466           In this namespace tasks see different info provided with the
 467           uname() system call
 468
 469 config IPC_NS
 470         bool "IPC namespace"
 471         depends on NAMESPACES && SYSVIPC
 472         help
 473           In this namespace tasks work with IPC ids which correspond to
 474           different IPC objects in different namespaces
 475
 476 config USER_NS
 477         bool "User namespace (EXPERIMENTAL)"
 478         depends on NAMESPACES && EXPERIMENTAL
 479         help
 480           This allows containers, i.e. vservers, to use user namespaces
 481           to provide different user info for different servers.
 482           If unsure, say N.
 483
 484 config PID_NS
 485         bool "PID Namespaces (EXPERIMENTAL)"
 486         default n
 487         depends on NAMESPACES && EXPERIMENTAL
 488         help
 489           Suport process id namespaces.  This allows having multiple
 490           process with the same pid as long as they are in different
 491           pid namespaces.  This is a building block of containers.
 492
 493           Unless you want to work with an experimental feature
 494           say N here.
 495
 496 config BLK_DEV_INITRD
 497         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 498         depends on BROKEN || !FRV
 499         help
 500           The initial RAM filesystem is a ramfs which is loaded by the
 501           boot loader (loadlin or lilo) and that is mounted as root
 502           before the normal boot procedure. It is typically used to
 503           load modules needed to mount the "real" root file system,
 504           etc. See <file:Documentation/initrd.txt> for details.
 505
 506           If RAM disk support (BLK_DEV_RAM) is also included, this
 507           also enables initial RAM disk (initrd) support and adds
 508           15 Kbytes (more on some other architectures) to the kernel size.
 509
 510           If unsure say Y.
 511
 512 if BLK_DEV_INITRD
 513
 514 source "usr/Kconfig"
 515
 516 endif
 517
 518 config CC_OPTIMIZE_FOR_SIZE
 519         bool "Optimize for size"
 520         default y
 521         help
 522           Enabling this option will pass "-Os" instead of "-O2" to gcc
 523           resulting in a smaller kernel.
 524
 525           If unsure, say N.
 526
 527 config SYSCTL
 528         bool
 529
 530 menuconfig EMBEDDED
 531         bool "Configure standard kernel features (for small systems)"
 532         help
 533           This option allows certain base kernel options and settings
 534           to be disabled or tweaked. This is for specialized
 535           environments which can tolerate a "non-standard" kernel.
 536           Only use this if you really know what you are doing.
 537
 538 config UID16
 539         bool "Enable 16-bit UID system calls" if EMBEDDED
 540         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 541         default y
 542         help
 543           This enables the legacy 16-bit UID syscall wrappers.
 544
 545 config SYSCTL_SYSCALL
 546         bool "Sysctl syscall support" if EMBEDDED
 547         default y
 548         select SYSCTL
 549         ---help---
 550           sys_sysctl uses binary paths that have been found challenging
 551           to properly maintain and use.  The interface in /proc/sys
 552           using paths with ascii names is now the primary path to this
 553           information.
 554
 555           Almost nothing using the binary sysctl interface so if you are
 556           trying to save some space it is probably safe to disable this,
 557           making your kernel marginally smaller.
 558
 559           If unsure say Y here.
 560
 561 config SYSCTL_SYSCALL_CHECK
 562         bool "Sysctl checks" if EMBEDDED
 563         depends on SYSCTL_SYSCALL
 564         default y
 565         ---help---
 566           sys_sysctl uses binary paths that have been found challenging
 567           to properly maintain and use. This enables checks that help
 568           you to keep things correct.
 569
 570           If unsure say Y here.
 571
 572 config KALLSYMS
 573          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 574          default y
 575          help
 576            Say Y here to let the kernel print out symbolic crash information and
 577            symbolic stack backtraces. This increases the size of the kernel
 578            somewhat, as all symbols have to be loaded into the kernel image.
 579
 580 config KALLSYMS_ALL
 581         bool "Include all symbols in kallsyms"
 582         depends on DEBUG_KERNEL && KALLSYMS
 583         help
 584            Normally kallsyms only contains the symbols of functions, for nicer
 585            OOPS messages.  Some debuggers can use kallsyms for other
 586            symbols too: say Y here to include all symbols, if you need them
 587            and you don't care about adding 300k to the size of your kernel.
 588
 589            Say N.
 590
 591 config KALLSYMS_EXTRA_PASS
 592         bool "Do an extra kallsyms pass"
 593         depends on KALLSYMS
 594         help
 595            If kallsyms is not working correctly, the build will fail with
 596            inconsistent kallsyms data.  If that occurs, log a bug report and
 597            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 598            Always say N here unless you find a bug in kallsyms, which must be
 599            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 600            you wait for kallsyms to be fixed.
 601
 602
 603 config HOTPLUG
 604         bool "Support for hot-pluggable devices" if EMBEDDED
 605         default y
 606         help
 607           This option is provided for the case where no hotplug or uevent
 608           capabilities is wanted by the kernel.  You should only consider
 609           disabling this option for embedded systems that do not use modules, a
 610           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 611
 612 config PRINTK
 613         default y
 614         bool "Enable support for printk" if EMBEDDED
 615         help
 616           This option enables normal printk support. Removing it
 617           eliminates most of the message strings from the kernel image
 618           and makes the kernel more or less silent. As this makes it
 619           very difficult to diagnose system problems, saying N here is
 620           strongly discouraged.
 621
 622 config BUG
 623         bool "BUG() support" if EMBEDDED
 624         default y
 625         help
 626           Disabling this option eliminates support for BUG and WARN, reducing
 627           the size of your kernel image and potentially quietly ignoring
 628           numerous fatal conditions. You should only consider disabling this
 629           option for embedded systems with no facilities for reporting errors.
 630           Just say Y.
 631
 632 config ELF_CORE
 633         default y
 634         bool "Enable ELF core dumps" if EMBEDDED
 635         help
 636           Enable support for generating core dumps. Disabling saves about 4k.
 637
 638 config PCSPKR_PLATFORM
 639         bool "Enable PC-Speaker support" if EMBEDDED
 640         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 641         default y
 642         help
 643           This option allows to disable the internal PC-Speaker
 644           support, saving some memory.
 645
 646 config COMPAT_BRK
 647         bool "Disable heap randomization"
 648         default y
 649         help
 650           Randomizing heap placement makes heap exploits harder, but it
 651           also breaks ancient binaries (including anything libc5 based).
 652           This option changes the bootup default to heap randomization
 653           disabled, and can be overriden runtime by setting
 654           /proc/sys/kernel/randomize_va_space to 2.
 655
 656           On non-ancient distros (post-2000 ones) N is usually a safe choice.
 657
 658 config BASE_FULL
 659         default y
 660         bool "Enable full-sized data structures for core" if EMBEDDED
 661         help
 662           Disabling this option reduces the size of miscellaneous core
 663           kernel data structures. This saves memory on small machines,
 664           but may reduce performance.
 665
 666 config FUTEX
 667         bool "Enable futex support" if EMBEDDED
 668         default y
 669         select RT_MUTEXES
 670         help
 671           Disabling this option will cause the kernel to be built without
 672           support for "fast userspace mutexes".  The resulting kernel may not
 673           run glibc-based applications correctly.
 674
 675 config ANON_INODES
 676         bool
 677
 678 config EPOLL
 679         bool "Enable eventpoll support" if EMBEDDED
 680         default y
 681         select ANON_INODES
 682         help
 683           Disabling this option will cause the kernel to be built without
 684           support for epoll family of system calls.
 685
 686 config SIGNALFD
 687         bool "Enable signalfd() system call" if EMBEDDED
 688         select ANON_INODES
 689         default y
 690         help
 691           Enable the signalfd() system call that allows to receive signals
 692           on a file descriptor.
 693
 694           If unsure, say Y.
 695
 696 config TIMERFD
 697         bool "Enable timerfd() system call" if EMBEDDED
 698         select ANON_INODES
 699         default y
 700         help
 701           Enable the timerfd() system call that allows to receive timer
 702           events on a file descriptor.
 703
 704           If unsure, say Y.
 705
 706 config EVENTFD
 707         bool "Enable eventfd() system call" if EMBEDDED
 708         select ANON_INODES
 709         default y
 710         help
 711           Enable the eventfd() system call that allows to receive both
 712           kernel notification (ie. KAIO) or userspace notifications.
 713
 714           If unsure, say Y.
 715
 716 config SHMEM
 717         bool "Use full shmem filesystem" if EMBEDDED
 718         default y
 719         depends on MMU
 720         help
 721           The shmem is an internal filesystem used to manage shared memory.
 722           It is backed by swap and manages resource limits. It is also exported
 723           to userspace as tmpfs if TMPFS is enabled. Disabling this
 724           option replaces shmem and tmpfs with the much simpler ramfs code,
 725           which may be appropriate on small systems without swap.
 726
 727 config VM_EVENT_COUNTERS
 728         default y
 729         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 730         help
 731           VM event counters are needed for event counts to be shown.
 732           This option allows the disabling of the VM event counters
 733           on EMBEDDED systems.  /proc/vmstat will only show page counts
 734           if VM event counters are disabled.
 735
 736 config SLUB_DEBUG
 737         default y
 738         bool "Enable SLUB debugging support" if EMBEDDED
 739         depends on SLUB && SYSFS
 740         help
 741           SLUB has extensive debug support features. Disabling these can
 742           result in significant savings in code size. This also disables
 743           SLUB sysfs support. /sys/slab will not exist and there will be
 744           no support for cache validation etc.
 745
 746 choice
 747         prompt "Choose SLAB allocator"
 748         default SLUB
 749         help
 750            This option allows to select a slab allocator.
 751
 752 config SLAB
 753         bool "SLAB"
 754         help
 755           The regular slab allocator that is established and known to work
 756           well in all environments. It organizes cache hot objects in
 757           per cpu and per node queues. SLAB is the default choice for
 758           a slab allocator.
 759
 760 config SLUB
 761         bool "SLUB (Unqueued Allocator)"
 762         help
 763            SLUB is a slab allocator that minimizes cache line usage
 764            instead of managing queues of cached objects (SLAB approach).
 765            Per cpu caching is realized using slabs of objects instead
 766            of queues of objects. SLUB can use memory efficiently
 767            and has enhanced diagnostics.
 768
 769 config SLOB
 770         depends on EMBEDDED
 771         bool "SLOB (Simple Allocator)"
 772         help
 773            SLOB replaces the stock allocator with a drastically simpler
 774            allocator. SLOB is generally more space efficient but
 775            does not perform as well on large systems.
 776
 777 endchoice
 778
 779 config PROFILING
 780         bool "Profiling support (EXPERIMENTAL)"
 781         help
 782           Say Y here to enable the extended profiling support mechanisms used
 783           by profilers such as OProfile.
 784
 785 config MARKERS
 786         bool "Activate markers"
 787         help
 788           Place an empty function call at each marker site. Can be
 789           dynamically changed for a probe function.
 790
 791 source "arch/Kconfig"
 792
 793 config PROC_PAGE_MONITOR
 794         default y
 795         depends on PROC_FS && MMU
 796         bool "Enable /proc page monitoring" if EMBEDDED
 797         help
 798           Various /proc files exist to monitor process memory utilization:
 799           /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
 800           /proc/kpagecount, and /proc/kpageflags. Disabling these
 801           interfaces will reduce the size of the kernel by approximately 4kb.
 802
 803 endmenu         # General setup
 804
 805 config SLABINFO
 806         bool
 807         depends on PROC_FS
 808         depends on SLAB || SLUB_DEBUG
 809         default y
 810
 811 config RT_MUTEXES
 812         boolean
 813         select PLIST
 814
 815 config TINY_SHMEM
 816         default !SHMEM
 817         bool
 818
 819 config BASE_SMALL
 820         int
 821         default 0 if BASE_FULL
 822         default 1 if !BASE_FULL
 823
 824 menuconfig MODULES
 825         bool "Enable loadable module support"
 826         help
 827           Kernel modules are small pieces of compiled code which can
 828           be inserted in the running kernel, rather than being
 829           permanently built into the kernel.  You use the "modprobe"
 830           tool to add (and sometimes remove) them.  If you say Y here,
 831           many parts of the kernel can be built as modules (by
 832           answering M instead of Y where indicated): this is most
 833           useful for infrequently used options which are not required
 834           for booting.  For more information, see the man pages for
 835           modprobe, lsmod, modinfo, insmod and rmmod.
 836
 837           If you say Y here, you will need to run "make
 838           modules_install" to put the modules under /lib/modules/
 839           where modprobe can find them (you may need to be root to do
 840           this).
 841
 842           If unsure, say Y.
 843
 844 config MODULE_FORCE_LOAD
 845         bool "Forced module loading"
 846         depends on MODULES
 847         default n
 848         help
 849           Allow loading of modules without version information (ie. modprobe
 850           --force).  Forced module loading sets the 'F' (forced) taint flag and
 851           is usually a really bad idea.
 852
 853 config MODULE_UNLOAD
 854         bool "Module unloading"
 855         depends on MODULES
 856         help
 857           Without this option you will not be able to unload any
 858           modules (note that some modules may not be unloadable
 859           anyway), which makes your kernel slightly smaller and
 860           simpler.  If unsure, say Y.
 861
 862 config MODULE_FORCE_UNLOAD
 863         bool "Forced module unloading"
 864         depends on MODULE_UNLOAD && EXPERIMENTAL
 865         help
 866           This option allows you to force a module to unload, even if the
 867           kernel believes it is unsafe: the kernel will remove the module
 868           without waiting for anyone to stop using it (using the -f option to
 869           rmmod).  This is mainly for kernel developers and desperate users.
 870           If unsure, say N.
 871
 872 config MODVERSIONS
 873         bool "Module versioning support"
 874         depends on MODULES
 875         help
 876           Usually, you have to use modules compiled with your kernel.
 877           Saying Y here makes it sometimes possible to use modules
 878           compiled for different kernels, by adding enough information
 879           to the modules to (hopefully) spot any changes which would
 880           make them incompatible with the kernel you are running.  If
 881           unsure, say N.
 882
 883 config MODULE_SRCVERSION_ALL
 884         bool "Source checksum for all modules"
 885         depends on MODULES
 886         help
 887           Modules which contain a MODULE_VERSION get an extra "srcversion"
 888           field inserted into their modinfo section, which contains a
 889           sum of the source files which made it.  This helps maintainers
 890           see exactly which source was used to build a module (since
 891           others sometimes change the module source without updating
 892           the version).  With this option, such a "srcversion" field
 893           will be created for all modules.  If unsure, say N.
 894
 895 config KMOD
 896         bool "Automatic kernel module loading"
 897         depends on MODULES
 898         help
 899           Normally when you have selected some parts of the kernel to
 900           be created as kernel modules, you must load them (using the
 901           "modprobe" command) before you can use them. If you say Y
 902           here, some parts of the kernel will be able to load modules
 903           automatically: when a part of the kernel needs a module, it
 904           runs modprobe with the appropriate arguments, thereby
 905           loading the module if it is available.  If unsure, say Y.
 906
 907 config STOP_MACHINE
 908         bool
 909         default y
 910         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 911         help
 912           Need stop_machine() primitive.
 913
 914 source "block/Kconfig"
 915
 916 config PREEMPT_NOTIFIERS
 917         bool
 918
 919 config CLASSIC_RCU
 920         def_bool !PREEMPT_RCU
 921         help
 922           This option selects the classic RCU implementation that is
 923           designed for best read-side performance on non-realtime
 924           systems.  Classic RCU is the default.  Note that the
 925           PREEMPT_RCU symbol is used to select/deselect this option.