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  42           drivers that have been replaced by something else, and/or are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 menu "RCU Subsystem"
 242
 243 choice
 244         prompt "RCU Implementation"
 245         default CLASSIC_RCU
 246
 247 config CLASSIC_RCU
 248         bool "Classic RCU"
 249         help
 250           This option selects the classic RCU implementation that is
 251           designed for best read-side performance on non-realtime
 252           systems.
 253
 254           Select this option if you are unsure.
 255
 256 config TREE_RCU
 257         bool "Tree-based hierarchical RCU"
 258         help
 259           This option selects the RCU implementation that is
 260           designed for very large SMP system with hundreds or
 261           thousands of CPUs.
 262
 263 config PREEMPT_RCU
 264         bool "Preemptible RCU"
 265         depends on PREEMPT
 266         help
 267           This option reduces the latency of the kernel by making certain
 268           RCU sections preemptible. Normally RCU code is non-preemptible, if
 269           this option is selected then read-only RCU sections become
 270           preemptible. This helps latency, but may expose bugs due to
 271           now-naive assumptions about each RCU read-side critical section
 272           remaining on a given CPU through its execution.
 273
 274 endchoice
 275
 276 config RCU_TRACE
 277         bool "Enable tracing for RCU"
 278         depends on TREE_RCU || PREEMPT_RCU
 279         help
 280           This option provides tracing in RCU which presents stats
 281           in debugfs for debugging RCU implementation.
 282
 283           Say Y here if you want to enable RCU tracing
 284           Say N if you are unsure.
 285
 286 config RCU_FANOUT
 287         int "Tree-based hierarchical RCU fanout value"
 288         range 2 64 if 64BIT
 289         range 2 32 if !64BIT
 290         depends on TREE_RCU
 291         default 64 if 64BIT
 292         default 32 if !64BIT
 293         help
 294           This option controls the fanout of hierarchical implementations
 295           of RCU, allowing RCU to work efficiently on machines with
 296           large numbers of CPUs.  This value must be at least the cube
 297           root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
 298           systems and up to 262,144 for 64-bit systems.
 299
 300           Select a specific number if testing RCU itself.
 301           Take the default if unsure.
 302
 303 config RCU_FANOUT_EXACT
 304         bool "Disable tree-based hierarchical RCU auto-balancing"
 305         depends on TREE_RCU
 306         default n
 307         help
 308           This option forces use of the exact RCU_FANOUT value specified,
 309           regardless of imbalances in the hierarchy.  This is useful for
 310           testing RCU itself, and might one day be useful on systems with
 311           strong NUMA behavior.
 312
 313           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 314
 315           Say N if unsure.
 316
 317 config TREE_RCU_TRACE
 318         def_bool RCU_TRACE && TREE_RCU
 319         select DEBUG_FS
 320         help
 321           This option provides tracing for the TREE_RCU implementation,
 322           permitting Makefile to trivially select kernel/rcutree_trace.c.
 323
 324 config PREEMPT_RCU_TRACE
 325         def_bool RCU_TRACE && PREEMPT_RCU
 326         select DEBUG_FS
 327         help
 328           This option provides tracing for the PREEMPT_RCU implementation,
 329           permitting Makefile to trivially select kernel/rcupreempt_trace.c.
 330
 331 endmenu # "RCU Subsystem"
 332
 333 config IKCONFIG
 334         tristate "Kernel .config support"
 335         ---help---
 336           This option enables the complete Linux kernel ".config" file
 337           contents to be saved in the kernel. It provides documentation
 338           of which kernel options are used in a running kernel or in an
 339           on-disk kernel.  This information can be extracted from the kernel
 340           image file with the script scripts/extract-ikconfig and used as
 341           input to rebuild the current kernel or to build another kernel.
 342           It can also be extracted from a running kernel by reading
 343           /proc/config.gz if enabled (below).
 344
 345 config IKCONFIG_PROC
 346         bool "Enable access to .config through /proc/config.gz"
 347         depends on IKCONFIG && PROC_FS
 348         ---help---
 349           This option enables access to the kernel configuration file
 350           through /proc/config.gz.
 351
 352 config LOG_BUF_SHIFT
 353         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 354         range 12 21
 355         default 17
 356         help
 357           Select kernel log buffer size as a power of 2.
 358           Examples:
 359                      17 => 128 KB
 360                      16 => 64 KB
 361                      15 => 32 KB
 362                      14 => 16 KB
 363                      13 =>  8 KB
 364                      12 =>  4 KB
 365
 366 #
 367 # Architectures with an unreliable sched_clock() should select this:
 368 #
 369 config HAVE_UNSTABLE_SCHED_CLOCK
 370         bool
 371
 372 config GROUP_SCHED
 373         bool "Group CPU scheduler"
 374         depends on EXPERIMENTAL
 375         default n
 376         help
 377           This feature lets CPU scheduler recognize task groups and control CPU
 378           bandwidth allocation to such task groups.
 379           In order to create a group from arbitrary set of processes, use
 380           CONFIG_CGROUPS. (See Control Group support.)
 381
 382 config FAIR_GROUP_SCHED
 383         bool "Group scheduling for SCHED_OTHER"
 384         depends on GROUP_SCHED
 385         default GROUP_SCHED
 386
 387 config RT_GROUP_SCHED
 388         bool "Group scheduling for SCHED_RR/FIFO"
 389         depends on EXPERIMENTAL
 390         depends on GROUP_SCHED
 391         default n
 392         help
 393           This feature lets you explicitly allocate real CPU bandwidth
 394           to users or control groups (depending on the "Basis for grouping tasks"
 395           setting below. If enabled, it will also make it impossible to
 396           schedule realtime tasks for non-root users until you allocate
 397           realtime bandwidth for them.
 398           See Documentation/scheduler/sched-rt-group.txt for more information.
 399
 400 choice
 401         depends on GROUP_SCHED
 402         prompt "Basis for grouping tasks"
 403         default USER_SCHED
 404
 405 config USER_SCHED
 406         bool "user id"
 407         help
 408           This option will choose userid as the basis for grouping
 409           tasks, thus providing equal CPU bandwidth to each user.
 410
 411 config CGROUP_SCHED
 412         bool "Control groups"
 413         depends on CGROUPS
 414         help
 415           This option allows you to create arbitrary task groups
 416           using the "cgroup" pseudo filesystem and control
 417           the cpu bandwidth allocated to each such task group.
 418           Refer to Documentation/cgroups/cgroups.txt for more
 419           information on "cgroup" pseudo filesystem.
 420
 421 endchoice
 422
 423 menuconfig CGROUPS
 424         boolean "Control Group support"
 425         help
 426           This option adds support for grouping sets of processes together, for
 427           use with process control subsystems such as Cpusets, CFS, memory
 428           controls or device isolation.
 429           See
 430                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 431                 - Documentation/cgroups/ (features for grouping, isolation
 432                                           and resource control)
 433
 434           Say N if unsure.
 435
 436 if CGROUPS
 437
 438 config CGROUP_DEBUG
 439         bool "Example debug cgroup subsystem"
 440         depends on CGROUPS
 441         default n
 442         help
 443           This option enables a simple cgroup subsystem that
 444           exports useful debugging information about the cgroups
 445           framework.
 446
 447           Say N if unsure.
 448
 449 config CGROUP_NS
 450         bool "Namespace cgroup subsystem"
 451         depends on CGROUPS
 452         help
 453           Provides a simple namespace cgroup subsystem to
 454           provide hierarchical naming of sets of namespaces,
 455           for instance virtual servers and checkpoint/restart
 456           jobs.
 457
 458 config CGROUP_FREEZER
 459         bool "Freezer cgroup subsystem"
 460         depends on CGROUPS
 461         help
 462           Provides a way to freeze and unfreeze all tasks in a
 463           cgroup.
 464
 465 config CGROUP_DEVICE
 466         bool "Device controller for cgroups"
 467         depends on CGROUPS && EXPERIMENTAL
 468         help
 469           Provides a cgroup implementing whitelists for devices which
 470           a process in the cgroup can mknod or open.
 471
 472 config CPUSETS
 473         bool "Cpuset support"
 474         depends on SMP && CGROUPS
 475         help
 476           This option will let you create and manage CPUSETs which
 477           allow dynamically partitioning a system into sets of CPUs and
 478           Memory Nodes and assigning tasks to run only within those sets.
 479           This is primarily useful on large SMP or NUMA systems.
 480
 481           Say N if unsure.
 482
 483 config PROC_PID_CPUSET
 484         bool "Include legacy /proc/<pid>/cpuset file"
 485         depends on CPUSETS
 486         default y
 487
 488 config CGROUP_CPUACCT
 489         bool "Simple CPU accounting cgroup subsystem"
 490         depends on CGROUPS
 491         help
 492           Provides a simple Resource Controller for monitoring the
 493           total CPU consumed by the tasks in a cgroup.
 494
 495 config RESOURCE_COUNTERS
 496         bool "Resource counters"
 497         help
 498           This option enables controller independent resource accounting
 499           infrastructure that works with cgroups.
 500         depends on CGROUPS
 501
 502 config CGROUP_MEM_RES_CTLR
 503         bool "Memory Resource Controller for Control Groups"
 504         depends on CGROUPS && RESOURCE_COUNTERS
 505         select MM_OWNER
 506         help
 507           Provides a memory resource controller that manages both anonymous
 508           memory and page cache. (See Documentation/controllers/memory.txt)
 509
 510           Note that setting this option increases fixed memory overhead
 511           associated with each page of memory in the system. By this,
 512           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 513           usage tracking struct at boot. Total amount of this is printed out
 514           at boot.
 515
 516           Only enable when you're ok with these trade offs and really
 517           sure you need the memory resource controller. Even when you enable
 518           this, you can set "cgroup_disable=memory" at your boot option to
 519           disable memory resource controller and you can avoid overheads.
 520           (and lose benefits of memory resource controller)
 521
 522           This config option also selects MM_OWNER config option, which
 523           could in turn add some fork/exit overhead.
 524
 525 config CGROUP_MEM_RES_CTLR_SWAP
 526         bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
 527         depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
 528         help
 529           Add swap management feature to memory resource controller. When you
 530           enable this, you can limit mem+swap usage per cgroup. In other words,
 531           when you disable this, memory resource controller has no cares to
 532           usage of swap...a process can exhaust all of the swap. This extension
 533           is useful when you want to avoid exhaustion swap but this itself
 534           adds more overheads and consumes memory for remembering information.
 535           Especially if you use 32bit system or small memory system, please
 536           be careful about enabling this. When memory resource controller
 537           is disabled by boot option, this will be automatically disabled and
 538           there will be no overhead from this. Even when you set this config=y,
 539           if boot option "noswapaccount" is set, swap will not be accounted.
 540
 541 endif # CGROUPS
 542
 543 config MM_OWNER
 544         bool
 545
 546 config SYSFS_DEPRECATED
 547         bool
 548
 549 config SYSFS_DEPRECATED_V2
 550         bool "Create deprecated sysfs layout for older userspace tools"
 551         depends on SYSFS
 552         default y
 553         select SYSFS_DEPRECATED
 554         help
 555           This option switches the layout of sysfs to the deprecated
 556           version.
 557
 558           The current sysfs layout features a unified device tree at
 559           /sys/devices/, which is able to express a hierarchy between
 560           class devices. If the deprecated option is set to Y, the
 561           unified device tree is split into a bus device tree at
 562           /sys/devices/ and several individual class device trees at
 563           /sys/class/. The class and bus devices will be connected by
 564           "<subsystem>:<name>" and the "device" links. The "block"
 565           class devices, will not show up in /sys/class/block/. Some
 566           subsystems will suppress the creation of some devices which
 567           depend on the unified device tree.
 568
 569           This option is not a pure compatibility option that can
 570           be safely enabled on newer distributions. It will change the
 571           layout of sysfs to the non-extensible deprecated version,
 572           and disable some features, which can not be exported without
 573           confusing older userspace tools. Since 2007/2008 all major
 574           distributions do not enable this option, and ship no tools which
 575           depend on the deprecated layout or this option.
 576
 577           If you are using a new kernel on an older distribution, or use
 578           older userspace tools, you might need to say Y here. Do not say Y,
 579           if the original kernel, that came with your distribution, has
 580           this option set to N.
 581
 582 config RELAY
 583         bool "Kernel->user space relay support (formerly relayfs)"
 584         help
 585           This option enables support for relay interface support in
 586           certain file systems (such as debugfs).
 587           It is designed to provide an efficient mechanism for tools and
 588           facilities to relay large amounts of data from kernel space to
 589           user space.
 590
 591           If unsure, say N.
 592
 593 config NAMESPACES
 594         bool "Namespaces support" if EMBEDDED
 595         default !EMBEDDED
 596         help
 597           Provides the way to make tasks work with different objects using
 598           the same id. For example same IPC id may refer to different objects
 599           or same user id or pid may refer to different tasks when used in
 600           different namespaces.
 601
 602 config UTS_NS
 603         bool "UTS namespace"
 604         depends on NAMESPACES
 605         help
 606           In this namespace tasks see different info provided with the
 607           uname() system call
 608
 609 config IPC_NS
 610         bool "IPC namespace"
 611         depends on NAMESPACES && SYSVIPC
 612         help
 613           In this namespace tasks work with IPC ids which correspond to
 614           different IPC objects in different namespaces
 615
 616 config USER_NS
 617         bool "User namespace (EXPERIMENTAL)"
 618         depends on NAMESPACES && EXPERIMENTAL
 619         help
 620           This allows containers, i.e. vservers, to use user namespaces
 621           to provide different user info for different servers.
 622           If unsure, say N.
 623
 624 config PID_NS
 625         bool "PID Namespaces (EXPERIMENTAL)"
 626         default n
 627         depends on NAMESPACES && EXPERIMENTAL
 628         help
 629           Support process id namespaces.  This allows having multiple
 630           process with the same pid as long as they are in different
 631           pid namespaces.  This is a building block of containers.
 632
 633           Unless you want to work with an experimental feature
 634           say N here.
 635
 636 config BLK_DEV_INITRD
 637         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 638         depends on BROKEN || !FRV
 639         help
 640           The initial RAM filesystem is a ramfs which is loaded by the
 641           boot loader (loadlin or lilo) and that is mounted as root
 642           before the normal boot procedure. It is typically used to
 643           load modules needed to mount the "real" root file system,
 644           etc. See <file:Documentation/initrd.txt> for details.
 645
 646           If RAM disk support (BLK_DEV_RAM) is also included, this
 647           also enables initial RAM disk (initrd) support and adds
 648           15 Kbytes (more on some other architectures) to the kernel size.
 649
 650           If unsure say Y.
 651
 652 if BLK_DEV_INITRD
 653
 654 source "usr/Kconfig"
 655
 656 endif
 657
 658 config CC_OPTIMIZE_FOR_SIZE
 659         bool "Optimize for size"
 660         default y
 661         help
 662           Enabling this option will pass "-Os" instead of "-O2" to gcc
 663           resulting in a smaller kernel.
 664
 665           If unsure, say Y.
 666
 667 config SYSCTL
 668         bool
 669
 670 menuconfig EMBEDDED
 671         bool "Configure standard kernel features (for small systems)"
 672         help
 673           This option allows certain base kernel options and settings
 674           to be disabled or tweaked. This is for specialized
 675           environments which can tolerate a "non-standard" kernel.
 676           Only use this if you really know what you are doing.
 677
 678 config UID16
 679         bool "Enable 16-bit UID system calls" if EMBEDDED
 680         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 681         default y
 682         help
 683           This enables the legacy 16-bit UID syscall wrappers.
 684
 685 config SYSCTL_SYSCALL
 686         bool "Sysctl syscall support" if EMBEDDED
 687         default y
 688         select SYSCTL
 689         ---help---
 690           sys_sysctl uses binary paths that have been found challenging
 691           to properly maintain and use.  The interface in /proc/sys
 692           using paths with ascii names is now the primary path to this
 693           information.
 694
 695           Almost nothing using the binary sysctl interface so if you are
 696           trying to save some space it is probably safe to disable this,
 697           making your kernel marginally smaller.
 698
 699           If unsure say Y here.
 700
 701 config KALLSYMS
 702          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 703          default y
 704          help
 705            Say Y here to let the kernel print out symbolic crash information and
 706            symbolic stack backtraces. This increases the size of the kernel
 707            somewhat, as all symbols have to be loaded into the kernel image.
 708
 709 config KALLSYMS_ALL
 710         bool "Include all symbols in kallsyms"
 711         depends on DEBUG_KERNEL && KALLSYMS
 712         help
 713            Normally kallsyms only contains the symbols of functions, for nicer
 714            OOPS messages.  Some debuggers can use kallsyms for other
 715            symbols too: say Y here to include all symbols, if you need them
 716            and you don't care about adding 300k to the size of your kernel.
 717
 718            Say N.
 719
 720 config KALLSYMS_STRIP_GENERATED
 721         bool "Strip machine generated symbols from kallsyms"
 722         depends on KALLSYMS_ALL
 723         default y
 724         help
 725           Say N if you want kallsyms to retain even machine generated symbols.
 726
 727 config KALLSYMS_EXTRA_PASS
 728         bool "Do an extra kallsyms pass"
 729         depends on KALLSYMS
 730         help
 731            If kallsyms is not working correctly, the build will fail with
 732            inconsistent kallsyms data.  If that occurs, log a bug report and
 733            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 734            Always say N here unless you find a bug in kallsyms, which must be
 735            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 736            you wait for kallsyms to be fixed.
 737
 738
 739 config HOTPLUG
 740         bool "Support for hot-pluggable devices" if EMBEDDED
 741         default y
 742         help
 743           This option is provided for the case where no hotplug or uevent
 744           capabilities is wanted by the kernel.  You should only consider
 745           disabling this option for embedded systems that do not use modules, a
 746           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 747
 748 config PRINTK
 749         default y
 750         bool "Enable support for printk" if EMBEDDED
 751         help
 752           This option enables normal printk support. Removing it
 753           eliminates most of the message strings from the kernel image
 754           and makes the kernel more or less silent. As this makes it
 755           very difficult to diagnose system problems, saying N here is
 756           strongly discouraged.
 757
 758 config BUG
 759         bool "BUG() support" if EMBEDDED
 760         default y
 761         help
 762           Disabling this option eliminates support for BUG and WARN, reducing
 763           the size of your kernel image and potentially quietly ignoring
 764           numerous fatal conditions. You should only consider disabling this
 765           option for embedded systems with no facilities for reporting errors.
 766           Just say Y.
 767
 768 config ELF_CORE
 769         default y
 770         bool "Enable ELF core dumps" if EMBEDDED
 771         help
 772           Enable support for generating core dumps. Disabling saves about 4k.
 773
 774 config PCSPKR_PLATFORM
 775         bool "Enable PC-Speaker support" if EMBEDDED
 776         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 777         default y
 778         help
 779           This option allows to disable the internal PC-Speaker
 780           support, saving some memory.
 781
 782 config COMPAT_BRK
 783         bool "Disable heap randomization"
 784         default y
 785         help
 786           Randomizing heap placement makes heap exploits harder, but it
 787           also breaks ancient binaries (including anything libc5 based).
 788           This option changes the bootup default to heap randomization
 789           disabled, and can be overriden runtime by setting
 790           /proc/sys/kernel/randomize_va_space to 2.
 791
 792           On non-ancient distros (post-2000 ones) N is usually a safe choice.
 793
 794 config BASE_FULL
 795         default y
 796         bool "Enable full-sized data structures for core" if EMBEDDED
 797         help
 798           Disabling this option reduces the size of miscellaneous core
 799           kernel data structures. This saves memory on small machines,
 800           but may reduce performance.
 801
 802 config FUTEX
 803         bool "Enable futex support" if EMBEDDED
 804         default y
 805         select RT_MUTEXES
 806         help
 807           Disabling this option will cause the kernel to be built without
 808           support for "fast userspace mutexes".  The resulting kernel may not
 809           run glibc-based applications correctly.
 810
 811 config ANON_INODES
 812         bool
 813
 814 config EPOLL
 815         bool "Enable eventpoll support" if EMBEDDED
 816         default y
 817         select ANON_INODES
 818         help
 819           Disabling this option will cause the kernel to be built without
 820           support for epoll family of system calls.
 821
 822 config SIGNALFD
 823         bool "Enable signalfd() system call" if EMBEDDED
 824         select ANON_INODES
 825         default y
 826         help
 827           Enable the signalfd() system call that allows to receive signals
 828           on a file descriptor.
 829
 830           If unsure, say Y.
 831
 832 config TIMERFD
 833         bool "Enable timerfd() system call" if EMBEDDED
 834         select ANON_INODES
 835         default y
 836         help
 837           Enable the timerfd() system call that allows to receive timer
 838           events on a file descriptor.
 839
 840           If unsure, say Y.
 841
 842 config EVENTFD
 843         bool "Enable eventfd() system call" if EMBEDDED
 844         select ANON_INODES
 845         default y
 846         help
 847           Enable the eventfd() system call that allows to receive both
 848           kernel notification (ie. KAIO) or userspace notifications.
 849
 850           If unsure, say Y.
 851
 852 config SHMEM
 853         bool "Use full shmem filesystem" if EMBEDDED
 854         default y
 855         depends on MMU
 856         help
 857           The shmem is an internal filesystem used to manage shared memory.
 858           It is backed by swap and manages resource limits. It is also exported
 859           to userspace as tmpfs if TMPFS is enabled. Disabling this
 860           option replaces shmem and tmpfs with the much simpler ramfs code,
 861           which may be appropriate on small systems without swap.
 862
 863 config AIO
 864         bool "Enable AIO support" if EMBEDDED
 865         default y
 866         help
 867           This option enables POSIX asynchronous I/O which may by used
 868           by some high performance threaded applications. Disabling
 869           this option saves about 7k.
 870
 871 config VM_EVENT_COUNTERS
 872         default y
 873         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 874         help
 875           VM event counters are needed for event counts to be shown.
 876           This option allows the disabling of the VM event counters
 877           on EMBEDDED systems.  /proc/vmstat will only show page counts
 878           if VM event counters are disabled.
 879
 880 config PCI_QUIRKS
 881         default y
 882         bool "Enable PCI quirk workarounds" if EMBEDDED
 883         depends on PCI
 884         help
 885           This enables workarounds for various PCI chipset
 886           bugs/quirks. Disable this only if your target machine is
 887           unaffected by PCI quirks.
 888
 889 config SLUB_DEBUG
 890         default y
 891         bool "Enable SLUB debugging support" if EMBEDDED
 892         depends on SLUB && SYSFS
 893         help
 894           SLUB has extensive debug support features. Disabling these can
 895           result in significant savings in code size. This also disables
 896           SLUB sysfs support. /sys/slab will not exist and there will be
 897           no support for cache validation etc.
 898
 899 choice
 900         prompt "Choose SLAB allocator"
 901         default SLUB
 902         help
 903            This option allows to select a slab allocator.
 904
 905 config SLAB
 906         bool "SLAB"
 907         help
 908           The regular slab allocator that is established and known to work
 909           well in all environments. It organizes cache hot objects in
 910           per cpu and per node queues.
 911
 912 config SLUB
 913         bool "SLUB (Unqueued Allocator)"
 914         help
 915            SLUB is a slab allocator that minimizes cache line usage
 916            instead of managing queues of cached objects (SLAB approach).
 917            Per cpu caching is realized using slabs of objects instead
 918            of queues of objects. SLUB can use memory efficiently
 919            and has enhanced diagnostics. SLUB is the default choice for
 920            a slab allocator.
 921
 922 config SLOB
 923         depends on EMBEDDED
 924         bool "SLOB (Simple Allocator)"
 925         help
 926            SLOB replaces the stock allocator with a drastically simpler
 927            allocator. SLOB is generally more space efficient but
 928            does not perform as well on large systems.
 929
 930 endchoice
 931
 932 config PROFILING
 933         bool "Profiling support (EXPERIMENTAL)"
 934         help
 935           Say Y here to enable the extended profiling support mechanisms used
 936           by profilers such as OProfile.
 937
 938 #
 939 # Place an empty function call at each tracepoint site. Can be
 940 # dynamically changed for a probe function.
 941 #
 942 config TRACEPOINTS
 943         bool
 944
 945 config MARKERS
 946         bool "Activate markers"
 947         depends on TRACEPOINTS
 948         help
 949           Place an empty function call at each marker site. Can be
 950           dynamically changed for a probe function.
 951
 952 source "arch/Kconfig"
 953
 954 endmenu         # General setup
 955
 956 config HAVE_GENERIC_DMA_COHERENT
 957         bool
 958         default n
 959
 960 config SLABINFO
 961         bool
 962         depends on PROC_FS
 963         depends on SLAB || SLUB_DEBUG
 964         default y
 965
 966 config RT_MUTEXES
 967         boolean
 968         select PLIST
 969
 970 config BASE_SMALL
 971         int
 972         default 0 if BASE_FULL
 973         default 1 if !BASE_FULL
 974
 975 menuconfig MODULES
 976         bool "Enable loadable module support"
 977         help
 978           Kernel modules are small pieces of compiled code which can
 979           be inserted in the running kernel, rather than being
 980           permanently built into the kernel.  You use the "modprobe"
 981           tool to add (and sometimes remove) them.  If you say Y here,
 982           many parts of the kernel can be built as modules (by
 983           answering M instead of Y where indicated): this is most
 984           useful for infrequently used options which are not required
 985           for booting.  For more information, see the man pages for
 986           modprobe, lsmod, modinfo, insmod and rmmod.
 987
 988           If you say Y here, you will need to run "make
 989           modules_install" to put the modules under /lib/modules/
 990           where modprobe can find them (you may need to be root to do
 991           this).
 992
 993           If unsure, say Y.
 994
 995 if MODULES
 996
 997 config MODULE_FORCE_LOAD
 998         bool "Forced module loading"
 999         default n
1000         help
1001           Allow loading of modules without version information (ie. modprobe
1002           --force).  Forced module loading sets the 'F' (forced) taint flag and
1003           is usually a really bad idea.
1004
1005 config MODULE_UNLOAD
1006         bool "Module unloading"
1007         help
1008           Without this option you will not be able to unload any
1009           modules (note that some modules may not be unloadable
1010           anyway), which makes your kernel smaller, faster
1011           and simpler.  If unsure, say Y.
1012
1013 config MODULE_FORCE_UNLOAD
1014         bool "Forced module unloading"
1015         depends on MODULE_UNLOAD && EXPERIMENTAL
1016         help
1017           This option allows you to force a module to unload, even if the
1018           kernel believes it is unsafe: the kernel will remove the module
1019           without waiting for anyone to stop using it (using the -f option to
1020           rmmod).  This is mainly for kernel developers and desperate users.
1021           If unsure, say N.
1022
1023 config MODVERSIONS
1024         bool "Module versioning support"
1025         help
1026           Usually, you have to use modules compiled with your kernel.
1027           Saying Y here makes it sometimes possible to use modules
1028           compiled for different kernels, by adding enough information
1029           to the modules to (hopefully) spot any changes which would
1030           make them incompatible with the kernel you are running.  If
1031           unsure, say N.
1032
1033 config MODULE_SRCVERSION_ALL
1034         bool "Source checksum for all modules"
1035         help
1036           Modules which contain a MODULE_VERSION get an extra "srcversion"
1037           field inserted into their modinfo section, which contains a
1038           sum of the source files which made it.  This helps maintainers
1039           see exactly which source was used to build a module (since
1040           others sometimes change the module source without updating
1041           the version).  With this option, such a "srcversion" field
1042           will be created for all modules.  If unsure, say N.
1043
1044 endif # MODULES
1045
1046 config INIT_ALL_POSSIBLE
1047         bool
1048         help
1049           Back when each arch used to define their own cpu_online_map and
1050           cpu_possible_map, some of them chose to initialize cpu_possible_map
1051           with all 1s, and others with all 0s.  When they were centralised,
1052           it was better to provide this option than to break all the archs
1053           and have several arch maintainers persuing me down dark alleys.
1054
1055 config STOP_MACHINE
1056         bool
1057         default y
1058         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1059         help
1060           Need stop_machine() primitive.
1061
1062 source "block/Kconfig"
1063
1064 config PREEMPT_NOTIFIERS
1065         bool
1066