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 config CONSTRUCTORS
  20         bool
  21         depends on !UML
  22         default y
  23
  24 menu "General setup"
  25
  26 config EXPERIMENTAL
  27         bool "Prompt for development and/or incomplete code/drivers"
  28         ---help---
  29           Some of the various things that Linux supports (such as network
  30           drivers, file systems, network protocols, etc.) can be in a state
  31           of development where the functionality, stability, or the level of
  32           testing is not yet high enough for general use. This is usually
  33           known as the "alpha-test" phase among developers. If a feature is
  34           currently in alpha-test, then the developers usually discourage
  35           uninformed widespread use of this feature by the general public to
  36           avoid "Why doesn't this work?" type mail messages. However, active
  37           testing and use of these systems is welcomed. Just be aware that it
  38           may not meet the normal level of reliability or it may fail to work
  39           in some special cases. Detailed bug reports from people familiar
  40           with the kernel internals are usually welcomed by the developers
  41           (before submitting bug reports, please read the documents
  42           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  43           <file:Documentation/BUG-HUNTING>, and
  44           <file:Documentation/oops-tracing.txt> in the kernel source).
  45
  46           This option will also make obsoleted drivers available. These are
  47           drivers that have been replaced by something else, and/or are
  48           scheduled to be removed in a future kernel release.
  49
  50           Unless you intend to help test and develop a feature or driver that
  51           falls into this category, or you have a situation that requires
  52           using these features, you should probably say N here, which will
  53           cause the configurator to present you with fewer choices. If
  54           you say Y here, you will be offered the choice of using features or
  55           drivers that are currently considered to be in the alpha-test phase.
  56
  57 config BROKEN
  58         bool
  59
  60 config BROKEN_ON_SMP
  61         bool
  62         depends on BROKEN || !SMP
  63         default y
  64
  65 config LOCK_KERNEL
  66         bool
  67         depends on SMP || PREEMPT
  68         default y
  69
  70 config INIT_ENV_ARG_LIMIT
  71         int
  72         default 32 if !UML
  73         default 128 if UML
  74         help
  75           Maximum of each of the number of arguments and environment
  76           variables passed to init from the kernel command line.
  77
  78
  79 config LOCALVERSION
  80         string "Local version - append to kernel release"
  81         help
  82           Append an extra string to the end of your kernel version.
  83           This will show up when you type uname, for example.
  84           The string you set here will be appended after the contents of
  85           any files with a filename matching localversion* in your
  86           object and source tree, in that order.  Your total string can
  87           be a maximum of 64 characters.
  88
  89 config LOCALVERSION_AUTO
  90         bool "Automatically append version information to the version string"
  91         default y
  92         help
  93           This will try to automatically determine if the current tree is a
  94           release tree by looking for git tags that belong to the current
  95           top of tree revision.
  96
  97           A string of the format -gxxxxxxxx will be added to the localversion
  98           if a git-based tree is found.  The string generated by this will be
  99           appended after any matching localversion* files, and after the value
 100           set in CONFIG_LOCALVERSION.
 101
 102           (The actual string used here is the first eight characters produced
 103           by running the command:
 104
 105             $ git rev-parse --verify HEAD
 106
 107           which is done within the script "scripts/setlocalversion".)
 108
 109 config HAVE_KERNEL_GZIP
 110         bool
 111
 112 config HAVE_KERNEL_BZIP2
 113         bool
 114
 115 config HAVE_KERNEL_LZMA
 116         bool
 117
 118 config HAVE_KERNEL_LZO
 119         bool
 120
 121 choice
 122         prompt "Kernel compression mode"
 123         default KERNEL_GZIP
 124         depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
 125         help
 126           The linux kernel is a kind of self-extracting executable.
 127           Several compression algorithms are available, which differ
 128           in efficiency, compression and decompression speed.
 129           Compression speed is only relevant when building a kernel.
 130           Decompression speed is relevant at each boot.
 131
 132           If you have any problems with bzip2 or lzma compressed
 133           kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 134           version of this functionality (bzip2 only), for 2.4, was
 135           supplied by Christian Ludwig)
 136
 137           High compression options are mostly useful for users, who
 138           are low on disk space (embedded systems), but for whom ram
 139           size matters less.
 140
 141           If in doubt, select 'gzip'
 142
 143 config KERNEL_GZIP
 144         bool "Gzip"
 145         depends on HAVE_KERNEL_GZIP
 146         help
 147           The old and tried gzip compression. It provides a good balance
 148           between compression ratio and decompression speed.
 149
 150 config KERNEL_BZIP2
 151         bool "Bzip2"
 152         depends on HAVE_KERNEL_BZIP2
 153         help
 154           Its compression ratio and speed is intermediate.
 155           Decompression speed is slowest among the three.  The kernel
 156           size is about 10% smaller with bzip2, in comparison to gzip.
 157           Bzip2 uses a large amount of memory. For modern kernels you
 158           will need at least 8MB RAM or more for booting.
 159
 160 config KERNEL_LZMA
 161         bool "LZMA"
 162         depends on HAVE_KERNEL_LZMA
 163         help
 164           The most recent compression algorithm.
 165           Its ratio is best, decompression speed is between the other
 166           two. Compression is slowest.  The kernel size is about 33%
 167           smaller with LZMA in comparison to gzip.
 168
 169 config KERNEL_LZO
 170         bool "LZO"
 171         depends on HAVE_KERNEL_LZO
 172         help
 173           Its compression ratio is the poorest among the 4. The kernel
 174           size is about about 10% bigger than gzip; however its speed
 175           (both compression and decompression) is the fastest.
 176
 177 endchoice
 178
 179 config SWAP
 180         bool "Support for paging of anonymous memory (swap)"
 181         depends on MMU && BLOCK
 182         default y
 183         help
 184           This option allows you to choose whether you want to have support
 185           for so called swap devices or swap files in your kernel that are
 186           used to provide more virtual memory than the actual RAM present
 187           in your computer.  If unsure say Y.
 188
 189 config SYSVIPC
 190         bool "System V IPC"
 191         ---help---
 192           Inter Process Communication is a suite of library functions and
 193           system calls which let processes (running programs) synchronize and
 194           exchange information. It is generally considered to be a good thing,
 195           and some programs won't run unless you say Y here. In particular, if
 196           you want to run the DOS emulator dosemu under Linux (read the
 197           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 198           you'll need to say Y here.
 199
 200           You can find documentation about IPC with "info ipc" and also in
 201           section 6.4 of the Linux Programmer's Guide, available from
 202           <http://www.tldp.org/guides.html>.
 203
 204 config SYSVIPC_SYSCTL
 205         bool
 206         depends on SYSVIPC
 207         depends on SYSCTL
 208         default y
 209
 210 config POSIX_MQUEUE
 211         bool "POSIX Message Queues"
 212         depends on NET && EXPERIMENTAL
 213         ---help---
 214           POSIX variant of message queues is a part of IPC. In POSIX message
 215           queues every message has a priority which decides about succession
 216           of receiving it by a process. If you want to compile and run
 217           programs written e.g. for Solaris with use of its POSIX message
 218           queues (functions mq_*) say Y here.
 219
 220           POSIX message queues are visible as a filesystem called 'mqueue'
 221           and can be mounted somewhere if you want to do filesystem
 222           operations on message queues.
 223
 224           If unsure, say Y.
 225
 226 config POSIX_MQUEUE_SYSCTL
 227         bool
 228         depends on POSIX_MQUEUE
 229         depends on SYSCTL
 230         default y
 231
 232 config BSD_PROCESS_ACCT
 233         bool "BSD Process Accounting"
 234         help
 235           If you say Y here, a user level program will be able to instruct the
 236           kernel (via a special system call) to write process accounting
 237           information to a file: whenever a process exits, information about
 238           that process will be appended to the file by the kernel.  The
 239           information includes things such as creation time, owning user,
 240           command name, memory usage, controlling terminal etc. (the complete
 241           list is in the struct acct in <file:include/linux/acct.h>).  It is
 242           up to the user level program to do useful things with this
 243           information.  This is generally a good idea, so say Y.
 244
 245 config BSD_PROCESS_ACCT_V3
 246         bool "BSD Process Accounting version 3 file format"
 247         depends on BSD_PROCESS_ACCT
 248         default n
 249         help
 250           If you say Y here, the process accounting information is written
 251           in a new file format that also logs the process IDs of each
 252           process and it's parent. Note that this file format is incompatible
 253           with previous v0/v1/v2 file formats, so you will need updated tools
 254           for processing it. A preliminary version of these tools is available
 255           at <http://www.gnu.org/software/acct/>.
 256
 257 config TASKSTATS
 258         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 259         depends on NET
 260         default n
 261         help
 262           Export selected statistics for tasks/processes through the
 263           generic netlink interface. Unlike BSD process accounting, the
 264           statistics are available during the lifetime of tasks/processes as
 265           responses to commands. Like BSD accounting, they are sent to user
 266           space on task exit.
 267
 268           Say N if unsure.
 269
 270 config TASK_DELAY_ACCT
 271         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 272         depends on TASKSTATS
 273         help
 274           Collect information on time spent by a task waiting for system
 275           resources like cpu, synchronous block I/O completion and swapping
 276           in pages. Such statistics can help in setting a task's priorities
 277           relative to other tasks for cpu, io, rss limits etc.
 278
 279           Say N if unsure.
 280
 281 config TASK_XACCT
 282         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 283         depends on TASKSTATS
 284         help
 285           Collect extended task accounting data and send the data
 286           to userland for processing over the taskstats interface.
 287
 288           Say N if unsure.
 289
 290 config TASK_IO_ACCOUNTING
 291         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 292         depends on TASK_XACCT
 293         help
 294           Collect information on the number of bytes of storage I/O which this
 295           task has caused.
 296
 297           Say N if unsure.
 298
 299 config AUDIT
 300         bool "Auditing support"
 301         depends on NET
 302         help
 303           Enable auditing infrastructure that can be used with another
 304           kernel subsystem, such as SELinux (which requires this for
 305           logging of avc messages output).  Does not do system-call
 306           auditing without CONFIG_AUDITSYSCALL.
 307
 308 config AUDITSYSCALL
 309         bool "Enable system-call auditing support"
 310         depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
 311         default y if SECURITY_SELINUX
 312         help
 313           Enable low-overhead system-call auditing infrastructure that
 314           can be used independently or with another kernel subsystem,
 315           such as SELinux.  To use audit's filesystem watch feature, please
 316           ensure that INOTIFY is configured.
 317
 318 config AUDIT_TREE
 319         def_bool y
 320         depends on AUDITSYSCALL
 321         select INOTIFY
 322
 323 menu "RCU Subsystem"
 324
 325 choice
 326         prompt "RCU Implementation"
 327         default TREE_RCU
 328
 329 config TREE_RCU
 330         bool "Tree-based hierarchical RCU"
 331         help
 332           This option selects the RCU implementation that is
 333           designed for very large SMP system with hundreds or
 334           thousands of CPUs.  It also scales down nicely to
 335           smaller systems.
 336
 337 config TREE_PREEMPT_RCU
 338         bool "Preemptable tree-based hierarchical RCU"
 339         depends on PREEMPT
 340         help
 341           This option selects the RCU implementation that is
 342           designed for very large SMP systems with hundreds or
 343           thousands of CPUs, but for which real-time response
 344           is also required.  It also scales down nicely to
 345           smaller systems.
 346
 347 config TINY_RCU
 348         bool "UP-only small-memory-footprint RCU"
 349         depends on !SMP
 350         help
 351           This option selects the RCU implementation that is
 352           designed for UP systems from which real-time response
 353           is not required.  This option greatly reduces the
 354           memory footprint of RCU.
 355
 356 endchoice
 357
 358 config RCU_TRACE
 359         bool "Enable tracing for RCU"
 360         depends on TREE_RCU || TREE_PREEMPT_RCU
 361         help
 362           This option provides tracing in RCU which presents stats
 363           in debugfs for debugging RCU implementation.
 364
 365           Say Y here if you want to enable RCU tracing
 366           Say N if you are unsure.
 367
 368 config RCU_FANOUT
 369         int "Tree-based hierarchical RCU fanout value"
 370         range 2 64 if 64BIT
 371         range 2 32 if !64BIT
 372         depends on TREE_RCU || TREE_PREEMPT_RCU
 373         default 64 if 64BIT
 374         default 32 if !64BIT
 375         help
 376           This option controls the fanout of hierarchical implementations
 377           of RCU, allowing RCU to work efficiently on machines with
 378           large numbers of CPUs.  This value must be at least the cube
 379           root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
 380           systems and up to 262,144 for 64-bit systems.
 381
 382           Select a specific number if testing RCU itself.
 383           Take the default if unsure.
 384
 385 config RCU_FANOUT_EXACT
 386         bool "Disable tree-based hierarchical RCU auto-balancing"
 387         depends on TREE_RCU || TREE_PREEMPT_RCU
 388         default n
 389         help
 390           This option forces use of the exact RCU_FANOUT value specified,
 391           regardless of imbalances in the hierarchy.  This is useful for
 392           testing RCU itself, and might one day be useful on systems with
 393           strong NUMA behavior.
 394
 395           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 396
 397           Say N if unsure.
 398
 399 config RCU_FAST_NO_HZ
 400         bool "Accelerate last non-dyntick-idle CPU's grace periods"
 401         depends on TREE_RCU && NO_HZ && SMP
 402         default n
 403         help
 404           This option causes RCU to attempt to accelerate grace periods
 405           in order to allow the final CPU to enter dynticks-idle state
 406           more quickly.  On the other hand, this option increases the
 407           overhead of the dynticks-idle checking, particularly on systems
 408           with large numbers of CPUs.
 409
 410           Say Y if energy efficiency is critically important, particularly
 411                 if you have relatively few CPUs.
 412
 413           Say N if you are unsure.
 414
 415 config TREE_RCU_TRACE
 416         def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 417         select DEBUG_FS
 418         help
 419           This option provides tracing for the TREE_RCU and
 420           TREE_PREEMPT_RCU implementations, permitting Makefile to
 421           trivially select kernel/rcutree_trace.c.
 422
 423 endmenu # "RCU Subsystem"
 424
 425 config IKCONFIG
 426         tristate "Kernel .config support"
 427         ---help---
 428           This option enables the complete Linux kernel ".config" file
 429           contents to be saved in the kernel. It provides documentation
 430           of which kernel options are used in a running kernel or in an
 431           on-disk kernel.  This information can be extracted from the kernel
 432           image file with the script scripts/extract-ikconfig and used as
 433           input to rebuild the current kernel or to build another kernel.
 434           It can also be extracted from a running kernel by reading
 435           /proc/config.gz if enabled (below).
 436
 437 config IKCONFIG_PROC
 438         bool "Enable access to .config through /proc/config.gz"
 439         depends on IKCONFIG && PROC_FS
 440         ---help---
 441           This option enables access to the kernel configuration file
 442           through /proc/config.gz.
 443
 444 config LOG_BUF_SHIFT
 445         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 446         range 12 21
 447         default 17
 448         help
 449           Select kernel log buffer size as a power of 2.
 450           Examples:
 451                      17 => 128 KB
 452                      16 => 64 KB
 453                      15 => 32 KB
 454                      14 => 16 KB
 455                      13 =>  8 KB
 456                      12 =>  4 KB
 457
 458 #
 459 # Architectures with an unreliable sched_clock() should select this:
 460 #
 461 config HAVE_UNSTABLE_SCHED_CLOCK
 462         bool
 463
 464 menuconfig CGROUPS
 465         boolean "Control Group support"
 466         depends on EVENTFD
 467         help
 468           This option adds support for grouping sets of processes together, for
 469           use with process control subsystems such as Cpusets, CFS, memory
 470           controls or device isolation.
 471           See
 472                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 473                 - Documentation/cgroups/ (features for grouping, isolation
 474                                           and resource control)
 475
 476           Say N if unsure.
 477
 478 if CGROUPS
 479
 480 config CGROUP_DEBUG
 481         bool "Example debug cgroup subsystem"
 482         depends on CGROUPS
 483         default n
 484         help
 485           This option enables a simple cgroup subsystem that
 486           exports useful debugging information about the cgroups
 487           framework.
 488
 489           Say N if unsure.
 490
 491 config CGROUP_NS
 492         bool "Namespace cgroup subsystem"
 493         depends on CGROUPS
 494         help
 495           Provides a simple namespace cgroup subsystem to
 496           provide hierarchical naming of sets of namespaces,
 497           for instance virtual servers and checkpoint/restart
 498           jobs.
 499
 500 config CGROUP_FREEZER
 501         bool "Freezer cgroup subsystem"
 502         depends on CGROUPS
 503         help
 504           Provides a way to freeze and unfreeze all tasks in a
 505           cgroup.
 506
 507 config CGROUP_DEVICE
 508         bool "Device controller for cgroups"
 509         depends on CGROUPS && EXPERIMENTAL
 510         help
 511           Provides a cgroup implementing whitelists for devices which
 512           a process in the cgroup can mknod or open.
 513
 514 config CPUSETS
 515         bool "Cpuset support"
 516         depends on CGROUPS
 517         help
 518           This option will let you create and manage CPUSETs which
 519           allow dynamically partitioning a system into sets of CPUs and
 520           Memory Nodes and assigning tasks to run only within those sets.
 521           This is primarily useful on large SMP or NUMA systems.
 522
 523           Say N if unsure.
 524
 525 config PROC_PID_CPUSET
 526         bool "Include legacy /proc/<pid>/cpuset file"
 527         depends on CPUSETS
 528         default y
 529
 530 config CGROUP_CPUACCT
 531         bool "Simple CPU accounting cgroup subsystem"
 532         depends on CGROUPS
 533         help
 534           Provides a simple Resource Controller for monitoring the
 535           total CPU consumed by the tasks in a cgroup.
 536
 537 config RESOURCE_COUNTERS
 538         bool "Resource counters"
 539         help
 540           This option enables controller independent resource accounting
 541           infrastructure that works with cgroups.
 542         depends on CGROUPS
 543
 544 config CGROUP_MEM_RES_CTLR
 545         bool "Memory Resource Controller for Control Groups"
 546         depends on CGROUPS && RESOURCE_COUNTERS
 547         select MM_OWNER
 548         help
 549           Provides a memory resource controller that manages both anonymous
 550           memory and page cache. (See Documentation/cgroups/memory.txt)
 551
 552           Note that setting this option increases fixed memory overhead
 553           associated with each page of memory in the system. By this,
 554           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 555           usage tracking struct at boot. Total amount of this is printed out
 556           at boot.
 557
 558           Only enable when you're ok with these trade offs and really
 559           sure you need the memory resource controller. Even when you enable
 560           this, you can set "cgroup_disable=memory" at your boot option to
 561           disable memory resource controller and you can avoid overheads.
 562           (and lose benefits of memory resource controller)
 563
 564           This config option also selects MM_OWNER config option, which
 565           could in turn add some fork/exit overhead.
 566
 567 config CGROUP_MEM_RES_CTLR_SWAP
 568         bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
 569         depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
 570         help
 571           Add swap management feature to memory resource controller. When you
 572           enable this, you can limit mem+swap usage per cgroup. In other words,
 573           when you disable this, memory resource controller has no cares to
 574           usage of swap...a process can exhaust all of the swap. This extension
 575           is useful when you want to avoid exhaustion swap but this itself
 576           adds more overheads and consumes memory for remembering information.
 577           Especially if you use 32bit system or small memory system, please
 578           be careful about enabling this. When memory resource controller
 579           is disabled by boot option, this will be automatically disabled and
 580           there will be no overhead from this. Even when you set this config=y,
 581           if boot option "noswapaccount" is set, swap will not be accounted.
 582           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 583           size is 4096bytes, 512k per 1Gbytes of swap.
 584
 585 menuconfig CGROUP_SCHED
 586         bool "Group CPU scheduler"
 587         depends on EXPERIMENTAL && CGROUPS
 588         default n
 589         help
 590           This feature lets CPU scheduler recognize task groups and control CPU
 591           bandwidth allocation to such task groups. It uses cgroups to group
 592           tasks.
 593
 594 if CGROUP_SCHED
 595 config FAIR_GROUP_SCHED
 596         bool "Group scheduling for SCHED_OTHER"
 597         depends on CGROUP_SCHED
 598         default CGROUP_SCHED
 599
 600 config RT_GROUP_SCHED
 601         bool "Group scheduling for SCHED_RR/FIFO"
 602         depends on EXPERIMENTAL
 603         depends on CGROUP_SCHED
 604         default n
 605         help
 606           This feature lets you explicitly allocate real CPU bandwidth
 607           to task groups. If enabled, it will also make it impossible to
 608           schedule realtime tasks for non-root users until you allocate
 609           realtime bandwidth for them.
 610           See Documentation/scheduler/sched-rt-group.txt for more information.
 611
 612 endif #CGROUP_SCHED
 613
 614 endif # CGROUPS
 615
 616 config MM_OWNER
 617         bool
 618
 619 config SYSFS_DEPRECATED
 620         bool
 621
 622 config SYSFS_DEPRECATED_V2
 623         bool "enable deprecated sysfs features to support old userspace tools"
 624         depends on SYSFS
 625         default n
 626         select SYSFS_DEPRECATED
 627         help
 628           This option switches the layout of sysfs to the deprecated
 629           version. Do not use it on recent distributions.
 630
 631           The current sysfs layout features a unified device tree at
 632           /sys/devices/, which is able to express a hierarchy between
 633           class devices. If the deprecated option is set to Y, the
 634           unified device tree is split into a bus device tree at
 635           /sys/devices/ and several individual class device trees at
 636           /sys/class/. The class and bus devices will be connected by
 637           "<subsystem>:<name>" and the "device" links. The "block"
 638           class devices, will not show up in /sys/class/block/. Some
 639           subsystems will suppress the creation of some devices which
 640           depend on the unified device tree.
 641
 642           This option is not a pure compatibility option that can
 643           be safely enabled on newer distributions. It will change the
 644           layout of sysfs to the non-extensible deprecated version,
 645           and disable some features, which can not be exported without
 646           confusing older userspace tools. Since 2007/2008 all major
 647           distributions do not enable this option, and ship no tools which
 648           depend on the deprecated layout or this option.
 649
 650           If you are using a new kernel on an older distribution, or use
 651           older userspace tools, you might need to say Y here. Do not say Y,
 652           if the original kernel, that came with your distribution, has
 653           this option set to N.
 654
 655 config RELAY
 656         bool "Kernel->user space relay support (formerly relayfs)"
 657         help
 658           This option enables support for relay interface support in
 659           certain file systems (such as debugfs).
 660           It is designed to provide an efficient mechanism for tools and
 661           facilities to relay large amounts of data from kernel space to
 662           user space.
 663
 664           If unsure, say N.
 665
 666 config NAMESPACES
 667         bool "Namespaces support" if EMBEDDED
 668         default !EMBEDDED
 669         help
 670           Provides the way to make tasks work with different objects using
 671           the same id. For example same IPC id may refer to different objects
 672           or same user id or pid may refer to different tasks when used in
 673           different namespaces.
 674
 675 config UTS_NS
 676         bool "UTS namespace"
 677         depends on NAMESPACES
 678         help
 679           In this namespace tasks see different info provided with the
 680           uname() system call
 681
 682 config IPC_NS
 683         bool "IPC namespace"
 684         depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
 685         help
 686           In this namespace tasks work with IPC ids which correspond to
 687           different IPC objects in different namespaces.
 688
 689 config USER_NS
 690         bool "User namespace (EXPERIMENTAL)"
 691         depends on NAMESPACES && EXPERIMENTAL
 692         help
 693           This allows containers, i.e. vservers, to use user namespaces
 694           to provide different user info for different servers.
 695           If unsure, say N.
 696
 697 config PID_NS
 698         bool "PID Namespaces (EXPERIMENTAL)"
 699         default n
 700         depends on NAMESPACES && EXPERIMENTAL
 701         help
 702           Support process id namespaces.  This allows having multiple
 703           processes with the same pid as long as they are in different
 704           pid namespaces.  This is a building block of containers.
 705
 706           Unless you want to work with an experimental feature
 707           say N here.
 708
 709 config NET_NS
 710         bool "Network namespace"
 711         default n
 712         depends on NAMESPACES && EXPERIMENTAL && NET
 713         help
 714           Allow user space to create what appear to be multiple instances
 715           of the network stack.
 716
 717 config BLK_DEV_INITRD
 718         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 719         depends on BROKEN || !FRV
 720         help
 721           The initial RAM filesystem is a ramfs which is loaded by the
 722           boot loader (loadlin or lilo) and that is mounted as root
 723           before the normal boot procedure. It is typically used to
 724           load modules needed to mount the "real" root file system,
 725           etc. See <file:Documentation/initrd.txt> for details.
 726
 727           If RAM disk support (BLK_DEV_RAM) is also included, this
 728           also enables initial RAM disk (initrd) support and adds
 729           15 Kbytes (more on some other architectures) to the kernel size.
 730
 731           If unsure say Y.
 732
 733 if BLK_DEV_INITRD
 734
 735 source "usr/Kconfig"
 736
 737 endif
 738
 739 config CC_OPTIMIZE_FOR_SIZE
 740         bool "Optimize for size"
 741         default y
 742         help
 743           Enabling this option will pass "-Os" instead of "-O2" to gcc
 744           resulting in a smaller kernel.
 745
 746           If unsure, say Y.
 747
 748 config SYSCTL
 749         bool
 750
 751 config ANON_INODES
 752         bool
 753
 754 menuconfig EMBEDDED
 755         bool "Configure standard kernel features (for small systems)"
 756         help
 757           This option allows certain base kernel options and settings
 758           to be disabled or tweaked. This is for specialized
 759           environments which can tolerate a "non-standard" kernel.
 760           Only use this if you really know what you are doing.
 761
 762 config UID16
 763         bool "Enable 16-bit UID system calls" if EMBEDDED
 764         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 765         default y
 766         help
 767           This enables the legacy 16-bit UID syscall wrappers.
 768
 769 config SYSCTL_SYSCALL
 770         bool "Sysctl syscall support" if EMBEDDED
 771         depends on PROC_SYSCTL
 772         default y
 773         select SYSCTL
 774         ---help---
 775           sys_sysctl uses binary paths that have been found challenging
 776           to properly maintain and use.  The interface in /proc/sys
 777           using paths with ascii names is now the primary path to this
 778           information.
 779
 780           Almost nothing using the binary sysctl interface so if you are
 781           trying to save some space it is probably safe to disable this,
 782           making your kernel marginally smaller.
 783
 784           If unsure say Y here.
 785
 786 config KALLSYMS
 787          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 788          default y
 789          help
 790            Say Y here to let the kernel print out symbolic crash information and
 791            symbolic stack backtraces. This increases the size of the kernel
 792            somewhat, as all symbols have to be loaded into the kernel image.
 793
 794 config KALLSYMS_ALL
 795         bool "Include all symbols in kallsyms"
 796         depends on DEBUG_KERNEL && KALLSYMS
 797         help
 798            Normally kallsyms only contains the symbols of functions, for nicer
 799            OOPS messages.  Some debuggers can use kallsyms for other
 800            symbols too: say Y here to include all symbols, if you need them
 801            and you don't care about adding 300k to the size of your kernel.
 802
 803            Say N.
 804
 805 config KALLSYMS_EXTRA_PASS
 806         bool "Do an extra kallsyms pass"
 807         depends on KALLSYMS
 808         help
 809            If kallsyms is not working correctly, the build will fail with
 810            inconsistent kallsyms data.  If that occurs, log a bug report and
 811            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 812            Always say N here unless you find a bug in kallsyms, which must be
 813            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 814            you wait for kallsyms to be fixed.
 815
 816
 817 config HOTPLUG
 818         bool "Support for hot-pluggable devices" if EMBEDDED
 819         default y
 820         help
 821           This option is provided for the case where no hotplug or uevent
 822           capabilities is wanted by the kernel.  You should only consider
 823           disabling this option for embedded systems that do not use modules, a
 824           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 825
 826 config PRINTK
 827         default y
 828         bool "Enable support for printk" if EMBEDDED
 829         help
 830           This option enables normal printk support. Removing it
 831           eliminates most of the message strings from the kernel image
 832           and makes the kernel more or less silent. As this makes it
 833           very difficult to diagnose system problems, saying N here is
 834           strongly discouraged.
 835
 836 config BUG
 837         bool "BUG() support" if EMBEDDED
 838         default y
 839         help
 840           Disabling this option eliminates support for BUG and WARN, reducing
 841           the size of your kernel image and potentially quietly ignoring
 842           numerous fatal conditions. You should only consider disabling this
 843           option for embedded systems with no facilities for reporting errors.
 844           Just say Y.
 845
 846 config ELF_CORE
 847         default y
 848         bool "Enable ELF core dumps" if EMBEDDED
 849         help
 850           Enable support for generating core dumps. Disabling saves about 4k.
 851
 852 config PCSPKR_PLATFORM
 853         bool "Enable PC-Speaker support" if EMBEDDED
 854         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 855         default y
 856         help
 857           This option allows to disable the internal PC-Speaker
 858           support, saving some memory.
 859
 860 config BASE_FULL
 861         default y
 862         bool "Enable full-sized data structures for core" if EMBEDDED
 863         help
 864           Disabling this option reduces the size of miscellaneous core
 865           kernel data structures. This saves memory on small machines,
 866           but may reduce performance.
 867
 868 config FUTEX
 869         bool "Enable futex support" if EMBEDDED
 870         default y
 871         select RT_MUTEXES
 872         help
 873           Disabling this option will cause the kernel to be built without
 874           support for "fast userspace mutexes".  The resulting kernel may not
 875           run glibc-based applications correctly.
 876
 877 config EPOLL
 878         bool "Enable eventpoll support" if EMBEDDED
 879         default y
 880         select ANON_INODES
 881         help
 882           Disabling this option will cause the kernel to be built without
 883           support for epoll family of system calls.
 884
 885 config SIGNALFD
 886         bool "Enable signalfd() system call" if EMBEDDED
 887         select ANON_INODES
 888         default y
 889         help
 890           Enable the signalfd() system call that allows to receive signals
 891           on a file descriptor.
 892
 893           If unsure, say Y.
 894
 895 config TIMERFD
 896         bool "Enable timerfd() system call" if EMBEDDED
 897         select ANON_INODES
 898         default y
 899         help
 900           Enable the timerfd() system call that allows to receive timer
 901           events on a file descriptor.
 902
 903           If unsure, say Y.
 904
 905 config EVENTFD
 906         bool "Enable eventfd() system call" if EMBEDDED
 907         select ANON_INODES
 908         default y
 909         help
 910           Enable the eventfd() system call that allows to receive both
 911           kernel notification (ie. KAIO) or userspace notifications.
 912
 913           If unsure, say Y.
 914
 915 config SHMEM
 916         bool "Use full shmem filesystem" if EMBEDDED
 917         default y
 918         depends on MMU
 919         help
 920           The shmem is an internal filesystem used to manage shared memory.
 921           It is backed by swap and manages resource limits. It is also exported
 922           to userspace as tmpfs if TMPFS is enabled. Disabling this
 923           option replaces shmem and tmpfs with the much simpler ramfs code,
 924           which may be appropriate on small systems without swap.
 925
 926 config AIO
 927         bool "Enable AIO support" if EMBEDDED
 928         default y
 929         help
 930           This option enables POSIX asynchronous I/O which may by used
 931           by some high performance threaded applications. Disabling
 932           this option saves about 7k.
 933
 934 config HAVE_PERF_EVENTS
 935         bool
 936         help
 937           See tools/perf/design.txt for details.
 938
 939 config PERF_USE_VMALLOC
 940         bool
 941         help
 942           See tools/perf/design.txt for details
 943
 944 menu "Kernel Performance Events And Counters"
 945
 946 config PERF_EVENTS
 947         bool "Kernel performance events and counters"
 948         default y if (PROFILING || PERF_COUNTERS)
 949         depends on HAVE_PERF_EVENTS
 950         select ANON_INODES
 951         help
 952           Enable kernel support for various performance events provided
 953           by software and hardware.
 954
 955           Software events are supported either built-in or via the
 956           use of generic tracepoints.
 957
 958           Most modern CPUs support performance events via performance
 959           counter registers. These registers count the number of certain
 960           types of hw events: such as instructions executed, cachemisses
 961           suffered, or branches mis-predicted - without slowing down the
 962           kernel or applications. These registers can also trigger interrupts
 963           when a threshold number of events have passed - and can thus be
 964           used to profile the code that runs on that CPU.
 965
 966           The Linux Performance Event subsystem provides an abstraction of
 967           these software and hardware event capabilities, available via a
 968           system call and used by the "perf" utility in tools/perf/. It
 969           provides per task and per CPU counters, and it provides event
 970           capabilities on top of those.
 971
 972           Say Y if unsure.
 973
 974 config PERF_COUNTERS
 975         bool "Kernel performance counters (old config option)"
 976         depends on HAVE_PERF_EVENTS
 977         help
 978           This config has been obsoleted by the PERF_EVENTS
 979           config option - please see that one for details.
 980
 981           It has no effect on the kernel whether you enable
 982           it or not, it is a compatibility placeholder.
 983
 984           Say N if unsure.
 985
 986 config DEBUG_PERF_USE_VMALLOC
 987         default n
 988         bool "Debug: use vmalloc to back perf mmap() buffers"
 989         depends on PERF_EVENTS && DEBUG_KERNEL
 990         select PERF_USE_VMALLOC
 991         help
 992          Use vmalloc memory to back perf mmap() buffers.
 993
 994          Mostly useful for debugging the vmalloc code on platforms
 995          that don't require it.
 996
 997          Say N if unsure.
 998
 999 endmenu
1000
1001 config VM_EVENT_COUNTERS
1002         default y
1003         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1004         help
1005           VM event counters are needed for event counts to be shown.
1006           This option allows the disabling of the VM event counters
1007           on EMBEDDED systems.  /proc/vmstat will only show page counts
1008           if VM event counters are disabled.
1009
1010 config PCI_QUIRKS
1011         default y
1012         bool "Enable PCI quirk workarounds" if EMBEDDED
1013         depends on PCI
1014         help
1015           This enables workarounds for various PCI chipset
1016           bugs/quirks. Disable this only if your target machine is
1017           unaffected by PCI quirks.
1018
1019 config SLUB_DEBUG
1020         default y
1021         bool "Enable SLUB debugging support" if EMBEDDED
1022         depends on SLUB && SYSFS
1023         help
1024           SLUB has extensive debug support features. Disabling these can
1025           result in significant savings in code size. This also disables
1026           SLUB sysfs support. /sys/slab will not exist and there will be
1027           no support for cache validation etc.
1028
1029 config COMPAT_BRK
1030         bool "Disable heap randomization"
1031         default y
1032         help
1033           Randomizing heap placement makes heap exploits harder, but it
1034           also breaks ancient binaries (including anything libc5 based).
1035           This option changes the bootup default to heap randomization
1036           disabled, and can be overridden at runtime by setting
1037           /proc/sys/kernel/randomize_va_space to 2.
1038
1039           On non-ancient distros (post-2000 ones) N is usually a safe choice.
1040
1041 choice
1042         prompt "Choose SLAB allocator"
1043         default SLUB
1044         help
1045            This option allows to select a slab allocator.
1046
1047 config SLAB
1048         bool "SLAB"
1049         help
1050           The regular slab allocator that is established and known to work
1051           well in all environments. It organizes cache hot objects in
1052           per cpu and per node queues.
1053
1054 config SLUB
1055         bool "SLUB (Unqueued Allocator)"
1056         help
1057            SLUB is a slab allocator that minimizes cache line usage
1058            instead of managing queues of cached objects (SLAB approach).
1059            Per cpu caching is realized using slabs of objects instead
1060            of queues of objects. SLUB can use memory efficiently
1061            and has enhanced diagnostics. SLUB is the default choice for
1062            a slab allocator.
1063
1064 config SLOB
1065         depends on EMBEDDED
1066         bool "SLOB (Simple Allocator)"
1067         help
1068            SLOB replaces the stock allocator with a drastically simpler
1069            allocator. SLOB is generally more space efficient but
1070            does not perform as well on large systems.
1071
1072 endchoice
1073
1074 config MMAP_ALLOW_UNINITIALIZED
1075         bool "Allow mmapped anonymous memory to be uninitialized"
1076         depends on EMBEDDED && !MMU
1077         default n
1078         help
1079           Normally, and according to the Linux spec, anonymous memory obtained
1080           from mmap() has it's contents cleared before it is passed to
1081           userspace.  Enabling this config option allows you to request that
1082           mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1083           providing a huge performance boost.  If this option is not enabled,
1084           then the flag will be ignored.
1085
1086           This is taken advantage of by uClibc's malloc(), and also by
1087           ELF-FDPIC binfmt's brk and stack allocator.
1088
1089           Because of the obvious security issues, this option should only be
1090           enabled on embedded devices where you control what is run in
1091           userspace.  Since that isn't generally a problem on no-MMU systems,
1092           it is normally safe to say Y here.
1093
1094           See Documentation/nommu-mmap.txt for more information.
1095
1096 config PROFILING
1097         bool "Profiling support"
1098         help
1099           Say Y here to enable the extended profiling support mechanisms used
1100           by profilers such as OProfile.
1101
1102 #
1103 # Place an empty function call at each tracepoint site. Can be
1104 # dynamically changed for a probe function.
1105 #
1106 config TRACEPOINTS
1107         bool
1108
1109 source "arch/Kconfig"
1110
1111 config SLOW_WORK
1112         default n
1113         bool
1114         help
1115           The slow work thread pool provides a number of dynamically allocated
1116           threads that can be used by the kernel to perform operations that
1117           take a relatively long time.
1118
1119           An example of this would be CacheFiles doing a path lookup followed
1120           by a series of mkdirs and a create call, all of which have to touch
1121           disk.
1122
1123           See Documentation/slow-work.txt.
1124
1125 config SLOW_WORK_DEBUG
1126         bool "Slow work debugging through debugfs"
1127         default n
1128         depends on SLOW_WORK && DEBUG_FS
1129         help
1130           Display the contents of the slow work run queue through debugfs,
1131           including items currently executing.
1132
1133           See Documentation/slow-work.txt.
1134
1135 endmenu         # General setup
1136
1137 config HAVE_GENERIC_DMA_COHERENT
1138         bool
1139         default n
1140
1141 config SLABINFO
1142         bool
1143         depends on PROC_FS
1144         depends on SLAB || SLUB_DEBUG
1145         default y
1146
1147 config RT_MUTEXES
1148         boolean
1149
1150 config BASE_SMALL
1151         int
1152         default 0 if BASE_FULL
1153         default 1 if !BASE_FULL
1154
1155 menuconfig MODULES
1156         bool "Enable loadable module support"
1157         help
1158           Kernel modules are small pieces of compiled code which can
1159           be inserted in the running kernel, rather than being
1160           permanently built into the kernel.  You use the "modprobe"
1161           tool to add (and sometimes remove) them.  If you say Y here,
1162           many parts of the kernel can be built as modules (by
1163           answering M instead of Y where indicated): this is most
1164           useful for infrequently used options which are not required
1165           for booting.  For more information, see the man pages for
1166           modprobe, lsmod, modinfo, insmod and rmmod.
1167
1168           If you say Y here, you will need to run "make
1169           modules_install" to put the modules under /lib/modules/
1170           where modprobe can find them (you may need to be root to do
1171           this).
1172
1173           If unsure, say Y.
1174
1175 if MODULES
1176
1177 config MODULE_FORCE_LOAD
1178         bool "Forced module loading"
1179         default n
1180         help
1181           Allow loading of modules without version information (ie. modprobe
1182           --force).  Forced module loading sets the 'F' (forced) taint flag and
1183           is usually a really bad idea.
1184
1185 config MODULE_UNLOAD
1186         bool "Module unloading"
1187         help
1188           Without this option you will not be able to unload any
1189           modules (note that some modules may not be unloadable
1190           anyway), which makes your kernel smaller, faster
1191           and simpler.  If unsure, say Y.
1192
1193 config MODULE_FORCE_UNLOAD
1194         bool "Forced module unloading"
1195         depends on MODULE_UNLOAD && EXPERIMENTAL
1196         help
1197           This option allows you to force a module to unload, even if the
1198           kernel believes it is unsafe: the kernel will remove the module
1199           without waiting for anyone to stop using it (using the -f option to
1200           rmmod).  This is mainly for kernel developers and desperate users.
1201           If unsure, say N.
1202
1203 config MODVERSIONS
1204         bool "Module versioning support"
1205         help
1206           Usually, you have to use modules compiled with your kernel.
1207           Saying Y here makes it sometimes possible to use modules
1208           compiled for different kernels, by adding enough information
1209           to the modules to (hopefully) spot any changes which would
1210           make them incompatible with the kernel you are running.  If
1211           unsure, say N.
1212
1213 config MODULE_SRCVERSION_ALL
1214         bool "Source checksum for all modules"
1215         help
1216           Modules which contain a MODULE_VERSION get an extra "srcversion"
1217           field inserted into their modinfo section, which contains a
1218           sum of the source files which made it.  This helps maintainers
1219           see exactly which source was used to build a module (since
1220           others sometimes change the module source without updating
1221           the version).  With this option, such a "srcversion" field
1222           will be created for all modules.  If unsure, say N.
1223
1224 endif # MODULES
1225
1226 config INIT_ALL_POSSIBLE
1227         bool
1228         help
1229           Back when each arch used to define their own cpu_online_map and
1230           cpu_possible_map, some of them chose to initialize cpu_possible_map
1231           with all 1s, and others with all 0s.  When they were centralised,
1232           it was better to provide this option than to break all the archs
1233           and have several arch maintainers pursuing me down dark alleys.
1234
1235 config STOP_MACHINE
1236         bool
1237         default y
1238         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1239         help
1240           Need stop_machine() primitive.
1241
1242 source "block/Kconfig"
1243
1244 config PREEMPT_NOTIFIERS
1245         bool
1246
1247 config PADATA
1248         depends on SMP
1249         bool
1250
1251 source "kernel/Kconfig.locks"