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  47           drivers that have been replaced by something else, and/or are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 CROSS_COMPILE
  80         string "Cross-compiler tool prefix"
  81         help
  82           Same as running 'make CROSS_COMPILE=prefix-' but stored for
  83           default make runs in this kernel build directory.  You don't
  84           need to set this unless you want the configured kernel build
  85           directory to select the cross-compiler automatically.
  86
  87 config LOCALVERSION
  88         string "Local version - append to kernel release"
  89         help
  90           Append an extra string to the end of your kernel version.
  91           This will show up when you type uname, for example.
  92           The string you set here will be appended after the contents of
  93           any files with a filename matching localversion* in your
  94           object and source tree, in that order.  Your total string can
  95           be a maximum of 64 characters.
  96
  97 config LOCALVERSION_AUTO
  98         bool "Automatically append version information to the version string"
  99         default y
 100         help
 101           This will try to automatically determine if the current tree is a
 102           release tree by looking for git tags that belong to the current
 103           top of tree revision.
 104
 105           A string of the format -gxxxxxxxx will be added to the localversion
 106           if a git-based tree is found.  The string generated by this will be
 107           appended after any matching localversion* files, and after the value
 108           set in CONFIG_LOCALVERSION.
 109
 110           (The actual string used here is the first eight characters produced
 111           by running the command:
 112
 113             $ git rev-parse --verify HEAD
 114
 115           which is done within the script "scripts/setlocalversion".)
 116
 117 config HAVE_KERNEL_GZIP
 118         bool
 119
 120 config HAVE_KERNEL_BZIP2
 121         bool
 122
 123 config HAVE_KERNEL_LZMA
 124         bool
 125
 126 config HAVE_KERNEL_LZO
 127         bool
 128
 129 choice
 130         prompt "Kernel compression mode"
 131         default KERNEL_GZIP
 132         depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
 133         help
 134           The linux kernel is a kind of self-extracting executable.
 135           Several compression algorithms are available, which differ
 136           in efficiency, compression and decompression speed.
 137           Compression speed is only relevant when building a kernel.
 138           Decompression speed is relevant at each boot.
 139
 140           If you have any problems with bzip2 or lzma compressed
 141           kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 142           version of this functionality (bzip2 only), for 2.4, was
 143           supplied by Christian Ludwig)
 144
 145           High compression options are mostly useful for users, who
 146           are low on disk space (embedded systems), but for whom ram
 147           size matters less.
 148
 149           If in doubt, select 'gzip'
 150
 151 config KERNEL_GZIP
 152         bool "Gzip"
 153         depends on HAVE_KERNEL_GZIP
 154         help
 155           The old and tried gzip compression. It provides a good balance
 156           between compression ratio and decompression speed.
 157
 158 config KERNEL_BZIP2
 159         bool "Bzip2"
 160         depends on HAVE_KERNEL_BZIP2
 161         help
 162           Its compression ratio and speed is intermediate.
 163           Decompression speed is slowest among the three.  The kernel
 164           size is about 10% smaller with bzip2, in comparison to gzip.
 165           Bzip2 uses a large amount of memory. For modern kernels you
 166           will need at least 8MB RAM or more for booting.
 167
 168 config KERNEL_LZMA
 169         bool "LZMA"
 170         depends on HAVE_KERNEL_LZMA
 171         help
 172           The most recent compression algorithm.
 173           Its ratio is best, decompression speed is between the other
 174           two. Compression is slowest.  The kernel size is about 33%
 175           smaller with LZMA in comparison to gzip.
 176
 177 config KERNEL_LZO
 178         bool "LZO"
 179         depends on HAVE_KERNEL_LZO
 180         help
 181           Its compression ratio is the poorest among the 4. The kernel
 182           size is about about 10% bigger than gzip; however its speed
 183           (both compression and decompression) is the fastest.
 184
 185 endchoice
 186
 187 config SWAP
 188         bool "Support for paging of anonymous memory (swap)"
 189         depends on MMU && BLOCK
 190         default y
 191         help
 192           This option allows you to choose whether you want to have support
 193           for so called swap devices or swap files in your kernel that are
 194           used to provide more virtual memory than the actual RAM present
 195           in your computer.  If unsure say Y.
 196
 197 config SYSVIPC
 198         bool "System V IPC"
 199         ---help---
 200           Inter Process Communication is a suite of library functions and
 201           system calls which let processes (running programs) synchronize and
 202           exchange information. It is generally considered to be a good thing,
 203           and some programs won't run unless you say Y here. In particular, if
 204           you want to run the DOS emulator dosemu under Linux (read the
 205           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 206           you'll need to say Y here.
 207
 208           You can find documentation about IPC with "info ipc" and also in
 209           section 6.4 of the Linux Programmer's Guide, available from
 210           <http://www.tldp.org/guides.html>.
 211
 212 config SYSVIPC_SYSCTL
 213         bool
 214         depends on SYSVIPC
 215         depends on SYSCTL
 216         default y
 217
 218 config POSIX_MQUEUE
 219         bool "POSIX Message Queues"
 220         depends on NET && EXPERIMENTAL
 221         ---help---
 222           POSIX variant of message queues is a part of IPC. In POSIX message
 223           queues every message has a priority which decides about succession
 224           of receiving it by a process. If you want to compile and run
 225           programs written e.g. for Solaris with use of its POSIX message
 226           queues (functions mq_*) say Y here.
 227
 228           POSIX message queues are visible as a filesystem called 'mqueue'
 229           and can be mounted somewhere if you want to do filesystem
 230           operations on message queues.
 231
 232           If unsure, say Y.
 233
 234 config POSIX_MQUEUE_SYSCTL
 235         bool
 236         depends on POSIX_MQUEUE
 237         depends on SYSCTL
 238         default y
 239
 240 config BSD_PROCESS_ACCT
 241         bool "BSD Process Accounting"
 242         help
 243           If you say Y here, a user level program will be able to instruct the
 244           kernel (via a special system call) to write process accounting
 245           information to a file: whenever a process exits, information about
 246           that process will be appended to the file by the kernel.  The
 247           information includes things such as creation time, owning user,
 248           command name, memory usage, controlling terminal etc. (the complete
 249           list is in the struct acct in <file:include/linux/acct.h>).  It is
 250           up to the user level program to do useful things with this
 251           information.  This is generally a good idea, so say Y.
 252
 253 config BSD_PROCESS_ACCT_V3
 254         bool "BSD Process Accounting version 3 file format"
 255         depends on BSD_PROCESS_ACCT
 256         default n
 257         help
 258           If you say Y here, the process accounting information is written
 259           in a new file format that also logs the process IDs of each
 260           process and it's parent. Note that this file format is incompatible
 261           with previous v0/v1/v2 file formats, so you will need updated tools
 262           for processing it. A preliminary version of these tools is available
 263           at <http://www.gnu.org/software/acct/>.
 264
 265 config TASKSTATS
 266         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 267         depends on NET
 268         default n
 269         help
 270           Export selected statistics for tasks/processes through the
 271           generic netlink interface. Unlike BSD process accounting, the
 272           statistics are available during the lifetime of tasks/processes as
 273           responses to commands. Like BSD accounting, they are sent to user
 274           space on task exit.
 275
 276           Say N if unsure.
 277
 278 config TASK_DELAY_ACCT
 279         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 280         depends on TASKSTATS
 281         help
 282           Collect information on time spent by a task waiting for system
 283           resources like cpu, synchronous block I/O completion and swapping
 284           in pages. Such statistics can help in setting a task's priorities
 285           relative to other tasks for cpu, io, rss limits etc.
 286
 287           Say N if unsure.
 288
 289 config TASK_XACCT
 290         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 291         depends on TASKSTATS
 292         help
 293           Collect extended task accounting data and send the data
 294           to userland for processing over the taskstats interface.
 295
 296           Say N if unsure.
 297
 298 config TASK_IO_ACCOUNTING
 299         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 300         depends on TASK_XACCT
 301         help
 302           Collect information on the number of bytes of storage I/O which this
 303           task has caused.
 304
 305           Say N if unsure.
 306
 307 config AUDIT
 308         bool "Auditing support"
 309         depends on NET
 310         help
 311           Enable auditing infrastructure that can be used with another
 312           kernel subsystem, such as SELinux (which requires this for
 313           logging of avc messages output).  Does not do system-call
 314           auditing without CONFIG_AUDITSYSCALL.
 315
 316 config AUDITSYSCALL
 317         bool "Enable system-call auditing support"
 318         depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
 319         default y if SECURITY_SELINUX
 320         help
 321           Enable low-overhead system-call auditing infrastructure that
 322           can be used independently or with another kernel subsystem,
 323           such as SELinux.
 324
 325 config AUDIT_WATCH
 326         def_bool y
 327         depends on AUDITSYSCALL
 328         select FSNOTIFY
 329
 330 config AUDIT_TREE
 331         def_bool y
 332         depends on AUDITSYSCALL
 333         select FSNOTIFY
 334
 335 menu "RCU Subsystem"
 336
 337 choice
 338         prompt "RCU Implementation"
 339         default TREE_RCU
 340
 341 config TREE_RCU
 342         bool "Tree-based hierarchical RCU"
 343         depends on !PREEMPT && SMP
 344         help
 345           This option selects the RCU implementation that is
 346           designed for very large SMP system with hundreds or
 347           thousands of CPUs.  It also scales down nicely to
 348           smaller systems.
 349
 350 config TREE_PREEMPT_RCU
 351         bool "Preemptible tree-based hierarchical RCU"
 352         depends on PREEMPT
 353         help
 354           This option selects the RCU implementation that is
 355           designed for very large SMP systems with hundreds or
 356           thousands of CPUs, but for which real-time response
 357           is also required.  It also scales down nicely to
 358           smaller systems.
 359
 360 config TINY_RCU
 361         bool "UP-only small-memory-footprint RCU"
 362         depends on !SMP
 363         help
 364           This option selects the RCU implementation that is
 365           designed for UP systems from which real-time response
 366           is not required.  This option greatly reduces the
 367           memory footprint of RCU.
 368
 369 config TINY_PREEMPT_RCU
 370         bool "Preemptible UP-only small-memory-footprint RCU"
 371         depends on !SMP && PREEMPT
 372         help
 373           This option selects the RCU implementation that is designed
 374           for real-time UP systems.  This option greatly reduces the
 375           memory footprint of RCU.
 376
 377 endchoice
 378
 379 config PREEMPT_RCU
 380         def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
 381         help
 382           This option enables preemptible-RCU code that is common between
 383           the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
 384
 385 config RCU_TRACE
 386         bool "Enable tracing for RCU"
 387         depends on TREE_RCU || TREE_PREEMPT_RCU
 388         help
 389           This option provides tracing in RCU which presents stats
 390           in debugfs for debugging RCU implementation.
 391
 392           Say Y here if you want to enable RCU tracing
 393           Say N if you are unsure.
 394
 395 config RCU_FANOUT
 396         int "Tree-based hierarchical RCU fanout value"
 397         range 2 64 if 64BIT
 398         range 2 32 if !64BIT
 399         depends on TREE_RCU || TREE_PREEMPT_RCU
 400         default 64 if 64BIT
 401         default 32 if !64BIT
 402         help
 403           This option controls the fanout of hierarchical implementations
 404           of RCU, allowing RCU to work efficiently on machines with
 405           large numbers of CPUs.  This value must be at least the fourth
 406           root of NR_CPUS, which allows NR_CPUS to be insanely large.
 407           The default value of RCU_FANOUT should be used for production
 408           systems, but if you are stress-testing the RCU implementation
 409           itself, small RCU_FANOUT values allow you to test large-system
 410           code paths on small(er) systems.
 411
 412           Select a specific number if testing RCU itself.
 413           Take the default if unsure.
 414
 415 config RCU_FANOUT_EXACT
 416         bool "Disable tree-based hierarchical RCU auto-balancing"
 417         depends on TREE_RCU || TREE_PREEMPT_RCU
 418         default n
 419         help
 420           This option forces use of the exact RCU_FANOUT value specified,
 421           regardless of imbalances in the hierarchy.  This is useful for
 422           testing RCU itself, and might one day be useful on systems with
 423           strong NUMA behavior.
 424
 425           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 426
 427           Say N if unsure.
 428
 429 config RCU_FAST_NO_HZ
 430         bool "Accelerate last non-dyntick-idle CPU's grace periods"
 431         depends on TREE_RCU && NO_HZ && SMP
 432         default n
 433         help
 434           This option causes RCU to attempt to accelerate grace periods
 435           in order to allow the final CPU to enter dynticks-idle state
 436           more quickly.  On the other hand, this option increases the
 437           overhead of the dynticks-idle checking, particularly on systems
 438           with large numbers of CPUs.
 439
 440           Say Y if energy efficiency is critically important, particularly
 441                 if you have relatively few CPUs.
 442
 443           Say N if you are unsure.
 444
 445 config TREE_RCU_TRACE
 446         def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 447         select DEBUG_FS
 448         help
 449           This option provides tracing for the TREE_RCU and
 450           TREE_PREEMPT_RCU implementations, permitting Makefile to
 451           trivially select kernel/rcutree_trace.c.
 452
 453 config RCU_BOOST
 454         bool "Enable RCU priority boosting"
 455         depends on RT_MUTEXES && TINY_PREEMPT_RCU
 456         default n
 457         help
 458           This option boosts the priority of preempted RCU readers that
 459           block the current preemptible RCU grace period for too long.
 460           This option also prevents heavy loads from blocking RCU
 461           callback invocation for all flavors of RCU.
 462
 463           Say Y here if you are working with real-time apps or heavy loads
 464           Say N here if you are unsure.
 465
 466 config RCU_BOOST_PRIO
 467         int "Real-time priority to boost RCU readers to"
 468         range 1 99
 469         depends on RCU_BOOST
 470         default 1
 471         help
 472           This option specifies the real-time priority to which preempted
 473           RCU readers are to be boosted.  If you are working with CPU-bound
 474           real-time applications, you should specify a priority higher then
 475           the highest-priority CPU-bound application.
 476
 477           Specify the real-time priority, or take the default if unsure.
 478
 479 config RCU_BOOST_DELAY
 480         int "Milliseconds to delay boosting after RCU grace-period start"
 481         range 0 3000
 482         depends on RCU_BOOST
 483         default 500
 484         help
 485           This option specifies the time to wait after the beginning of
 486           a given grace period before priority-boosting preempted RCU
 487           readers blocking that grace period.  Note that any RCU reader
 488           blocking an expedited RCU grace period is boosted immediately.
 489
 490           Accept the default if unsure.
 491
 492 endmenu # "RCU Subsystem"
 493
 494 config IKCONFIG
 495         tristate "Kernel .config support"
 496         ---help---
 497           This option enables the complete Linux kernel ".config" file
 498           contents to be saved in the kernel. It provides documentation
 499           of which kernel options are used in a running kernel or in an
 500           on-disk kernel.  This information can be extracted from the kernel
 501           image file with the script scripts/extract-ikconfig and used as
 502           input to rebuild the current kernel or to build another kernel.
 503           It can also be extracted from a running kernel by reading
 504           /proc/config.gz if enabled (below).
 505
 506 config IKCONFIG_PROC
 507         bool "Enable access to .config through /proc/config.gz"
 508         depends on IKCONFIG && PROC_FS
 509         ---help---
 510           This option enables access to the kernel configuration file
 511           through /proc/config.gz.
 512
 513 config LOG_BUF_SHIFT
 514         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 515         range 12 21
 516         default 17
 517         help
 518           Select kernel log buffer size as a power of 2.
 519           Examples:
 520                      17 => 128 KB
 521                      16 => 64 KB
 522                      15 => 32 KB
 523                      14 => 16 KB
 524                      13 =>  8 KB
 525                      12 =>  4 KB
 526
 527 #
 528 # Architectures with an unreliable sched_clock() should select this:
 529 #
 530 config HAVE_UNSTABLE_SCHED_CLOCK
 531         bool
 532
 533 menuconfig CGROUPS
 534         boolean "Control Group support"
 535         depends on EVENTFD
 536         help
 537           This option adds support for grouping sets of processes together, for
 538           use with process control subsystems such as Cpusets, CFS, memory
 539           controls or device isolation.
 540           See
 541                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 542                 - Documentation/cgroups/ (features for grouping, isolation
 543                                           and resource control)
 544
 545           Say N if unsure.
 546
 547 if CGROUPS
 548
 549 config CGROUP_DEBUG
 550         bool "Example debug cgroup subsystem"
 551         depends on CGROUPS
 552         default n
 553         help
 554           This option enables a simple cgroup subsystem that
 555           exports useful debugging information about the cgroups
 556           framework.
 557
 558           Say N if unsure.
 559
 560 config CGROUP_NS
 561         bool "Namespace cgroup subsystem"
 562         depends on CGROUPS
 563         help
 564           Provides a simple namespace cgroup subsystem to
 565           provide hierarchical naming of sets of namespaces,
 566           for instance virtual servers and checkpoint/restart
 567           jobs.
 568
 569 config CGROUP_FREEZER
 570         bool "Freezer cgroup subsystem"
 571         depends on CGROUPS
 572         help
 573           Provides a way to freeze and unfreeze all tasks in a
 574           cgroup.
 575
 576 config CGROUP_DEVICE
 577         bool "Device controller for cgroups"
 578         depends on CGROUPS && EXPERIMENTAL
 579         help
 580           Provides a cgroup implementing whitelists for devices which
 581           a process in the cgroup can mknod or open.
 582
 583 config CPUSETS
 584         bool "Cpuset support"
 585         depends on CGROUPS
 586         help
 587           This option will let you create and manage CPUSETs which
 588           allow dynamically partitioning a system into sets of CPUs and
 589           Memory Nodes and assigning tasks to run only within those sets.
 590           This is primarily useful on large SMP or NUMA systems.
 591
 592           Say N if unsure.
 593
 594 config PROC_PID_CPUSET
 595         bool "Include legacy /proc/<pid>/cpuset file"
 596         depends on CPUSETS
 597         default y
 598
 599 config CGROUP_CPUACCT
 600         bool "Simple CPU accounting cgroup subsystem"
 601         depends on CGROUPS
 602         help
 603           Provides a simple Resource Controller for monitoring the
 604           total CPU consumed by the tasks in a cgroup.
 605
 606 config RESOURCE_COUNTERS
 607         bool "Resource counters"
 608         help
 609           This option enables controller independent resource accounting
 610           infrastructure that works with cgroups.
 611         depends on CGROUPS
 612
 613 config CGROUP_MEM_RES_CTLR
 614         bool "Memory Resource Controller for Control Groups"
 615         depends on CGROUPS && RESOURCE_COUNTERS
 616         select MM_OWNER
 617         help
 618           Provides a memory resource controller that manages both anonymous
 619           memory and page cache. (See Documentation/cgroups/memory.txt)
 620
 621           Note that setting this option increases fixed memory overhead
 622           associated with each page of memory in the system. By this,
 623           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 624           usage tracking struct at boot. Total amount of this is printed out
 625           at boot.
 626
 627           Only enable when you're ok with these trade offs and really
 628           sure you need the memory resource controller. Even when you enable
 629           this, you can set "cgroup_disable=memory" at your boot option to
 630           disable memory resource controller and you can avoid overheads.
 631           (and lose benefits of memory resource controller)
 632
 633           This config option also selects MM_OWNER config option, which
 634           could in turn add some fork/exit overhead.
 635
 636 config CGROUP_MEM_RES_CTLR_SWAP
 637         bool "Memory Resource Controller Swap Extension"
 638         depends on CGROUP_MEM_RES_CTLR && SWAP
 639         help
 640           Add swap management feature to memory resource controller. When you
 641           enable this, you can limit mem+swap usage per cgroup. In other words,
 642           when you disable this, memory resource controller has no cares to
 643           usage of swap...a process can exhaust all of the swap. This extension
 644           is useful when you want to avoid exhaustion swap but this itself
 645           adds more overheads and consumes memory for remembering information.
 646           Especially if you use 32bit system or small memory system, please
 647           be careful about enabling this. When memory resource controller
 648           is disabled by boot option, this will be automatically disabled and
 649           there will be no overhead from this. Even when you set this config=y,
 650           if boot option "noswapaccount" is set, swap will not be accounted.
 651           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 652           size is 4096bytes, 512k per 1Gbytes of swap.
 653
 654 menuconfig CGROUP_SCHED
 655         bool "Group CPU scheduler"
 656         depends on EXPERIMENTAL && CGROUPS
 657         default n
 658         help
 659           This feature lets CPU scheduler recognize task groups and control CPU
 660           bandwidth allocation to such task groups. It uses cgroups to group
 661           tasks.
 662
 663 if CGROUP_SCHED
 664 config FAIR_GROUP_SCHED
 665         bool "Group scheduling for SCHED_OTHER"
 666         depends on CGROUP_SCHED
 667         default CGROUP_SCHED
 668
 669 config RT_GROUP_SCHED
 670         bool "Group scheduling for SCHED_RR/FIFO"
 671         depends on EXPERIMENTAL
 672         depends on CGROUP_SCHED
 673         default n
 674         help
 675           This feature lets you explicitly allocate real CPU bandwidth
 676           to task groups. If enabled, it will also make it impossible to
 677           schedule realtime tasks for non-root users until you allocate
 678           realtime bandwidth for them.
 679           See Documentation/scheduler/sched-rt-group.txt for more information.
 680
 681 endif #CGROUP_SCHED
 682
 683 config BLK_CGROUP
 684         tristate "Block IO controller"
 685         depends on CGROUPS && BLOCK
 686         default n
 687         ---help---
 688         Generic block IO controller cgroup interface. This is the common
 689         cgroup interface which should be used by various IO controlling
 690         policies.
 691
 692         Currently, CFQ IO scheduler uses it to recognize task groups and
 693         control disk bandwidth allocation (proportional time slice allocation)
 694         to such task groups.
 695
 696         This option only enables generic Block IO controller infrastructure.
 697         One needs to also enable actual IO controlling logic in CFQ for it
 698         to take effect. (CONFIG_CFQ_GROUP_IOSCHED=y).
 699
 700         See Documentation/cgroups/blkio-controller.txt for more information.
 701
 702 config DEBUG_BLK_CGROUP
 703         bool "Enable Block IO controller debugging"
 704         depends on BLK_CGROUP
 705         default n
 706         ---help---
 707         Enable some debugging help. Currently it exports additional stat
 708         files in a cgroup which can be useful for debugging.
 709
 710 endif # CGROUPS
 711
 712 config MM_OWNER
 713         bool
 714
 715 config SYSFS_DEPRECATED
 716         bool
 717
 718 config SYSFS_DEPRECATED_V2
 719         bool "enable deprecated sysfs features to support old userspace tools"
 720         depends on SYSFS
 721         default n
 722         select SYSFS_DEPRECATED
 723         help
 724           This option switches the layout of sysfs to the deprecated
 725           version. Do not use it on recent distributions.
 726
 727           The current sysfs layout features a unified device tree at
 728           /sys/devices/, which is able to express a hierarchy between
 729           class devices. If the deprecated option is set to Y, the
 730           unified device tree is split into a bus device tree at
 731           /sys/devices/ and several individual class device trees at
 732           /sys/class/. The class and bus devices will be connected by
 733           "<subsystem>:<name>" and the "device" links. The "block"
 734           class devices, will not show up in /sys/class/block/. Some
 735           subsystems will suppress the creation of some devices which
 736           depend on the unified device tree.
 737
 738           This option is not a pure compatibility option that can
 739           be safely enabled on newer distributions. It will change the
 740           layout of sysfs to the non-extensible deprecated version,
 741           and disable some features, which can not be exported without
 742           confusing older userspace tools. Since 2007/2008 all major
 743           distributions do not enable this option, and ship no tools which
 744           depend on the deprecated layout or this option.
 745
 746           If you are using a new kernel on an older distribution, or use
 747           older userspace tools, you might need to say Y here. Do not say Y,
 748           if the original kernel, that came with your distribution, has
 749           this option set to N.
 750
 751 config RELAY
 752         bool "Kernel->user space relay support (formerly relayfs)"
 753         help
 754           This option enables support for relay interface support in
 755           certain file systems (such as debugfs).
 756           It is designed to provide an efficient mechanism for tools and
 757           facilities to relay large amounts of data from kernel space to
 758           user space.
 759
 760           If unsure, say N.
 761
 762 config NAMESPACES
 763         bool "Namespaces support" if EMBEDDED
 764         default !EMBEDDED
 765         help
 766           Provides the way to make tasks work with different objects using
 767           the same id. For example same IPC id may refer to different objects
 768           or same user id or pid may refer to different tasks when used in
 769           different namespaces.
 770
 771 config UTS_NS
 772         bool "UTS namespace"
 773         depends on NAMESPACES
 774         help
 775           In this namespace tasks see different info provided with the
 776           uname() system call
 777
 778 config IPC_NS
 779         bool "IPC namespace"
 780         depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
 781         help
 782           In this namespace tasks work with IPC ids which correspond to
 783           different IPC objects in different namespaces.
 784
 785 config USER_NS
 786         bool "User namespace (EXPERIMENTAL)"
 787         depends on NAMESPACES && EXPERIMENTAL
 788         help
 789           This allows containers, i.e. vservers, to use user namespaces
 790           to provide different user info for different servers.
 791           If unsure, say N.
 792
 793 config PID_NS
 794         bool "PID Namespaces (EXPERIMENTAL)"
 795         default n
 796         depends on NAMESPACES && EXPERIMENTAL
 797         help
 798           Support process id namespaces.  This allows having multiple
 799           processes with the same pid as long as they are in different
 800           pid namespaces.  This is a building block of containers.
 801
 802           Unless you want to work with an experimental feature
 803           say N here.
 804
 805 config NET_NS
 806         bool "Network namespace"
 807         default n
 808         depends on NAMESPACES && EXPERIMENTAL && NET
 809         help
 810           Allow user space to create what appear to be multiple instances
 811           of the network stack.
 812
 813 config BLK_DEV_INITRD
 814         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 815         depends on BROKEN || !FRV
 816         help
 817           The initial RAM filesystem is a ramfs which is loaded by the
 818           boot loader (loadlin or lilo) and that is mounted as root
 819           before the normal boot procedure. It is typically used to
 820           load modules needed to mount the "real" root file system,
 821           etc. See <file:Documentation/initrd.txt> for details.
 822
 823           If RAM disk support (BLK_DEV_RAM) is also included, this
 824           also enables initial RAM disk (initrd) support and adds
 825           15 Kbytes (more on some other architectures) to the kernel size.
 826
 827           If unsure say Y.
 828
 829 if BLK_DEV_INITRD
 830
 831 source "usr/Kconfig"
 832
 833 endif
 834
 835 config CC_OPTIMIZE_FOR_SIZE
 836         bool "Optimize for size"
 837         default y
 838         help
 839           Enabling this option will pass "-Os" instead of "-O2" to gcc
 840           resulting in a smaller kernel.
 841
 842           If unsure, say Y.
 843
 844 config SYSCTL
 845         bool
 846
 847 config ANON_INODES
 848         bool
 849
 850 menuconfig EMBEDDED
 851         bool "Configure standard kernel features (for small systems)"
 852         help
 853           This option allows certain base kernel options and settings
 854           to be disabled or tweaked. This is for specialized
 855           environments which can tolerate a "non-standard" kernel.
 856           Only use this if you really know what you are doing.
 857
 858 config UID16
 859         bool "Enable 16-bit UID system calls" if EMBEDDED
 860         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 861         default y
 862         help
 863           This enables the legacy 16-bit UID syscall wrappers.
 864
 865 config SYSCTL_SYSCALL
 866         bool "Sysctl syscall support" if EMBEDDED
 867         depends on PROC_SYSCTL
 868         default y
 869         select SYSCTL
 870         ---help---
 871           sys_sysctl uses binary paths that have been found challenging
 872           to properly maintain and use.  The interface in /proc/sys
 873           using paths with ascii names is now the primary path to this
 874           information.
 875
 876           Almost nothing using the binary sysctl interface so if you are
 877           trying to save some space it is probably safe to disable this,
 878           making your kernel marginally smaller.
 879
 880           If unsure say Y here.
 881
 882 config KALLSYMS
 883          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 884          default y
 885          help
 886            Say Y here to let the kernel print out symbolic crash information and
 887            symbolic stack backtraces. This increases the size of the kernel
 888            somewhat, as all symbols have to be loaded into the kernel image.
 889
 890 config KALLSYMS_ALL
 891         bool "Include all symbols in kallsyms"
 892         depends on DEBUG_KERNEL && KALLSYMS
 893         help
 894            Normally kallsyms only contains the symbols of functions, for nicer
 895            OOPS messages.  Some debuggers can use kallsyms for other
 896            symbols too: say Y here to include all symbols, if you need them
 897            and you don't care about adding 300k to the size of your kernel.
 898
 899            Say N.
 900
 901 config KALLSYMS_EXTRA_PASS
 902         bool "Do an extra kallsyms pass"
 903         depends on KALLSYMS
 904         help
 905            If kallsyms is not working correctly, the build will fail with
 906            inconsistent kallsyms data.  If that occurs, log a bug report and
 907            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 908            Always say N here unless you find a bug in kallsyms, which must be
 909            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 910            you wait for kallsyms to be fixed.
 911
 912
 913 config HOTPLUG
 914         bool "Support for hot-pluggable devices" if EMBEDDED
 915         default y
 916         help
 917           This option is provided for the case where no hotplug or uevent
 918           capabilities is wanted by the kernel.  You should only consider
 919           disabling this option for embedded systems that do not use modules, a
 920           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 921
 922 config PRINTK
 923         default y
 924         bool "Enable support for printk" if EMBEDDED
 925         help
 926           This option enables normal printk support. Removing it
 927           eliminates most of the message strings from the kernel image
 928           and makes the kernel more or less silent. As this makes it
 929           very difficult to diagnose system problems, saying N here is
 930           strongly discouraged.
 931
 932 config BUG
 933         bool "BUG() support" if EMBEDDED
 934         default y
 935         help
 936           Disabling this option eliminates support for BUG and WARN, reducing
 937           the size of your kernel image and potentially quietly ignoring
 938           numerous fatal conditions. You should only consider disabling this
 939           option for embedded systems with no facilities for reporting errors.
 940           Just say Y.
 941
 942 config ELF_CORE
 943         default y
 944         bool "Enable ELF core dumps" if EMBEDDED
 945         help
 946           Enable support for generating core dumps. Disabling saves about 4k.
 947
 948 config PCSPKR_PLATFORM
 949         bool "Enable PC-Speaker support" if EMBEDDED
 950         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 951         default y
 952         help
 953           This option allows to disable the internal PC-Speaker
 954           support, saving some memory.
 955
 956 config BASE_FULL
 957         default y
 958         bool "Enable full-sized data structures for core" if EMBEDDED
 959         help
 960           Disabling this option reduces the size of miscellaneous core
 961           kernel data structures. This saves memory on small machines,
 962           but may reduce performance.
 963
 964 config FUTEX
 965         bool "Enable futex support" if EMBEDDED
 966         default y
 967         select RT_MUTEXES
 968         help
 969           Disabling this option will cause the kernel to be built without
 970           support for "fast userspace mutexes".  The resulting kernel may not
 971           run glibc-based applications correctly.
 972
 973 config EPOLL
 974         bool "Enable eventpoll support" if EMBEDDED
 975         default y
 976         select ANON_INODES
 977         help
 978           Disabling this option will cause the kernel to be built without
 979           support for epoll family of system calls.
 980
 981 config SIGNALFD
 982         bool "Enable signalfd() system call" if EMBEDDED
 983         select ANON_INODES
 984         default y
 985         help
 986           Enable the signalfd() system call that allows to receive signals
 987           on a file descriptor.
 988
 989           If unsure, say Y.
 990
 991 config TIMERFD
 992         bool "Enable timerfd() system call" if EMBEDDED
 993         select ANON_INODES
 994         default y
 995         help
 996           Enable the timerfd() system call that allows to receive timer
 997           events on a file descriptor.
 998
 999           If unsure, say Y.
1000
1001 config EVENTFD
1002         bool "Enable eventfd() system call" if EMBEDDED
1003         select ANON_INODES
1004         default y
1005         help
1006           Enable the eventfd() system call that allows to receive both
1007           kernel notification (ie. KAIO) or userspace notifications.
1008
1009           If unsure, say Y.
1010
1011 config SHMEM
1012         bool "Use full shmem filesystem" if EMBEDDED
1013         default y
1014         depends on MMU
1015         help
1016           The shmem is an internal filesystem used to manage shared memory.
1017           It is backed by swap and manages resource limits. It is also exported
1018           to userspace as tmpfs if TMPFS is enabled. Disabling this
1019           option replaces shmem and tmpfs with the much simpler ramfs code,
1020           which may be appropriate on small systems without swap.
1021
1022 config AIO
1023         bool "Enable AIO support" if EMBEDDED
1024         default y
1025         help
1026           This option enables POSIX asynchronous I/O which may by used
1027           by some high performance threaded applications. Disabling
1028           this option saves about 7k.
1029
1030 config HAVE_PERF_EVENTS
1031         bool
1032         help
1033           See tools/perf/design.txt for details.
1034
1035 config PERF_USE_VMALLOC
1036         bool
1037         help
1038           See tools/perf/design.txt for details
1039
1040 menu "Kernel Performance Events And Counters"
1041
1042 config PERF_EVENTS
1043         bool "Kernel performance events and counters"
1044         default y if (PROFILING || PERF_COUNTERS)
1045         depends on HAVE_PERF_EVENTS
1046         select ANON_INODES
1047         help
1048           Enable kernel support for various performance events provided
1049           by software and hardware.
1050
1051           Software events are supported either built-in or via the
1052           use of generic tracepoints.
1053
1054           Most modern CPUs support performance events via performance
1055           counter registers. These registers count the number of certain
1056           types of hw events: such as instructions executed, cachemisses
1057           suffered, or branches mis-predicted - without slowing down the
1058           kernel or applications. These registers can also trigger interrupts
1059           when a threshold number of events have passed - and can thus be
1060           used to profile the code that runs on that CPU.
1061
1062           The Linux Performance Event subsystem provides an abstraction of
1063           these software and hardware event capabilities, available via a
1064           system call and used by the "perf" utility in tools/perf/. It
1065           provides per task and per CPU counters, and it provides event
1066           capabilities on top of those.
1067
1068           Say Y if unsure.
1069
1070 config PERF_COUNTERS
1071         bool "Kernel performance counters (old config option)"
1072         depends on HAVE_PERF_EVENTS
1073         help
1074           This config has been obsoleted by the PERF_EVENTS
1075           config option - please see that one for details.
1076
1077           It has no effect on the kernel whether you enable
1078           it or not, it is a compatibility placeholder.
1079
1080           Say N if unsure.
1081
1082 config DEBUG_PERF_USE_VMALLOC
1083         default n
1084         bool "Debug: use vmalloc to back perf mmap() buffers"
1085         depends on PERF_EVENTS && DEBUG_KERNEL
1086         select PERF_USE_VMALLOC
1087         help
1088          Use vmalloc memory to back perf mmap() buffers.
1089
1090          Mostly useful for debugging the vmalloc code on platforms
1091          that don't require it.
1092
1093          Say N if unsure.
1094
1095 endmenu
1096
1097 config VM_EVENT_COUNTERS
1098         default y
1099         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1100         help
1101           VM event counters are needed for event counts to be shown.
1102           This option allows the disabling of the VM event counters
1103           on EMBEDDED systems.  /proc/vmstat will only show page counts
1104           if VM event counters are disabled.
1105
1106 config PCI_QUIRKS
1107         default y
1108         bool "Enable PCI quirk workarounds" if EMBEDDED
1109         depends on PCI
1110         help
1111           This enables workarounds for various PCI chipset
1112           bugs/quirks. Disable this only if your target machine is
1113           unaffected by PCI quirks.
1114
1115 config SLUB_DEBUG
1116         default y
1117         bool "Enable SLUB debugging support" if EMBEDDED
1118         depends on SLUB && SYSFS
1119         help
1120           SLUB has extensive debug support features. Disabling these can
1121           result in significant savings in code size. This also disables
1122           SLUB sysfs support. /sys/slab will not exist and there will be
1123           no support for cache validation etc.
1124
1125 config COMPAT_BRK
1126         bool "Disable heap randomization"
1127         default y
1128         help
1129           Randomizing heap placement makes heap exploits harder, but it
1130           also breaks ancient binaries (including anything libc5 based).
1131           This option changes the bootup default to heap randomization
1132           disabled, and can be overridden at runtime by setting
1133           /proc/sys/kernel/randomize_va_space to 2.
1134
1135           On non-ancient distros (post-2000 ones) N is usually a safe choice.
1136
1137 choice
1138         prompt "Choose SLAB allocator"
1139         default SLUB
1140         help
1141            This option allows to select a slab allocator.
1142
1143 config SLAB
1144         bool "SLAB"
1145         help
1146           The regular slab allocator that is established and known to work
1147           well in all environments. It organizes cache hot objects in
1148           per cpu and per node queues.
1149
1150 config SLUB
1151         bool "SLUB (Unqueued Allocator)"
1152         help
1153            SLUB is a slab allocator that minimizes cache line usage
1154            instead of managing queues of cached objects (SLAB approach).
1155            Per cpu caching is realized using slabs of objects instead
1156            of queues of objects. SLUB can use memory efficiently
1157            and has enhanced diagnostics. SLUB is the default choice for
1158            a slab allocator.
1159
1160 config SLOB
1161         depends on EMBEDDED
1162         bool "SLOB (Simple Allocator)"
1163         help
1164            SLOB replaces the stock allocator with a drastically simpler
1165            allocator. SLOB is generally more space efficient but
1166            does not perform as well on large systems.
1167
1168 endchoice
1169
1170 config MMAP_ALLOW_UNINITIALIZED
1171         bool "Allow mmapped anonymous memory to be uninitialized"
1172         depends on EMBEDDED && !MMU
1173         default n
1174         help
1175           Normally, and according to the Linux spec, anonymous memory obtained
1176           from mmap() has it's contents cleared before it is passed to
1177           userspace.  Enabling this config option allows you to request that
1178           mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1179           providing a huge performance boost.  If this option is not enabled,
1180           then the flag will be ignored.
1181
1182           This is taken advantage of by uClibc's malloc(), and also by
1183           ELF-FDPIC binfmt's brk and stack allocator.
1184
1185           Because of the obvious security issues, this option should only be
1186           enabled on embedded devices where you control what is run in
1187           userspace.  Since that isn't generally a problem on no-MMU systems,
1188           it is normally safe to say Y here.
1189
1190           See Documentation/nommu-mmap.txt for more information.
1191
1192 config PROFILING
1193         bool "Profiling support"
1194         help
1195           Say Y here to enable the extended profiling support mechanisms used
1196           by profilers such as OProfile.
1197
1198 #
1199 # Place an empty function call at each tracepoint site. Can be
1200 # dynamically changed for a probe function.
1201 #
1202 config TRACEPOINTS
1203         bool
1204
1205 source "arch/Kconfig"
1206
1207 endmenu         # General setup
1208
1209 config HAVE_GENERIC_DMA_COHERENT
1210         bool
1211         default n
1212
1213 config SLABINFO
1214         bool
1215         depends on PROC_FS
1216         depends on SLAB || SLUB_DEBUG
1217         default y
1218
1219 config RT_MUTEXES
1220         boolean
1221
1222 config BASE_SMALL
1223         int
1224         default 0 if BASE_FULL
1225         default 1 if !BASE_FULL
1226
1227 menuconfig MODULES
1228         bool "Enable loadable module support"
1229         help
1230           Kernel modules are small pieces of compiled code which can
1231           be inserted in the running kernel, rather than being
1232           permanently built into the kernel.  You use the "modprobe"
1233           tool to add (and sometimes remove) them.  If you say Y here,
1234           many parts of the kernel can be built as modules (by
1235           answering M instead of Y where indicated): this is most
1236           useful for infrequently used options which are not required
1237           for booting.  For more information, see the man pages for
1238           modprobe, lsmod, modinfo, insmod and rmmod.
1239
1240           If you say Y here, you will need to run "make
1241           modules_install" to put the modules under /lib/modules/
1242           where modprobe can find them (you may need to be root to do
1243           this).
1244
1245           If unsure, say Y.
1246
1247 if MODULES
1248
1249 config MODULE_FORCE_LOAD
1250         bool "Forced module loading"
1251         default n
1252         help
1253           Allow loading of modules without version information (ie. modprobe
1254           --force).  Forced module loading sets the 'F' (forced) taint flag and
1255           is usually a really bad idea.
1256
1257 config MODULE_UNLOAD
1258         bool "Module unloading"
1259         help
1260           Without this option you will not be able to unload any
1261           modules (note that some modules may not be unloadable
1262           anyway), which makes your kernel smaller, faster
1263           and simpler.  If unsure, say Y.
1264
1265 config MODULE_FORCE_UNLOAD
1266         bool "Forced module unloading"
1267         depends on MODULE_UNLOAD && EXPERIMENTAL
1268         help
1269           This option allows you to force a module to unload, even if the
1270           kernel believes it is unsafe: the kernel will remove the module
1271           without waiting for anyone to stop using it (using the -f option to
1272           rmmod).  This is mainly for kernel developers and desperate users.
1273           If unsure, say N.
1274
1275 config MODVERSIONS
1276         bool "Module versioning support"
1277         help
1278           Usually, you have to use modules compiled with your kernel.
1279           Saying Y here makes it sometimes possible to use modules
1280           compiled for different kernels, by adding enough information
1281           to the modules to (hopefully) spot any changes which would
1282           make them incompatible with the kernel you are running.  If
1283           unsure, say N.
1284
1285 config MODULE_SRCVERSION_ALL
1286         bool "Source checksum for all modules"
1287         help
1288           Modules which contain a MODULE_VERSION get an extra "srcversion"
1289           field inserted into their modinfo section, which contains a
1290           sum of the source files which made it.  This helps maintainers
1291           see exactly which source was used to build a module (since
1292           others sometimes change the module source without updating
1293           the version).  With this option, such a "srcversion" field
1294           will be created for all modules.  If unsure, say N.
1295
1296 endif # MODULES
1297
1298 config INIT_ALL_POSSIBLE
1299         bool
1300         help
1301           Back when each arch used to define their own cpu_online_map and
1302           cpu_possible_map, some of them chose to initialize cpu_possible_map
1303           with all 1s, and others with all 0s.  When they were centralised,
1304           it was better to provide this option than to break all the archs
1305           and have several arch maintainers pursuing me down dark alleys.
1306
1307 config STOP_MACHINE
1308         bool
1309         default y
1310         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1311         help
1312           Need stop_machine() primitive.
1313
1314 source "block/Kconfig"
1315
1316 config PREEMPT_NOTIFIERS
1317         bool
1318
1319 config PADATA
1320         depends on SMP
1321         bool
1322
1323 source "kernel/Kconfig.locks"