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  54           drivers that have been replaced by something else, and/or are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) && BKL
  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 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 source "kernel/irq/Kconfig"
 343
 344 menu "RCU Subsystem"
 345
 346 choice
 347         prompt "RCU Implementation"
 348         default TREE_RCU
 349
 350 config TREE_RCU
 351         bool "Tree-based hierarchical RCU"
 352         depends on !PREEMPT && SMP
 353         help
 354           This option selects the RCU implementation that is
 355           designed for very large SMP system with hundreds or
 356           thousands of CPUs.  It also scales down nicely to
 357           smaller systems.
 358
 359 config TREE_PREEMPT_RCU
 360         bool "Preemptible tree-based hierarchical RCU"
 361         depends on PREEMPT
 362         help
 363           This option selects the RCU implementation that is
 364           designed for very large SMP systems with hundreds or
 365           thousands of CPUs, but for which real-time response
 366           is also required.  It also scales down nicely to
 367           smaller systems.
 368
 369 config TINY_RCU
 370         bool "UP-only small-memory-footprint RCU"
 371         depends on !SMP
 372         help
 373           This option selects the RCU implementation that is
 374           designed for UP systems from which real-time response
 375           is not required.  This option greatly reduces the
 376           memory footprint of RCU.
 377
 378 config TINY_PREEMPT_RCU
 379         bool "Preemptible UP-only small-memory-footprint RCU"
 380         depends on !SMP && PREEMPT
 381         help
 382           This option selects the RCU implementation that is designed
 383           for real-time UP systems.  This option greatly reduces the
 384           memory footprint of RCU.
 385
 386 endchoice
 387
 388 config PREEMPT_RCU
 389         def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
 390         help
 391           This option enables preemptible-RCU code that is common between
 392           the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
 393
 394 config RCU_TRACE
 395         bool "Enable tracing for RCU"
 396         depends on TREE_RCU || TREE_PREEMPT_RCU
 397         help
 398           This option provides tracing in RCU which presents stats
 399           in debugfs for debugging RCU implementation.
 400
 401           Say Y here if you want to enable RCU tracing
 402           Say N if you are unsure.
 403
 404 config RCU_FANOUT
 405         int "Tree-based hierarchical RCU fanout value"
 406         range 2 64 if 64BIT
 407         range 2 32 if !64BIT
 408         depends on TREE_RCU || TREE_PREEMPT_RCU
 409         default 64 if 64BIT
 410         default 32 if !64BIT
 411         help
 412           This option controls the fanout of hierarchical implementations
 413           of RCU, allowing RCU to work efficiently on machines with
 414           large numbers of CPUs.  This value must be at least the fourth
 415           root of NR_CPUS, which allows NR_CPUS to be insanely large.
 416           The default value of RCU_FANOUT should be used for production
 417           systems, but if you are stress-testing the RCU implementation
 418           itself, small RCU_FANOUT values allow you to test large-system
 419           code paths on small(er) systems.
 420
 421           Select a specific number if testing RCU itself.
 422           Take the default if unsure.
 423
 424 config RCU_FANOUT_EXACT
 425         bool "Disable tree-based hierarchical RCU auto-balancing"
 426         depends on TREE_RCU || TREE_PREEMPT_RCU
 427         default n
 428         help
 429           This option forces use of the exact RCU_FANOUT value specified,
 430           regardless of imbalances in the hierarchy.  This is useful for
 431           testing RCU itself, and might one day be useful on systems with
 432           strong NUMA behavior.
 433
 434           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 435
 436           Say N if unsure.
 437
 438 config RCU_FAST_NO_HZ
 439         bool "Accelerate last non-dyntick-idle CPU's grace periods"
 440         depends on TREE_RCU && NO_HZ && SMP
 441         default n
 442         help
 443           This option causes RCU to attempt to accelerate grace periods
 444           in order to allow the final CPU to enter dynticks-idle state
 445           more quickly.  On the other hand, this option increases the
 446           overhead of the dynticks-idle checking, particularly on systems
 447           with large numbers of CPUs.
 448
 449           Say Y if energy efficiency is critically important, particularly
 450                 if you have relatively few CPUs.
 451
 452           Say N if you are unsure.
 453
 454 config TREE_RCU_TRACE
 455         def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 456         select DEBUG_FS
 457         help
 458           This option provides tracing for the TREE_RCU and
 459           TREE_PREEMPT_RCU implementations, permitting Makefile to
 460           trivially select kernel/rcutree_trace.c.
 461
 462 endmenu # "RCU Subsystem"
 463
 464 config IKCONFIG
 465         tristate "Kernel .config support"
 466         ---help---
 467           This option enables the complete Linux kernel ".config" file
 468           contents to be saved in the kernel. It provides documentation
 469           of which kernel options are used in a running kernel or in an
 470           on-disk kernel.  This information can be extracted from the kernel
 471           image file with the script scripts/extract-ikconfig and used as
 472           input to rebuild the current kernel or to build another kernel.
 473           It can also be extracted from a running kernel by reading
 474           /proc/config.gz if enabled (below).
 475
 476 config IKCONFIG_PROC
 477         bool "Enable access to .config through /proc/config.gz"
 478         depends on IKCONFIG && PROC_FS
 479         ---help---
 480           This option enables access to the kernel configuration file
 481           through /proc/config.gz.
 482
 483 config LOG_BUF_SHIFT
 484         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 485         range 12 21
 486         default 17
 487         help
 488           Select kernel log buffer size as a power of 2.
 489           Examples:
 490                      17 => 128 KB
 491                      16 => 64 KB
 492                      15 => 32 KB
 493                      14 => 16 KB
 494                      13 =>  8 KB
 495                      12 =>  4 KB
 496
 497 #
 498 # Architectures with an unreliable sched_clock() should select this:
 499 #
 500 config HAVE_UNSTABLE_SCHED_CLOCK
 501         bool
 502
 503 menuconfig CGROUPS
 504         boolean "Control Group support"
 505         depends on EVENTFD
 506         help
 507           This option adds support for grouping sets of processes together, for
 508           use with process control subsystems such as Cpusets, CFS, memory
 509           controls or device isolation.
 510           See
 511                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 512                 - Documentation/cgroups/ (features for grouping, isolation
 513                                           and resource control)
 514
 515           Say N if unsure.
 516
 517 if CGROUPS
 518
 519 config CGROUP_DEBUG
 520         bool "Example debug cgroup subsystem"
 521         default n
 522         help
 523           This option enables a simple cgroup subsystem that
 524           exports useful debugging information about the cgroups
 525           framework.
 526
 527           Say N if unsure.
 528
 529 config CGROUP_NS
 530         bool "Namespace cgroup subsystem"
 531         help
 532           Provides a simple namespace cgroup subsystem to
 533           provide hierarchical naming of sets of namespaces,
 534           for instance virtual servers and checkpoint/restart
 535           jobs.
 536
 537 config CGROUP_FREEZER
 538         bool "Freezer cgroup subsystem"
 539         help
 540           Provides a way to freeze and unfreeze all tasks in a
 541           cgroup.
 542
 543 config CGROUP_DEVICE
 544         bool "Device controller for cgroups"
 545         help
 546           Provides a cgroup implementing whitelists for devices which
 547           a process in the cgroup can mknod or open.
 548
 549 config CPUSETS
 550         bool "Cpuset support"
 551         help
 552           This option will let you create and manage CPUSETs which
 553           allow dynamically partitioning a system into sets of CPUs and
 554           Memory Nodes and assigning tasks to run only within those sets.
 555           This is primarily useful on large SMP or NUMA systems.
 556
 557           Say N if unsure.
 558
 559 config PROC_PID_CPUSET
 560         bool "Include legacy /proc/<pid>/cpuset file"
 561         depends on CPUSETS
 562         default y
 563
 564 config CGROUP_CPUACCT
 565         bool "Simple CPU accounting cgroup subsystem"
 566         help
 567           Provides a simple Resource Controller for monitoring the
 568           total CPU consumed by the tasks in a cgroup.
 569
 570 config RESOURCE_COUNTERS
 571         bool "Resource counters"
 572         help
 573           This option enables controller independent resource accounting
 574           infrastructure that works with cgroups.
 575
 576 config CGROUP_MEM_RES_CTLR
 577         bool "Memory Resource Controller for Control Groups"
 578         depends on RESOURCE_COUNTERS
 579         select MM_OWNER
 580         help
 581           Provides a memory resource controller that manages both anonymous
 582           memory and page cache. (See Documentation/cgroups/memory.txt)
 583
 584           Note that setting this option increases fixed memory overhead
 585           associated with each page of memory in the system. By this,
 586           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 587           usage tracking struct at boot. Total amount of this is printed out
 588           at boot.
 589
 590           Only enable when you're ok with these trade offs and really
 591           sure you need the memory resource controller. Even when you enable
 592           this, you can set "cgroup_disable=memory" at your boot option to
 593           disable memory resource controller and you can avoid overheads.
 594           (and lose benefits of memory resource controller)
 595
 596           This config option also selects MM_OWNER config option, which
 597           could in turn add some fork/exit overhead.
 598
 599 config CGROUP_MEM_RES_CTLR_SWAP
 600         bool "Memory Resource Controller Swap Extension"
 601         depends on CGROUP_MEM_RES_CTLR && SWAP
 602         help
 603           Add swap management feature to memory resource controller. When you
 604           enable this, you can limit mem+swap usage per cgroup. In other words,
 605           when you disable this, memory resource controller has no cares to
 606           usage of swap...a process can exhaust all of the swap. This extension
 607           is useful when you want to avoid exhaustion swap but this itself
 608           adds more overheads and consumes memory for remembering information.
 609           Especially if you use 32bit system or small memory system, please
 610           be careful about enabling this. When memory resource controller
 611           is disabled by boot option, this will be automatically disabled and
 612           there will be no overhead from this. Even when you set this config=y,
 613           if boot option "noswapaccount" is set, swap will not be accounted.
 614           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 615           size is 4096bytes, 512k per 1Gbytes of swap.
 616
 617 menuconfig CGROUP_SCHED
 618         bool "Group CPU scheduler"
 619         depends on EXPERIMENTAL
 620         default n
 621         help
 622           This feature lets CPU scheduler recognize task groups and control CPU
 623           bandwidth allocation to such task groups. It uses cgroups to group
 624           tasks.
 625
 626 if CGROUP_SCHED
 627 config FAIR_GROUP_SCHED
 628         bool "Group scheduling for SCHED_OTHER"
 629         depends on CGROUP_SCHED
 630         default CGROUP_SCHED
 631
 632 config RT_GROUP_SCHED
 633         bool "Group scheduling for SCHED_RR/FIFO"
 634         depends on EXPERIMENTAL
 635         depends on CGROUP_SCHED
 636         default n
 637         help
 638           This feature lets you explicitly allocate real CPU bandwidth
 639           to task groups. If enabled, it will also make it impossible to
 640           schedule realtime tasks for non-root users until you allocate
 641           realtime bandwidth for them.
 642           See Documentation/scheduler/sched-rt-group.txt for more information.
 643
 644 endif #CGROUP_SCHED
 645
 646 config BLK_CGROUP
 647         tristate "Block IO controller"
 648         depends on BLOCK
 649         default n
 650         ---help---
 651         Generic block IO controller cgroup interface. This is the common
 652         cgroup interface which should be used by various IO controlling
 653         policies.
 654
 655         Currently, CFQ IO scheduler uses it to recognize task groups and
 656         control disk bandwidth allocation (proportional time slice allocation)
 657         to such task groups. It is also used by bio throttling logic in
 658         block layer to implement upper limit in IO rates on a device.
 659
 660         This option only enables generic Block IO controller infrastructure.
 661         One needs to also enable actual IO controlling logic/policy. For
 662         enabling proportional weight division of disk bandwidth in CFQ seti
 663         CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
 664         CONFIG_BLK_THROTTLE=y.
 665
 666         See Documentation/cgroups/blkio-controller.txt for more information.
 667
 668 config DEBUG_BLK_CGROUP
 669         bool "Enable Block IO controller debugging"
 670         depends on BLK_CGROUP
 671         default n
 672         ---help---
 673         Enable some debugging help. Currently it exports additional stat
 674         files in a cgroup which can be useful for debugging.
 675
 676 endif # CGROUPS
 677
 678 menuconfig NAMESPACES
 679         bool "Namespaces support" if EMBEDDED
 680         default !EMBEDDED
 681         help
 682           Provides the way to make tasks work with different objects using
 683           the same id. For example same IPC id may refer to different objects
 684           or same user id or pid may refer to different tasks when used in
 685           different namespaces.
 686
 687 if NAMESPACES
 688
 689 config UTS_NS
 690         bool "UTS namespace"
 691         default y
 692         help
 693           In this namespace tasks see different info provided with the
 694           uname() system call
 695
 696 config IPC_NS
 697         bool "IPC namespace"
 698         depends on (SYSVIPC || POSIX_MQUEUE)
 699         default y
 700         help
 701           In this namespace tasks work with IPC ids which correspond to
 702           different IPC objects in different namespaces.
 703
 704 config USER_NS
 705         bool "User namespace (EXPERIMENTAL)"
 706         depends on EXPERIMENTAL
 707         default y
 708         help
 709           This allows containers, i.e. vservers, to use user namespaces
 710           to provide different user info for different servers.
 711           If unsure, say N.
 712
 713 config PID_NS
 714         bool "PID Namespaces"
 715         default y
 716         help
 717           Support process id namespaces.  This allows having multiple
 718           processes with the same pid as long as they are in different
 719           pid namespaces.  This is a building block of containers.
 720
 721 config NET_NS
 722         bool "Network namespace"
 723         depends on NET
 724         default y
 725         help
 726           Allow user space to create what appear to be multiple instances
 727           of the network stack.
 728
 729 endif # NAMESPACES
 730
 731 config SCHED_AUTOGROUP
 732         bool "Automatic process group scheduling"
 733         select EVENTFD
 734         select CGROUPS
 735         select CGROUP_SCHED
 736         select FAIR_GROUP_SCHED
 737         help
 738           This option optimizes the scheduler for common desktop workloads by
 739           automatically creating and populating task groups.  This separation
 740           of workloads isolates aggressive CPU burners (like build jobs) from
 741           desktop applications.  Task group autogeneration is currently based
 742           upon task session.
 743
 744 config MM_OWNER
 745         bool
 746
 747 config SYSFS_DEPRECATED
 748         bool "enable deprecated sysfs features to support old userspace tools"
 749         depends on SYSFS
 750         default n
 751         help
 752           This option adds code that switches the layout of the "block" class
 753           devices, to not show up in /sys/class/block/, but only in
 754           /sys/block/.
 755
 756           This switch is only active when the sysfs.deprecated=1 boot option is
 757           passed or the SYSFS_DEPRECATED_V2 option is set.
 758
 759           This option allows new kernels to run on old distributions and tools,
 760           which might get confused by /sys/class/block/. Since 2007/2008 all
 761           major distributions and tools handle this just fine.
 762
 763           Recent distributions and userspace tools after 2009/2010 depend on
 764           the existence of /sys/class/block/, and will not work with this
 765           option enabled.
 766
 767           Only if you are using a new kernel on an old distribution, you might
 768           need to say Y here.
 769
 770 config SYSFS_DEPRECATED_V2
 771         bool "enabled deprecated sysfs features by default"
 772         default n
 773         depends on SYSFS
 774         depends on SYSFS_DEPRECATED
 775         help
 776           Enable deprecated sysfs by default.
 777
 778           See the CONFIG_SYSFS_DEPRECATED option for more details about this
 779           option.
 780
 781           Only if you are using a new kernel on an old distribution, you might
 782           need to say Y here. Even then, odds are you would not need it
 783           enabled, you can always pass the boot option if absolutely necessary.
 784
 785 config RELAY
 786         bool "Kernel->user space relay support (formerly relayfs)"
 787         help
 788           This option enables support for relay interface support in
 789           certain file systems (such as debugfs).
 790           It is designed to provide an efficient mechanism for tools and
 791           facilities to relay large amounts of data from kernel space to
 792           user space.
 793
 794           If unsure, say N.
 795
 796 config BLK_DEV_INITRD
 797         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 798         depends on BROKEN || !FRV
 799         help
 800           The initial RAM filesystem is a ramfs which is loaded by the
 801           boot loader (loadlin or lilo) and that is mounted as root
 802           before the normal boot procedure. It is typically used to
 803           load modules needed to mount the "real" root file system,
 804           etc. See <file:Documentation/initrd.txt> for details.
 805
 806           If RAM disk support (BLK_DEV_RAM) is also included, this
 807           also enables initial RAM disk (initrd) support and adds
 808           15 Kbytes (more on some other architectures) to the kernel size.
 809
 810           If unsure say Y.
 811
 812 if BLK_DEV_INITRD
 813
 814 source "usr/Kconfig"
 815
 816 endif
 817
 818 config CC_OPTIMIZE_FOR_SIZE
 819         bool "Optimize for size"
 820         default y
 821         help
 822           Enabling this option will pass "-Os" instead of "-O2" to gcc
 823           resulting in a smaller kernel.
 824
 825           If unsure, say Y.
 826
 827 config SYSCTL
 828         bool
 829
 830 config ANON_INODES
 831         bool
 832
 833 menuconfig EMBEDDED
 834         bool "Configure standard kernel features (for small systems)"
 835         help
 836           This option allows certain base kernel options and settings
 837           to be disabled or tweaked. This is for specialized
 838           environments which can tolerate a "non-standard" kernel.
 839           Only use this if you really know what you are doing.
 840
 841 config UID16
 842         bool "Enable 16-bit UID system calls" if EMBEDDED
 843         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 844         default y
 845         help
 846           This enables the legacy 16-bit UID syscall wrappers.
 847
 848 config SYSCTL_SYSCALL
 849         bool "Sysctl syscall support" if EMBEDDED
 850         depends on PROC_SYSCTL
 851         default y
 852         select SYSCTL
 853         ---help---
 854           sys_sysctl uses binary paths that have been found challenging
 855           to properly maintain and use.  The interface in /proc/sys
 856           using paths with ascii names is now the primary path to this
 857           information.
 858
 859           Almost nothing using the binary sysctl interface so if you are
 860           trying to save some space it is probably safe to disable this,
 861           making your kernel marginally smaller.
 862
 863           If unsure say Y here.
 864
 865 config KALLSYMS
 866          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 867          default y
 868          help
 869            Say Y here to let the kernel print out symbolic crash information and
 870            symbolic stack backtraces. This increases the size of the kernel
 871            somewhat, as all symbols have to be loaded into the kernel image.
 872
 873 config KALLSYMS_ALL
 874         bool "Include all symbols in kallsyms"
 875         depends on DEBUG_KERNEL && KALLSYMS
 876         help
 877            Normally kallsyms only contains the symbols of functions, for nicer
 878            OOPS messages.  Some debuggers can use kallsyms for other
 879            symbols too: say Y here to include all symbols, if you need them
 880            and you don't care about adding 300k to the size of your kernel.
 881
 882            Say N.
 883
 884 config KALLSYMS_EXTRA_PASS
 885         bool "Do an extra kallsyms pass"
 886         depends on KALLSYMS
 887         help
 888            If kallsyms is not working correctly, the build will fail with
 889            inconsistent kallsyms data.  If that occurs, log a bug report and
 890            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 891            Always say N here unless you find a bug in kallsyms, which must be
 892            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 893            you wait for kallsyms to be fixed.
 894
 895
 896 config HOTPLUG
 897         bool "Support for hot-pluggable devices" if EMBEDDED
 898         default y
 899         help
 900           This option is provided for the case where no hotplug or uevent
 901           capabilities is wanted by the kernel.  You should only consider
 902           disabling this option for embedded systems that do not use modules, a
 903           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 904
 905 config PRINTK
 906         default y
 907         bool "Enable support for printk" if EMBEDDED
 908         help
 909           This option enables normal printk support. Removing it
 910           eliminates most of the message strings from the kernel image
 911           and makes the kernel more or less silent. As this makes it
 912           very difficult to diagnose system problems, saying N here is
 913           strongly discouraged.
 914
 915 config BUG
 916         bool "BUG() support" if EMBEDDED
 917         default y
 918         help
 919           Disabling this option eliminates support for BUG and WARN, reducing
 920           the size of your kernel image and potentially quietly ignoring
 921           numerous fatal conditions. You should only consider disabling this
 922           option for embedded systems with no facilities for reporting errors.
 923           Just say Y.
 924
 925 config ELF_CORE
 926         default y
 927         bool "Enable ELF core dumps" if EMBEDDED
 928         help
 929           Enable support for generating core dumps. Disabling saves about 4k.
 930
 931 config PCSPKR_PLATFORM
 932         bool "Enable PC-Speaker support" if EMBEDDED
 933         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 934         default y
 935         help
 936           This option allows to disable the internal PC-Speaker
 937           support, saving some memory.
 938
 939 config BASE_FULL
 940         default y
 941         bool "Enable full-sized data structures for core" if EMBEDDED
 942         help
 943           Disabling this option reduces the size of miscellaneous core
 944           kernel data structures. This saves memory on small machines,
 945           but may reduce performance.
 946
 947 config FUTEX
 948         bool "Enable futex support" if EMBEDDED
 949         default y
 950         select RT_MUTEXES
 951         help
 952           Disabling this option will cause the kernel to be built without
 953           support for "fast userspace mutexes".  The resulting kernel may not
 954           run glibc-based applications correctly.
 955
 956 config EPOLL
 957         bool "Enable eventpoll support" if EMBEDDED
 958         default y
 959         select ANON_INODES
 960         help
 961           Disabling this option will cause the kernel to be built without
 962           support for epoll family of system calls.
 963
 964 config SIGNALFD
 965         bool "Enable signalfd() system call" if EMBEDDED
 966         select ANON_INODES
 967         default y
 968         help
 969           Enable the signalfd() system call that allows to receive signals
 970           on a file descriptor.
 971
 972           If unsure, say Y.
 973
 974 config TIMERFD
 975         bool "Enable timerfd() system call" if EMBEDDED
 976         select ANON_INODES
 977         default y
 978         help
 979           Enable the timerfd() system call that allows to receive timer
 980           events on a file descriptor.
 981
 982           If unsure, say Y.
 983
 984 config EVENTFD
 985         bool "Enable eventfd() system call" if EMBEDDED
 986         select ANON_INODES
 987         default y
 988         help
 989           Enable the eventfd() system call that allows to receive both
 990           kernel notification (ie. KAIO) or userspace notifications.
 991
 992           If unsure, say Y.
 993
 994 config SHMEM
 995         bool "Use full shmem filesystem" if EMBEDDED
 996         default y
 997         depends on MMU
 998         help
 999           The shmem is an internal filesystem used to manage shared memory.
1000           It is backed by swap and manages resource limits. It is also exported
1001           to userspace as tmpfs if TMPFS is enabled. Disabling this
1002           option replaces shmem and tmpfs with the much simpler ramfs code,
1003           which may be appropriate on small systems without swap.
1004
1005 config AIO
1006         bool "Enable AIO support" if EMBEDDED
1007         default y
1008         help
1009           This option enables POSIX asynchronous I/O which may by used
1010           by some high performance threaded applications. Disabling
1011           this option saves about 7k.
1012
1013 config HAVE_PERF_EVENTS
1014         bool
1015         help
1016           See tools/perf/design.txt for details.
1017
1018 config PERF_USE_VMALLOC
1019         bool
1020         help
1021           See tools/perf/design.txt for details
1022
1023 menu "Kernel Performance Events And Counters"
1024
1025 config PERF_EVENTS
1026         bool "Kernel performance events and counters"
1027         default y if (PROFILING || PERF_COUNTERS)
1028         depends on HAVE_PERF_EVENTS
1029         select ANON_INODES
1030         select IRQ_WORK
1031         help
1032           Enable kernel support for various performance events provided
1033           by software and hardware.
1034
1035           Software events are supported either built-in or via the
1036           use of generic tracepoints.
1037
1038           Most modern CPUs support performance events via performance
1039           counter registers. These registers count the number of certain
1040           types of hw events: such as instructions executed, cachemisses
1041           suffered, or branches mis-predicted - without slowing down the
1042           kernel or applications. These registers can also trigger interrupts
1043           when a threshold number of events have passed - and can thus be
1044           used to profile the code that runs on that CPU.
1045
1046           The Linux Performance Event subsystem provides an abstraction of
1047           these software and hardware event capabilities, available via a
1048           system call and used by the "perf" utility in tools/perf/. It
1049           provides per task and per CPU counters, and it provides event
1050           capabilities on top of those.
1051
1052           Say Y if unsure.
1053
1054 config PERF_COUNTERS
1055         bool "Kernel performance counters (old config option)"
1056         depends on HAVE_PERF_EVENTS
1057         help
1058           This config has been obsoleted by the PERF_EVENTS
1059           config option - please see that one for details.
1060
1061           It has no effect on the kernel whether you enable
1062           it or not, it is a compatibility placeholder.
1063
1064           Say N if unsure.
1065
1066 config DEBUG_PERF_USE_VMALLOC
1067         default n
1068         bool "Debug: use vmalloc to back perf mmap() buffers"
1069         depends on PERF_EVENTS && DEBUG_KERNEL
1070         select PERF_USE_VMALLOC
1071         help
1072          Use vmalloc memory to back perf mmap() buffers.
1073
1074          Mostly useful for debugging the vmalloc code on platforms
1075          that don't require it.
1076
1077          Say N if unsure.
1078
1079 endmenu
1080
1081 config VM_EVENT_COUNTERS
1082         default y
1083         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1084         help
1085           VM event counters are needed for event counts to be shown.
1086           This option allows the disabling of the VM event counters
1087           on EMBEDDED systems.  /proc/vmstat will only show page counts
1088           if VM event counters are disabled.
1089
1090 config PCI_QUIRKS
1091         default y
1092         bool "Enable PCI quirk workarounds" if EMBEDDED
1093         depends on PCI
1094         help
1095           This enables workarounds for various PCI chipset
1096           bugs/quirks. Disable this only if your target machine is
1097           unaffected by PCI quirks.
1098
1099 config SLUB_DEBUG
1100         default y
1101         bool "Enable SLUB debugging support" if EMBEDDED
1102         depends on SLUB && SYSFS
1103         help
1104           SLUB has extensive debug support features. Disabling these can
1105           result in significant savings in code size. This also disables
1106           SLUB sysfs support. /sys/slab will not exist and there will be
1107           no support for cache validation etc.
1108
1109 config COMPAT_BRK
1110         bool "Disable heap randomization"
1111         default y
1112         help
1113           Randomizing heap placement makes heap exploits harder, but it
1114           also breaks ancient binaries (including anything libc5 based).
1115           This option changes the bootup default to heap randomization
1116           disabled, and can be overridden at runtime by setting
1117           /proc/sys/kernel/randomize_va_space to 2.
1118
1119           On non-ancient distros (post-2000 ones) N is usually a safe choice.
1120
1121 choice
1122         prompt "Choose SLAB allocator"
1123         default SLUB
1124         help
1125            This option allows to select a slab allocator.
1126
1127 config SLAB
1128         bool "SLAB"
1129         help
1130           The regular slab allocator that is established and known to work
1131           well in all environments. It organizes cache hot objects in
1132           per cpu and per node queues.
1133
1134 config SLUB
1135         bool "SLUB (Unqueued Allocator)"
1136         help
1137            SLUB is a slab allocator that minimizes cache line usage
1138            instead of managing queues of cached objects (SLAB approach).
1139            Per cpu caching is realized using slabs of objects instead
1140            of queues of objects. SLUB can use memory efficiently
1141            and has enhanced diagnostics. SLUB is the default choice for
1142            a slab allocator.
1143
1144 config SLOB
1145         depends on EMBEDDED
1146         bool "SLOB (Simple Allocator)"
1147         help
1148            SLOB replaces the stock allocator with a drastically simpler
1149            allocator. SLOB is generally more space efficient but
1150            does not perform as well on large systems.
1151
1152 endchoice
1153
1154 config MMAP_ALLOW_UNINITIALIZED
1155         bool "Allow mmapped anonymous memory to be uninitialized"
1156         depends on EMBEDDED && !MMU
1157         default n
1158         help
1159           Normally, and according to the Linux spec, anonymous memory obtained
1160           from mmap() has it's contents cleared before it is passed to
1161           userspace.  Enabling this config option allows you to request that
1162           mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1163           providing a huge performance boost.  If this option is not enabled,
1164           then the flag will be ignored.
1165
1166           This is taken advantage of by uClibc's malloc(), and also by
1167           ELF-FDPIC binfmt's brk and stack allocator.
1168
1169           Because of the obvious security issues, this option should only be
1170           enabled on embedded devices where you control what is run in
1171           userspace.  Since that isn't generally a problem on no-MMU systems,
1172           it is normally safe to say Y here.
1173
1174           See Documentation/nommu-mmap.txt for more information.
1175
1176 config PROFILING
1177         bool "Profiling support"
1178         help
1179           Say Y here to enable the extended profiling support mechanisms used
1180           by profilers such as OProfile.
1181
1182 #
1183 # Place an empty function call at each tracepoint site. Can be
1184 # dynamically changed for a probe function.
1185 #
1186 config TRACEPOINTS
1187         bool
1188
1189 source "arch/Kconfig"
1190
1191 endmenu         # General setup
1192
1193 config HAVE_GENERIC_DMA_COHERENT
1194         bool
1195         default n
1196
1197 config SLABINFO
1198         bool
1199         depends on PROC_FS
1200         depends on SLAB || SLUB_DEBUG
1201         default y
1202
1203 config RT_MUTEXES
1204         boolean
1205
1206 config BASE_SMALL
1207         int
1208         default 0 if BASE_FULL
1209         default 1 if !BASE_FULL
1210
1211 menuconfig MODULES
1212         bool "Enable loadable module support"
1213         help
1214           Kernel modules are small pieces of compiled code which can
1215           be inserted in the running kernel, rather than being
1216           permanently built into the kernel.  You use the "modprobe"
1217           tool to add (and sometimes remove) them.  If you say Y here,
1218           many parts of the kernel can be built as modules (by
1219           answering M instead of Y where indicated): this is most
1220           useful for infrequently used options which are not required
1221           for booting.  For more information, see the man pages for
1222           modprobe, lsmod, modinfo, insmod and rmmod.
1223
1224           If you say Y here, you will need to run "make
1225           modules_install" to put the modules under /lib/modules/
1226           where modprobe can find them (you may need to be root to do
1227           this).
1228
1229           If unsure, say Y.
1230
1231 if MODULES
1232
1233 config MODULE_FORCE_LOAD
1234         bool "Forced module loading"
1235         default n
1236         help
1237           Allow loading of modules without version information (ie. modprobe
1238           --force).  Forced module loading sets the 'F' (forced) taint flag and
1239           is usually a really bad idea.
1240
1241 config MODULE_UNLOAD
1242         bool "Module unloading"
1243         help
1244           Without this option you will not be able to unload any
1245           modules (note that some modules may not be unloadable
1246           anyway), which makes your kernel smaller, faster
1247           and simpler.  If unsure, say Y.
1248
1249 config MODULE_FORCE_UNLOAD
1250         bool "Forced module unloading"
1251         depends on MODULE_UNLOAD && EXPERIMENTAL
1252         help
1253           This option allows you to force a module to unload, even if the
1254           kernel believes it is unsafe: the kernel will remove the module
1255           without waiting for anyone to stop using it (using the -f option to
1256           rmmod).  This is mainly for kernel developers and desperate users.
1257           If unsure, say N.
1258
1259 config MODVERSIONS
1260         bool "Module versioning support"
1261         help
1262           Usually, you have to use modules compiled with your kernel.
1263           Saying Y here makes it sometimes possible to use modules
1264           compiled for different kernels, by adding enough information
1265           to the modules to (hopefully) spot any changes which would
1266           make them incompatible with the kernel you are running.  If
1267           unsure, say N.
1268
1269 config MODULE_SRCVERSION_ALL
1270         bool "Source checksum for all modules"
1271         help
1272           Modules which contain a MODULE_VERSION get an extra "srcversion"
1273           field inserted into their modinfo section, which contains a
1274           sum of the source files which made it.  This helps maintainers
1275           see exactly which source was used to build a module (since
1276           others sometimes change the module source without updating
1277           the version).  With this option, such a "srcversion" field
1278           will be created for all modules.  If unsure, say N.
1279
1280 endif # MODULES
1281
1282 config INIT_ALL_POSSIBLE
1283         bool
1284         help
1285           Back when each arch used to define their own cpu_online_map and
1286           cpu_possible_map, some of them chose to initialize cpu_possible_map
1287           with all 1s, and others with all 0s.  When they were centralised,
1288           it was better to provide this option than to break all the archs
1289           and have several arch maintainers pursuing me down dark alleys.
1290
1291 config STOP_MACHINE
1292         bool
1293         default y
1294         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1295         help
1296           Need stop_machine() primitive.
1297
1298 source "block/Kconfig"
1299
1300 config PREEMPT_NOTIFIERS
1301         bool
1302
1303 config PADATA
1304         depends on SMP
1305         bool
1306
1307 source "kernel/Kconfig.locks"