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  41           drivers that have been replaced by something else, and/or are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 #
 320 # Architectures with an unreliable sched_clock() should select this:
 321 #
 322 config HAVE_UNSTABLE_SCHED_CLOCK
 323         bool
 324
 325 config GROUP_SCHED
 326         bool "Group CPU scheduler"
 327         depends on EXPERIMENTAL
 328         default n
 329         help
 330           This feature lets CPU scheduler recognize task groups and control CPU
 331           bandwidth allocation to such task groups.
 332
 333 config FAIR_GROUP_SCHED
 334         bool "Group scheduling for SCHED_OTHER"
 335         depends on GROUP_SCHED
 336         default GROUP_SCHED
 337
 338 config RT_GROUP_SCHED
 339         bool "Group scheduling for SCHED_RR/FIFO"
 340         depends on EXPERIMENTAL
 341         depends on GROUP_SCHED
 342         default n
 343         help
 344           This feature lets you explicitly allocate real CPU bandwidth
 345           to users or control groups (depending on the "Basis for grouping tasks"
 346           setting below. If enabled, it will also make it impossible to
 347           schedule realtime tasks for non-root users until you allocate
 348           realtime bandwidth for them.
 349           See Documentation/sched-rt-group.txt for more information.
 350
 351 choice
 352         depends on GROUP_SCHED
 353         prompt "Basis for grouping tasks"
 354         default USER_SCHED
 355
 356 config USER_SCHED
 357         bool "user id"
 358         help
 359           This option will choose userid as the basis for grouping
 360           tasks, thus providing equal CPU bandwidth to each user.
 361
 362 config CGROUP_SCHED
 363         bool "Control groups"
 364         depends on CGROUPS
 365         help
 366           This option allows you to create arbitrary task groups
 367           using the "cgroup" pseudo filesystem and control
 368           the cpu bandwidth allocated to each such task group.
 369           Refer to Documentation/cgroups.txt for more information
 370           on "cgroup" pseudo filesystem.
 371
 372 endchoice
 373
 374 config CGROUP_CPUACCT
 375         bool "Simple CPU accounting cgroup subsystem"
 376         depends on CGROUPS
 377         help
 378           Provides a simple Resource Controller for monitoring the
 379           total CPU consumed by the tasks in a cgroup
 380
 381 config RESOURCE_COUNTERS
 382         bool "Resource counters"
 383         help
 384           This option enables controller independent resource accounting
 385           infrastructure that works with cgroups
 386         depends on CGROUPS
 387
 388 config MM_OWNER
 389         bool
 390
 391 config CGROUP_MEM_RES_CTLR
 392         bool "Memory Resource Controller for Control Groups"
 393         depends on CGROUPS && RESOURCE_COUNTERS
 394         select MM_OWNER
 395         help
 396           Provides a memory resource controller that manages both page cache and
 397           RSS memory.
 398
 399           Note that setting this option increases fixed memory overhead
 400           associated with each page of memory in the system by 4/8 bytes
 401           and also increases cache misses because struct page on many 64bit
 402           systems will not fit into a single cache line anymore.
 403
 404           Only enable when you're ok with these trade offs and really
 405           sure you need the memory resource controller.
 406
 407           This config option also selects MM_OWNER config option, which
 408           could in turn add some fork/exit overhead.
 409
 410 config SYSFS_DEPRECATED
 411         bool
 412
 413 config SYSFS_DEPRECATED_V2
 414         bool "Create deprecated sysfs files"
 415         depends on SYSFS
 416         default y
 417         select SYSFS_DEPRECATED
 418         help
 419           This option creates deprecated symlinks such as the
 420           "device"-link, the <subsystem>:<name>-link, and the
 421           "bus"-link. It may also add deprecated key in the
 422           uevent environment.
 423           None of these features or values should be used today, as
 424           they export driver core implementation details to userspace
 425           or export properties which can't be kept stable across kernel
 426           releases.
 427
 428           If enabled, this option will also move any device structures
 429           that belong to a class, back into the /sys/class hierarchy, in
 430           order to support older versions of udev and some userspace
 431           programs.
 432
 433           If you are using a distro with the most recent userspace
 434           packages, it should be safe to say N here.
 435
 436 config PROC_PID_CPUSET
 437         bool "Include legacy /proc/<pid>/cpuset file"
 438         depends on CPUSETS
 439         default y
 440
 441 config RELAY
 442         bool "Kernel->user space relay support (formerly relayfs)"
 443         help
 444           This option enables support for relay interface support in
 445           certain file systems (such as debugfs).
 446           It is designed to provide an efficient mechanism for tools and
 447           facilities to relay large amounts of data from kernel space to
 448           user space.
 449
 450           If unsure, say N.
 451
 452 config NAMESPACES
 453         bool "Namespaces support" if EMBEDDED
 454         default !EMBEDDED
 455         help
 456           Provides the way to make tasks work with different objects using
 457           the same id. For example same IPC id may refer to different objects
 458           or same user id or pid may refer to different tasks when used in
 459           different namespaces.
 460
 461 config UTS_NS
 462         bool "UTS namespace"
 463         depends on NAMESPACES
 464         help
 465           In this namespace tasks see different info provided with the
 466           uname() system call
 467
 468 config IPC_NS
 469         bool "IPC namespace"
 470         depends on NAMESPACES && SYSVIPC
 471         help
 472           In this namespace tasks work with IPC ids which correspond to
 473           different IPC objects in different namespaces
 474
 475 config USER_NS
 476         bool "User namespace (EXPERIMENTAL)"
 477         depends on NAMESPACES && EXPERIMENTAL
 478         help
 479           This allows containers, i.e. vservers, to use user namespaces
 480           to provide different user info for different servers.
 481           If unsure, say N.
 482
 483 config PID_NS
 484         bool "PID Namespaces (EXPERIMENTAL)"
 485         default n
 486         depends on NAMESPACES && EXPERIMENTAL
 487         help
 488           Suport process id namespaces.  This allows having multiple
 489           process with the same pid as long as they are in different
 490           pid namespaces.  This is a building block of containers.
 491
 492           Unless you want to work with an experimental feature
 493           say N here.
 494
 495 config BLK_DEV_INITRD
 496         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 497         depends on BROKEN || !FRV
 498         help
 499           The initial RAM filesystem is a ramfs which is loaded by the
 500           boot loader (loadlin or lilo) and that is mounted as root
 501           before the normal boot procedure. It is typically used to
 502           load modules needed to mount the "real" root file system,
 503           etc. See <file:Documentation/initrd.txt> for details.
 504
 505           If RAM disk support (BLK_DEV_RAM) is also included, this
 506           also enables initial RAM disk (initrd) support and adds
 507           15 Kbytes (more on some other architectures) to the kernel size.
 508
 509           If unsure say Y.
 510
 511 if BLK_DEV_INITRD
 512
 513 source "usr/Kconfig"
 514
 515 endif
 516
 517 config CC_OPTIMIZE_FOR_SIZE
 518         bool "Optimize for size"
 519         default y
 520         help
 521           Enabling this option will pass "-Os" instead of "-O2" to gcc
 522           resulting in a smaller kernel.
 523
 524           If unsure, say N.
 525
 526 config SYSCTL
 527         bool
 528
 529 menuconfig EMBEDDED
 530         bool "Configure standard kernel features (for small systems)"
 531         help
 532           This option allows certain base kernel options and settings
 533           to be disabled or tweaked. This is for specialized
 534           environments which can tolerate a "non-standard" kernel.
 535           Only use this if you really know what you are doing.
 536
 537 config UID16
 538         bool "Enable 16-bit UID system calls" if EMBEDDED
 539         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 540         default y
 541         help
 542           This enables the legacy 16-bit UID syscall wrappers.
 543
 544 config SYSCTL_SYSCALL
 545         bool "Sysctl syscall support" if EMBEDDED
 546         default y
 547         select SYSCTL
 548         ---help---
 549           sys_sysctl uses binary paths that have been found challenging
 550           to properly maintain and use.  The interface in /proc/sys
 551           using paths with ascii names is now the primary path to this
 552           information.
 553
 554           Almost nothing using the binary sysctl interface so if you are
 555           trying to save some space it is probably safe to disable this,
 556           making your kernel marginally smaller.
 557
 558           If unsure say Y here.
 559
 560 config SYSCTL_SYSCALL_CHECK
 561         bool "Sysctl checks" if EMBEDDED
 562         depends on SYSCTL_SYSCALL
 563         default y
 564         ---help---
 565           sys_sysctl uses binary paths that have been found challenging
 566           to properly maintain and use. This enables checks that help
 567           you to keep things correct.
 568
 569           If unsure say Y here.
 570
 571 config KALLSYMS
 572          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 573          default y
 574          help
 575            Say Y here to let the kernel print out symbolic crash information and
 576            symbolic stack backtraces. This increases the size of the kernel
 577            somewhat, as all symbols have to be loaded into the kernel image.
 578
 579 config KALLSYMS_ALL
 580         bool "Include all symbols in kallsyms"
 581         depends on DEBUG_KERNEL && KALLSYMS
 582         help
 583            Normally kallsyms only contains the symbols of functions, for nicer
 584            OOPS messages.  Some debuggers can use kallsyms for other
 585            symbols too: say Y here to include all symbols, if you need them
 586            and you don't care about adding 300k to the size of your kernel.
 587
 588            Say N.
 589
 590 config KALLSYMS_EXTRA_PASS
 591         bool "Do an extra kallsyms pass"
 592         depends on KALLSYMS
 593         help
 594            If kallsyms is not working correctly, the build will fail with
 595            inconsistent kallsyms data.  If that occurs, log a bug report and
 596            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 597            Always say N here unless you find a bug in kallsyms, which must be
 598            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 599            you wait for kallsyms to be fixed.
 600
 601
 602 config HOTPLUG
 603         bool "Support for hot-pluggable devices" if EMBEDDED
 604         default y
 605         help
 606           This option is provided for the case where no hotplug or uevent
 607           capabilities is wanted by the kernel.  You should only consider
 608           disabling this option for embedded systems that do not use modules, a
 609           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 610
 611 config PRINTK
 612         default y
 613         bool "Enable support for printk" if EMBEDDED
 614         help
 615           This option enables normal printk support. Removing it
 616           eliminates most of the message strings from the kernel image
 617           and makes the kernel more or less silent. As this makes it
 618           very difficult to diagnose system problems, saying N here is
 619           strongly discouraged.
 620
 621 config BUG
 622         bool "BUG() support" if EMBEDDED
 623         default y
 624         help
 625           Disabling this option eliminates support for BUG and WARN, reducing
 626           the size of your kernel image and potentially quietly ignoring
 627           numerous fatal conditions. You should only consider disabling this
 628           option for embedded systems with no facilities for reporting errors.
 629           Just say Y.
 630
 631 config ELF_CORE
 632         default y
 633         bool "Enable ELF core dumps" if EMBEDDED
 634         help
 635           Enable support for generating core dumps. Disabling saves about 4k.
 636
 637 config PCSPKR_PLATFORM
 638         bool "Enable PC-Speaker support" if EMBEDDED
 639         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 640         default y
 641         help
 642           This option allows to disable the internal PC-Speaker
 643           support, saving some memory.
 644
 645 config COMPAT_BRK
 646         bool "Disable heap randomization"
 647         default y
 648         help
 649           Randomizing heap placement makes heap exploits harder, but it
 650           also breaks ancient binaries (including anything libc5 based).
 651           This option changes the bootup default to heap randomization
 652           disabled, and can be overriden runtime by setting
 653           /proc/sys/kernel/randomize_va_space to 2.
 654
 655           On non-ancient distros (post-2000 ones) N is usually a safe choice.
 656
 657 config BASE_FULL
 658         default y
 659         bool "Enable full-sized data structures for core" if EMBEDDED
 660         help
 661           Disabling this option reduces the size of miscellaneous core
 662           kernel data structures. This saves memory on small machines,
 663           but may reduce performance.
 664
 665 config FUTEX
 666         bool "Enable futex support" if EMBEDDED
 667         default y
 668         select RT_MUTEXES
 669         help
 670           Disabling this option will cause the kernel to be built without
 671           support for "fast userspace mutexes".  The resulting kernel may not
 672           run glibc-based applications correctly.
 673
 674 config ANON_INODES
 675         bool
 676
 677 config EPOLL
 678         bool "Enable eventpoll support" if EMBEDDED
 679         default y
 680         select ANON_INODES
 681         help
 682           Disabling this option will cause the kernel to be built without
 683           support for epoll family of system calls.
 684
 685 config SIGNALFD
 686         bool "Enable signalfd() system call" if EMBEDDED
 687         select ANON_INODES
 688         default y
 689         help
 690           Enable the signalfd() system call that allows to receive signals
 691           on a file descriptor.
 692
 693           If unsure, say Y.
 694
 695 config TIMERFD
 696         bool "Enable timerfd() system call" if EMBEDDED
 697         select ANON_INODES
 698         default y
 699         help
 700           Enable the timerfd() system call that allows to receive timer
 701           events on a file descriptor.
 702
 703           If unsure, say Y.
 704
 705 config EVENTFD
 706         bool "Enable eventfd() system call" if EMBEDDED
 707         select ANON_INODES
 708         default y
 709         help
 710           Enable the eventfd() system call that allows to receive both
 711           kernel notification (ie. KAIO) or userspace notifications.
 712
 713           If unsure, say Y.
 714
 715 config SHMEM
 716         bool "Use full shmem filesystem" if EMBEDDED
 717         default y
 718         depends on MMU
 719         help
 720           The shmem is an internal filesystem used to manage shared memory.
 721           It is backed by swap and manages resource limits. It is also exported
 722           to userspace as tmpfs if TMPFS is enabled. Disabling this
 723           option replaces shmem and tmpfs with the much simpler ramfs code,
 724           which may be appropriate on small systems without swap.
 725
 726 config VM_EVENT_COUNTERS
 727         default y
 728         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 729         help
 730           VM event counters are needed for event counts to be shown.
 731           This option allows the disabling of the VM event counters
 732           on EMBEDDED systems.  /proc/vmstat will only show page counts
 733           if VM event counters are disabled.
 734
 735 config SLUB_DEBUG
 736         default y
 737         bool "Enable SLUB debugging support" if EMBEDDED
 738         depends on SLUB && SYSFS
 739         help
 740           SLUB has extensive debug support features. Disabling these can
 741           result in significant savings in code size. This also disables
 742           SLUB sysfs support. /sys/slab will not exist and there will be
 743           no support for cache validation etc.
 744
 745 choice
 746         prompt "Choose SLAB allocator"
 747         default SLUB
 748         help
 749            This option allows to select a slab allocator.
 750
 751 config SLAB
 752         bool "SLAB"
 753         help
 754           The regular slab allocator that is established and known to work
 755           well in all environments. It organizes cache hot objects in
 756           per cpu and per node queues. SLAB is the default choice for
 757           a slab allocator.
 758
 759 config SLUB
 760         bool "SLUB (Unqueued Allocator)"
 761         help
 762            SLUB is a slab allocator that minimizes cache line usage
 763            instead of managing queues of cached objects (SLAB approach).
 764            Per cpu caching is realized using slabs of objects instead
 765            of queues of objects. SLUB can use memory efficiently
 766            and has enhanced diagnostics.
 767
 768 config SLOB
 769         depends on EMBEDDED
 770         bool "SLOB (Simple Allocator)"
 771         help
 772            SLOB replaces the stock allocator with a drastically simpler
 773            allocator. SLOB is generally more space efficient but
 774            does not perform as well on large systems.
 775
 776 endchoice
 777
 778 config PROFILING
 779         bool "Profiling support (EXPERIMENTAL)"
 780         help
 781           Say Y here to enable the extended profiling support mechanisms used
 782           by profilers such as OProfile.
 783
 784 config MARKERS
 785         bool "Activate markers"
 786         help
 787           Place an empty function call at each marker site. Can be
 788           dynamically changed for a probe function.
 789
 790 source "arch/Kconfig"
 791
 792 config PROC_PAGE_MONITOR
 793         default y
 794         depends on PROC_FS && MMU
 795         bool "Enable /proc page monitoring" if EMBEDDED
 796         help
 797           Various /proc files exist to monitor process memory utilization:
 798           /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
 799           /proc/kpagecount, and /proc/kpageflags. Disabling these
 800           interfaces will reduce the size of the kernel by approximately 4kb.
 801
 802 endmenu         # General setup
 803
 804 config SLABINFO
 805         bool
 806         depends on PROC_FS
 807         depends on SLAB || SLUB_DEBUG
 808         default y
 809
 810 config RT_MUTEXES
 811         boolean
 812         select PLIST
 813
 814 config TINY_SHMEM
 815         default !SHMEM
 816         bool
 817
 818 config BASE_SMALL
 819         int
 820         default 0 if BASE_FULL
 821         default 1 if !BASE_FULL
 822
 823 menuconfig MODULES
 824         bool "Enable loadable module support"
 825         help
 826           Kernel modules are small pieces of compiled code which can
 827           be inserted in the running kernel, rather than being
 828           permanently built into the kernel.  You use the "modprobe"
 829           tool to add (and sometimes remove) them.  If you say Y here,
 830           many parts of the kernel can be built as modules (by
 831           answering M instead of Y where indicated): this is most
 832           useful for infrequently used options which are not required
 833           for booting.  For more information, see the man pages for
 834           modprobe, lsmod, modinfo, insmod and rmmod.
 835
 836           If you say Y here, you will need to run "make
 837           modules_install" to put the modules under /lib/modules/
 838           where modprobe can find them (you may need to be root to do
 839           this).
 840
 841           If unsure, say Y.
 842
 843 config MODULE_FORCE_LOAD
 844         bool "Forced module loading"
 845         depends on MODULES
 846         default n
 847         help
 848           This option allows loading of modules even if that would set the
 849           'F' (forced) taint, due to lack of version info.  Which is
 850           usually a really bad idea.
 851
 852 config MODULE_UNLOAD
 853         bool "Module unloading"
 854         depends on MODULES
 855         help
 856           Without this option you will not be able to unload any
 857           modules (note that some modules may not be unloadable
 858           anyway), which makes your kernel slightly smaller and
 859           simpler.  If unsure, say Y.
 860
 861 config MODULE_FORCE_UNLOAD
 862         bool "Forced module unloading"
 863         depends on MODULE_UNLOAD && EXPERIMENTAL
 864         help
 865           This option allows you to force a module to unload, even if the
 866           kernel believes it is unsafe: the kernel will remove the module
 867           without waiting for anyone to stop using it (using the -f option to
 868           rmmod).  This is mainly for kernel developers and desperate users.
 869           If unsure, say N.
 870
 871 config MODVERSIONS
 872         bool "Module versioning support"
 873         depends on MODULES
 874         help
 875           Usually, you have to use modules compiled with your kernel.
 876           Saying Y here makes it sometimes possible to use modules
 877           compiled for different kernels, by adding enough information
 878           to the modules to (hopefully) spot any changes which would
 879           make them incompatible with the kernel you are running.  If
 880           unsure, say N.
 881
 882 config MODULE_SRCVERSION_ALL
 883         bool "Source checksum for all modules"
 884         depends on MODULES
 885         help
 886           Modules which contain a MODULE_VERSION get an extra "srcversion"
 887           field inserted into their modinfo section, which contains a
 888           sum of the source files which made it.  This helps maintainers
 889           see exactly which source was used to build a module (since
 890           others sometimes change the module source without updating
 891           the version).  With this option, such a "srcversion" field
 892           will be created for all modules.  If unsure, say N.
 893
 894 config KMOD
 895         bool "Automatic kernel module loading"
 896         depends on MODULES
 897         help
 898           Normally when you have selected some parts of the kernel to
 899           be created as kernel modules, you must load them (using the
 900           "modprobe" command) before you can use them. If you say Y
 901           here, some parts of the kernel will be able to load modules
 902           automatically: when a part of the kernel needs a module, it
 903           runs modprobe with the appropriate arguments, thereby
 904           loading the module if it is available.  If unsure, say Y.
 905
 906 config STOP_MACHINE
 907         bool
 908         default y
 909         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 910         help
 911           Need stop_machine() primitive.
 912
 913 source "block/Kconfig"
 914
 915 config PREEMPT_NOTIFIERS
 916         bool
 917
 918 config CLASSIC_RCU
 919         def_bool !PREEMPT_RCU
 920         help
 921           This option selects the classic RCU implementation that is
 922           designed for best read-side performance on non-realtime
 923           systems.  Classic RCU is the default.  Note that the
 924           PREEMPT_RCU symbol is used to select/deselect this option.