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 config HAVE_IRQ_WORK
  25         bool
  26
  27 config IRQ_WORK
  28         bool
  29         depends on HAVE_IRQ_WORK
  30
  31 menu "General setup"
  32
  33 config EXPERIMENTAL
  34         bool "Prompt for development and/or incomplete code/drivers"
  35         ---help---
  36           Some of the various things that Linux supports (such as network
  37           drivers, file systems, network protocols, etc.) can be in a state
  38           of development where the functionality, stability, or the level of
  39           testing is not yet high enough for general use. This is usually
  40           known as the "alpha-test" phase among developers. If a feature is
  41           currently in alpha-test, then the developers usually discourage
  42           uninformed widespread use of this feature by the general public to
  43           avoid "Why doesn't this work?" type mail messages. However, active
  44           testing and use of these systems is welcomed. Just be aware that it
  45           may not meet the normal level of reliability or it may fail to work
  46           in some special cases. Detailed bug reports from people familiar
  47           with the kernel internals are usually welcomed by the developers
  48           (before submitting bug reports, please read the documents
  49           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  50           <file:Documentation/BUG-HUNTING>, and
  51           <file:Documentation/oops-tracing.txt> in the kernel source).
  52
  53           This option will also make obsoleted drivers available. These are
  54           drivers that have been replaced by something else, and/or are
  55           scheduled to be removed in a future kernel release.
  56
  57           Unless you intend to help test and develop a feature or driver that
  58           falls into this category, or you have a situation that requires
  59           using these features, you should probably say N here, which will
  60           cause the configurator to present you with fewer choices. If
  61           you say Y here, you will be offered the choice of using features or
  62           drivers that are currently considered to be in the alpha-test phase.
  63
  64 config BROKEN
  65         bool
  66
  67 config BROKEN_ON_SMP
  68         bool
  69         depends on BROKEN || !SMP
  70         default y
  71
  72 config LOCK_KERNEL
  73         bool
  74         depends on SMP || PREEMPT
  75         default y
  76
  77 config INIT_ENV_ARG_LIMIT
  78         int
  79         default 32 if !UML
  80         default 128 if UML
  81         help
  82           Maximum of each of the number of arguments and environment
  83           variables passed to init from the kernel command line.
  84
  85
  86 config CROSS_COMPILE
  87         string "Cross-compiler tool prefix"
  88         help
  89           Same as running 'make CROSS_COMPILE=prefix-' but stored for
  90           default make runs in this kernel build directory.  You don't
  91           need to set this unless you want the configured kernel build
  92           directory to select the cross-compiler automatically.
  93
  94 config LOCALVERSION
  95         string "Local version - append to kernel release"
  96         help
  97           Append an extra string to the end of your kernel version.
  98           This will show up when you type uname, for example.
  99           The string you set here will be appended after the contents of
 100           any files with a filename matching localversion* in your
 101           object and source tree, in that order.  Your total string can
 102           be a maximum of 64 characters.
 103
 104 config LOCALVERSION_AUTO
 105         bool "Automatically append version information to the version string"
 106         default y
 107         help
 108           This will try to automatically determine if the current tree is a
 109           release tree by looking for git tags that belong to the current
 110           top of tree revision.
 111
 112           A string of the format -gxxxxxxxx will be added to the localversion
 113           if a git-based tree is found.  The string generated by this will be
 114           appended after any matching localversion* files, and after the value
 115           set in CONFIG_LOCALVERSION.
 116
 117           (The actual string used here is the first eight characters produced
 118           by running the command:
 119
 120             $ git rev-parse --verify HEAD
 121
 122           which is done within the script "scripts/setlocalversion".)
 123
 124 config HAVE_KERNEL_GZIP
 125         bool
 126
 127 config HAVE_KERNEL_BZIP2
 128         bool
 129
 130 config HAVE_KERNEL_LZMA
 131         bool
 132
 133 config HAVE_KERNEL_LZO
 134         bool
 135
 136 choice
 137         prompt "Kernel compression mode"
 138         default KERNEL_GZIP
 139         depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
 140         help
 141           The linux kernel is a kind of self-extracting executable.
 142           Several compression algorithms are available, which differ
 143           in efficiency, compression and decompression speed.
 144           Compression speed is only relevant when building a kernel.
 145           Decompression speed is relevant at each boot.
 146
 147           If you have any problems with bzip2 or lzma compressed
 148           kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 149           version of this functionality (bzip2 only), for 2.4, was
 150           supplied by Christian Ludwig)
 151
 152           High compression options are mostly useful for users, who
 153           are low on disk space (embedded systems), but for whom ram
 154           size matters less.
 155
 156           If in doubt, select 'gzip'
 157
 158 config KERNEL_GZIP
 159         bool "Gzip"
 160         depends on HAVE_KERNEL_GZIP
 161         help
 162           The old and tried gzip compression. It provides a good balance
 163           between compression ratio and decompression speed.
 164
 165 config KERNEL_BZIP2
 166         bool "Bzip2"
 167         depends on HAVE_KERNEL_BZIP2
 168         help
 169           Its compression ratio and speed is intermediate.
 170           Decompression speed is slowest among the three.  The kernel
 171           size is about 10% smaller with bzip2, in comparison to gzip.
 172           Bzip2 uses a large amount of memory. For modern kernels you
 173           will need at least 8MB RAM or more for booting.
 174
 175 config KERNEL_LZMA
 176         bool "LZMA"
 177         depends on HAVE_KERNEL_LZMA
 178         help
 179           The most recent compression algorithm.
 180           Its ratio is best, decompression speed is between the other
 181           two. Compression is slowest.  The kernel size is about 33%
 182           smaller with LZMA in comparison to gzip.
 183
 184 config KERNEL_LZO
 185         bool "LZO"
 186         depends on HAVE_KERNEL_LZO
 187         help
 188           Its compression ratio is the poorest among the 4. The kernel
 189           size is about about 10% bigger than gzip; however its speed
 190           (both compression and decompression) is the fastest.
 191
 192 endchoice
 193
 194 config SWAP
 195         bool "Support for paging of anonymous memory (swap)"
 196         depends on MMU && BLOCK
 197         default y
 198         help
 199           This option allows you to choose whether you want to have support
 200           for so called swap devices or swap files in your kernel that are
 201           used to provide more virtual memory than the actual RAM present
 202           in your computer.  If unsure say Y.
 203
 204 config SYSVIPC
 205         bool "System V IPC"
 206         ---help---
 207           Inter Process Communication is a suite of library functions and
 208           system calls which let processes (running programs) synchronize and
 209           exchange information. It is generally considered to be a good thing,
 210           and some programs won't run unless you say Y here. In particular, if
 211           you want to run the DOS emulator dosemu under Linux (read the
 212           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 213           you'll need to say Y here.
 214
 215           You can find documentation about IPC with "info ipc" and also in
 216           section 6.4 of the Linux Programmer's Guide, available from
 217           <http://www.tldp.org/guides.html>.
 218
 219 config SYSVIPC_SYSCTL
 220         bool
 221         depends on SYSVIPC
 222         depends on SYSCTL
 223         default y
 224
 225 config POSIX_MQUEUE
 226         bool "POSIX Message Queues"
 227         depends on NET && EXPERIMENTAL
 228         ---help---
 229           POSIX variant of message queues is a part of IPC. In POSIX message
 230           queues every message has a priority which decides about succession
 231           of receiving it by a process. If you want to compile and run
 232           programs written e.g. for Solaris with use of its POSIX message
 233           queues (functions mq_*) say Y here.
 234
 235           POSIX message queues are visible as a filesystem called 'mqueue'
 236           and can be mounted somewhere if you want to do filesystem
 237           operations on message queues.
 238
 239           If unsure, say Y.
 240
 241 config POSIX_MQUEUE_SYSCTL
 242         bool
 243         depends on POSIX_MQUEUE
 244         depends on SYSCTL
 245         default y
 246
 247 config BSD_PROCESS_ACCT
 248         bool "BSD Process Accounting"
 249         help
 250           If you say Y here, a user level program will be able to instruct the
 251           kernel (via a special system call) to write process accounting
 252           information to a file: whenever a process exits, information about
 253           that process will be appended to the file by the kernel.  The
 254           information includes things such as creation time, owning user,
 255           command name, memory usage, controlling terminal etc. (the complete
 256           list is in the struct acct in <file:include/linux/acct.h>).  It is
 257           up to the user level program to do useful things with this
 258           information.  This is generally a good idea, so say Y.
 259
 260 config BSD_PROCESS_ACCT_V3
 261         bool "BSD Process Accounting version 3 file format"
 262         depends on BSD_PROCESS_ACCT
 263         default n
 264         help
 265           If you say Y here, the process accounting information is written
 266           in a new file format that also logs the process IDs of each
 267           process and it's parent. Note that this file format is incompatible
 268           with previous v0/v1/v2 file formats, so you will need updated tools
 269           for processing it. A preliminary version of these tools is available
 270           at <http://www.gnu.org/software/acct/>.
 271
 272 config TASKSTATS
 273         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 274         depends on NET
 275         default n
 276         help
 277           Export selected statistics for tasks/processes through the
 278           generic netlink interface. Unlike BSD process accounting, the
 279           statistics are available during the lifetime of tasks/processes as
 280           responses to commands. Like BSD accounting, they are sent to user
 281           space on task exit.
 282
 283           Say N if unsure.
 284
 285 config TASK_DELAY_ACCT
 286         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 287         depends on TASKSTATS
 288         help
 289           Collect information on time spent by a task waiting for system
 290           resources like cpu, synchronous block I/O completion and swapping
 291           in pages. Such statistics can help in setting a task's priorities
 292           relative to other tasks for cpu, io, rss limits etc.
 293
 294           Say N if unsure.
 295
 296 config TASK_XACCT
 297         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 298         depends on TASKSTATS
 299         help
 300           Collect extended task accounting data and send the data
 301           to userland for processing over the taskstats interface.
 302
 303           Say N if unsure.
 304
 305 config TASK_IO_ACCOUNTING
 306         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 307         depends on TASK_XACCT
 308         help
 309           Collect information on the number of bytes of storage I/O which this
 310           task has caused.
 311
 312           Say N if unsure.
 313
 314 config AUDIT
 315         bool "Auditing support"
 316         depends on NET
 317         help
 318           Enable auditing infrastructure that can be used with another
 319           kernel subsystem, such as SELinux (which requires this for
 320           logging of avc messages output).  Does not do system-call
 321           auditing without CONFIG_AUDITSYSCALL.
 322
 323 config AUDITSYSCALL
 324         bool "Enable system-call auditing support"
 325         depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
 326         default y if SECURITY_SELINUX
 327         help
 328           Enable low-overhead system-call auditing infrastructure that
 329           can be used independently or with another kernel subsystem,
 330           such as SELinux.
 331
 332 config AUDIT_WATCH
 333         def_bool y
 334         depends on AUDITSYSCALL
 335         select FSNOTIFY
 336
 337 config AUDIT_TREE
 338         def_bool y
 339         depends on AUDITSYSCALL
 340         select FSNOTIFY
 341
 342 menu "RCU Subsystem"
 343
 344 choice
 345         prompt "RCU Implementation"
 346         default TREE_RCU
 347
 348 config TREE_RCU
 349         bool "Tree-based hierarchical RCU"
 350         help
 351           This option selects the RCU implementation that is
 352           designed for very large SMP system with hundreds or
 353           thousands of CPUs.  It also scales down nicely to
 354           smaller systems.
 355
 356 config TREE_PREEMPT_RCU
 357         bool "Preemptable tree-based hierarchical RCU"
 358         depends on PREEMPT
 359         help
 360           This option selects the RCU implementation that is
 361           designed for very large SMP systems with hundreds or
 362           thousands of CPUs, but for which real-time response
 363           is also required.  It also scales down nicely to
 364           smaller systems.
 365
 366 config TINY_RCU
 367         bool "UP-only small-memory-footprint RCU"
 368         depends on !SMP
 369         help
 370           This option selects the RCU implementation that is
 371           designed for UP systems from which real-time response
 372           is not required.  This option greatly reduces the
 373           memory footprint of RCU.
 374
 375 endchoice
 376
 377 config RCU_TRACE
 378         bool "Enable tracing for RCU"
 379         depends on TREE_RCU || TREE_PREEMPT_RCU
 380         help
 381           This option provides tracing in RCU which presents stats
 382           in debugfs for debugging RCU implementation.
 383
 384           Say Y here if you want to enable RCU tracing
 385           Say N if you are unsure.
 386
 387 config RCU_FANOUT
 388         int "Tree-based hierarchical RCU fanout value"
 389         range 2 64 if 64BIT
 390         range 2 32 if !64BIT
 391         depends on TREE_RCU || TREE_PREEMPT_RCU
 392         default 64 if 64BIT
 393         default 32 if !64BIT
 394         help
 395           This option controls the fanout of hierarchical implementations
 396           of RCU, allowing RCU to work efficiently on machines with
 397           large numbers of CPUs.  This value must be at least the cube
 398           root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
 399           systems and up to 262,144 for 64-bit systems.
 400
 401           Select a specific number if testing RCU itself.
 402           Take the default if unsure.
 403
 404 config RCU_FANOUT_EXACT
 405         bool "Disable tree-based hierarchical RCU auto-balancing"
 406         depends on TREE_RCU || TREE_PREEMPT_RCU
 407         default n
 408         help
 409           This option forces use of the exact RCU_FANOUT value specified,
 410           regardless of imbalances in the hierarchy.  This is useful for
 411           testing RCU itself, and might one day be useful on systems with
 412           strong NUMA behavior.
 413
 414           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 415
 416           Say N if unsure.
 417
 418 config RCU_FAST_NO_HZ
 419         bool "Accelerate last non-dyntick-idle CPU's grace periods"
 420         depends on TREE_RCU && NO_HZ && SMP
 421         default n
 422         help
 423           This option causes RCU to attempt to accelerate grace periods
 424           in order to allow the final CPU to enter dynticks-idle state
 425           more quickly.  On the other hand, this option increases the
 426           overhead of the dynticks-idle checking, particularly on systems
 427           with large numbers of CPUs.
 428
 429           Say Y if energy efficiency is critically important, particularly
 430                 if you have relatively few CPUs.
 431
 432           Say N if you are unsure.
 433
 434 config TREE_RCU_TRACE
 435         def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 436         select DEBUG_FS
 437         help
 438           This option provides tracing for the TREE_RCU and
 439           TREE_PREEMPT_RCU implementations, permitting Makefile to
 440           trivially select kernel/rcutree_trace.c.
 441
 442 endmenu # "RCU Subsystem"
 443
 444 config IKCONFIG
 445         tristate "Kernel .config support"
 446         ---help---
 447           This option enables the complete Linux kernel ".config" file
 448           contents to be saved in the kernel. It provides documentation
 449           of which kernel options are used in a running kernel or in an
 450           on-disk kernel.  This information can be extracted from the kernel
 451           image file with the script scripts/extract-ikconfig and used as
 452           input to rebuild the current kernel or to build another kernel.
 453           It can also be extracted from a running kernel by reading
 454           /proc/config.gz if enabled (below).
 455
 456 config IKCONFIG_PROC
 457         bool "Enable access to .config through /proc/config.gz"
 458         depends on IKCONFIG && PROC_FS
 459         ---help---
 460           This option enables access to the kernel configuration file
 461           through /proc/config.gz.
 462
 463 config LOG_BUF_SHIFT
 464         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 465         range 12 21
 466         default 17
 467         help
 468           Select kernel log buffer size as a power of 2.
 469           Examples:
 470                      17 => 128 KB
 471                      16 => 64 KB
 472                      15 => 32 KB
 473                      14 => 16 KB
 474                      13 =>  8 KB
 475                      12 =>  4 KB
 476
 477 #
 478 # Architectures with an unreliable sched_clock() should select this:
 479 #
 480 config HAVE_UNSTABLE_SCHED_CLOCK
 481         bool
 482
 483 menuconfig CGROUPS
 484         boolean "Control Group support"
 485         depends on EVENTFD
 486         help
 487           This option adds support for grouping sets of processes together, for
 488           use with process control subsystems such as Cpusets, CFS, memory
 489           controls or device isolation.
 490           See
 491                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 492                 - Documentation/cgroups/ (features for grouping, isolation
 493                                           and resource control)
 494
 495           Say N if unsure.
 496
 497 if CGROUPS
 498
 499 config CGROUP_DEBUG
 500         bool "Example debug cgroup subsystem"
 501         depends on CGROUPS
 502         default n
 503         help
 504           This option enables a simple cgroup subsystem that
 505           exports useful debugging information about the cgroups
 506           framework.
 507
 508           Say N if unsure.
 509
 510 config CGROUP_NS
 511         bool "Namespace cgroup subsystem"
 512         depends on CGROUPS
 513         help
 514           Provides a simple namespace cgroup subsystem to
 515           provide hierarchical naming of sets of namespaces,
 516           for instance virtual servers and checkpoint/restart
 517           jobs.
 518
 519 config CGROUP_FREEZER
 520         bool "Freezer cgroup subsystem"
 521         depends on CGROUPS
 522         help
 523           Provides a way to freeze and unfreeze all tasks in a
 524           cgroup.
 525
 526 config CGROUP_DEVICE
 527         bool "Device controller for cgroups"
 528         depends on CGROUPS && EXPERIMENTAL
 529         help
 530           Provides a cgroup implementing whitelists for devices which
 531           a process in the cgroup can mknod or open.
 532
 533 config CPUSETS
 534         bool "Cpuset support"
 535         depends on CGROUPS
 536         help
 537           This option will let you create and manage CPUSETs which
 538           allow dynamically partitioning a system into sets of CPUs and
 539           Memory Nodes and assigning tasks to run only within those sets.
 540           This is primarily useful on large SMP or NUMA systems.
 541
 542           Say N if unsure.
 543
 544 config PROC_PID_CPUSET
 545         bool "Include legacy /proc/<pid>/cpuset file"
 546         depends on CPUSETS
 547         default y
 548
 549 config CGROUP_CPUACCT
 550         bool "Simple CPU accounting cgroup subsystem"
 551         depends on CGROUPS
 552         help
 553           Provides a simple Resource Controller for monitoring the
 554           total CPU consumed by the tasks in a cgroup.
 555
 556 config RESOURCE_COUNTERS
 557         bool "Resource counters"
 558         help
 559           This option enables controller independent resource accounting
 560           infrastructure that works with cgroups.
 561         depends on CGROUPS
 562
 563 config CGROUP_MEM_RES_CTLR
 564         bool "Memory Resource Controller for Control Groups"
 565         depends on CGROUPS && RESOURCE_COUNTERS
 566         select MM_OWNER
 567         help
 568           Provides a memory resource controller that manages both anonymous
 569           memory and page cache. (See Documentation/cgroups/memory.txt)
 570
 571           Note that setting this option increases fixed memory overhead
 572           associated with each page of memory in the system. By this,
 573           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 574           usage tracking struct at boot. Total amount of this is printed out
 575           at boot.
 576
 577           Only enable when you're ok with these trade offs and really
 578           sure you need the memory resource controller. Even when you enable
 579           this, you can set "cgroup_disable=memory" at your boot option to
 580           disable memory resource controller and you can avoid overheads.
 581           (and lose benefits of memory resource controller)
 582
 583           This config option also selects MM_OWNER config option, which
 584           could in turn add some fork/exit overhead.
 585
 586 config CGROUP_MEM_RES_CTLR_SWAP
 587         bool "Memory Resource Controller Swap Extension"
 588         depends on CGROUP_MEM_RES_CTLR && SWAP
 589         help
 590           Add swap management feature to memory resource controller. When you
 591           enable this, you can limit mem+swap usage per cgroup. In other words,
 592           when you disable this, memory resource controller has no cares to
 593           usage of swap...a process can exhaust all of the swap. This extension
 594           is useful when you want to avoid exhaustion swap but this itself
 595           adds more overheads and consumes memory for remembering information.
 596           Especially if you use 32bit system or small memory system, please
 597           be careful about enabling this. When memory resource controller
 598           is disabled by boot option, this will be automatically disabled and
 599           there will be no overhead from this. Even when you set this config=y,
 600           if boot option "noswapaccount" is set, swap will not be accounted.
 601           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 602           size is 4096bytes, 512k per 1Gbytes of swap.
 603
 604 menuconfig CGROUP_SCHED
 605         bool "Group CPU scheduler"
 606         depends on EXPERIMENTAL && CGROUPS
 607         default n
 608         help
 609           This feature lets CPU scheduler recognize task groups and control CPU
 610           bandwidth allocation to such task groups. It uses cgroups to group
 611           tasks.
 612
 613 if CGROUP_SCHED
 614 config FAIR_GROUP_SCHED
 615         bool "Group scheduling for SCHED_OTHER"
 616         depends on CGROUP_SCHED
 617         default CGROUP_SCHED
 618
 619 config RT_GROUP_SCHED
 620         bool "Group scheduling for SCHED_RR/FIFO"
 621         depends on EXPERIMENTAL
 622         depends on CGROUP_SCHED
 623         default n
 624         help
 625           This feature lets you explicitly allocate real CPU bandwidth
 626           to task groups. If enabled, it will also make it impossible to
 627           schedule realtime tasks for non-root users until you allocate
 628           realtime bandwidth for them.
 629           See Documentation/scheduler/sched-rt-group.txt for more information.
 630
 631 endif #CGROUP_SCHED
 632
 633 config BLK_CGROUP
 634         tristate "Block IO controller"
 635         depends on CGROUPS && BLOCK
 636         default n
 637         ---help---
 638         Generic block IO controller cgroup interface. This is the common
 639         cgroup interface which should be used by various IO controlling
 640         policies.
 641
 642         Currently, CFQ IO scheduler uses it to recognize task groups and
 643         control disk bandwidth allocation (proportional time slice allocation)
 644         to such task groups.
 645
 646         This option only enables generic Block IO controller infrastructure.
 647         One needs to also enable actual IO controlling logic in CFQ for it
 648         to take effect. (CONFIG_CFQ_GROUP_IOSCHED=y).
 649
 650         See Documentation/cgroups/blkio-controller.txt for more information.
 651
 652 config DEBUG_BLK_CGROUP
 653         bool "Enable Block IO controller debugging"
 654         depends on BLK_CGROUP
 655         default n
 656         ---help---
 657         Enable some debugging help. Currently it exports additional stat
 658         files in a cgroup which can be useful for debugging.
 659
 660 endif # CGROUPS
 661
 662 config MM_OWNER
 663         bool
 664
 665 config SYSFS_DEPRECATED
 666         bool
 667
 668 config SYSFS_DEPRECATED_V2
 669         bool "enable deprecated sysfs features to support old userspace tools"
 670         depends on SYSFS
 671         default n
 672         select SYSFS_DEPRECATED
 673         help
 674           This option switches the layout of sysfs to the deprecated
 675           version. Do not use it on recent distributions.
 676
 677           The current sysfs layout features a unified device tree at
 678           /sys/devices/, which is able to express a hierarchy between
 679           class devices. If the deprecated option is set to Y, the
 680           unified device tree is split into a bus device tree at
 681           /sys/devices/ and several individual class device trees at
 682           /sys/class/. The class and bus devices will be connected by
 683           "<subsystem>:<name>" and the "device" links. The "block"
 684           class devices, will not show up in /sys/class/block/. Some
 685           subsystems will suppress the creation of some devices which
 686           depend on the unified device tree.
 687
 688           This option is not a pure compatibility option that can
 689           be safely enabled on newer distributions. It will change the
 690           layout of sysfs to the non-extensible deprecated version,
 691           and disable some features, which can not be exported without
 692           confusing older userspace tools. Since 2007/2008 all major
 693           distributions do not enable this option, and ship no tools which
 694           depend on the deprecated layout or this option.
 695
 696           If you are using a new kernel on an older distribution, or use
 697           older userspace tools, you might need to say Y here. Do not say Y,
 698           if the original kernel, that came with your distribution, has
 699           this option set to N.
 700
 701 config RELAY
 702         bool "Kernel->user space relay support (formerly relayfs)"
 703         help
 704           This option enables support for relay interface support in
 705           certain file systems (such as debugfs).
 706           It is designed to provide an efficient mechanism for tools and
 707           facilities to relay large amounts of data from kernel space to
 708           user space.
 709
 710           If unsure, say N.
 711
 712 config NAMESPACES
 713         bool "Namespaces support" if EMBEDDED
 714         default !EMBEDDED
 715         help
 716           Provides the way to make tasks work with different objects using
 717           the same id. For example same IPC id may refer to different objects
 718           or same user id or pid may refer to different tasks when used in
 719           different namespaces.
 720
 721 config UTS_NS
 722         bool "UTS namespace"
 723         depends on NAMESPACES
 724         help
 725           In this namespace tasks see different info provided with the
 726           uname() system call
 727
 728 config IPC_NS
 729         bool "IPC namespace"
 730         depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
 731         help
 732           In this namespace tasks work with IPC ids which correspond to
 733           different IPC objects in different namespaces.
 734
 735 config USER_NS
 736         bool "User namespace (EXPERIMENTAL)"
 737         depends on NAMESPACES && EXPERIMENTAL
 738         help
 739           This allows containers, i.e. vservers, to use user namespaces
 740           to provide different user info for different servers.
 741           If unsure, say N.
 742
 743 config PID_NS
 744         bool "PID Namespaces (EXPERIMENTAL)"
 745         default n
 746         depends on NAMESPACES && EXPERIMENTAL
 747         help
 748           Support process id namespaces.  This allows having multiple
 749           processes with the same pid as long as they are in different
 750           pid namespaces.  This is a building block of containers.
 751
 752           Unless you want to work with an experimental feature
 753           say N here.
 754
 755 config NET_NS
 756         bool "Network namespace"
 757         default n
 758         depends on NAMESPACES && EXPERIMENTAL && NET
 759         help
 760           Allow user space to create what appear to be multiple instances
 761           of the network stack.
 762
 763 config BLK_DEV_INITRD
 764         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 765         depends on BROKEN || !FRV
 766         help
 767           The initial RAM filesystem is a ramfs which is loaded by the
 768           boot loader (loadlin or lilo) and that is mounted as root
 769           before the normal boot procedure. It is typically used to
 770           load modules needed to mount the "real" root file system,
 771           etc. See <file:Documentation/initrd.txt> for details.
 772
 773           If RAM disk support (BLK_DEV_RAM) is also included, this
 774           also enables initial RAM disk (initrd) support and adds
 775           15 Kbytes (more on some other architectures) to the kernel size.
 776
 777           If unsure say Y.
 778
 779 if BLK_DEV_INITRD
 780
 781 source "usr/Kconfig"
 782
 783 endif
 784
 785 config CC_OPTIMIZE_FOR_SIZE
 786         bool "Optimize for size"
 787         default y
 788         help
 789           Enabling this option will pass "-Os" instead of "-O2" to gcc
 790           resulting in a smaller kernel.
 791
 792           If unsure, say Y.
 793
 794 config SYSCTL
 795         bool
 796
 797 config ANON_INODES
 798         bool
 799
 800 menuconfig EMBEDDED
 801         bool "Configure standard kernel features (for small systems)"
 802         help
 803           This option allows certain base kernel options and settings
 804           to be disabled or tweaked. This is for specialized
 805           environments which can tolerate a "non-standard" kernel.
 806           Only use this if you really know what you are doing.
 807
 808 config UID16
 809         bool "Enable 16-bit UID system calls" if EMBEDDED
 810         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 811         default y
 812         help
 813           This enables the legacy 16-bit UID syscall wrappers.
 814
 815 config SYSCTL_SYSCALL
 816         bool "Sysctl syscall support" if EMBEDDED
 817         depends on PROC_SYSCTL
 818         default y
 819         select SYSCTL
 820         ---help---
 821           sys_sysctl uses binary paths that have been found challenging
 822           to properly maintain and use.  The interface in /proc/sys
 823           using paths with ascii names is now the primary path to this
 824           information.
 825
 826           Almost nothing using the binary sysctl interface so if you are
 827           trying to save some space it is probably safe to disable this,
 828           making your kernel marginally smaller.
 829
 830           If unsure say Y here.
 831
 832 config KALLSYMS
 833          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 834          default y
 835          help
 836            Say Y here to let the kernel print out symbolic crash information and
 837            symbolic stack backtraces. This increases the size of the kernel
 838            somewhat, as all symbols have to be loaded into the kernel image.
 839
 840 config KALLSYMS_ALL
 841         bool "Include all symbols in kallsyms"
 842         depends on DEBUG_KERNEL && KALLSYMS
 843         help
 844            Normally kallsyms only contains the symbols of functions, for nicer
 845            OOPS messages.  Some debuggers can use kallsyms for other
 846            symbols too: say Y here to include all symbols, if you need them
 847            and you don't care about adding 300k to the size of your kernel.
 848
 849            Say N.
 850
 851 config KALLSYMS_EXTRA_PASS
 852         bool "Do an extra kallsyms pass"
 853         depends on KALLSYMS
 854         help
 855            If kallsyms is not working correctly, the build will fail with
 856            inconsistent kallsyms data.  If that occurs, log a bug report and
 857            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 858            Always say N here unless you find a bug in kallsyms, which must be
 859            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 860            you wait for kallsyms to be fixed.
 861
 862
 863 config HOTPLUG
 864         bool "Support for hot-pluggable devices" if EMBEDDED
 865         default y
 866         help
 867           This option is provided for the case where no hotplug or uevent
 868           capabilities is wanted by the kernel.  You should only consider
 869           disabling this option for embedded systems that do not use modules, a
 870           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 871
 872 config PRINTK
 873         default y
 874         bool "Enable support for printk" if EMBEDDED
 875         help
 876           This option enables normal printk support. Removing it
 877           eliminates most of the message strings from the kernel image
 878           and makes the kernel more or less silent. As this makes it
 879           very difficult to diagnose system problems, saying N here is
 880           strongly discouraged.
 881
 882 config BUG
 883         bool "BUG() support" if EMBEDDED
 884         default y
 885         help
 886           Disabling this option eliminates support for BUG and WARN, reducing
 887           the size of your kernel image and potentially quietly ignoring
 888           numerous fatal conditions. You should only consider disabling this
 889           option for embedded systems with no facilities for reporting errors.
 890           Just say Y.
 891
 892 config ELF_CORE
 893         default y
 894         bool "Enable ELF core dumps" if EMBEDDED
 895         help
 896           Enable support for generating core dumps. Disabling saves about 4k.
 897
 898 config PCSPKR_PLATFORM
 899         bool "Enable PC-Speaker support" if EMBEDDED
 900         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 901         default y
 902         help
 903           This option allows to disable the internal PC-Speaker
 904           support, saving some memory.
 905
 906 config BASE_FULL
 907         default y
 908         bool "Enable full-sized data structures for core" if EMBEDDED
 909         help
 910           Disabling this option reduces the size of miscellaneous core
 911           kernel data structures. This saves memory on small machines,
 912           but may reduce performance.
 913
 914 config FUTEX
 915         bool "Enable futex support" if EMBEDDED
 916         default y
 917         select RT_MUTEXES
 918         help
 919           Disabling this option will cause the kernel to be built without
 920           support for "fast userspace mutexes".  The resulting kernel may not
 921           run glibc-based applications correctly.
 922
 923 config EPOLL
 924         bool "Enable eventpoll support" if EMBEDDED
 925         default y
 926         select ANON_INODES
 927         help
 928           Disabling this option will cause the kernel to be built without
 929           support for epoll family of system calls.
 930
 931 config SIGNALFD
 932         bool "Enable signalfd() system call" if EMBEDDED
 933         select ANON_INODES
 934         default y
 935         help
 936           Enable the signalfd() system call that allows to receive signals
 937           on a file descriptor.
 938
 939           If unsure, say Y.
 940
 941 config TIMERFD
 942         bool "Enable timerfd() system call" if EMBEDDED
 943         select ANON_INODES
 944         default y
 945         help
 946           Enable the timerfd() system call that allows to receive timer
 947           events on a file descriptor.
 948
 949           If unsure, say Y.
 950
 951 config EVENTFD
 952         bool "Enable eventfd() system call" if EMBEDDED
 953         select ANON_INODES
 954         default y
 955         help
 956           Enable the eventfd() system call that allows to receive both
 957           kernel notification (ie. KAIO) or userspace notifications.
 958
 959           If unsure, say Y.
 960
 961 config SHMEM
 962         bool "Use full shmem filesystem" if EMBEDDED
 963         default y
 964         depends on MMU
 965         help
 966           The shmem is an internal filesystem used to manage shared memory.
 967           It is backed by swap and manages resource limits. It is also exported
 968           to userspace as tmpfs if TMPFS is enabled. Disabling this
 969           option replaces shmem and tmpfs with the much simpler ramfs code,
 970           which may be appropriate on small systems without swap.
 971
 972 config AIO
 973         bool "Enable AIO support" if EMBEDDED
 974         default y
 975         help
 976           This option enables POSIX asynchronous I/O which may by used
 977           by some high performance threaded applications. Disabling
 978           this option saves about 7k.
 979
 980 config HAVE_PERF_EVENTS
 981         bool
 982         help
 983           See tools/perf/design.txt for details.
 984
 985 config PERF_USE_VMALLOC
 986         bool
 987         help
 988           See tools/perf/design.txt for details
 989
 990 menu "Kernel Performance Events And Counters"
 991
 992 config PERF_EVENTS
 993         bool "Kernel performance events and counters"
 994         default y if (PROFILING || PERF_COUNTERS)
 995         depends on HAVE_PERF_EVENTS
 996         select ANON_INODES
 997         select IRQ_WORK
 998         help
 999           Enable kernel support for various performance events provided
1000           by software and hardware.
1001
1002           Software events are supported either built-in or via the
1003           use of generic tracepoints.
1004
1005           Most modern CPUs support performance events via performance
1006           counter registers. These registers count the number of certain
1007           types of hw events: such as instructions executed, cachemisses
1008           suffered, or branches mis-predicted - without slowing down the
1009           kernel or applications. These registers can also trigger interrupts
1010           when a threshold number of events have passed - and can thus be
1011           used to profile the code that runs on that CPU.
1012
1013           The Linux Performance Event subsystem provides an abstraction of
1014           these software and hardware event capabilities, available via a
1015           system call and used by the "perf" utility in tools/perf/. It
1016           provides per task and per CPU counters, and it provides event
1017           capabilities on top of those.
1018
1019           Say Y if unsure.
1020
1021 config PERF_COUNTERS
1022         bool "Kernel performance counters (old config option)"
1023         depends on HAVE_PERF_EVENTS
1024         help
1025           This config has been obsoleted by the PERF_EVENTS
1026           config option - please see that one for details.
1027
1028           It has no effect on the kernel whether you enable
1029           it or not, it is a compatibility placeholder.
1030
1031           Say N if unsure.
1032
1033 config DEBUG_PERF_USE_VMALLOC
1034         default n
1035         bool "Debug: use vmalloc to back perf mmap() buffers"
1036         depends on PERF_EVENTS && DEBUG_KERNEL
1037         select PERF_USE_VMALLOC
1038         help
1039          Use vmalloc memory to back perf mmap() buffers.
1040
1041          Mostly useful for debugging the vmalloc code on platforms
1042          that don't require it.
1043
1044          Say N if unsure.
1045
1046 endmenu
1047
1048 config VM_EVENT_COUNTERS
1049         default y
1050         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1051         help
1052           VM event counters are needed for event counts to be shown.
1053           This option allows the disabling of the VM event counters
1054           on EMBEDDED systems.  /proc/vmstat will only show page counts
1055           if VM event counters are disabled.
1056
1057 config PCI_QUIRKS
1058         default y
1059         bool "Enable PCI quirk workarounds" if EMBEDDED
1060         depends on PCI
1061         help
1062           This enables workarounds for various PCI chipset
1063           bugs/quirks. Disable this only if your target machine is
1064           unaffected by PCI quirks.
1065
1066 config SLUB_DEBUG
1067         default y
1068         bool "Enable SLUB debugging support" if EMBEDDED
1069         depends on SLUB && SYSFS
1070         help
1071           SLUB has extensive debug support features. Disabling these can
1072           result in significant savings in code size. This also disables
1073           SLUB sysfs support. /sys/slab will not exist and there will be
1074           no support for cache validation etc.
1075
1076 config COMPAT_BRK
1077         bool "Disable heap randomization"
1078         default y
1079         help
1080           Randomizing heap placement makes heap exploits harder, but it
1081           also breaks ancient binaries (including anything libc5 based).
1082           This option changes the bootup default to heap randomization
1083           disabled, and can be overridden at runtime by setting
1084           /proc/sys/kernel/randomize_va_space to 2.
1085
1086           On non-ancient distros (post-2000 ones) N is usually a safe choice.
1087
1088 choice
1089         prompt "Choose SLAB allocator"
1090         default SLUB
1091         help
1092            This option allows to select a slab allocator.
1093
1094 config SLAB
1095         bool "SLAB"
1096         help
1097           The regular slab allocator that is established and known to work
1098           well in all environments. It organizes cache hot objects in
1099           per cpu and per node queues.
1100
1101 config SLUB
1102         bool "SLUB (Unqueued Allocator)"
1103         help
1104            SLUB is a slab allocator that minimizes cache line usage
1105            instead of managing queues of cached objects (SLAB approach).
1106            Per cpu caching is realized using slabs of objects instead
1107            of queues of objects. SLUB can use memory efficiently
1108            and has enhanced diagnostics. SLUB is the default choice for
1109            a slab allocator.
1110
1111 config SLOB
1112         depends on EMBEDDED
1113         bool "SLOB (Simple Allocator)"
1114         help
1115            SLOB replaces the stock allocator with a drastically simpler
1116            allocator. SLOB is generally more space efficient but
1117            does not perform as well on large systems.
1118
1119 endchoice
1120
1121 config MMAP_ALLOW_UNINITIALIZED
1122         bool "Allow mmapped anonymous memory to be uninitialized"
1123         depends on EMBEDDED && !MMU
1124         default n
1125         help
1126           Normally, and according to the Linux spec, anonymous memory obtained
1127           from mmap() has it's contents cleared before it is passed to
1128           userspace.  Enabling this config option allows you to request that
1129           mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1130           providing a huge performance boost.  If this option is not enabled,
1131           then the flag will be ignored.
1132
1133           This is taken advantage of by uClibc's malloc(), and also by
1134           ELF-FDPIC binfmt's brk and stack allocator.
1135
1136           Because of the obvious security issues, this option should only be
1137           enabled on embedded devices where you control what is run in
1138           userspace.  Since that isn't generally a problem on no-MMU systems,
1139           it is normally safe to say Y here.
1140
1141           See Documentation/nommu-mmap.txt for more information.
1142
1143 config PROFILING
1144         bool "Profiling support"
1145         help
1146           Say Y here to enable the extended profiling support mechanisms used
1147           by profilers such as OProfile.
1148
1149 #
1150 # Place an empty function call at each tracepoint site. Can be
1151 # dynamically changed for a probe function.
1152 #
1153 config TRACEPOINTS
1154         bool
1155
1156 source "arch/Kconfig"
1157
1158 endmenu         # General setup
1159
1160 config HAVE_GENERIC_DMA_COHERENT
1161         bool
1162         default n
1163
1164 config SLABINFO
1165         bool
1166         depends on PROC_FS
1167         depends on SLAB || SLUB_DEBUG
1168         default y
1169
1170 config RT_MUTEXES
1171         boolean
1172
1173 config BASE_SMALL
1174         int
1175         default 0 if BASE_FULL
1176         default 1 if !BASE_FULL
1177
1178 menuconfig MODULES
1179         bool "Enable loadable module support"
1180         help
1181           Kernel modules are small pieces of compiled code which can
1182           be inserted in the running kernel, rather than being
1183           permanently built into the kernel.  You use the "modprobe"
1184           tool to add (and sometimes remove) them.  If you say Y here,
1185           many parts of the kernel can be built as modules (by
1186           answering M instead of Y where indicated): this is most
1187           useful for infrequently used options which are not required
1188           for booting.  For more information, see the man pages for
1189           modprobe, lsmod, modinfo, insmod and rmmod.
1190
1191           If you say Y here, you will need to run "make
1192           modules_install" to put the modules under /lib/modules/
1193           where modprobe can find them (you may need to be root to do
1194           this).
1195
1196           If unsure, say Y.
1197
1198 if MODULES
1199
1200 config MODULE_FORCE_LOAD
1201         bool "Forced module loading"
1202         default n
1203         help
1204           Allow loading of modules without version information (ie. modprobe
1205           --force).  Forced module loading sets the 'F' (forced) taint flag and
1206           is usually a really bad idea.
1207
1208 config MODULE_UNLOAD
1209         bool "Module unloading"
1210         help
1211           Without this option you will not be able to unload any
1212           modules (note that some modules may not be unloadable
1213           anyway), which makes your kernel smaller, faster
1214           and simpler.  If unsure, say Y.
1215
1216 config MODULE_FORCE_UNLOAD
1217         bool "Forced module unloading"
1218         depends on MODULE_UNLOAD && EXPERIMENTAL
1219         help
1220           This option allows you to force a module to unload, even if the
1221           kernel believes it is unsafe: the kernel will remove the module
1222           without waiting for anyone to stop using it (using the -f option to
1223           rmmod).  This is mainly for kernel developers and desperate users.
1224           If unsure, say N.
1225
1226 config MODVERSIONS
1227         bool "Module versioning support"
1228         help
1229           Usually, you have to use modules compiled with your kernel.
1230           Saying Y here makes it sometimes possible to use modules
1231           compiled for different kernels, by adding enough information
1232           to the modules to (hopefully) spot any changes which would
1233           make them incompatible with the kernel you are running.  If
1234           unsure, say N.
1235
1236 config MODULE_SRCVERSION_ALL
1237         bool "Source checksum for all modules"
1238         help
1239           Modules which contain a MODULE_VERSION get an extra "srcversion"
1240           field inserted into their modinfo section, which contains a
1241           sum of the source files which made it.  This helps maintainers
1242           see exactly which source was used to build a module (since
1243           others sometimes change the module source without updating
1244           the version).  With this option, such a "srcversion" field
1245           will be created for all modules.  If unsure, say N.
1246
1247 endif # MODULES
1248
1249 config INIT_ALL_POSSIBLE
1250         bool
1251         help
1252           Back when each arch used to define their own cpu_online_map and
1253           cpu_possible_map, some of them chose to initialize cpu_possible_map
1254           with all 1s, and others with all 0s.  When they were centralised,
1255           it was better to provide this option than to break all the archs
1256           and have several arch maintainers pursuing me down dark alleys.
1257
1258 config STOP_MACHINE
1259         bool
1260         default y
1261         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1262         help
1263           Need stop_machine() primitive.
1264
1265 source "block/Kconfig"
1266
1267 config PREEMPT_NOTIFIERS
1268         bool
1269
1270 config PADATA
1271         depends on SMP
1272         bool
1273
1274 source "kernel/Kconfig.locks"