1config ARCH
   2        string
   3        option env="ARCH"
   6        string
   7        option env="KERNELVERSION"
  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"
  20        bool
  21        depends on !UML
  22        default y
  24menu "General setup"
  27        bool "Prompt for development and/or incomplete code/drivers"
  28        ---help---
  29          Some of the various things that Linux supports (such as network
  30          drivers, file systems, network protocols, etc.) can be in a state
  31          of development where the functionality, stability, or the level of
  32          testing is not yet high enough for general use. This is usually
  33          known as the "alpha-test" phase among developers. If a feature is
  34          currently in alpha-test, then the developers usually discourage
  35          uninformed widespread use of this feature by the general public to
  36          avoid "Why doesn't this work?" type mail messages. However, active
  37          testing and use of these systems is welcomed. Just be aware that it
  38          may not meet the normal level of reliability or it may fail to work
  39          in some special cases. Detailed bug reports from people familiar
  40          with the kernel internals are usually welcomed by the developers
  41          (before submitting bug reports, please read the documents
  42          <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  43          <file:Documentation/BUG-HUNTING>, and
  44          <file:Documentation/oops-tracing.txt> in the kernel source).
  46          This option will also make obsoleted drivers available. These are
  47          drivers that have been replaced by something else, and/or are
  48          scheduled to be removed in a future kernel release.
  50          Unless you intend to help test and develop a feature or driver that
  51          falls into this category, or you have a situation that requires
  52          using these features, you should probably say N here, which will
  53          cause the configurator to present you with fewer choices. If
  54          you say Y here, you will be offered the choice of using features or
  55          drivers that are currently considered to be in the alpha-test phase.
  57config BROKEN
  58        bool
  60config BROKEN_ON_SMP
  61        bool
  62        depends on BROKEN || !SMP
  63        default y
  65config LOCK_KERNEL
  66        bool
  67        depends on SMP || PREEMPT
  68        default y
  71        int
  72        default 32 if !UML
  73        default 128 if UML
  74        help
  75          Maximum of each of the number of arguments and environment
  76          variables passed to init from the kernel command line.
  80        string "Local version - append to kernel release"
  81        help
  82          Append an extra string to the end of your kernel version.
  83          This will show up when you type uname, for example.
  84          The string you set here will be appended after the contents of
  85          any files with a filename matching localversion* in your
  86          object and source tree, in that order.  Your total string can
  87          be a maximum of 64 characters.
  90        bool "Automatically append version information to the version string"
  91        default y
  92        help
  93          This will try to automatically determine if the current tree is a
  94          release tree by looking for git tags that belong to the current
  95          top of tree revision.
  97          A string of the format -gxxxxxxxx will be added to the localversion
  98          if a git-based tree is found.  The string generated by this will be
  99          appended after any matching localversion* files, and after the value
 100          set in CONFIG_LOCALVERSION.
 102          (The actual string used here is the first eight characters produced
 103          by running the command:
 105            $ git rev-parse --verify HEAD
 107          which is done within the script "scripts/setlocalversion".)
 110        bool
 112config HAVE_KERNEL_BZIP2
 113        bool
 116        bool
 119        prompt "Kernel compression mode"
 120        default KERNEL_GZIP
 122        help
 123          The linux kernel is a kind of self-extracting executable.
 124          Several compression algorithms are available, which differ
 125          in efficiency, compression and decompression speed.
 126          Compression speed is only relevant when building a kernel.
 127          Decompression speed is relevant at each boot.
 129          If you have any problems with bzip2 or lzma compressed
 130          kernels, mail me (Alain Knaff) <>. (An older
 131          version of this functionality (bzip2 only), for 2.4, was
 132          supplied by Christian Ludwig)
 134          High compression options are mostly useful for users, who
 135          are low on disk space (embedded systems), but for whom ram
 136          size matters less.
 138          If in doubt, select 'gzip'
 140config KERNEL_GZIP
 141        bool "Gzip"
 142        depends on HAVE_KERNEL_GZIP
 143        help
 144          The old and tried gzip compression. Its compression ratio is
 145          the poorest among the 3 choices; however its speed (both
 146          compression and decompression) is the fastest.
 148config KERNEL_BZIP2
 149        bool "Bzip2"
 150        depends on HAVE_KERNEL_BZIP2
 151        help
 152          Its compression ratio and speed is intermediate.
 153          Decompression speed is slowest among the three.  The kernel
 154          size is about 10% smaller with bzip2, in comparison to gzip.
 155          Bzip2 uses a large amount of memory. For modern kernels you
 156          will need at least 8MB RAM or more for booting.
 158config KERNEL_LZMA
 159        bool "LZMA"
 160        depends on HAVE_KERNEL_LZMA
 161        help
 162          The most recent compression algorithm.
 163          Its ratio is best, decompression speed is between the other
 164          two. Compression is slowest.  The kernel size is about 33%
 165          smaller with LZMA in comparison to gzip.
 169config SWAP
 170        bool "Support for paging of anonymous memory (swap)"
 171        depends on MMU && BLOCK
 172        default y
 173        help
 174          This option allows you to choose whether you want to have support
 175          for so called swap devices or swap files in your kernel that are
 176          used to provide more virtual memory than the actual RAM present
 177          in your computer.  If unsure say Y.
 179config SYSVIPC
 180        bool "System V IPC"
 181        ---help---
 182          Inter Process Communication is a suite of library functions and
 183          system calls which let processes (running programs) synchronize and
 184          exchange information. It is generally considered to be a good thing,
 185          and some programs won't run unless you say Y here. In particular, if
 186          you want to run the DOS emulator dosemu under Linux (read the
 187          DOSEMU-HOWTO, available from <>),
 188          you'll need to say Y here.
 190          You can find documentation about IPC with "info ipc" and also in
 191          section 6.4 of the Linux Programmer's Guide, available from
 192          <>.
 195        bool
 196        depends on SYSVIPC
 197        depends on SYSCTL
 198        default y
 200config POSIX_MQUEUE
 201        bool "POSIX Message Queues"
 202        depends on NET && EXPERIMENTAL
 203        ---help---
 204          POSIX variant of message queues is a part of IPC. In POSIX message
 205          queues every message has a priority which decides about succession
 206          of receiving it by a process. If you want to compile and run
 207          programs written e.g. for Solaris with use of its POSIX message
 208          queues (functions mq_*) say Y here.
 210          POSIX message queues are visible as a filesystem called 'mqueue'
 211          and can be mounted somewhere if you want to do filesystem
 212          operations on message queues.
 214          If unsure, say Y.
 217        bool
 218        depends on POSIX_MQUEUE
 219        depends on SYSCTL
 220        default y
 223        bool "BSD Process Accounting"
 224        help
 225          If you say Y here, a user level program will be able to instruct the
 226          kernel (via a special system call) to write process accounting
 227          information to a file: whenever a process exits, information about
 228          that process will be appended to the file by the kernel.  The
 229          information includes things such as creation time, owning user,
 230          command name, memory usage, controlling terminal etc. (the complete
 231          list is in the struct acct in <file:include/linux/acct.h>).  It is
 232          up to the user level program to do useful things with this
 233          information.  This is generally a good idea, so say Y.
 235config BSD_PROCESS_ACCT_V3
 236        bool "BSD Process Accounting version 3 file format"
 237        depends on BSD_PROCESS_ACCT
 238        default n
 239        help
 240          If you say Y here, the process accounting information is written
 241          in a new file format that also logs the process IDs of each
 242          process and it's parent. Note that this file format is incompatible
 243          with previous v0/v1/v2 file formats, so you will need updated tools
 244          for processing it. A preliminary version of these tools is available
 245          at <>.
 247config TASKSTATS
 248        bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 249        depends on NET
 250        default n
 251        help
 252          Export selected statistics for tasks/processes through the
 253          generic netlink interface. Unlike BSD process accounting, the
 254          statistics are available during the lifetime of tasks/processes as
 255          responses to commands. Like BSD accounting, they are sent to user
 256          space on task exit.
 258          Say N if unsure.
 260config TASK_DELAY_ACCT
 261        bool "Enable per-task delay accounting (EXPERIMENTAL)"
 262        depends on TASKSTATS
 263        help
 264          Collect information on time spent by a task waiting for system
 265          resources like cpu, synchronous block I/O completion and swapping
 266          in pages. Such statistics can help in setting a task's priorities
 267          relative to other tasks for cpu, io, rss limits etc.
 269          Say N if unsure.
 271config TASK_XACCT
 272        bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 273        depends on TASKSTATS
 274        help
 275          Collect extended task accounting data and send the data
 276          to userland for processing over the taskstats interface.
 278          Say N if unsure.
 281        bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 282        depends on TASK_XACCT
 283        help
 284          Collect information on the number of bytes of storage I/O which this
 285          task has caused.
 287          Say N if unsure.
 289config AUDIT
 290        bool "Auditing support"
 291        depends on NET
 292        help
 293          Enable auditing infrastructure that can be used with another
 294          kernel subsystem, such as SELinux (which requires this for
 295          logging of avc messages output).  Does not do system-call
 296          auditing without CONFIG_AUDITSYSCALL.
 299        bool "Enable system-call auditing support"
 300        depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
 301        default y if SECURITY_SELINUX
 302        help
 303          Enable low-overhead system-call auditing infrastructure that
 304          can be used independently or with another kernel subsystem,
 305          such as SELinux.  To use audit's filesystem watch feature, please
 306          ensure that INOTIFY is configured.
 308config AUDIT_TREE
 309        def_bool y
 310        depends on AUDITSYSCALL
 311        select INOTIFY
 313menu "RCU Subsystem"
 316        prompt "RCU Implementation"
 317        default TREE_RCU
 319config TREE_RCU
 320        bool "Tree-based hierarchical RCU"
 321        help
 322          This option selects the RCU implementation that is
 323          designed for very large SMP system with hundreds or
 324          thousands of CPUs.  It also scales down nicely to
 325          smaller systems.
 328        bool "Preemptable tree-based hierarchical RCU"
 329        depends on PREEMPT
 330        help
 331          This option selects the RCU implementation that is
 332          designed for very large SMP systems with hundreds or
 333          thousands of CPUs, but for which real-time response
 334          is also required.  It also scales down nicely to
 335          smaller systems.
 339config RCU_TRACE
 340        bool "Enable tracing for RCU"
 341        depends on TREE_RCU || TREE_PREEMPT_RCU
 342        help
 343          This option provides tracing in RCU which presents stats
 344          in debugfs for debugging RCU implementation.
 346          Say Y here if you want to enable RCU tracing
 347          Say N if you are unsure.
 349config RCU_FANOUT
 350        int "Tree-based hierarchical RCU fanout value"
 351        range 2 64 if 64BIT
 352        range 2 32 if !64BIT
 353        depends on TREE_RCU || TREE_PREEMPT_RCU
 354        default 64 if 64BIT
 355        default 32 if !64BIT
 356        help
 357          This option controls the fanout of hierarchical implementations
 358          of RCU, allowing RCU to work efficiently on machines with
 359          large numbers of CPUs.  This value must be at least the cube
 360          root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
 361          systems and up to 262,144 for 64-bit systems.
 363          Select a specific number if testing RCU itself.
 364          Take the default if unsure.
 367        bool "Disable tree-based hierarchical RCU auto-balancing"
 368        depends on TREE_RCU || TREE_PREEMPT_RCU
 369        default n
 370        help
 371          This option forces use of the exact RCU_FANOUT value specified,
 372          regardless of imbalances in the hierarchy.  This is useful for
 373          testing RCU itself, and might one day be useful on systems with
 374          strong NUMA behavior.
 376          Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 378          Say N if unsure.
 380config TREE_RCU_TRACE
 381        def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 382        select DEBUG_FS
 383        help
 384          This option provides tracing for the TREE_RCU and
 385          TREE_PREEMPT_RCU implementations, permitting Makefile to
 386          trivially select kernel/rcutree_trace.c.
 388endmenu # "RCU Subsystem"
 390config IKCONFIG
 391        tristate "Kernel .config support"
 392        ---help---
 393          This option enables the complete Linux kernel ".config" file
 394          contents to be saved in the kernel. It provides documentation
 395          of which kernel options are used in a running kernel or in an
 396          on-disk kernel.  This information can be extracted from the kernel
 397          image file with the script scripts/extract-ikconfig and used as
 398          input to rebuild the current kernel or to build another kernel.
 399          It can also be extracted from a running kernel by reading
 400          /proc/config.gz if enabled (below).
 402config IKCONFIG_PROC
 403        bool "Enable access to .config through /proc/config.gz"
 404        depends on IKCONFIG && PROC_FS
 405        ---help---
 406          This option enables access to the kernel configuration file
 407          through /proc/config.gz.
 409config LOG_BUF_SHIFT
 410        int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 411        range 12 21
 412        default 17
 413        help
 414          Select kernel log buffer size as a power of 2.
 415          Examples:
 416                     17 => 128 KB
 417                     16 => 64 KB
 418                     15 => 32 KB
 419                     14 => 16 KB
 420                     13 =>  8 KB
 421                     12 =>  4 KB
 424# Architectures with an unreliable sched_clock() should select this:
 427        bool
 429config GROUP_SCHED
 430        bool "Group CPU scheduler"
 431        depends on EXPERIMENTAL
 432        default n
 433        help
 434          This feature lets CPU scheduler recognize task groups and control CPU
 435          bandwidth allocation to such task groups.
 436          In order to create a group from arbitrary set of processes, use
 437          CONFIG_CGROUPS. (See Control Group support.)
 440        bool "Group scheduling for SCHED_OTHER"
 441        depends on GROUP_SCHED
 442        default GROUP_SCHED
 444config RT_GROUP_SCHED
 445        bool "Group scheduling for SCHED_RR/FIFO"
 446        depends on EXPERIMENTAL
 447        depends on GROUP_SCHED
 448        default n
 449        help
 450          This feature lets you explicitly allocate real CPU bandwidth
 451          to users or control groups (depending on the "Basis for grouping tasks"
 452          setting below. If enabled, it will also make it impossible to
 453          schedule realtime tasks for non-root users until you allocate
 454          realtime bandwidth for them.
 455          See Documentation/scheduler/sched-rt-group.txt for more information.
 458        depends on GROUP_SCHED
 459        prompt "Basis for grouping tasks"
 460        default USER_SCHED
 462config USER_SCHED
 463        bool "user id"
 464        help
 465          This option will choose userid as the basis for grouping
 466          tasks, thus providing equal CPU bandwidth to each user.
 468config CGROUP_SCHED
 469        bool "Control groups"
 470        depends on CGROUPS
 471        help
 472          This option allows you to create arbitrary task groups
 473          using the "cgroup" pseudo filesystem and control
 474          the cpu bandwidth allocated to each such task group.
 475          Refer to Documentation/cgroups/cgroups.txt for more
 476          information on "cgroup" pseudo filesystem.
 480menuconfig CGROUPS
 481        boolean "Control Group support"
 482        help
 483          This option adds support for grouping sets of processes together, for
 484          use with process control subsystems such as Cpusets, CFS, memory
 485          controls or device isolation.
 486          See
 487                - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 488                - Documentation/cgroups/ (features for grouping, isolation
 489                                          and resource control)
 491          Say N if unsure.
 493if CGROUPS
 495config CGROUP_DEBUG
 496        bool "Example debug cgroup subsystem"
 497        depends on CGROUPS
 498        default n
 499        help
 500          This option enables a simple cgroup subsystem that
 501          exports useful debugging information about the cgroups
 502          framework.
 504          Say N if unsure.
 506config CGROUP_NS
 507        bool "Namespace cgroup subsystem"
 508        depends on CGROUPS
 509        help
 510          Provides a simple namespace cgroup subsystem to
 511          provide hierarchical naming of sets of namespaces,
 512          for instance virtual servers and checkpoint/restart
 513          jobs.
 516        bool "Freezer cgroup subsystem"
 517        depends on CGROUPS
 518        help
 519          Provides a way to freeze and unfreeze all tasks in a
 520          cgroup.
 522config CGROUP_DEVICE
 523        bool "Device controller for cgroups"
 524        depends on CGROUPS && EXPERIMENTAL
 525        help
 526          Provides a cgroup implementing whitelists for devices which
 527          a process in the cgroup can mknod or open.
 529config CPUSETS
 530        bool "Cpuset support"
 531        depends on CGROUPS
 532        help
 533          This option will let you create and manage CPUSETs which
 534          allow dynamically partitioning a system into sets of CPUs and
 535          Memory Nodes and assigning tasks to run only within those sets.
 536          This is primarily useful on large SMP or NUMA systems.
 538          Say N if unsure.
 540config PROC_PID_CPUSET
 541        bool "Include legacy /proc/<pid>/cpuset file"
 542        depends on CPUSETS
 543        default y
 546        bool "Simple CPU accounting cgroup subsystem"
 547        depends on CGROUPS
 548        help
 549          Provides a simple Resource Controller for monitoring the
 550          total CPU consumed by the tasks in a cgroup.
 553        bool "Resource counters"
 554        help
 555          This option enables controller independent resource accounting
 556          infrastructure that works with cgroups.
 557        depends on CGROUPS
 560        bool "Memory Resource Controller for Control Groups"
 561        depends on CGROUPS && RESOURCE_COUNTERS
 562        select MM_OWNER
 563        help
 564          Provides a memory resource controller that manages both anonymous
 565          memory and page cache. (See Documentation/cgroups/memory.txt)
 567          Note that setting this option increases fixed memory overhead
 568          associated with each page of memory in the system. By this,
 569          20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 570          usage tracking struct at boot. Total amount of this is printed out
 571          at boot.
 573          Only enable when you're ok with these trade offs and really
 574          sure you need the memory resource controller. Even when you enable
 575          this, you can set "cgroup_disable=memory" at your boot option to
 576          disable memory resource controller and you can avoid overheads.
 577          (and lose benefits of memory resource controller)
 579          This config option also selects MM_OWNER config option, which
 580          could in turn add some fork/exit overhead.
 583        bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
 584        depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
 585        help
 586          Add swap management feature to memory resource controller. When you
 587          enable this, you can limit mem+swap usage per cgroup. In other words,
 588          when you disable this, memory resource controller has no cares to
 589          usage of swap...a process can exhaust all of the swap. This extension
 590          is useful when you want to avoid exhaustion swap but this itself
 591          adds more overheads and consumes memory for remembering information.
 592          Especially if you use 32bit system or small memory system, please
 593          be careful about enabling this. When memory resource controller
 594          is disabled by boot option, this will be automatically disabled and
 595          there will be no overhead from this. Even when you set this config=y,
 596          if boot option "noswapaccount" is set, swap will not be accounted.
 597          Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 598          size is 4096bytes, 512k per 1Gbytes of swap.
 600endif # CGROUPS
 602config MM_OWNER
 603        bool
 606        bool
 609        bool "enable deprecated sysfs features which may confuse old userspace tools"
 610        depends on SYSFS
 611        default n
 612        select SYSFS_DEPRECATED
 613        help
 614          This option switches the layout of sysfs to the deprecated
 615          version. Do not use it on recent distributions.
 617          The current sysfs layout features a unified device tree at
 618          /sys/devices/, which is able to express a hierarchy between
 619          class devices. If the deprecated option is set to Y, the
 620          unified device tree is split into a bus device tree at
 621          /sys/devices/ and several individual class device trees at
 622          /sys/class/. The class and bus devices will be connected by
 623          "<subsystem>:<name>" and the "device" links. The "block"
 624          class devices, will not show up in /sys/class/block/. Some
 625          subsystems will suppress the creation of some devices which
 626          depend on the unified device tree.
 628          This option is not a pure compatibility option that can
 629          be safely enabled on newer distributions. It will change the
 630          layout of sysfs to the non-extensible deprecated version,
 631          and disable some features, which can not be exported without
 632          confusing older userspace tools. Since 2007/2008 all major
 633          distributions do not enable this option, and ship no tools which
 634          depend on the deprecated layout or this option.
 636          If you are using a new kernel on an older distribution, or use
 637          older userspace tools, you might need to say Y here. Do not say Y,
 638          if the original kernel, that came with your distribution, has
 639          this option set to N.
 641config RELAY
 642        bool "Kernel->user space relay support (formerly relayfs)"
 643        help
 644          This option enables support for relay interface support in
 645          certain file systems (such as debugfs).
 646          It is designed to provide an efficient mechanism for tools and
 647          facilities to relay large amounts of data from kernel space to
 648          user space.
 650          If unsure, say N.
 652config NAMESPACES
 653        bool "Namespaces support" if EMBEDDED
 654        default !EMBEDDED
 655        help
 656          Provides the way to make tasks work with different objects using
 657          the same id. For example same IPC id may refer to different objects
 658          or same user id or pid may refer to different tasks when used in
 659          different namespaces.
 661config UTS_NS
 662        bool "UTS namespace"
 663        depends on NAMESPACES
 664        help
 665          In this namespace tasks see different info provided with the
 666          uname() system call
 668config IPC_NS
 669        bool "IPC namespace"
 670        depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
 671        help
 672          In this namespace tasks work with IPC ids which correspond to
 673          different IPC objects in different namespaces.
 675config USER_NS
 676        bool "User namespace (EXPERIMENTAL)"
 677        depends on NAMESPACES && EXPERIMENTAL
 678        help
 679          This allows containers, i.e. vservers, to use user namespaces
 680          to provide different user info for different servers.
 681          If unsure, say N.
 683config PID_NS
 684        bool "PID Namespaces (EXPERIMENTAL)"
 685        default n
 686        depends on NAMESPACES && EXPERIMENTAL
 687        help
 688          Support process id namespaces.  This allows having multiple
 689          processes with the same pid as long as they are in different
 690          pid namespaces.  This is a building block of containers.
 692          Unless you want to work with an experimental feature
 693          say N here.
 695config NET_NS
 696        bool "Network namespace"
 697        default n
 698        depends on NAMESPACES && EXPERIMENTAL && NET
 699        help
 700          Allow user space to create what appear to be multiple instances
 701          of the network stack.
 703config BLK_DEV_INITRD
 704        bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 705        depends on BROKEN || !FRV
 706        help
 707          The initial RAM filesystem is a ramfs which is loaded by the
 708          boot loader (loadlin or lilo) and that is mounted as root
 709          before the normal boot procedure. It is typically used to
 710          load modules needed to mount the "real" root file system,
 711          etc. See <file:Documentation/initrd.txt> for details.
 713          If RAM disk support (BLK_DEV_RAM) is also included, this
 714          also enables initial RAM disk (initrd) support and adds
 715          15 Kbytes (more on some other architectures) to the kernel size.
 717          If unsure say Y.
 721source "usr/Kconfig"
 726        bool "Optimize for size"
 727        default y
 728        help
 729          Enabling this option will pass "-Os" instead of "-O2" to gcc
 730          resulting in a smaller kernel.
 732          If unsure, say Y.
 734config SYSCTL
 735        bool
 737config ANON_INODES
 738        bool
 740menuconfig EMBEDDED
 741        bool "Configure standard kernel features (for small systems)"
 742        help
 743          This option allows certain base kernel options and settings
 744          to be disabled or tweaked. This is for specialized
 745          environments which can tolerate a "non-standard" kernel.
 746          Only use this if you really know what you are doing.
 748config UID16
 749        bool "Enable 16-bit UID system calls" if EMBEDDED
 750        depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 751        default y
 752        help
 753          This enables the legacy 16-bit UID syscall wrappers.
 756        bool "Sysctl syscall support" if EMBEDDED
 757        default y
 758        select SYSCTL
 759        ---help---
 760          sys_sysctl uses binary paths that have been found challenging
 761          to properly maintain and use.  The interface in /proc/sys
 762          using paths with ascii names is now the primary path to this
 763          information.
 765          Almost nothing using the binary sysctl interface so if you are
 766          trying to save some space it is probably safe to disable this,
 767          making your kernel marginally smaller.
 769          If unsure say Y here.
 771config KALLSYMS
 772         bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 773         default y
 774         help
 775           Say Y here to let the kernel print out symbolic crash information and
 776           symbolic stack backtraces. This increases the size of the kernel
 777           somewhat, as all symbols have to be loaded into the kernel image.
 779config KALLSYMS_ALL
 780        bool "Include all symbols in kallsyms"
 781        depends on DEBUG_KERNEL && KALLSYMS
 782        help
 783           Normally kallsyms only contains the symbols of functions, for nicer
 784           OOPS messages.  Some debuggers can use kallsyms for other
 785           symbols too: say Y here to include all symbols, if you need them 
 786           and you don't care about adding 300k to the size of your kernel.
 788           Say N.
 791        bool "Do an extra kallsyms pass"
 792        depends on KALLSYMS
 793        help
 794           If kallsyms is not working correctly, the build will fail with
 795           inconsistent kallsyms data.  If that occurs, log a bug report and
 796           turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 797           Always say N here unless you find a bug in kallsyms, which must be
 798           reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 799           you wait for kallsyms to be fixed.
 802config HOTPLUG
 803        bool "Support for hot-pluggable devices" if EMBEDDED
 804        default y
 805        help
 806          This option is provided for the case where no hotplug or uevent
 807          capabilities is wanted by the kernel.  You should only consider
 808          disabling this option for embedded systems that do not use modules, a
 809          dynamic /dev tree, or dynamic device discovery.  Just say Y.
 811config PRINTK
 812        default y
 813        bool "Enable support for printk" if EMBEDDED
 814        help
 815          This option enables normal printk support. Removing it
 816          eliminates most of the message strings from the kernel image
 817          and makes the kernel more or less silent. As this makes it
 818          very difficult to diagnose system problems, saying N here is
 819          strongly discouraged.
 821config BUG
 822        bool "BUG() support" if EMBEDDED
 823        default y
 824        help
 825          Disabling this option eliminates support for BUG and WARN, reducing
 826          the size of your kernel image and potentially quietly ignoring
 827          numerous fatal conditions. You should only consider disabling this
 828          option for embedded systems with no facilities for reporting errors.
 829          Just say Y.
 831config ELF_CORE
 832        default y
 833        bool "Enable ELF core dumps" if EMBEDDED
 834        help
 835          Enable support for generating core dumps. Disabling saves about 4k.
 838        bool "Enable PC-Speaker support" if EMBEDDED
 839        depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 840        default y
 841        help
 842          This option allows to disable the internal PC-Speaker
 843          support, saving some memory.
 845config BASE_FULL
 846        default y
 847        bool "Enable full-sized data structures for core" if EMBEDDED
 848        help
 849          Disabling this option reduces the size of miscellaneous core
 850          kernel data structures. This saves memory on small machines,
 851          but may reduce performance.
 853config FUTEX
 854        bool "Enable futex support" if EMBEDDED
 855        default y
 856        select RT_MUTEXES
 857        help
 858          Disabling this option will cause the kernel to be built without
 859          support for "fast userspace mutexes".  The resulting kernel may not
 860          run glibc-based applications correctly.
 862config EPOLL
 863        bool "Enable eventpoll support" if EMBEDDED
 864        default y
 865        select ANON_INODES
 866        help
 867          Disabling this option will cause the kernel to be built without
 868          support for epoll family of system calls.
 870config SIGNALFD
 871        bool "Enable signalfd() system call" if EMBEDDED
 872        select ANON_INODES
 873        default y
 874        help
 875          Enable the signalfd() system call that allows to receive signals
 876          on a file descriptor.
 878          If unsure, say Y.
 880config TIMERFD
 881        bool "Enable timerfd() system call" if EMBEDDED
 882        select ANON_INODES
 883        default y
 884        help
 885          Enable the timerfd() system call that allows to receive timer
 886          events on a file descriptor.
 888          If unsure, say Y.
 890config EVENTFD
 891        bool "Enable eventfd() system call" if EMBEDDED
 892        select ANON_INODES
 893        default y
 894        help
 895          Enable the eventfd() system call that allows to receive both
 896          kernel notification (ie. KAIO) or userspace notifications.
 898          If unsure, say Y.
 900config SHMEM
 901        bool "Use full shmem filesystem" if EMBEDDED
 902        default y
 903        depends on MMU
 904        help
 905          The shmem is an internal filesystem used to manage shared memory.
 906          It is backed by swap and manages resource limits. It is also exported
 907          to userspace as tmpfs if TMPFS is enabled. Disabling this
 908          option replaces shmem and tmpfs with the much simpler ramfs code,
 909          which may be appropriate on small systems without swap.
 911config AIO
 912        bool "Enable AIO support" if EMBEDDED
 913        default y
 914        help
 915          This option enables POSIX asynchronous I/O which may by used
 916          by some high performance threaded applications. Disabling
 917          this option saves about 7k.
 920        bool
 921        help
 922          See tools/perf/design.txt for details.
 925        bool
 926        help
 927          See tools/perf/design.txt for details
 929menu "Kernel Performance Events And Counters"
 931config PERF_EVENTS
 932        bool "Kernel performance events and counters"
 933        default y if (PROFILING || PERF_COUNTERS)
 934        depends on HAVE_PERF_EVENTS
 935        select ANON_INODES
 936        help
 937          Enable kernel support for various performance events provided
 938          by software and hardware.
 940          Software events are supported either built-in or via the
 941          use of generic tracepoints.
 943          Most modern CPUs support performance events via performance
 944          counter registers. These registers count the number of certain
 945          types of hw events: such as instructions executed, cachemisses
 946          suffered, or branches mis-predicted - without slowing down the
 947          kernel or applications. These registers can also trigger interrupts
 948          when a threshold number of events have passed - and can thus be
 949          used to profile the code that runs on that CPU.
 951          The Linux Performance Event subsystem provides an abstraction of
 952          these software and hardware event capabilities, available via a
 953          system call and used by the "perf" utility in tools/perf/. It
 954          provides per task and per CPU counters, and it provides event
 955          capabilities on top of those.
 957          Say Y if unsure.
 959config EVENT_PROFILE
 960        bool "Tracepoint profiling sources"
 961        depends on PERF_EVENTS && EVENT_TRACING
 962        default y
 963        help
 964         Allow the use of tracepoints as software performance events.
 966         When this is enabled, you can create perf events based on
 967         tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
 968         found in debugfs://tracing/events/*/*/id. (The -e/--events
 969         option to the perf tool can parse and interpret symbolic
 970         tracepoints, in the subsystem:tracepoint_name format.)
 972config PERF_COUNTERS
 973        bool "Kernel performance counters (old config option)"
 974        depends on HAVE_PERF_EVENTS
 975        help
 976          This config has been obsoleted by the PERF_EVENTS
 977          config option - please see that one for details.
 979          It has no effect on the kernel whether you enable
 980          it or not, it is a compatibility placeholder.
 982          Say N if unsure.
 985        default n
 986        bool "Debug: use vmalloc to back perf mmap() buffers"
 987        depends on PERF_EVENTS && DEBUG_KERNEL
 988        select PERF_USE_VMALLOC
 989        help
 990         Use vmalloc memory to back perf mmap() buffers.
 992         Mostly useful for debugging the vmalloc code on platforms
 993         that don't require it.
 995         Say N if unsure.
1000        default y
1001        bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1002        help
1003          VM event counters are needed for event counts to be shown.
1004          This option allows the disabling of the VM event counters
1005          on EMBEDDED systems.  /proc/vmstat will only show page counts
1006          if VM event counters are disabled.
1008config PCI_QUIRKS
1009        default y
1010        bool "Enable PCI quirk workarounds" if EMBEDDED
1011        depends on PCI
1012        help
1013          This enables workarounds for various PCI chipset
1014          bugs/quirks. Disable this only if your target machine is
1015          unaffected by PCI quirks.
1017config SLUB_DEBUG
1018        default y
1019        bool "Enable SLUB debugging support" if EMBEDDED
1020        depends on SLUB && SYSFS
1021        help
1022          SLUB has extensive debug support features. Disabling these can
1023          result in significant savings in code size. This also disables
1024          SLUB sysfs support. /sys/slab will not exist and there will be
1025          no support for cache validation etc.
1027config COMPAT_BRK
1028        bool "Disable heap randomization"
1029        default y
1030        help
1031          Randomizing heap placement makes heap exploits harder, but it
1032          also breaks ancient binaries (including anything libc5 based).
1033          This option changes the bootup default to heap randomization
1034          disabled, and can be overridden at runtime by setting
1035          /proc/sys/kernel/randomize_va_space to 2.
1037          On non-ancient distros (post-2000 ones) N is usually a safe choice.
1040        prompt "Choose SLAB allocator"
1041        default SLUB
1042        help
1043           This option allows to select a slab allocator.
1045config SLAB
1046        bool "SLAB"
1047        help
1048          The regular slab allocator that is established and known to work
1049          well in all environments. It organizes cache hot objects in
1050          per cpu and per node queues.
1052config SLUB
1053        bool "SLUB (Unqueued Allocator)"
1054        help
1055           SLUB is a slab allocator that minimizes cache line usage
1056           instead of managing queues of cached objects (SLAB approach).
1057           Per cpu caching is realized using slabs of objects instead
1058           of queues of objects. SLUB can use memory efficiently
1059           and has enhanced diagnostics. SLUB is the default choice for
1060           a slab allocator.
1062config SLOB
1063        depends on EMBEDDED
1064        bool "SLOB (Simple Allocator)"
1065        help
1066           SLOB replaces the stock allocator with a drastically simpler
1067           allocator. SLOB is generally more space efficient but
1068           does not perform as well on large systems.
1072config PROFILING
1073        bool "Profiling support (EXPERIMENTAL)"
1074        help
1075          Say Y here to enable the extended profiling support mechanisms used
1076          by profilers such as OProfile.
1079# Place an empty function call at each tracepoint site. Can be
1080# dynamically changed for a probe function.
1082config TRACEPOINTS
1083        bool
1085source "arch/Kconfig"
1087config SLOW_WORK
1088        default n
1089        bool
1090        help
1091          The slow work thread pool provides a number of dynamically allocated
1092          threads that can be used by the kernel to perform operations that
1093          take a relatively long time.
1095          An example of this would be CacheFiles doing a path lookup followed
1096          by a series of mkdirs and a create call, all of which have to touch
1097          disk.
1099          See Documentation/slow-work.txt.
1101config SLOW_WORK_DEBUG
1102        bool "Slow work debugging through debugfs"
1103        default n
1104        depends on SLOW_WORK && DEBUG_FS
1105        help
1106          Display the contents of the slow work run queue through debugfs,
1107          including items currently executing.
1109          See Documentation/slow-work.txt.
1111endmenu         # General setup
1114        bool
1115        default n
1117config SLABINFO
1118        bool
1119        depends on PROC_FS
1120        depends on SLAB || SLUB_DEBUG
1121        default y
1123config RT_MUTEXES
1124        boolean
1126config BASE_SMALL
1127        int
1128        default 0 if BASE_FULL
1129        default 1 if !BASE_FULL
1131menuconfig MODULES
1132        bool "Enable loadable module support"
1133        help
1134          Kernel modules are small pieces of compiled code which can
1135          be inserted in the running kernel, rather than being
1136          permanently built into the kernel.  You use the "modprobe"
1137          tool to add (and sometimes remove) them.  If you say Y here,
1138          many parts of the kernel can be built as modules (by
1139          answering M instead of Y where indicated): this is most
1140          useful for infrequently used options which are not required
1141          for booting.  For more information, see the man pages for
1142          modprobe, lsmod, modinfo, insmod and rmmod.
1144          If you say Y here, you will need to run "make
1145          modules_install" to put the modules under /lib/modules/
1146          where modprobe can find them (you may need to be root to do
1147          this).
1149          If unsure, say Y.
1151if MODULES
1154        bool "Forced module loading"
1155        default n
1156        help
1157          Allow loading of modules without version information (ie. modprobe
1158          --force).  Forced module loading sets the 'F' (forced) taint flag and
1159          is usually a really bad idea.
1161config MODULE_UNLOAD
1162        bool "Module unloading"
1163        help
1164          Without this option you will not be able to unload any
1165          modules (note that some modules may not be unloadable
1166          anyway), which makes your kernel smaller, faster
1167          and simpler.  If unsure, say Y.
1170        bool "Forced module unloading"
1171        depends on MODULE_UNLOAD && EXPERIMENTAL
1172        help
1173          This option allows you to force a module to unload, even if the
1174          kernel believes it is unsafe: the kernel will remove the module
1175          without waiting for anyone to stop using it (using the -f option to
1176          rmmod).  This is mainly for kernel developers and desperate users.
1177          If unsure, say N.
1179config MODVERSIONS
1180        bool "Module versioning support"
1181        help
1182          Usually, you have to use modules compiled with your kernel.
1183          Saying Y here makes it sometimes possible to use modules
1184          compiled for different kernels, by adding enough information
1185          to the modules to (hopefully) spot any changes which would
1186          make them incompatible with the kernel you are running.  If
1187          unsure, say N.
1190        bool "Source checksum for all modules"
1191        help
1192          Modules which contain a MODULE_VERSION get an extra "srcversion"
1193          field inserted into their modinfo section, which contains a
1194          sum of the source files which made it.  This helps maintainers
1195          see exactly which source was used to build a module (since
1196          others sometimes change the module source without updating
1197          the version).  With this option, such a "srcversion" field
1198          will be created for all modules.  If unsure, say N.
1200endif # MODULES
1203        bool
1204        help
1205          Back when each arch used to define their own cpu_online_map and
1206          cpu_possible_map, some of them chose to initialize cpu_possible_map
1207          with all 1s, and others with all 0s.  When they were centralised,
1208          it was better to provide this option than to break all the archs
1209          and have several arch maintainers pursuing me down dark alleys.
1211config STOP_MACHINE
1212        bool
1213        default y
1214        depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1215        help
1216          Need stop_machine() primitive.
1218source "block/Kconfig"
1221        bool