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  42           drivers that have been replaced by something else, and/or are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 NET_NS
 637         bool "Network namespace"
 638         default n
 639         depends on NAMESPACES && EXPERIMENTAL && NET
 640         help
 641           Allow user space to create what appear to be multiple instances
 642           of the network stack.
 643
 644 config BLK_DEV_INITRD
 645         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 646         depends on BROKEN || !FRV
 647         help
 648           The initial RAM filesystem is a ramfs which is loaded by the
 649           boot loader (loadlin or lilo) and that is mounted as root
 650           before the normal boot procedure. It is typically used to
 651           load modules needed to mount the "real" root file system,
 652           etc. See <file:Documentation/initrd.txt> for details.
 653
 654           If RAM disk support (BLK_DEV_RAM) is also included, this
 655           also enables initial RAM disk (initrd) support and adds
 656           15 Kbytes (more on some other architectures) to the kernel size.
 657
 658           If unsure say Y.
 659
 660 if BLK_DEV_INITRD
 661
 662 source "usr/Kconfig"
 663
 664 endif
 665
 666 config CC_OPTIMIZE_FOR_SIZE
 667         bool "Optimize for size"
 668         default y
 669         help
 670           Enabling this option will pass "-Os" instead of "-O2" to gcc
 671           resulting in a smaller kernel.
 672
 673           If unsure, say Y.
 674
 675 config SYSCTL
 676         bool
 677
 678 config ANON_INODES
 679         bool
 680
 681 menuconfig EMBEDDED
 682         bool "Configure standard kernel features (for small systems)"
 683         help
 684           This option allows certain base kernel options and settings
 685           to be disabled or tweaked. This is for specialized
 686           environments which can tolerate a "non-standard" kernel.
 687           Only use this if you really know what you are doing.
 688
 689 config UID16
 690         bool "Enable 16-bit UID system calls" if EMBEDDED
 691         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 692         default y
 693         help
 694           This enables the legacy 16-bit UID syscall wrappers.
 695
 696 config SYSCTL_SYSCALL
 697         bool "Sysctl syscall support" if EMBEDDED
 698         default y
 699         select SYSCTL
 700         ---help---
 701           sys_sysctl uses binary paths that have been found challenging
 702           to properly maintain and use.  The interface in /proc/sys
 703           using paths with ascii names is now the primary path to this
 704           information.
 705
 706           Almost nothing using the binary sysctl interface so if you are
 707           trying to save some space it is probably safe to disable this,
 708           making your kernel marginally smaller.
 709
 710           If unsure say Y here.
 711
 712 config KALLSYMS
 713          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 714          default y
 715          help
 716            Say Y here to let the kernel print out symbolic crash information and
 717            symbolic stack backtraces. This increases the size of the kernel
 718            somewhat, as all symbols have to be loaded into the kernel image.
 719
 720 config KALLSYMS_ALL
 721         bool "Include all symbols in kallsyms"
 722         depends on DEBUG_KERNEL && KALLSYMS
 723         help
 724            Normally kallsyms only contains the symbols of functions, for nicer
 725            OOPS messages.  Some debuggers can use kallsyms for other
 726            symbols too: say Y here to include all symbols, if you need them
 727            and you don't care about adding 300k to the size of your kernel.
 728
 729            Say N.
 730
 731 config KALLSYMS_EXTRA_PASS
 732         bool "Do an extra kallsyms pass"
 733         depends on KALLSYMS
 734         help
 735            If kallsyms is not working correctly, the build will fail with
 736            inconsistent kallsyms data.  If that occurs, log a bug report and
 737            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 738            Always say N here unless you find a bug in kallsyms, which must be
 739            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 740            you wait for kallsyms to be fixed.
 741
 742
 743 config HOTPLUG
 744         bool "Support for hot-pluggable devices" if EMBEDDED
 745         default y
 746         help
 747           This option is provided for the case where no hotplug or uevent
 748           capabilities is wanted by the kernel.  You should only consider
 749           disabling this option for embedded systems that do not use modules, a
 750           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 751
 752 config PRINTK
 753         default y
 754         bool "Enable support for printk" if EMBEDDED
 755         help
 756           This option enables normal printk support. Removing it
 757           eliminates most of the message strings from the kernel image
 758           and makes the kernel more or less silent. As this makes it
 759           very difficult to diagnose system problems, saying N here is
 760           strongly discouraged.
 761
 762 config BUG
 763         bool "BUG() support" if EMBEDDED
 764         default y
 765         help
 766           Disabling this option eliminates support for BUG and WARN, reducing
 767           the size of your kernel image and potentially quietly ignoring
 768           numerous fatal conditions. You should only consider disabling this
 769           option for embedded systems with no facilities for reporting errors.
 770           Just say Y.
 771
 772 config ELF_CORE
 773         default y
 774         bool "Enable ELF core dumps" if EMBEDDED
 775         help
 776           Enable support for generating core dumps. Disabling saves about 4k.
 777
 778 config PCSPKR_PLATFORM
 779         bool "Enable PC-Speaker support" if EMBEDDED
 780         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 781         default y
 782         help
 783           This option allows to disable the internal PC-Speaker
 784           support, saving some memory.
 785
 786 config BASE_FULL
 787         default y
 788         bool "Enable full-sized data structures for core" if EMBEDDED
 789         help
 790           Disabling this option reduces the size of miscellaneous core
 791           kernel data structures. This saves memory on small machines,
 792           but may reduce performance.
 793
 794 config FUTEX
 795         bool "Enable futex support" if EMBEDDED
 796         default y
 797         select RT_MUTEXES
 798         help
 799           Disabling this option will cause the kernel to be built without
 800           support for "fast userspace mutexes".  The resulting kernel may not
 801           run glibc-based applications correctly.
 802
 803 config EPOLL
 804         bool "Enable eventpoll support" if EMBEDDED
 805         default y
 806         select ANON_INODES
 807         help
 808           Disabling this option will cause the kernel to be built without
 809           support for epoll family of system calls.
 810
 811 config SIGNALFD
 812         bool "Enable signalfd() system call" if EMBEDDED
 813         select ANON_INODES
 814         default y
 815         help
 816           Enable the signalfd() system call that allows to receive signals
 817           on a file descriptor.
 818
 819           If unsure, say Y.
 820
 821 config TIMERFD
 822         bool "Enable timerfd() system call" if EMBEDDED
 823         select ANON_INODES
 824         default y
 825         help
 826           Enable the timerfd() system call that allows to receive timer
 827           events on a file descriptor.
 828
 829           If unsure, say Y.
 830
 831 config EVENTFD
 832         bool "Enable eventfd() system call" if EMBEDDED
 833         select ANON_INODES
 834         default y
 835         help
 836           Enable the eventfd() system call that allows to receive both
 837           kernel notification (ie. KAIO) or userspace notifications.
 838
 839           If unsure, say Y.
 840
 841 config SHMEM
 842         bool "Use full shmem filesystem" if EMBEDDED
 843         default y
 844         depends on MMU
 845         help
 846           The shmem is an internal filesystem used to manage shared memory.
 847           It is backed by swap and manages resource limits. It is also exported
 848           to userspace as tmpfs if TMPFS is enabled. Disabling this
 849           option replaces shmem and tmpfs with the much simpler ramfs code,
 850           which may be appropriate on small systems without swap.
 851
 852 config AIO
 853         bool "Enable AIO support" if EMBEDDED
 854         default y
 855         help
 856           This option enables POSIX asynchronous I/O which may by used
 857           by some high performance threaded applications. Disabling
 858           this option saves about 7k.
 859
 860 config VM_EVENT_COUNTERS
 861         default y
 862         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 863         help
 864           VM event counters are needed for event counts to be shown.
 865           This option allows the disabling of the VM event counters
 866           on EMBEDDED systems.  /proc/vmstat will only show page counts
 867           if VM event counters are disabled.
 868
 869 config PCI_QUIRKS
 870         default y
 871         bool "Enable PCI quirk workarounds" if EMBEDDED
 872         depends on PCI
 873         help
 874           This enables workarounds for various PCI chipset
 875           bugs/quirks. Disable this only if your target machine is
 876           unaffected by PCI quirks.
 877
 878 config SLUB_DEBUG
 879         default y
 880         bool "Enable SLUB debugging support" if EMBEDDED
 881         depends on SLUB && SYSFS
 882         help
 883           SLUB has extensive debug support features. Disabling these can
 884           result in significant savings in code size. This also disables
 885           SLUB sysfs support. /sys/slab will not exist and there will be
 886           no support for cache validation etc.
 887
 888 config COMPAT_BRK
 889         bool "Disable heap randomization"
 890         default y
 891         help
 892           Randomizing heap placement makes heap exploits harder, but it
 893           also breaks ancient binaries (including anything libc5 based).
 894           This option changes the bootup default to heap randomization
 895           disabled, and can be overriden runtime by setting
 896           /proc/sys/kernel/randomize_va_space to 2.
 897
 898           On non-ancient distros (post-2000 ones) N is usually a safe choice.
 899
 900 choice
 901         prompt "Choose SLAB allocator"
 902         default SLUB
 903         help
 904            This option allows to select a slab allocator.
 905
 906 config SLAB
 907         bool "SLAB"
 908         help
 909           The regular slab allocator that is established and known to work
 910           well in all environments. It organizes cache hot objects in
 911           per cpu and per node queues.
 912
 913 config SLUB
 914         bool "SLUB (Unqueued Allocator)"
 915         help
 916            SLUB is a slab allocator that minimizes cache line usage
 917            instead of managing queues of cached objects (SLAB approach).
 918            Per cpu caching is realized using slabs of objects instead
 919            of queues of objects. SLUB can use memory efficiently
 920            and has enhanced diagnostics. SLUB is the default choice for
 921            a slab allocator.
 922
 923 config SLOB
 924         depends on EMBEDDED
 925         bool "SLOB (Simple Allocator)"
 926         help
 927            SLOB replaces the stock allocator with a drastically simpler
 928            allocator. SLOB is generally more space efficient but
 929            does not perform as well on large systems.
 930
 931 endchoice
 932
 933 config PROFILING
 934         bool "Profiling support (EXPERIMENTAL)"
 935         help
 936           Say Y here to enable the extended profiling support mechanisms used
 937           by profilers such as OProfile.
 938
 939 #
 940 # Place an empty function call at each tracepoint site. Can be
 941 # dynamically changed for a probe function.
 942 #
 943 config TRACEPOINTS
 944         bool
 945
 946 config MARKERS
 947         bool "Activate markers"
 948         depends on TRACEPOINTS
 949         help
 950           Place an empty function call at each marker site. Can be
 951           dynamically changed for a probe function.
 952
 953 source "arch/Kconfig"
 954
 955 endmenu         # General setup
 956
 957 config HAVE_GENERIC_DMA_COHERENT
 958         bool
 959         default n
 960
 961 config SLABINFO
 962         bool
 963         depends on PROC_FS
 964         depends on SLAB || SLUB_DEBUG
 965         default y
 966
 967 config RT_MUTEXES
 968         boolean
 969         select PLIST
 970
 971 config BASE_SMALL
 972         int
 973         default 0 if BASE_FULL
 974         default 1 if !BASE_FULL
 975
 976 menuconfig MODULES
 977         bool "Enable loadable module support"
 978         help
 979           Kernel modules are small pieces of compiled code which can
 980           be inserted in the running kernel, rather than being
 981           permanently built into the kernel.  You use the "modprobe"
 982           tool to add (and sometimes remove) them.  If you say Y here,
 983           many parts of the kernel can be built as modules (by
 984           answering M instead of Y where indicated): this is most
 985           useful for infrequently used options which are not required
 986           for booting.  For more information, see the man pages for
 987           modprobe, lsmod, modinfo, insmod and rmmod.
 988
 989           If you say Y here, you will need to run "make
 990           modules_install" to put the modules under /lib/modules/
 991           where modprobe can find them (you may need to be root to do
 992           this).
 993
 994           If unsure, say Y.
 995
 996 if MODULES
 997
 998 config MODULE_FORCE_LOAD
 999         bool "Forced module loading"
1000         default n
1001         help
1002           Allow loading of modules without version information (ie. modprobe
1003           --force).  Forced module loading sets the 'F' (forced) taint flag and
1004           is usually a really bad idea.
1005
1006 config MODULE_UNLOAD
1007         bool "Module unloading"
1008         help
1009           Without this option you will not be able to unload any
1010           modules (note that some modules may not be unloadable
1011           anyway), which makes your kernel smaller, faster
1012           and simpler.  If unsure, say Y.
1013
1014 config MODULE_FORCE_UNLOAD
1015         bool "Forced module unloading"
1016         depends on MODULE_UNLOAD && EXPERIMENTAL
1017         help
1018           This option allows you to force a module to unload, even if the
1019           kernel believes it is unsafe: the kernel will remove the module
1020           without waiting for anyone to stop using it (using the -f option to
1021           rmmod).  This is mainly for kernel developers and desperate users.
1022           If unsure, say N.
1023
1024 config MODVERSIONS
1025         bool "Module versioning support"
1026         help
1027           Usually, you have to use modules compiled with your kernel.
1028           Saying Y here makes it sometimes possible to use modules
1029           compiled for different kernels, by adding enough information
1030           to the modules to (hopefully) spot any changes which would
1031           make them incompatible with the kernel you are running.  If
1032           unsure, say N.
1033
1034 config MODULE_SRCVERSION_ALL
1035         bool "Source checksum for all modules"
1036         help
1037           Modules which contain a MODULE_VERSION get an extra "srcversion"
1038           field inserted into their modinfo section, which contains a
1039           sum of the source files which made it.  This helps maintainers
1040           see exactly which source was used to build a module (since
1041           others sometimes change the module source without updating
1042           the version).  With this option, such a "srcversion" field
1043           will be created for all modules.  If unsure, say N.
1044
1045 endif # MODULES
1046
1047 config INIT_ALL_POSSIBLE
1048         bool
1049         help
1050           Back when each arch used to define their own cpu_online_map and
1051           cpu_possible_map, some of them chose to initialize cpu_possible_map
1052           with all 1s, and others with all 0s.  When they were centralised,
1053           it was better to provide this option than to break all the archs
1054           and have several arch maintainers persuing me down dark alleys.
1055
1056 config STOP_MACHINE
1057         bool
1058         default y
1059         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1060         help
1061           Need stop_machine() primitive.
1062
1063 source "block/Kconfig"
1064
1065 config PREEMPT_NOTIFIERS
1066         bool
1067