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  42           drivers that have been replaced by something else, and/or are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.gnu.org/software/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_FREEZER
 303         bool "control group freezer subsystem"
 304         depends on CGROUPS
 305         help
 306           Provides a way to freeze and unfreeze all tasks in a
 307           cgroup.
 308
 309 config CGROUP_DEVICE
 310         bool "Device controller for cgroups"
 311         depends on CGROUPS && EXPERIMENTAL
 312         help
 313           Provides a cgroup implementing whitelists for devices which
 314           a process in the cgroup can mknod or open.
 315
 316 config CPUSETS
 317         bool "Cpuset support"
 318         depends on SMP && CGROUPS
 319         help
 320           This option will let you create and manage CPUSETs which
 321           allow dynamically partitioning a system into sets of CPUs and
 322           Memory Nodes and assigning tasks to run only within those sets.
 323           This is primarily useful on large SMP or NUMA systems.
 324
 325           Say N if unsure.
 326
 327 #
 328 # Architectures with an unreliable sched_clock() should select this:
 329 #
 330 config HAVE_UNSTABLE_SCHED_CLOCK
 331         bool
 332
 333 config GROUP_SCHED
 334         bool "Group CPU scheduler"
 335         depends on EXPERIMENTAL
 336         default n
 337         help
 338           This feature lets CPU scheduler recognize task groups and control CPU
 339           bandwidth allocation to such task groups.
 340
 341 config FAIR_GROUP_SCHED
 342         bool "Group scheduling for SCHED_OTHER"
 343         depends on GROUP_SCHED
 344         default GROUP_SCHED
 345
 346 config RT_GROUP_SCHED
 347         bool "Group scheduling for SCHED_RR/FIFO"
 348         depends on EXPERIMENTAL
 349         depends on GROUP_SCHED
 350         default n
 351         help
 352           This feature lets you explicitly allocate real CPU bandwidth
 353           to users or control groups (depending on the "Basis for grouping tasks"
 354           setting below. If enabled, it will also make it impossible to
 355           schedule realtime tasks for non-root users until you allocate
 356           realtime bandwidth for them.
 357           See Documentation/scheduler/sched-rt-group.txt for more information.
 358
 359 choice
 360         depends on GROUP_SCHED
 361         prompt "Basis for grouping tasks"
 362         default USER_SCHED
 363
 364 config USER_SCHED
 365         bool "user id"
 366         help
 367           This option will choose userid as the basis for grouping
 368           tasks, thus providing equal CPU bandwidth to each user.
 369
 370 config CGROUP_SCHED
 371         bool "Control groups"
 372         depends on CGROUPS
 373         help
 374           This option allows you to create arbitrary task groups
 375           using the "cgroup" pseudo filesystem and control
 376           the cpu bandwidth allocated to each such task group.
 377           Refer to Documentation/cgroups.txt for more information
 378           on "cgroup" pseudo filesystem.
 379
 380 endchoice
 381
 382 config CGROUP_CPUACCT
 383         bool "Simple CPU accounting cgroup subsystem"
 384         depends on CGROUPS
 385         help
 386           Provides a simple Resource Controller for monitoring the
 387           total CPU consumed by the tasks in a cgroup
 388
 389 config RESOURCE_COUNTERS
 390         bool "Resource counters"
 391         help
 392           This option enables controller independent resource accounting
 393           infrastructure that works with cgroups
 394         depends on CGROUPS
 395
 396 config MM_OWNER
 397         bool
 398
 399 config CGROUP_MEM_RES_CTLR
 400         bool "Memory Resource Controller for Control Groups"
 401         depends on CGROUPS && RESOURCE_COUNTERS
 402         select MM_OWNER
 403         help
 404           Provides a memory resource controller that manages both anonymous
 405           memory and page cache. (See Documentation/controllers/memory.txt)
 406
 407           Note that setting this option increases fixed memory overhead
 408           associated with each page of memory in the system. By this,
 409           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 410           usage tracking struct at boot. Total amount of this is printed out
 411           at boot.
 412
 413           Only enable when you're ok with these trade offs and really
 414           sure you need the memory resource controller. Even when you enable
 415           this, you can set "cgroup_disable=memory" at your boot option to
 416           disable memory resource controller and you can avoid overheads.
 417           (and lose benefits of memory resource contoller)
 418
 419           This config option also selects MM_OWNER config option, which
 420           could in turn add some fork/exit overhead.
 421
 422 config SYSFS_DEPRECATED
 423         bool
 424
 425 config SYSFS_DEPRECATED_V2
 426         bool "Create deprecated sysfs files"
 427         depends on SYSFS
 428         default y
 429         select SYSFS_DEPRECATED
 430         help
 431           This option creates deprecated symlinks such as the
 432           "device"-link, the <subsystem>:<name>-link, and the
 433           "bus"-link. It may also add deprecated key in the
 434           uevent environment.
 435           None of these features or values should be used today, as
 436           they export driver core implementation details to userspace
 437           or export properties which can't be kept stable across kernel
 438           releases.
 439
 440           If enabled, this option will also move any device structures
 441           that belong to a class, back into the /sys/class hierarchy, in
 442           order to support older versions of udev and some userspace
 443           programs.
 444
 445           If you are using a distro with the most recent userspace
 446           packages, it should be safe to say N here.
 447
 448 config PROC_PID_CPUSET
 449         bool "Include legacy /proc/<pid>/cpuset file"
 450         depends on CPUSETS
 451         default y
 452
 453 config RELAY
 454         bool "Kernel->user space relay support (formerly relayfs)"
 455         help
 456           This option enables support for relay interface support in
 457           certain file systems (such as debugfs).
 458           It is designed to provide an efficient mechanism for tools and
 459           facilities to relay large amounts of data from kernel space to
 460           user space.
 461
 462           If unsure, say N.
 463
 464 config NAMESPACES
 465         bool "Namespaces support" if EMBEDDED
 466         default !EMBEDDED
 467         help
 468           Provides the way to make tasks work with different objects using
 469           the same id. For example same IPC id may refer to different objects
 470           or same user id or pid may refer to different tasks when used in
 471           different namespaces.
 472
 473 config UTS_NS
 474         bool "UTS namespace"
 475         depends on NAMESPACES
 476         help
 477           In this namespace tasks see different info provided with the
 478           uname() system call
 479
 480 config IPC_NS
 481         bool "IPC namespace"
 482         depends on NAMESPACES && SYSVIPC
 483         help
 484           In this namespace tasks work with IPC ids which correspond to
 485           different IPC objects in different namespaces
 486
 487 config USER_NS
 488         bool "User namespace (EXPERIMENTAL)"
 489         depends on NAMESPACES && EXPERIMENTAL
 490         help
 491           This allows containers, i.e. vservers, to use user namespaces
 492           to provide different user info for different servers.
 493           If unsure, say N.
 494
 495 config PID_NS
 496         bool "PID Namespaces (EXPERIMENTAL)"
 497         default n
 498         depends on NAMESPACES && EXPERIMENTAL
 499         help
 500           Support process id namespaces.  This allows having multiple
 501           process with the same pid as long as they are in different
 502           pid namespaces.  This is a building block of containers.
 503
 504           Unless you want to work with an experimental feature
 505           say N here.
 506
 507 config BLK_DEV_INITRD
 508         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 509         depends on BROKEN || !FRV
 510         help
 511           The initial RAM filesystem is a ramfs which is loaded by the
 512           boot loader (loadlin or lilo) and that is mounted as root
 513           before the normal boot procedure. It is typically used to
 514           load modules needed to mount the "real" root file system,
 515           etc. See <file:Documentation/initrd.txt> for details.
 516
 517           If RAM disk support (BLK_DEV_RAM) is also included, this
 518           also enables initial RAM disk (initrd) support and adds
 519           15 Kbytes (more on some other architectures) to the kernel size.
 520
 521           If unsure say Y.
 522
 523 if BLK_DEV_INITRD
 524
 525 source "usr/Kconfig"
 526
 527 endif
 528
 529 config CC_OPTIMIZE_FOR_SIZE
 530         bool "Optimize for size"
 531         default y
 532         help
 533           Enabling this option will pass "-Os" instead of "-O2" to gcc
 534           resulting in a smaller kernel.
 535
 536           If unsure, say Y.
 537
 538 config SYSCTL
 539         bool
 540
 541 menuconfig EMBEDDED
 542         bool "Configure standard kernel features (for small systems)"
 543         help
 544           This option allows certain base kernel options and settings
 545           to be disabled or tweaked. This is for specialized
 546           environments which can tolerate a "non-standard" kernel.
 547           Only use this if you really know what you are doing.
 548
 549 config UID16
 550         bool "Enable 16-bit UID system calls" if EMBEDDED
 551         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 552         default y
 553         help
 554           This enables the legacy 16-bit UID syscall wrappers.
 555
 556 config SYSCTL_SYSCALL
 557         bool "Sysctl syscall support" if EMBEDDED
 558         default y
 559         select SYSCTL
 560         ---help---
 561           sys_sysctl uses binary paths that have been found challenging
 562           to properly maintain and use.  The interface in /proc/sys
 563           using paths with ascii names is now the primary path to this
 564           information.
 565
 566           Almost nothing using the binary sysctl interface so if you are
 567           trying to save some space it is probably safe to disable this,
 568           making your kernel marginally smaller.
 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_STRIP_GENERATED
 592         bool "Strip machine generated symbols from kallsyms"
 593         depends on KALLSYMS_ALL
 594         default y
 595         help
 596           Say N if you want kallsyms to retain even machine generated symbols.
 597
 598 config KALLSYMS_EXTRA_PASS
 599         bool "Do an extra kallsyms pass"
 600         depends on KALLSYMS
 601         help
 602            If kallsyms is not working correctly, the build will fail with
 603            inconsistent kallsyms data.  If that occurs, log a bug report and
 604            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 605            Always say N here unless you find a bug in kallsyms, which must be
 606            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 607            you wait for kallsyms to be fixed.
 608
 609
 610 config HOTPLUG
 611         bool "Support for hot-pluggable devices" if EMBEDDED
 612         default y
 613         help
 614           This option is provided for the case where no hotplug or uevent
 615           capabilities is wanted by the kernel.  You should only consider
 616           disabling this option for embedded systems that do not use modules, a
 617           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 618
 619 config PRINTK
 620         default y
 621         bool "Enable support for printk" if EMBEDDED
 622         help
 623           This option enables normal printk support. Removing it
 624           eliminates most of the message strings from the kernel image
 625           and makes the kernel more or less silent. As this makes it
 626           very difficult to diagnose system problems, saying N here is
 627           strongly discouraged.
 628
 629 config BUG
 630         bool "BUG() support" if EMBEDDED
 631         default y
 632         help
 633           Disabling this option eliminates support for BUG and WARN, reducing
 634           the size of your kernel image and potentially quietly ignoring
 635           numerous fatal conditions. You should only consider disabling this
 636           option for embedded systems with no facilities for reporting errors.
 637           Just say Y.
 638
 639 config ELF_CORE
 640         default y
 641         bool "Enable ELF core dumps" if EMBEDDED
 642         help
 643           Enable support for generating core dumps. Disabling saves about 4k.
 644
 645 config PCSPKR_PLATFORM
 646         bool "Enable PC-Speaker support" if EMBEDDED
 647         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 648         default y
 649         help
 650           This option allows to disable the internal PC-Speaker
 651           support, saving some memory.
 652
 653 config COMPAT_BRK
 654         bool "Disable heap randomization"
 655         default y
 656         help
 657           Randomizing heap placement makes heap exploits harder, but it
 658           also breaks ancient binaries (including anything libc5 based).
 659           This option changes the bootup default to heap randomization
 660           disabled, and can be overriden runtime by setting
 661           /proc/sys/kernel/randomize_va_space to 2.
 662
 663           On non-ancient distros (post-2000 ones) N is usually a safe choice.
 664
 665 config BASE_FULL
 666         default y
 667         bool "Enable full-sized data structures for core" if EMBEDDED
 668         help
 669           Disabling this option reduces the size of miscellaneous core
 670           kernel data structures. This saves memory on small machines,
 671           but may reduce performance.
 672
 673 config FUTEX
 674         bool "Enable futex support" if EMBEDDED
 675         default y
 676         select RT_MUTEXES
 677         help
 678           Disabling this option will cause the kernel to be built without
 679           support for "fast userspace mutexes".  The resulting kernel may not
 680           run glibc-based applications correctly.
 681
 682 config ANON_INODES
 683         bool
 684
 685 config EPOLL
 686         bool "Enable eventpoll support" if EMBEDDED
 687         default y
 688         select ANON_INODES
 689         help
 690           Disabling this option will cause the kernel to be built without
 691           support for epoll family of system calls.
 692
 693 config SIGNALFD
 694         bool "Enable signalfd() system call" if EMBEDDED
 695         select ANON_INODES
 696         default y
 697         help
 698           Enable the signalfd() system call that allows to receive signals
 699           on a file descriptor.
 700
 701           If unsure, say Y.
 702
 703 config TIMERFD
 704         bool "Enable timerfd() system call" if EMBEDDED
 705         select ANON_INODES
 706         default y
 707         help
 708           Enable the timerfd() system call that allows to receive timer
 709           events on a file descriptor.
 710
 711           If unsure, say Y.
 712
 713 config EVENTFD
 714         bool "Enable eventfd() system call" if EMBEDDED
 715         select ANON_INODES
 716         default y
 717         help
 718           Enable the eventfd() system call that allows to receive both
 719           kernel notification (ie. KAIO) or userspace notifications.
 720
 721           If unsure, say Y.
 722
 723 config SHMEM
 724         bool "Use full shmem filesystem" if EMBEDDED
 725         default y
 726         depends on MMU
 727         help
 728           The shmem is an internal filesystem used to manage shared memory.
 729           It is backed by swap and manages resource limits. It is also exported
 730           to userspace as tmpfs if TMPFS is enabled. Disabling this
 731           option replaces shmem and tmpfs with the much simpler ramfs code,
 732           which may be appropriate on small systems without swap.
 733
 734 config AIO
 735         bool "Enable AIO support" if EMBEDDED
 736         default y
 737         help
 738           This option enables POSIX asynchronous I/O which may by used
 739           by some high performance threaded applications. Disabling
 740           this option saves about 7k.
 741
 742 config VM_EVENT_COUNTERS
 743         default y
 744         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 745         help
 746           VM event counters are needed for event counts to be shown.
 747           This option allows the disabling of the VM event counters
 748           on EMBEDDED systems.  /proc/vmstat will only show page counts
 749           if VM event counters are disabled.
 750
 751 config PCI_QUIRKS
 752         default y
 753         bool "Enable PCI quirk workarounds" if EMBEDDED
 754         depends on PCI
 755         help
 756           This enables workarounds for various PCI chipset
 757           bugs/quirks. Disable this only if your target machine is
 758           unaffected by PCI quirks.
 759
 760 config SLUB_DEBUG
 761         default y
 762         bool "Enable SLUB debugging support" if EMBEDDED
 763         depends on SLUB && SYSFS
 764         help
 765           SLUB has extensive debug support features. Disabling these can
 766           result in significant savings in code size. This also disables
 767           SLUB sysfs support. /sys/slab will not exist and there will be
 768           no support for cache validation etc.
 769
 770 choice
 771         prompt "Choose SLAB allocator"
 772         default SLUB
 773         help
 774            This option allows to select a slab allocator.
 775
 776 config SLAB
 777         bool "SLAB"
 778         help
 779           The regular slab allocator that is established and known to work
 780           well in all environments. It organizes cache hot objects in
 781           per cpu and per node queues.
 782
 783 config SLUB
 784         bool "SLUB (Unqueued Allocator)"
 785         help
 786            SLUB is a slab allocator that minimizes cache line usage
 787            instead of managing queues of cached objects (SLAB approach).
 788            Per cpu caching is realized using slabs of objects instead
 789            of queues of objects. SLUB can use memory efficiently
 790            and has enhanced diagnostics. SLUB is the default choice for
 791            a slab allocator.
 792
 793 config SLOB
 794         depends on EMBEDDED
 795         bool "SLOB (Simple Allocator)"
 796         help
 797            SLOB replaces the stock allocator with a drastically simpler
 798            allocator. SLOB is generally more space efficient but
 799            does not perform as well on large systems.
 800
 801 endchoice
 802
 803 config PROFILING
 804         bool "Profiling support (EXPERIMENTAL)"
 805         help
 806           Say Y here to enable the extended profiling support mechanisms used
 807           by profilers such as OProfile.
 808
 809 #
 810 # Place an empty function call at each tracepoint site. Can be
 811 # dynamically changed for a probe function.
 812 #
 813 config TRACEPOINTS
 814         bool
 815
 816 config MARKERS
 817         bool "Activate markers"
 818         depends on TRACEPOINTS
 819         help
 820           Place an empty function call at each marker site. Can be
 821           dynamically changed for a probe function.
 822
 823 source "arch/Kconfig"
 824
 825 endmenu         # General setup
 826
 827 config HAVE_GENERIC_DMA_COHERENT
 828         bool
 829         default n
 830
 831 config SLABINFO
 832         bool
 833         depends on PROC_FS
 834         depends on SLAB || SLUB_DEBUG
 835         default y
 836
 837 config RT_MUTEXES
 838         boolean
 839         select PLIST
 840
 841 config TINY_SHMEM
 842         default !SHMEM
 843         bool
 844
 845 config BASE_SMALL
 846         int
 847         default 0 if BASE_FULL
 848         default 1 if !BASE_FULL
 849
 850 menuconfig MODULES
 851         bool "Enable loadable module support"
 852         help
 853           Kernel modules are small pieces of compiled code which can
 854           be inserted in the running kernel, rather than being
 855           permanently built into the kernel.  You use the "modprobe"
 856           tool to add (and sometimes remove) them.  If you say Y here,
 857           many parts of the kernel can be built as modules (by
 858           answering M instead of Y where indicated): this is most
 859           useful for infrequently used options which are not required
 860           for booting.  For more information, see the man pages for
 861           modprobe, lsmod, modinfo, insmod and rmmod.
 862
 863           If you say Y here, you will need to run "make
 864           modules_install" to put the modules under /lib/modules/
 865           where modprobe can find them (you may need to be root to do
 866           this).
 867
 868           If unsure, say Y.
 869
 870 if MODULES
 871
 872 config MODULE_FORCE_LOAD
 873         bool "Forced module loading"
 874         default n
 875         help
 876           Allow loading of modules without version information (ie. modprobe
 877           --force).  Forced module loading sets the 'F' (forced) taint flag and
 878           is usually a really bad idea.
 879
 880 config MODULE_UNLOAD
 881         bool "Module unloading"
 882         help
 883           Without this option you will not be able to unload any
 884           modules (note that some modules may not be unloadable
 885           anyway), which makes your kernel smaller, faster
 886           and simpler.  If unsure, say Y.
 887
 888 config MODULE_FORCE_UNLOAD
 889         bool "Forced module unloading"
 890         depends on MODULE_UNLOAD && EXPERIMENTAL
 891         help
 892           This option allows you to force a module to unload, even if the
 893           kernel believes it is unsafe: the kernel will remove the module
 894           without waiting for anyone to stop using it (using the -f option to
 895           rmmod).  This is mainly for kernel developers and desperate users.
 896           If unsure, say N.
 897
 898 config MODVERSIONS
 899         bool "Module versioning support"
 900         help
 901           Usually, you have to use modules compiled with your kernel.
 902           Saying Y here makes it sometimes possible to use modules
 903           compiled for different kernels, by adding enough information
 904           to the modules to (hopefully) spot any changes which would
 905           make them incompatible with the kernel you are running.  If
 906           unsure, say N.
 907
 908 config MODULE_SRCVERSION_ALL
 909         bool "Source checksum for all modules"
 910         help
 911           Modules which contain a MODULE_VERSION get an extra "srcversion"
 912           field inserted into their modinfo section, which contains a
 913           sum of the source files which made it.  This helps maintainers
 914           see exactly which source was used to build a module (since
 915           others sometimes change the module source without updating
 916           the version).  With this option, such a "srcversion" field
 917           will be created for all modules.  If unsure, say N.
 918
 919 config KMOD
 920         def_bool y
 921         help
 922           This is being removed soon.  These days, CONFIG_MODULES
 923           implies CONFIG_KMOD, so use that instead.
 924
 925 endif # MODULES
 926
 927 config INIT_ALL_POSSIBLE
 928         bool
 929         help
 930           Back when each arch used to define their own cpu_online_map and
 931           cpu_possible_map, some of them chose to initialize cpu_possible_map
 932           with all 1s, and others with all 0s.  When they were centralised,
 933           it was better to provide this option than to break all the archs
 934           and have several arch maintainers persuing me down dark alleys.
 935
 936 config STOP_MACHINE
 937         bool
 938         default y
 939         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 940         help
 941           Need stop_machine() primitive.
 942
 943 source "block/Kconfig"
 944
 945 config PREEMPT_NOTIFIERS
 946         bool
 947
 948 choice
 949         prompt "RCU Implementation"
 950         default CLASSIC_RCU
 951
 952 config CLASSIC_RCU
 953         bool "Classic RCU"
 954         help
 955           This option selects the classic RCU implementation that is
 956           designed for best read-side performance on non-realtime
 957           systems.
 958
 959           Select this option if you are unsure.
 960
 961 config TREE_RCU
 962         bool "Tree-based hierarchical RCU"
 963         help
 964           This option selects the RCU implementation that is
 965           designed for very large SMP system with hundreds or
 966           thousands of CPUs.
 967
 968 config PREEMPT_RCU
 969         bool "Preemptible RCU"
 970         depends on PREEMPT
 971         help
 972           This option reduces the latency of the kernel by making certain
 973           RCU sections preemptible. Normally RCU code is non-preemptible, if
 974           this option is selected then read-only RCU sections become
 975           preemptible. This helps latency, but may expose bugs due to
 976           now-naive assumptions about each RCU read-side critical section
 977           remaining on a given CPU through its execution.
 978
 979 endchoice
 980
 981 config RCU_TRACE
 982         bool "Enable tracing for RCU"
 983         depends on TREE_RCU || PREEMPT_RCU
 984         help
 985           This option provides tracing in RCU which presents stats
 986           in debugfs for debugging RCU implementation.
 987
 988           Say Y here if you want to enable RCU tracing
 989           Say N if you are unsure.
 990
 991 config RCU_FANOUT
 992         int "Tree-based hierarchical RCU fanout value"
 993         range 2 64 if 64BIT
 994         range 2 32 if !64BIT
 995         depends on TREE_RCU
 996         default 64 if 64BIT
 997         default 32 if !64BIT
 998         help
 999           This option controls the fanout of hierarchical implementations
1000           of RCU, allowing RCU to work efficiently on machines with
1001           large numbers of CPUs.  This value must be at least the cube
1002           root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
1003           systems and up to 262,144 for 64-bit systems.
1004
1005           Select a specific number if testing RCU itself.
1006           Take the default if unsure.
1007
1008 config RCU_FANOUT_EXACT
1009         bool "Disable tree-based hierarchical RCU auto-balancing"
1010         depends on TREE_RCU
1011         default n
1012         help
1013           This option forces use of the exact RCU_FANOUT value specified,
1014           regardless of imbalances in the hierarchy.  This is useful for
1015           testing RCU itself, and might one day be useful on systems with
1016           strong NUMA behavior.
1017
1018           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
1019
1020           Say N if unsure.
1021
1022 config TREE_RCU_TRACE
1023         def_bool RCU_TRACE && TREE_RCU
1024         select DEBUG_FS
1025         help
1026           This option provides tracing for the TREE_RCU implementation,
1027           permitting Makefile to trivially select kernel/rcutree_trace.c.
1028
1029 config PREEMPT_RCU_TRACE
1030         def_bool RCU_TRACE && PREEMPT_RCU
1031         select DEBUG_FS
1032         help
1033           This option provides tracing for the PREEMPT_RCU implementation,
1034           permitting Makefile to trivially select kernel/rcupreempt_trace.c.