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  42           drivers that have been replaced by something else, and/or are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 HAVE_KERNEL_GZIP
 105         bool
 106
 107 config HAVE_KERNEL_BZIP2
 108         bool
 109
 110 config HAVE_KERNEL_LZMA
 111         bool
 112
 113 choice
 114         prompt "Kernel compression mode"
 115         default KERNEL_GZIP
 116         depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
 117         help
 118           The linux kernel is a kind of self-extracting executable.
 119           Several compression algorithms are available, which differ
 120           in efficiency, compression and decompression speed.
 121           Compression speed is only relevant when building a kernel.
 122           Decompression speed is relevant at each boot.
 123
 124           If you have any problems with bzip2 or lzma compressed
 125           kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 126           version of this functionality (bzip2 only), for 2.4, was
 127           supplied by Christian Ludwig)
 128
 129           High compression options are mostly useful for users, who
 130           are low on disk space (embedded systems), but for whom ram
 131           size matters less.
 132
 133           If in doubt, select 'gzip'
 134
 135 config KERNEL_GZIP
 136         bool "Gzip"
 137         depends on HAVE_KERNEL_GZIP
 138         help
 139           The old and tried gzip compression. Its compression ratio is
 140           the poorest among the 3 choices; however its speed (both
 141           compression and decompression) is the fastest.
 142
 143 config KERNEL_BZIP2
 144         bool "Bzip2"
 145         depends on HAVE_KERNEL_BZIP2
 146         help
 147           Its compression ratio and speed is intermediate.
 148           Decompression speed is slowest among the three.  The kernel
 149           size is about 10% smaller with bzip2, in comparison to gzip.
 150           Bzip2 uses a large amount of memory. For modern kernels you
 151           will need at least 8MB RAM or more for booting.
 152
 153 config KERNEL_LZMA
 154         bool "LZMA"
 155         depends on HAVE_KERNEL_LZMA
 156         help
 157           The most recent compression algorithm.
 158           Its ratio is best, decompression speed is between the other
 159           two. Compression is slowest.  The kernel size is about 33%
 160           smaller with LZMA in comparison to gzip.
 161
 162 endchoice
 163
 164 config SWAP
 165         bool "Support for paging of anonymous memory (swap)"
 166         depends on MMU && BLOCK
 167         default y
 168         help
 169           This option allows you to choose whether you want to have support
 170           for so called swap devices or swap files in your kernel that are
 171           used to provide more virtual memory than the actual RAM present
 172           in your computer.  If unsure say Y.
 173
 174 config SYSVIPC
 175         bool "System V IPC"
 176         ---help---
 177           Inter Process Communication is a suite of library functions and
 178           system calls which let processes (running programs) synchronize and
 179           exchange information. It is generally considered to be a good thing,
 180           and some programs won't run unless you say Y here. In particular, if
 181           you want to run the DOS emulator dosemu under Linux (read the
 182           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 183           you'll need to say Y here.
 184
 185           You can find documentation about IPC with "info ipc" and also in
 186           section 6.4 of the Linux Programmer's Guide, available from
 187           <http://www.tldp.org/guides.html>.
 188
 189 config SYSVIPC_SYSCTL
 190         bool
 191         depends on SYSVIPC
 192         depends on SYSCTL
 193         default y
 194
 195 config POSIX_MQUEUE
 196         bool "POSIX Message Queues"
 197         depends on NET && EXPERIMENTAL
 198         ---help---
 199           POSIX variant of message queues is a part of IPC. In POSIX message
 200           queues every message has a priority which decides about succession
 201           of receiving it by a process. If you want to compile and run
 202           programs written e.g. for Solaris with use of its POSIX message
 203           queues (functions mq_*) say Y here.
 204
 205           POSIX message queues are visible as a filesystem called 'mqueue'
 206           and can be mounted somewhere if you want to do filesystem
 207           operations on message queues.
 208
 209           If unsure, say Y.
 210
 211 config BSD_PROCESS_ACCT
 212         bool "BSD Process Accounting"
 213         help
 214           If you say Y here, a user level program will be able to instruct the
 215           kernel (via a special system call) to write process accounting
 216           information to a file: whenever a process exits, information about
 217           that process will be appended to the file by the kernel.  The
 218           information includes things such as creation time, owning user,
 219           command name, memory usage, controlling terminal etc. (the complete
 220           list is in the struct acct in <file:include/linux/acct.h>).  It is
 221           up to the user level program to do useful things with this
 222           information.  This is generally a good idea, so say Y.
 223
 224 config BSD_PROCESS_ACCT_V3
 225         bool "BSD Process Accounting version 3 file format"
 226         depends on BSD_PROCESS_ACCT
 227         default n
 228         help
 229           If you say Y here, the process accounting information is written
 230           in a new file format that also logs the process IDs of each
 231           process and it's parent. Note that this file format is incompatible
 232           with previous v0/v1/v2 file formats, so you will need updated tools
 233           for processing it. A preliminary version of these tools is available
 234           at <http://www.gnu.org/software/acct/>.
 235
 236 config TASKSTATS
 237         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 238         depends on NET
 239         default n
 240         help
 241           Export selected statistics for tasks/processes through the
 242           generic netlink interface. Unlike BSD process accounting, the
 243           statistics are available during the lifetime of tasks/processes as
 244           responses to commands. Like BSD accounting, they are sent to user
 245           space on task exit.
 246
 247           Say N if unsure.
 248
 249 config TASK_DELAY_ACCT
 250         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 251         depends on TASKSTATS
 252         help
 253           Collect information on time spent by a task waiting for system
 254           resources like cpu, synchronous block I/O completion and swapping
 255           in pages. Such statistics can help in setting a task's priorities
 256           relative to other tasks for cpu, io, rss limits etc.
 257
 258           Say N if unsure.
 259
 260 config TASK_XACCT
 261         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 262         depends on TASKSTATS
 263         help
 264           Collect extended task accounting data and send the data
 265           to userland for processing over the taskstats interface.
 266
 267           Say N if unsure.
 268
 269 config TASK_IO_ACCOUNTING
 270         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 271         depends on TASK_XACCT
 272         help
 273           Collect information on the number of bytes of storage I/O which this
 274           task has caused.
 275
 276           Say N if unsure.
 277
 278 config AUDIT
 279         bool "Auditing support"
 280         depends on NET
 281         help
 282           Enable auditing infrastructure that can be used with another
 283           kernel subsystem, such as SELinux (which requires this for
 284           logging of avc messages output).  Does not do system-call
 285           auditing without CONFIG_AUDITSYSCALL.
 286
 287 config AUDITSYSCALL
 288         bool "Enable system-call auditing support"
 289         depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
 290         default y if SECURITY_SELINUX
 291         help
 292           Enable low-overhead system-call auditing infrastructure that
 293           can be used independently or with another kernel subsystem,
 294           such as SELinux.  To use audit's filesystem watch feature, please
 295           ensure that INOTIFY is configured.
 296
 297 config AUDIT_TREE
 298         def_bool y
 299         depends on AUDITSYSCALL && INOTIFY
 300
 301 menu "RCU Subsystem"
 302
 303 choice
 304         prompt "RCU Implementation"
 305         default CLASSIC_RCU
 306
 307 config CLASSIC_RCU
 308         bool "Classic RCU"
 309         help
 310           This option selects the classic RCU implementation that is
 311           designed for best read-side performance on non-realtime
 312           systems.
 313
 314           Select this option if you are unsure.
 315
 316 config TREE_RCU
 317         bool "Tree-based hierarchical RCU"
 318         help
 319           This option selects the RCU implementation that is
 320           designed for very large SMP system with hundreds or
 321           thousands of CPUs.
 322
 323 config PREEMPT_RCU
 324         bool "Preemptible RCU"
 325         depends on PREEMPT
 326         help
 327           This option reduces the latency of the kernel by making certain
 328           RCU sections preemptible. Normally RCU code is non-preemptible, if
 329           this option is selected then read-only RCU sections become
 330           preemptible. This helps latency, but may expose bugs due to
 331           now-naive assumptions about each RCU read-side critical section
 332           remaining on a given CPU through its execution.
 333
 334 endchoice
 335
 336 config RCU_TRACE
 337         bool "Enable tracing for RCU"
 338         depends on TREE_RCU || PREEMPT_RCU
 339         help
 340           This option provides tracing in RCU which presents stats
 341           in debugfs for debugging RCU implementation.
 342
 343           Say Y here if you want to enable RCU tracing
 344           Say N if you are unsure.
 345
 346 config RCU_FANOUT
 347         int "Tree-based hierarchical RCU fanout value"
 348         range 2 64 if 64BIT
 349         range 2 32 if !64BIT
 350         depends on TREE_RCU
 351         default 64 if 64BIT
 352         default 32 if !64BIT
 353         help
 354           This option controls the fanout of hierarchical implementations
 355           of RCU, allowing RCU to work efficiently on machines with
 356           large numbers of CPUs.  This value must be at least the cube
 357           root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
 358           systems and up to 262,144 for 64-bit systems.
 359
 360           Select a specific number if testing RCU itself.
 361           Take the default if unsure.
 362
 363 config RCU_FANOUT_EXACT
 364         bool "Disable tree-based hierarchical RCU auto-balancing"
 365         depends on TREE_RCU
 366         default n
 367         help
 368           This option forces use of the exact RCU_FANOUT value specified,
 369           regardless of imbalances in the hierarchy.  This is useful for
 370           testing RCU itself, and might one day be useful on systems with
 371           strong NUMA behavior.
 372
 373           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 374
 375           Say N if unsure.
 376
 377 config TREE_RCU_TRACE
 378         def_bool RCU_TRACE && TREE_RCU
 379         select DEBUG_FS
 380         help
 381           This option provides tracing for the TREE_RCU implementation,
 382           permitting Makefile to trivially select kernel/rcutree_trace.c.
 383
 384 config PREEMPT_RCU_TRACE
 385         def_bool RCU_TRACE && PREEMPT_RCU
 386         select DEBUG_FS
 387         help
 388           This option provides tracing for the PREEMPT_RCU implementation,
 389           permitting Makefile to trivially select kernel/rcupreempt_trace.c.
 390
 391 endmenu # "RCU Subsystem"
 392
 393 config IKCONFIG
 394         tristate "Kernel .config support"
 395         ---help---
 396           This option enables the complete Linux kernel ".config" file
 397           contents to be saved in the kernel. It provides documentation
 398           of which kernel options are used in a running kernel or in an
 399           on-disk kernel.  This information can be extracted from the kernel
 400           image file with the script scripts/extract-ikconfig and used as
 401           input to rebuild the current kernel or to build another kernel.
 402           It can also be extracted from a running kernel by reading
 403           /proc/config.gz if enabled (below).
 404
 405 config IKCONFIG_PROC
 406         bool "Enable access to .config through /proc/config.gz"
 407         depends on IKCONFIG && PROC_FS
 408         ---help---
 409           This option enables access to the kernel configuration file
 410           through /proc/config.gz.
 411
 412 config LOG_BUF_SHIFT
 413         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 414         range 12 21
 415         default 17
 416         help
 417           Select kernel log buffer size as a power of 2.
 418           Examples:
 419                      17 => 128 KB
 420                      16 => 64 KB
 421                      15 => 32 KB
 422                      14 => 16 KB
 423                      13 =>  8 KB
 424                      12 =>  4 KB
 425
 426 #
 427 # Architectures with an unreliable sched_clock() should select this:
 428 #
 429 config HAVE_UNSTABLE_SCHED_CLOCK
 430         bool
 431
 432 config GROUP_SCHED
 433         bool "Group CPU scheduler"
 434         depends on EXPERIMENTAL
 435         default n
 436         help
 437           This feature lets CPU scheduler recognize task groups and control CPU
 438           bandwidth allocation to such task groups.
 439           In order to create a group from arbitrary set of processes, use
 440           CONFIG_CGROUPS. (See Control Group support.)
 441
 442 config FAIR_GROUP_SCHED
 443         bool "Group scheduling for SCHED_OTHER"
 444         depends on GROUP_SCHED
 445         default GROUP_SCHED
 446
 447 config RT_GROUP_SCHED
 448         bool "Group scheduling for SCHED_RR/FIFO"
 449         depends on EXPERIMENTAL
 450         depends on GROUP_SCHED
 451         default n
 452         help
 453           This feature lets you explicitly allocate real CPU bandwidth
 454           to users or control groups (depending on the "Basis for grouping tasks"
 455           setting below. If enabled, it will also make it impossible to
 456           schedule realtime tasks for non-root users until you allocate
 457           realtime bandwidth for them.
 458           See Documentation/scheduler/sched-rt-group.txt for more information.
 459
 460 choice
 461         depends on GROUP_SCHED
 462         prompt "Basis for grouping tasks"
 463         default USER_SCHED
 464
 465 config USER_SCHED
 466         bool "user id"
 467         help
 468           This option will choose userid as the basis for grouping
 469           tasks, thus providing equal CPU bandwidth to each user.
 470
 471 config CGROUP_SCHED
 472         bool "Control groups"
 473         depends on CGROUPS
 474         help
 475           This option allows you to create arbitrary task groups
 476           using the "cgroup" pseudo filesystem and control
 477           the cpu bandwidth allocated to each such task group.
 478           Refer to Documentation/cgroups/cgroups.txt for more
 479           information on "cgroup" pseudo filesystem.
 480
 481 endchoice
 482
 483 menuconfig CGROUPS
 484         boolean "Control Group support"
 485         help
 486           This option adds support for grouping sets of processes together, for
 487           use with process control subsystems such as Cpusets, CFS, memory
 488           controls or device isolation.
 489           See
 490                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 491                 - Documentation/cgroups/ (features for grouping, isolation
 492                                           and resource control)
 493
 494           Say N if unsure.
 495
 496 if CGROUPS
 497
 498 config CGROUP_DEBUG
 499         bool "Example debug cgroup subsystem"
 500         depends on CGROUPS
 501         default n
 502         help
 503           This option enables a simple cgroup subsystem that
 504           exports useful debugging information about the cgroups
 505           framework.
 506
 507           Say N if unsure.
 508
 509 config CGROUP_NS
 510         bool "Namespace cgroup subsystem"
 511         depends on CGROUPS
 512         help
 513           Provides a simple namespace cgroup subsystem to
 514           provide hierarchical naming of sets of namespaces,
 515           for instance virtual servers and checkpoint/restart
 516           jobs.
 517
 518 config CGROUP_FREEZER
 519         bool "Freezer cgroup subsystem"
 520         depends on CGROUPS
 521         help
 522           Provides a way to freeze and unfreeze all tasks in a
 523           cgroup.
 524
 525 config CGROUP_DEVICE
 526         bool "Device controller for cgroups"
 527         depends on CGROUPS && EXPERIMENTAL
 528         help
 529           Provides a cgroup implementing whitelists for devices which
 530           a process in the cgroup can mknod or open.
 531
 532 config CPUSETS
 533         bool "Cpuset support"
 534         depends on CGROUPS
 535         help
 536           This option will let you create and manage CPUSETs which
 537           allow dynamically partitioning a system into sets of CPUs and
 538           Memory Nodes and assigning tasks to run only within those sets.
 539           This is primarily useful on large SMP or NUMA systems.
 540
 541           Say N if unsure.
 542
 543 config PROC_PID_CPUSET
 544         bool "Include legacy /proc/<pid>/cpuset file"
 545         depends on CPUSETS
 546         default y
 547
 548 config CGROUP_CPUACCT
 549         bool "Simple CPU accounting cgroup subsystem"
 550         depends on CGROUPS
 551         help
 552           Provides a simple Resource Controller for monitoring the
 553           total CPU consumed by the tasks in a cgroup.
 554
 555 config RESOURCE_COUNTERS
 556         bool "Resource counters"
 557         help
 558           This option enables controller independent resource accounting
 559           infrastructure that works with cgroups.
 560         depends on CGROUPS
 561
 562 config CGROUP_MEM_RES_CTLR
 563         bool "Memory Resource Controller for Control Groups"
 564         depends on CGROUPS && RESOURCE_COUNTERS
 565         select MM_OWNER
 566         help
 567           Provides a memory resource controller that manages both anonymous
 568           memory and page cache. (See Documentation/cgroups/memory.txt)
 569
 570           Note that setting this option increases fixed memory overhead
 571           associated with each page of memory in the system. By this,
 572           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 573           usage tracking struct at boot. Total amount of this is printed out
 574           at boot.
 575
 576           Only enable when you're ok with these trade offs and really
 577           sure you need the memory resource controller. Even when you enable
 578           this, you can set "cgroup_disable=memory" at your boot option to
 579           disable memory resource controller and you can avoid overheads.
 580           (and lose benefits of memory resource controller)
 581
 582           This config option also selects MM_OWNER config option, which
 583           could in turn add some fork/exit overhead.
 584
 585 config CGROUP_MEM_RES_CTLR_SWAP
 586         bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
 587         depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
 588         help
 589           Add swap management feature to memory resource controller. When you
 590           enable this, you can limit mem+swap usage per cgroup. In other words,
 591           when you disable this, memory resource controller has no cares to
 592           usage of swap...a process can exhaust all of the swap. This extension
 593           is useful when you want to avoid exhaustion swap but this itself
 594           adds more overheads and consumes memory for remembering information.
 595           Especially if you use 32bit system or small memory system, please
 596           be careful about enabling this. When memory resource controller
 597           is disabled by boot option, this will be automatically disabled and
 598           there will be no overhead from this. Even when you set this config=y,
 599           if boot option "noswapaccount" is set, swap will not be accounted.
 600           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 601           size is 4096bytes, 512k per 1Gbytes of swap.
 602
 603 endif # CGROUPS
 604
 605 config MM_OWNER
 606         bool
 607
 608 config SYSFS_DEPRECATED
 609         bool
 610
 611 config SYSFS_DEPRECATED_V2
 612         bool "Create deprecated sysfs layout for older userspace tools"
 613         depends on SYSFS
 614         default y
 615         select SYSFS_DEPRECATED
 616         help
 617           This option switches the layout of sysfs to the deprecated
 618           version.
 619
 620           The current sysfs layout features a unified device tree at
 621           /sys/devices/, which is able to express a hierarchy between
 622           class devices. If the deprecated option is set to Y, the
 623           unified device tree is split into a bus device tree at
 624           /sys/devices/ and several individual class device trees at
 625           /sys/class/. The class and bus devices will be connected by
 626           "<subsystem>:<name>" and the "device" links. The "block"
 627           class devices, will not show up in /sys/class/block/. Some
 628           subsystems will suppress the creation of some devices which
 629           depend on the unified device tree.
 630
 631           This option is not a pure compatibility option that can
 632           be safely enabled on newer distributions. It will change the
 633           layout of sysfs to the non-extensible deprecated version,
 634           and disable some features, which can not be exported without
 635           confusing older userspace tools. Since 2007/2008 all major
 636           distributions do not enable this option, and ship no tools which
 637           depend on the deprecated layout or this option.
 638
 639           If you are using a new kernel on an older distribution, or use
 640           older userspace tools, you might need to say Y here. Do not say Y,
 641           if the original kernel, that came with your distribution, has
 642           this option set to N.
 643
 644 config RELAY
 645         bool "Kernel->user space relay support (formerly relayfs)"
 646         help
 647           This option enables support for relay interface support in
 648           certain file systems (such as debugfs).
 649           It is designed to provide an efficient mechanism for tools and
 650           facilities to relay large amounts of data from kernel space to
 651           user space.
 652
 653           If unsure, say N.
 654
 655 config NAMESPACES
 656         bool "Namespaces support" if EMBEDDED
 657         default !EMBEDDED
 658         help
 659           Provides the way to make tasks work with different objects using
 660           the same id. For example same IPC id may refer to different objects
 661           or same user id or pid may refer to different tasks when used in
 662           different namespaces.
 663
 664 config UTS_NS
 665         bool "UTS namespace"
 666         depends on NAMESPACES
 667         help
 668           In this namespace tasks see different info provided with the
 669           uname() system call
 670
 671 config IPC_NS
 672         bool "IPC namespace"
 673         depends on NAMESPACES && SYSVIPC
 674         help
 675           In this namespace tasks work with IPC ids which correspond to
 676           different IPC objects in different namespaces
 677
 678 config USER_NS
 679         bool "User namespace (EXPERIMENTAL)"
 680         depends on NAMESPACES && EXPERIMENTAL
 681         help
 682           This allows containers, i.e. vservers, to use user namespaces
 683           to provide different user info for different servers.
 684           If unsure, say N.
 685
 686 config PID_NS
 687         bool "PID Namespaces (EXPERIMENTAL)"
 688         default n
 689         depends on NAMESPACES && EXPERIMENTAL
 690         help
 691           Support process id namespaces.  This allows having multiple
 692           processes with the same pid as long as they are in different
 693           pid namespaces.  This is a building block of containers.
 694
 695           Unless you want to work with an experimental feature
 696           say N here.
 697
 698 config NET_NS
 699         bool "Network namespace"
 700         default n
 701         depends on NAMESPACES && EXPERIMENTAL && NET
 702         help
 703           Allow user space to create what appear to be multiple instances
 704           of the network stack.
 705
 706 config BLK_DEV_INITRD
 707         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 708         depends on BROKEN || !FRV
 709         help
 710           The initial RAM filesystem is a ramfs which is loaded by the
 711           boot loader (loadlin or lilo) and that is mounted as root
 712           before the normal boot procedure. It is typically used to
 713           load modules needed to mount the "real" root file system,
 714           etc. See <file:Documentation/initrd.txt> for details.
 715
 716           If RAM disk support (BLK_DEV_RAM) is also included, this
 717           also enables initial RAM disk (initrd) support and adds
 718           15 Kbytes (more on some other architectures) to the kernel size.
 719
 720           If unsure say Y.
 721
 722 if BLK_DEV_INITRD
 723
 724 source "usr/Kconfig"
 725
 726 endif
 727
 728 config CC_OPTIMIZE_FOR_SIZE
 729         bool "Optimize for size"
 730         default y
 731         help
 732           Enabling this option will pass "-Os" instead of "-O2" to gcc
 733           resulting in a smaller kernel.
 734
 735           If unsure, say Y.
 736
 737 config SYSCTL
 738         bool
 739
 740 config ANON_INODES
 741         bool
 742
 743 menuconfig EMBEDDED
 744         bool "Configure standard kernel features (for small systems)"
 745         help
 746           This option allows certain base kernel options and settings
 747           to be disabled or tweaked. This is for specialized
 748           environments which can tolerate a "non-standard" kernel.
 749           Only use this if you really know what you are doing.
 750
 751 config UID16
 752         bool "Enable 16-bit UID system calls" if EMBEDDED
 753         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 754         default y
 755         help
 756           This enables the legacy 16-bit UID syscall wrappers.
 757
 758 config SYSCTL_SYSCALL
 759         bool "Sysctl syscall support" if EMBEDDED
 760         default y
 761         select SYSCTL
 762         ---help---
 763           sys_sysctl uses binary paths that have been found challenging
 764           to properly maintain and use.  The interface in /proc/sys
 765           using paths with ascii names is now the primary path to this
 766           information.
 767
 768           Almost nothing using the binary sysctl interface so if you are
 769           trying to save some space it is probably safe to disable this,
 770           making your kernel marginally smaller.
 771
 772           If unsure say Y here.
 773
 774 config KALLSYMS
 775          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 776          default y
 777          help
 778            Say Y here to let the kernel print out symbolic crash information and
 779            symbolic stack backtraces. This increases the size of the kernel
 780            somewhat, as all symbols have to be loaded into the kernel image.
 781
 782 config KALLSYMS_ALL
 783         bool "Include all symbols in kallsyms"
 784         depends on DEBUG_KERNEL && KALLSYMS
 785         help
 786            Normally kallsyms only contains the symbols of functions, for nicer
 787            OOPS messages.  Some debuggers can use kallsyms for other
 788            symbols too: say Y here to include all symbols, if you need them
 789            and you don't care about adding 300k to the size of your kernel.
 790
 791            Say N.
 792
 793 config KALLSYMS_EXTRA_PASS
 794         bool "Do an extra kallsyms pass"
 795         depends on KALLSYMS
 796         help
 797            If kallsyms is not working correctly, the build will fail with
 798            inconsistent kallsyms data.  If that occurs, log a bug report and
 799            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 800            Always say N here unless you find a bug in kallsyms, which must be
 801            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 802            you wait for kallsyms to be fixed.
 803
 804
 805 config HOTPLUG
 806         bool "Support for hot-pluggable devices" if EMBEDDED
 807         default y
 808         help
 809           This option is provided for the case where no hotplug or uevent
 810           capabilities is wanted by the kernel.  You should only consider
 811           disabling this option for embedded systems that do not use modules, a
 812           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 813
 814 config PRINTK
 815         default y
 816         bool "Enable support for printk" if EMBEDDED
 817         help
 818           This option enables normal printk support. Removing it
 819           eliminates most of the message strings from the kernel image
 820           and makes the kernel more or less silent. As this makes it
 821           very difficult to diagnose system problems, saying N here is
 822           strongly discouraged.
 823
 824 config BUG
 825         bool "BUG() support" if EMBEDDED
 826         default y
 827         help
 828           Disabling this option eliminates support for BUG and WARN, reducing
 829           the size of your kernel image and potentially quietly ignoring
 830           numerous fatal conditions. You should only consider disabling this
 831           option for embedded systems with no facilities for reporting errors.
 832           Just say Y.
 833
 834 config ELF_CORE
 835         default y
 836         bool "Enable ELF core dumps" if EMBEDDED
 837         help
 838           Enable support for generating core dumps. Disabling saves about 4k.
 839
 840 config PCSPKR_PLATFORM
 841         bool "Enable PC-Speaker support" if EMBEDDED
 842         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 843         default y
 844         help
 845           This option allows to disable the internal PC-Speaker
 846           support, saving some memory.
 847
 848 config BASE_FULL
 849         default y
 850         bool "Enable full-sized data structures for core" if EMBEDDED
 851         help
 852           Disabling this option reduces the size of miscellaneous core
 853           kernel data structures. This saves memory on small machines,
 854           but may reduce performance.
 855
 856 config FUTEX
 857         bool "Enable futex support" if EMBEDDED
 858         default y
 859         select RT_MUTEXES
 860         help
 861           Disabling this option will cause the kernel to be built without
 862           support for "fast userspace mutexes".  The resulting kernel may not
 863           run glibc-based applications correctly.
 864
 865 config EPOLL
 866         bool "Enable eventpoll support" if EMBEDDED
 867         default y
 868         select ANON_INODES
 869         help
 870           Disabling this option will cause the kernel to be built without
 871           support for epoll family of system calls.
 872
 873 config SIGNALFD
 874         bool "Enable signalfd() system call" if EMBEDDED
 875         select ANON_INODES
 876         default y
 877         help
 878           Enable the signalfd() system call that allows to receive signals
 879           on a file descriptor.
 880
 881           If unsure, say Y.
 882
 883 config TIMERFD
 884         bool "Enable timerfd() system call" if EMBEDDED
 885         select ANON_INODES
 886         default y
 887         help
 888           Enable the timerfd() system call that allows to receive timer
 889           events on a file descriptor.
 890
 891           If unsure, say Y.
 892
 893 config EVENTFD
 894         bool "Enable eventfd() system call" if EMBEDDED
 895         select ANON_INODES
 896         default y
 897         help
 898           Enable the eventfd() system call that allows to receive both
 899           kernel notification (ie. KAIO) or userspace notifications.
 900
 901           If unsure, say Y.
 902
 903 config SHMEM
 904         bool "Use full shmem filesystem" if EMBEDDED
 905         default y
 906         depends on MMU
 907         help
 908           The shmem is an internal filesystem used to manage shared memory.
 909           It is backed by swap and manages resource limits. It is also exported
 910           to userspace as tmpfs if TMPFS is enabled. Disabling this
 911           option replaces shmem and tmpfs with the much simpler ramfs code,
 912           which may be appropriate on small systems without swap.
 913
 914 config AIO
 915         bool "Enable AIO support" if EMBEDDED
 916         default y
 917         help
 918           This option enables POSIX asynchronous I/O which may by used
 919           by some high performance threaded applications. Disabling
 920           this option saves about 7k.
 921
 922 config VM_EVENT_COUNTERS
 923         default y
 924         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 925         help
 926           VM event counters are needed for event counts to be shown.
 927           This option allows the disabling of the VM event counters
 928           on EMBEDDED systems.  /proc/vmstat will only show page counts
 929           if VM event counters are disabled.
 930
 931 config PCI_QUIRKS
 932         default y
 933         bool "Enable PCI quirk workarounds" if EMBEDDED
 934         depends on PCI
 935         help
 936           This enables workarounds for various PCI chipset
 937           bugs/quirks. Disable this only if your target machine is
 938           unaffected by PCI quirks.
 939
 940 config SLUB_DEBUG
 941         default y
 942         bool "Enable SLUB debugging support" if EMBEDDED
 943         depends on SLUB && SYSFS
 944         help
 945           SLUB has extensive debug support features. Disabling these can
 946           result in significant savings in code size. This also disables
 947           SLUB sysfs support. /sys/slab will not exist and there will be
 948           no support for cache validation etc.
 949
 950 config COMPAT_BRK
 951         bool "Disable heap randomization"
 952         default y
 953         help
 954           Randomizing heap placement makes heap exploits harder, but it
 955           also breaks ancient binaries (including anything libc5 based).
 956           This option changes the bootup default to heap randomization
 957           disabled, and can be overridden at runtime by setting
 958           /proc/sys/kernel/randomize_va_space to 2.
 959
 960           On non-ancient distros (post-2000 ones) N is usually a safe choice.
 961
 962 choice
 963         prompt "Choose SLAB allocator"
 964         default SLUB
 965         help
 966            This option allows to select a slab allocator.
 967
 968 config SLAB
 969         bool "SLAB"
 970         help
 971           The regular slab allocator that is established and known to work
 972           well in all environments. It organizes cache hot objects in
 973           per cpu and per node queues.
 974
 975 config SLUB
 976         bool "SLUB (Unqueued Allocator)"
 977         help
 978            SLUB is a slab allocator that minimizes cache line usage
 979            instead of managing queues of cached objects (SLAB approach).
 980            Per cpu caching is realized using slabs of objects instead
 981            of queues of objects. SLUB can use memory efficiently
 982            and has enhanced diagnostics. SLUB is the default choice for
 983            a slab allocator.
 984
 985 config SLOB
 986         depends on EMBEDDED
 987         bool "SLOB (Simple Allocator)"
 988         help
 989            SLOB replaces the stock allocator with a drastically simpler
 990            allocator. SLOB is generally more space efficient but
 991            does not perform as well on large systems.
 992
 993 endchoice
 994
 995 config PROFILING
 996         bool "Profiling support (EXPERIMENTAL)"
 997         help
 998           Say Y here to enable the extended profiling support mechanisms used
 999           by profilers such as OProfile.
1000
1001 #
1002 # Place an empty function call at each tracepoint site. Can be
1003 # dynamically changed for a probe function.
1004 #
1005 config TRACEPOINTS
1006         bool
1007
1008 config MARKERS
1009         bool "Activate markers"
1010         depends on TRACEPOINTS
1011         help
1012           Place an empty function call at each marker site. Can be
1013           dynamically changed for a probe function.
1014
1015 source "arch/Kconfig"
1016
1017 config SLOW_WORK
1018         default n
1019         bool "Enable slow work thread pool"
1020         help
1021           The slow work thread pool provides a number of dynamically allocated
1022           threads that can be used by the kernel to perform operations that
1023           take a relatively long time.
1024
1025           An example of this would be CacheFiles doing a path lookup followed
1026           by a series of mkdirs and a create call, all of which have to touch
1027           disk.
1028
1029 endmenu         # General setup
1030
1031 config HAVE_GENERIC_DMA_COHERENT
1032         bool
1033         default n
1034
1035 config SLABINFO
1036         bool
1037         depends on PROC_FS
1038         depends on SLAB || SLUB_DEBUG
1039         default y
1040
1041 config RT_MUTEXES
1042         boolean
1043
1044 config BASE_SMALL
1045         int
1046         default 0 if BASE_FULL
1047         default 1 if !BASE_FULL
1048
1049 menuconfig MODULES
1050         bool "Enable loadable module support"
1051         help
1052           Kernel modules are small pieces of compiled code which can
1053           be inserted in the running kernel, rather than being
1054           permanently built into the kernel.  You use the "modprobe"
1055           tool to add (and sometimes remove) them.  If you say Y here,
1056           many parts of the kernel can be built as modules (by
1057           answering M instead of Y where indicated): this is most
1058           useful for infrequently used options which are not required
1059           for booting.  For more information, see the man pages for
1060           modprobe, lsmod, modinfo, insmod and rmmod.
1061
1062           If you say Y here, you will need to run "make
1063           modules_install" to put the modules under /lib/modules/
1064           where modprobe can find them (you may need to be root to do
1065           this).
1066
1067           If unsure, say Y.
1068
1069 if MODULES
1070
1071 config MODULE_FORCE_LOAD
1072         bool "Forced module loading"
1073         default n
1074         help
1075           Allow loading of modules without version information (ie. modprobe
1076           --force).  Forced module loading sets the 'F' (forced) taint flag and
1077           is usually a really bad idea.
1078
1079 config MODULE_UNLOAD
1080         bool "Module unloading"
1081         help
1082           Without this option you will not be able to unload any
1083           modules (note that some modules may not be unloadable
1084           anyway), which makes your kernel smaller, faster
1085           and simpler.  If unsure, say Y.
1086
1087 config MODULE_FORCE_UNLOAD
1088         bool "Forced module unloading"
1089         depends on MODULE_UNLOAD && EXPERIMENTAL
1090         help
1091           This option allows you to force a module to unload, even if the
1092           kernel believes it is unsafe: the kernel will remove the module
1093           without waiting for anyone to stop using it (using the -f option to
1094           rmmod).  This is mainly for kernel developers and desperate users.
1095           If unsure, say N.
1096
1097 config MODVERSIONS
1098         bool "Module versioning support"
1099         help
1100           Usually, you have to use modules compiled with your kernel.
1101           Saying Y here makes it sometimes possible to use modules
1102           compiled for different kernels, by adding enough information
1103           to the modules to (hopefully) spot any changes which would
1104           make them incompatible with the kernel you are running.  If
1105           unsure, say N.
1106
1107 config MODULE_SRCVERSION_ALL
1108         bool "Source checksum for all modules"
1109         help
1110           Modules which contain a MODULE_VERSION get an extra "srcversion"
1111           field inserted into their modinfo section, which contains a
1112           sum of the source files which made it.  This helps maintainers
1113           see exactly which source was used to build a module (since
1114           others sometimes change the module source without updating
1115           the version).  With this option, such a "srcversion" field
1116           will be created for all modules.  If unsure, say N.
1117
1118 endif # MODULES
1119
1120 config INIT_ALL_POSSIBLE
1121         bool
1122         help
1123           Back when each arch used to define their own cpu_online_map and
1124           cpu_possible_map, some of them chose to initialize cpu_possible_map
1125           with all 1s, and others with all 0s.  When they were centralised,
1126           it was better to provide this option than to break all the archs
1127           and have several arch maintainers pursuing me down dark alleys.
1128
1129 config STOP_MACHINE
1130         bool
1131         default y
1132         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1133         help
1134           Need stop_machine() primitive.
1135
1136 source "block/Kconfig"
1137
1138 config PREEMPT_NOTIFIERS
1139         bool
1140