init/Kconfig

   1 config ARCH
   2         string
   3         option env="ARCH"
   4
   5 config KERNELVERSION
   6         string
   7         option env="KERNELVERSION"
   8
   9 config DEFCONFIG_LIST
  10         string
  11         depends on !UML
  12         option defconfig_list
  13         default "/lib/modules/$UNAME_RELEASE/.config"
  14         default "/etc/kernel-config"
  15         default "/boot/config-$UNAME_RELEASE"
  16         default "$ARCH_DEFCONFIG"
  17         default "arch/$ARCH/defconfig"
  18
  19 config CONSTRUCTORS
  20         bool
  21         depends on !UML
  22         default y
  23
  24 menu "General setup"
  25
  26 config EXPERIMENTAL
  27         bool "Prompt for development and/or incomplete code/drivers"
  28         ---help---
  29           Some of the various things that Linux supports (such as network
  30           drivers, file systems, network protocols, etc.) can be in a state
  31           of development where the functionality, stability, or the level of
  32           testing is not yet high enough for general use. This is usually
  33           known as the "alpha-test" phase among developers. If a feature is
  34           currently in alpha-test, then the developers usually discourage
  35           uninformed widespread use of this feature by the general public to
  36           avoid "Why doesn't this work?" type mail messages. However, active
  37           testing and use of these systems is welcomed. Just be aware that it
  38           may not meet the normal level of reliability or it may fail to work
  39           in some special cases. Detailed bug reports from people familiar
  40           with the kernel internals are usually welcomed by the developers
  41           (before submitting bug reports, please read the documents
  42           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  43           <file:Documentation/BUG-HUNTING>, and
  44           <file:Documentation/oops-tracing.txt> in the kernel source).
  45
  46           This option will also make obsoleted drivers available. These are
  47           drivers that have been replaced by something else, and/or are
  48           scheduled to be removed in a future kernel release.
  49
  50           Unless you intend to help test and develop a feature or driver that
  51           falls into this category, or you have a situation that requires
  52           using these features, you should probably say N here, which will
  53           cause the configurator to present you with fewer choices. If
  54           you say Y here, you will be offered the choice of using features or
  55           drivers that are currently considered to be in the alpha-test phase.
  56
  57 config BROKEN
  58         bool
  59
  60 config BROKEN_ON_SMP
  61         bool
  62         depends on BROKEN || !SMP
  63         default y
  64
  65 config LOCK_KERNEL
  66         bool
  67         depends on SMP || PREEMPT
  68         default y
  69
  70 config INIT_ENV_ARG_LIMIT
  71         int
  72         default 32 if !UML
  73         default 128 if UML
  74         help
  75           Maximum of each of the number of arguments and environment
  76           variables passed to init from the kernel command line.
  77
  78
  79 config LOCALVERSION
  80         string "Local version - append to kernel release"
  81         help
  82           Append an extra string to the end of your kernel version.
  83           This will show up when you type uname, for example.
  84           The string you set here will be appended after the contents of
  85           any files with a filename matching localversion* in your
  86           object and source tree, in that order.  Your total string can
  87           be a maximum of 64 characters.
  88
  89 config LOCALVERSION_AUTO
  90         bool "Automatically append version information to the version string"
  91         default y
  92         help
  93           This will try to automatically determine if the current tree is a
  94           release tree by looking for git tags that belong to the current
  95           top of tree revision.
  96
  97           A string of the format -gxxxxxxxx will be added to the localversion
  98           if a git-based tree is found.  The string generated by this will be
  99           appended after any matching localversion* files, and after the value
 100           set in CONFIG_LOCALVERSION.
 101
 102           (The actual string used here is the first eight characters produced
 103           by running the command:
 104
 105             $ git rev-parse --verify HEAD
 106
 107           which is done within the script "scripts/setlocalversion".)
 108
 109 config HAVE_KERNEL_GZIP
 110         bool
 111
 112 config HAVE_KERNEL_BZIP2
 113         bool
 114
 115 config HAVE_KERNEL_LZMA
 116         bool
 117
 118 config HAVE_KERNEL_LZO
 119         bool
 120
 121 choice
 122         prompt "Kernel compression mode"
 123         default KERNEL_GZIP
 124         depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
 125         help
 126           The linux kernel is a kind of self-extracting executable.
 127           Several compression algorithms are available, which differ
 128           in efficiency, compression and decompression speed.
 129           Compression speed is only relevant when building a kernel.
 130           Decompression speed is relevant at each boot.
 131
 132           If you have any problems with bzip2 or lzma compressed
 133           kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 134           version of this functionality (bzip2 only), for 2.4, was
 135           supplied by Christian Ludwig)
 136
 137           High compression options are mostly useful for users, who
 138           are low on disk space (embedded systems), but for whom ram
 139           size matters less.
 140
 141           If in doubt, select 'gzip'
 142
 143 config KERNEL_GZIP
 144         bool "Gzip"
 145         depends on HAVE_KERNEL_GZIP
 146         help
 147           The old and tried gzip compression. It provides a good balance
 148           between compression ratio and decompression speed.
 149
 150 config KERNEL_BZIP2
 151         bool "Bzip2"
 152         depends on HAVE_KERNEL_BZIP2
 153         help
 154           Its compression ratio and speed is intermediate.
 155           Decompression speed is slowest among the three.  The kernel
 156           size is about 10% smaller with bzip2, in comparison to gzip.
 157           Bzip2 uses a large amount of memory. For modern kernels you
 158           will need at least 8MB RAM or more for booting.
 159
 160 config KERNEL_LZMA
 161         bool "LZMA"
 162         depends on HAVE_KERNEL_LZMA
 163         help
 164           The most recent compression algorithm.
 165           Its ratio is best, decompression speed is between the other
 166           two. Compression is slowest.  The kernel size is about 33%
 167           smaller with LZMA in comparison to gzip.
 168
 169 config KERNEL_LZO
 170         bool "LZO"
 171         depends on HAVE_KERNEL_LZO
 172         help
 173           Its compression ratio is the poorest among the 4. The kernel
 174           size is about about 10% bigger than gzip; however its speed
 175           (both compression and decompression) is the fastest.
 176
 177 endchoice
 178
 179 config SWAP
 180         bool "Support for paging of anonymous memory (swap)"
 181         depends on MMU && BLOCK
 182         default y
 183         help
 184           This option allows you to choose whether you want to have support
 185           for so called swap devices or swap files in your kernel that are
 186           used to provide more virtual memory than the actual RAM present
 187           in your computer.  If unsure say Y.
 188
 189 config SYSVIPC
 190         bool "System V IPC"
 191         ---help---
 192           Inter Process Communication is a suite of library functions and
 193           system calls which let processes (running programs) synchronize and
 194           exchange information. It is generally considered to be a good thing,
 195           and some programs won't run unless you say Y here. In particular, if
 196           you want to run the DOS emulator dosemu under Linux (read the
 197           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 198           you'll need to say Y here.
 199
 200           You can find documentation about IPC with "info ipc" and also in
 201           section 6.4 of the Linux Programmer's Guide, available from
 202           <http://www.tldp.org/guides.html>.
 203
 204 config SYSVIPC_SYSCTL
 205         bool
 206         depends on SYSVIPC
 207         depends on SYSCTL
 208         default y
 209
 210 config POSIX_MQUEUE
 211         bool "POSIX Message Queues"
 212         depends on NET && EXPERIMENTAL
 213         ---help---
 214           POSIX variant of message queues is a part of IPC. In POSIX message
 215           queues every message has a priority which decides about succession
 216           of receiving it by a process. If you want to compile and run
 217           programs written e.g. for Solaris with use of its POSIX message
 218           queues (functions mq_*) say Y here.
 219
 220           POSIX message queues are visible as a filesystem called 'mqueue'
 221           and can be mounted somewhere if you want to do filesystem
 222           operations on message queues.
 223
 224           If unsure, say Y.
 225
 226 config POSIX_MQUEUE_SYSCTL
 227         bool
 228         depends on POSIX_MQUEUE
 229         depends on SYSCTL
 230         default y
 231
 232 config BSD_PROCESS_ACCT
 233         bool "BSD Process Accounting"
 234         help
 235           If you say Y here, a user level program will be able to instruct the
 236           kernel (via a special system call) to write process accounting
 237           information to a file: whenever a process exits, information about
 238           that process will be appended to the file by the kernel.  The
 239           information includes things such as creation time, owning user,
 240           command name, memory usage, controlling terminal etc. (the complete
 241           list is in the struct acct in <file:include/linux/acct.h>).  It is
 242           up to the user level program to do useful things with this
 243           information.  This is generally a good idea, so say Y.
 244
 245 config BSD_PROCESS_ACCT_V3
 246         bool "BSD Process Accounting version 3 file format"
 247         depends on BSD_PROCESS_ACCT
 248         default n
 249         help
 250           If you say Y here, the process accounting information is written
 251           in a new file format that also logs the process IDs of each
 252           process and it's parent. Note that this file format is incompatible
 253           with previous v0/v1/v2 file formats, so you will need updated tools
 254           for processing it. A preliminary version of these tools is available
 255           at <http://www.gnu.org/software/acct/>.
 256
 257 config TASKSTATS
 258         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 259         depends on NET
 260         default n
 261         help
 262           Export selected statistics for tasks/processes through the
 263           generic netlink interface. Unlike BSD process accounting, the
 264           statistics are available during the lifetime of tasks/processes as
 265           responses to commands. Like BSD accounting, they are sent to user
 266           space on task exit.
 267
 268           Say N if unsure.
 269
 270 config TASK_DELAY_ACCT
 271         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 272         depends on TASKSTATS
 273         help
 274           Collect information on time spent by a task waiting for system
 275           resources like cpu, synchronous block I/O completion and swapping
 276           in pages. Such statistics can help in setting a task's priorities
 277           relative to other tasks for cpu, io, rss limits etc.
 278
 279           Say N if unsure.
 280
 281 config TASK_XACCT
 282         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 283         depends on TASKSTATS
 284         help
 285           Collect extended task accounting data and send the data
 286           to userland for processing over the taskstats interface.
 287
 288           Say N if unsure.
 289
 290 config TASK_IO_ACCOUNTING
 291         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 292         depends on TASK_XACCT
 293         help
 294           Collect information on the number of bytes of storage I/O which this
 295           task has caused.
 296
 297           Say N if unsure.
 298
 299 config AUDIT
 300         bool "Auditing support"
 301         depends on NET
 302         help
 303           Enable auditing infrastructure that can be used with another
 304           kernel subsystem, such as SELinux (which requires this for
 305           logging of avc messages output).  Does not do system-call
 306           auditing without CONFIG_AUDITSYSCALL.
 307
 308 config AUDITSYSCALL
 309         bool "Enable system-call auditing support"
 310         depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
 311         default y if SECURITY_SELINUX
 312         help
 313           Enable low-overhead system-call auditing infrastructure that
 314           can be used independently or with another kernel subsystem,
 315           such as SELinux.  To use audit's filesystem watch feature, please
 316           ensure that INOTIFY is configured.
 317
 318 config AUDIT_TREE
 319         def_bool y
 320         depends on AUDITSYSCALL
 321         select INOTIFY
 322
 323 menu "RCU Subsystem"
 324
 325 choice
 326         prompt "RCU Implementation"
 327         default TREE_RCU
 328
 329 config TREE_RCU
 330         bool "Tree-based hierarchical RCU"
 331         help
 332           This option selects the RCU implementation that is
 333           designed for very large SMP system with hundreds or
 334           thousands of CPUs.  It also scales down nicely to
 335           smaller systems.
 336
 337 config TREE_PREEMPT_RCU
 338         bool "Preemptable tree-based hierarchical RCU"
 339         depends on PREEMPT
 340         help
 341           This option selects the RCU implementation that is
 342           designed for very large SMP systems with hundreds or
 343           thousands of CPUs, but for which real-time response
 344           is also required.  It also scales down nicely to
 345           smaller systems.
 346
 347 config TINY_RCU
 348         bool "UP-only small-memory-footprint RCU"
 349         depends on !SMP
 350         help
 351           This option selects the RCU implementation that is
 352           designed for UP systems from which real-time response
 353           is not required.  This option greatly reduces the
 354           memory footprint of RCU.
 355
 356 endchoice
 357
 358 config RCU_TRACE
 359         bool "Enable tracing for RCU"
 360         depends on TREE_RCU || TREE_PREEMPT_RCU
 361         help
 362           This option provides tracing in RCU which presents stats
 363           in debugfs for debugging RCU implementation.
 364
 365           Say Y here if you want to enable RCU tracing
 366           Say N if you are unsure.
 367
 368 config RCU_FANOUT
 369         int "Tree-based hierarchical RCU fanout value"
 370         range 2 64 if 64BIT
 371         range 2 32 if !64BIT
 372         depends on TREE_RCU || TREE_PREEMPT_RCU
 373         default 64 if 64BIT
 374         default 32 if !64BIT
 375         help
 376           This option controls the fanout of hierarchical implementations
 377           of RCU, allowing RCU to work efficiently on machines with
 378           large numbers of CPUs.  This value must be at least the cube
 379           root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
 380           systems and up to 262,144 for 64-bit systems.
 381
 382           Select a specific number if testing RCU itself.
 383           Take the default if unsure.
 384
 385 config RCU_FANOUT_EXACT
 386         bool "Disable tree-based hierarchical RCU auto-balancing"
 387         depends on TREE_RCU || TREE_PREEMPT_RCU
 388         default n
 389         help
 390           This option forces use of the exact RCU_FANOUT value specified,
 391           regardless of imbalances in the hierarchy.  This is useful for
 392           testing RCU itself, and might one day be useful on systems with
 393           strong NUMA behavior.
 394
 395           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 396
 397           Say N if unsure.
 398
 399 config TREE_RCU_TRACE
 400         def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 401         select DEBUG_FS
 402         help
 403           This option provides tracing for the TREE_RCU and
 404           TREE_PREEMPT_RCU implementations, permitting Makefile to
 405           trivially select kernel/rcutree_trace.c.
 406
 407 endmenu # "RCU Subsystem"
 408
 409 config IKCONFIG
 410         tristate "Kernel .config support"
 411         ---help---
 412           This option enables the complete Linux kernel ".config" file
 413           contents to be saved in the kernel. It provides documentation
 414           of which kernel options are used in a running kernel or in an
 415           on-disk kernel.  This information can be extracted from the kernel
 416           image file with the script scripts/extract-ikconfig and used as
 417           input to rebuild the current kernel or to build another kernel.
 418           It can also be extracted from a running kernel by reading
 419           /proc/config.gz if enabled (below).
 420
 421 config IKCONFIG_PROC
 422         bool "Enable access to .config through /proc/config.gz"
 423         depends on IKCONFIG && PROC_FS
 424         ---help---
 425           This option enables access to the kernel configuration file
 426           through /proc/config.gz.
 427
 428 config LOG_BUF_SHIFT
 429         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 430         range 12 21
 431         default 17
 432         help
 433           Select kernel log buffer size as a power of 2.
 434           Examples:
 435                      17 => 128 KB
 436                      16 => 64 KB
 437                      15 => 32 KB
 438                      14 => 16 KB
 439                      13 =>  8 KB
 440                      12 =>  4 KB
 441
 442 #
 443 # Architectures with an unreliable sched_clock() should select this:
 444 #
 445 config HAVE_UNSTABLE_SCHED_CLOCK
 446         bool
 447
 448 config GROUP_SCHED
 449         bool "Group CPU scheduler"
 450         depends on EXPERIMENTAL
 451         default n
 452         help
 453           This feature lets CPU scheduler recognize task groups and control CPU
 454           bandwidth allocation to such task groups.
 455           In order to create a group from arbitrary set of processes, use
 456           CONFIG_CGROUPS. (See Control Group support.)
 457
 458 config FAIR_GROUP_SCHED
 459         bool "Group scheduling for SCHED_OTHER"
 460         depends on GROUP_SCHED
 461         default GROUP_SCHED
 462
 463 config RT_GROUP_SCHED
 464         bool "Group scheduling for SCHED_RR/FIFO"
 465         depends on EXPERIMENTAL
 466         depends on GROUP_SCHED
 467         default n
 468         help
 469           This feature lets you explicitly allocate real CPU bandwidth
 470           to users or control groups (depending on the "Basis for grouping tasks"
 471           setting below. If enabled, it will also make it impossible to
 472           schedule realtime tasks for non-root users until you allocate
 473           realtime bandwidth for them.
 474           See Documentation/scheduler/sched-rt-group.txt for more information.
 475
 476 choice
 477         depends on GROUP_SCHED
 478         prompt "Basis for grouping tasks"
 479         default USER_SCHED
 480
 481 config USER_SCHED
 482         bool "user id"
 483         help
 484           This option will choose userid as the basis for grouping
 485           tasks, thus providing equal CPU bandwidth to each user.
 486
 487 config CGROUP_SCHED
 488         bool "Control groups"
 489         depends on CGROUPS
 490         help
 491           This option allows you to create arbitrary task groups
 492           using the "cgroup" pseudo filesystem and control
 493           the cpu bandwidth allocated to each such task group.
 494           Refer to Documentation/cgroups/cgroups.txt for more
 495           information on "cgroup" pseudo filesystem.
 496
 497 endchoice
 498
 499 menuconfig CGROUPS
 500         boolean "Control Group support"
 501         help
 502           This option adds support for grouping sets of processes together, for
 503           use with process control subsystems such as Cpusets, CFS, memory
 504           controls or device isolation.
 505           See
 506                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 507                 - Documentation/cgroups/ (features for grouping, isolation
 508                                           and resource control)
 509
 510           Say N if unsure.
 511
 512 if CGROUPS
 513
 514 config CGROUP_DEBUG
 515         bool "Example debug cgroup subsystem"
 516         depends on CGROUPS
 517         default n
 518         help
 519           This option enables a simple cgroup subsystem that
 520           exports useful debugging information about the cgroups
 521           framework.
 522
 523           Say N if unsure.
 524
 525 config CGROUP_NS
 526         bool "Namespace cgroup subsystem"
 527         depends on CGROUPS
 528         help
 529           Provides a simple namespace cgroup subsystem to
 530           provide hierarchical naming of sets of namespaces,
 531           for instance virtual servers and checkpoint/restart
 532           jobs.
 533
 534 config CGROUP_FREEZER
 535         bool "Freezer cgroup subsystem"
 536         depends on CGROUPS
 537         help
 538           Provides a way to freeze and unfreeze all tasks in a
 539           cgroup.
 540
 541 config CGROUP_DEVICE
 542         bool "Device controller for cgroups"
 543         depends on CGROUPS && EXPERIMENTAL
 544         help
 545           Provides a cgroup implementing whitelists for devices which
 546           a process in the cgroup can mknod or open.
 547
 548 config CPUSETS
 549         bool "Cpuset support"
 550         depends on CGROUPS
 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         depends on CGROUPS
 567         help
 568           Provides a simple Resource Controller for monitoring the
 569           total CPU consumed by the tasks in a cgroup.
 570
 571 config RESOURCE_COUNTERS
 572         bool "Resource counters"
 573         help
 574           This option enables controller independent resource accounting
 575           infrastructure that works with cgroups.
 576         depends on CGROUPS
 577
 578 config CGROUP_MEM_RES_CTLR
 579         bool "Memory Resource Controller for Control Groups"
 580         depends on CGROUPS && RESOURCE_COUNTERS
 581         select MM_OWNER
 582         help
 583           Provides a memory resource controller that manages both anonymous
 584           memory and page cache. (See Documentation/cgroups/memory.txt)
 585
 586           Note that setting this option increases fixed memory overhead
 587           associated with each page of memory in the system. By this,
 588           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 589           usage tracking struct at boot. Total amount of this is printed out
 590           at boot.
 591
 592           Only enable when you're ok with these trade offs and really
 593           sure you need the memory resource controller. Even when you enable
 594           this, you can set "cgroup_disable=memory" at your boot option to
 595           disable memory resource controller and you can avoid overheads.
 596           (and lose benefits of memory resource controller)
 597
 598           This config option also selects MM_OWNER config option, which
 599           could in turn add some fork/exit overhead.
 600
 601 config CGROUP_MEM_RES_CTLR_SWAP
 602         bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
 603         depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
 604         help
 605           Add swap management feature to memory resource controller. When you
 606           enable this, you can limit mem+swap usage per cgroup. In other words,
 607           when you disable this, memory resource controller has no cares to
 608           usage of swap...a process can exhaust all of the swap. This extension
 609           is useful when you want to avoid exhaustion swap but this itself
 610           adds more overheads and consumes memory for remembering information.
 611           Especially if you use 32bit system or small memory system, please
 612           be careful about enabling this. When memory resource controller
 613           is disabled by boot option, this will be automatically disabled and
 614           there will be no overhead from this. Even when you set this config=y,
 615           if boot option "noswapaccount" is set, swap will not be accounted.
 616           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 617           size is 4096bytes, 512k per 1Gbytes of swap.
 618
 619 endif # CGROUPS
 620
 621 config MM_OWNER
 622         bool
 623
 624 config SYSFS_DEPRECATED
 625         bool
 626
 627 config SYSFS_DEPRECATED_V2
 628         bool "enable deprecated sysfs features to support old userspace tools"
 629         depends on SYSFS
 630         default n
 631         select SYSFS_DEPRECATED
 632         help
 633           This option switches the layout of sysfs to the deprecated
 634           version. Do not use it on recent distributions.
 635
 636           The current sysfs layout features a unified device tree at
 637           /sys/devices/, which is able to express a hierarchy between
 638           class devices. If the deprecated option is set to Y, the
 639           unified device tree is split into a bus device tree at
 640           /sys/devices/ and several individual class device trees at
 641           /sys/class/. The class and bus devices will be connected by
 642           "<subsystem>:<name>" and the "device" links. The "block"
 643           class devices, will not show up in /sys/class/block/. Some
 644           subsystems will suppress the creation of some devices which
 645           depend on the unified device tree.
 646
 647           This option is not a pure compatibility option that can
 648           be safely enabled on newer distributions. It will change the
 649           layout of sysfs to the non-extensible deprecated version,
 650           and disable some features, which can not be exported without
 651           confusing older userspace tools. Since 2007/2008 all major
 652           distributions do not enable this option, and ship no tools which
 653           depend on the deprecated layout or this option.
 654
 655           If you are using a new kernel on an older distribution, or use
 656           older userspace tools, you might need to say Y here. Do not say Y,
 657           if the original kernel, that came with your distribution, has
 658           this option set to N.
 659
 660 config RELAY
 661         bool "Kernel->user space relay support (formerly relayfs)"
 662         help
 663           This option enables support for relay interface support in
 664           certain file systems (such as debugfs).
 665           It is designed to provide an efficient mechanism for tools and
 666           facilities to relay large amounts of data from kernel space to
 667           user space.
 668
 669           If unsure, say N.
 670
 671 config NAMESPACES
 672         bool "Namespaces support" if EMBEDDED
 673         default !EMBEDDED
 674         help
 675           Provides the way to make tasks work with different objects using
 676           the same id. For example same IPC id may refer to different objects
 677           or same user id or pid may refer to different tasks when used in
 678           different namespaces.
 679
 680 config UTS_NS
 681         bool "UTS namespace"
 682         depends on NAMESPACES
 683         help
 684           In this namespace tasks see different info provided with the
 685           uname() system call
 686
 687 config IPC_NS
 688         bool "IPC namespace"
 689         depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
 690         help
 691           In this namespace tasks work with IPC ids which correspond to
 692           different IPC objects in different namespaces.
 693
 694 config USER_NS
 695         bool "User namespace (EXPERIMENTAL)"
 696         depends on NAMESPACES && EXPERIMENTAL
 697         help
 698           This allows containers, i.e. vservers, to use user namespaces
 699           to provide different user info for different servers.
 700           If unsure, say N.
 701
 702 config PID_NS
 703         bool "PID Namespaces (EXPERIMENTAL)"
 704         default n
 705         depends on NAMESPACES && EXPERIMENTAL
 706         help
 707           Support process id namespaces.  This allows having multiple
 708           processes with the same pid as long as they are in different
 709           pid namespaces.  This is a building block of containers.
 710
 711           Unless you want to work with an experimental feature
 712           say N here.
 713
 714 config NET_NS
 715         bool "Network namespace"
 716         default n
 717         depends on NAMESPACES && EXPERIMENTAL && NET
 718         help
 719           Allow user space to create what appear to be multiple instances
 720           of the network stack.
 721
 722 config BLK_DEV_INITRD
 723         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 724         depends on BROKEN || !FRV
 725         help
 726           The initial RAM filesystem is a ramfs which is loaded by the
 727           boot loader (loadlin or lilo) and that is mounted as root
 728           before the normal boot procedure. It is typically used to
 729           load modules needed to mount the "real" root file system,
 730           etc. See <file:Documentation/initrd.txt> for details.
 731
 732           If RAM disk support (BLK_DEV_RAM) is also included, this
 733           also enables initial RAM disk (initrd) support and adds
 734           15 Kbytes (more on some other architectures) to the kernel size.
 735
 736           If unsure say Y.
 737
 738 if BLK_DEV_INITRD
 739
 740 source "usr/Kconfig"
 741
 742 endif
 743
 744 config CC_OPTIMIZE_FOR_SIZE
 745         bool "Optimize for size"
 746         default y
 747         help
 748           Enabling this option will pass "-Os" instead of "-O2" to gcc
 749           resulting in a smaller kernel.
 750
 751           If unsure, say Y.
 752
 753 config SYSCTL
 754         bool
 755
 756 config ANON_INODES
 757         bool
 758
 759 menuconfig EMBEDDED
 760         bool "Configure standard kernel features (for small systems)"
 761         help
 762           This option allows certain base kernel options and settings
 763           to be disabled or tweaked. This is for specialized
 764           environments which can tolerate a "non-standard" kernel.
 765           Only use this if you really know what you are doing.
 766
 767 config UID16
 768         bool "Enable 16-bit UID system calls" if EMBEDDED
 769         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 770         default y
 771         help
 772           This enables the legacy 16-bit UID syscall wrappers.
 773
 774 config SYSCTL_SYSCALL
 775         bool "Sysctl syscall support" if EMBEDDED
 776         depends on PROC_SYSCTL
 777         default y
 778         select SYSCTL
 779         ---help---
 780           sys_sysctl uses binary paths that have been found challenging
 781           to properly maintain and use.  The interface in /proc/sys
 782           using paths with ascii names is now the primary path to this
 783           information.
 784
 785           Almost nothing using the binary sysctl interface so if you are
 786           trying to save some space it is probably safe to disable this,
 787           making your kernel marginally smaller.
 788
 789           If unsure say Y here.
 790
 791 config KALLSYMS
 792          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 793          default y
 794          help
 795            Say Y here to let the kernel print out symbolic crash information and
 796            symbolic stack backtraces. This increases the size of the kernel
 797            somewhat, as all symbols have to be loaded into the kernel image.
 798
 799 config KALLSYMS_ALL
 800         bool "Include all symbols in kallsyms"
 801         depends on DEBUG_KERNEL && KALLSYMS
 802         help
 803            Normally kallsyms only contains the symbols of functions, for nicer
 804            OOPS messages.  Some debuggers can use kallsyms for other
 805            symbols too: say Y here to include all symbols, if you need them
 806            and you don't care about adding 300k to the size of your kernel.
 807
 808            Say N.
 809
 810 config KALLSYMS_EXTRA_PASS
 811         bool "Do an extra kallsyms pass"
 812         depends on KALLSYMS
 813         help
 814            If kallsyms is not working correctly, the build will fail with
 815            inconsistent kallsyms data.  If that occurs, log a bug report and
 816            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 817            Always say N here unless you find a bug in kallsyms, which must be
 818            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 819            you wait for kallsyms to be fixed.
 820
 821
 822 config HOTPLUG
 823         bool "Support for hot-pluggable devices" if EMBEDDED
 824         default y
 825         help
 826           This option is provided for the case where no hotplug or uevent
 827           capabilities is wanted by the kernel.  You should only consider
 828           disabling this option for embedded systems that do not use modules, a
 829           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 830
 831 config PRINTK
 832         default y
 833         bool "Enable support for printk" if EMBEDDED
 834         help
 835           This option enables normal printk support. Removing it
 836           eliminates most of the message strings from the kernel image
 837           and makes the kernel more or less silent. As this makes it
 838           very difficult to diagnose system problems, saying N here is
 839           strongly discouraged.
 840
 841 config BUG
 842         bool "BUG() support" if EMBEDDED
 843         default y
 844         help
 845           Disabling this option eliminates support for BUG and WARN, reducing
 846           the size of your kernel image and potentially quietly ignoring
 847           numerous fatal conditions. You should only consider disabling this
 848           option for embedded systems with no facilities for reporting errors.
 849           Just say Y.
 850
 851 config ELF_CORE
 852         default y
 853         bool "Enable ELF core dumps" if EMBEDDED
 854         help
 855           Enable support for generating core dumps. Disabling saves about 4k.
 856
 857 config PCSPKR_PLATFORM
 858         bool "Enable PC-Speaker support" if EMBEDDED
 859         depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
 860         default y
 861         help
 862           This option allows to disable the internal PC-Speaker
 863           support, saving some memory.
 864
 865 config BASE_FULL
 866         default y
 867         bool "Enable full-sized data structures for core" if EMBEDDED
 868         help
 869           Disabling this option reduces the size of miscellaneous core
 870           kernel data structures. This saves memory on small machines,
 871           but may reduce performance.
 872
 873 config FUTEX
 874         bool "Enable futex support" if EMBEDDED
 875         default y
 876         select RT_MUTEXES
 877         help
 878           Disabling this option will cause the kernel to be built without
 879           support for "fast userspace mutexes".  The resulting kernel may not
 880           run glibc-based applications correctly.
 881
 882 config EPOLL
 883         bool "Enable eventpoll support" if EMBEDDED
 884         default y
 885         select ANON_INODES
 886         help
 887           Disabling this option will cause the kernel to be built without
 888           support for epoll family of system calls.
 889
 890 config SIGNALFD
 891         bool "Enable signalfd() system call" if EMBEDDED
 892         select ANON_INODES
 893         default y
 894         help
 895           Enable the signalfd() system call that allows to receive signals
 896           on a file descriptor.
 897
 898           If unsure, say Y.
 899
 900 config TIMERFD
 901         bool "Enable timerfd() system call" if EMBEDDED
 902         select ANON_INODES
 903         default y
 904         help
 905           Enable the timerfd() system call that allows to receive timer
 906           events on a file descriptor.
 907
 908           If unsure, say Y.
 909
 910 config EVENTFD
 911         bool "Enable eventfd() system call" if EMBEDDED
 912         select ANON_INODES
 913         default y
 914         help
 915           Enable the eventfd() system call that allows to receive both
 916           kernel notification (ie. KAIO) or userspace notifications.
 917
 918           If unsure, say Y.
 919
 920 config SHMEM
 921         bool "Use full shmem filesystem" if EMBEDDED
 922         default y
 923         depends on MMU
 924         help
 925           The shmem is an internal filesystem used to manage shared memory.
 926           It is backed by swap and manages resource limits. It is also exported
 927           to userspace as tmpfs if TMPFS is enabled. Disabling this
 928           option replaces shmem and tmpfs with the much simpler ramfs code,
 929           which may be appropriate on small systems without swap.
 930
 931 config AIO
 932         bool "Enable AIO support" if EMBEDDED
 933         default y
 934         help
 935           This option enables POSIX asynchronous I/O which may by used
 936           by some high performance threaded applications. Disabling
 937           this option saves about 7k.
 938
 939 config HAVE_PERF_EVENTS
 940         bool
 941         help
 942           See tools/perf/design.txt for details.
 943
 944 config PERF_USE_VMALLOC
 945         bool
 946         help
 947           See tools/perf/design.txt for details
 948
 949 menu "Kernel Performance Events And Counters"
 950
 951 config PERF_EVENTS
 952         bool "Kernel performance events and counters"
 953         default y if (PROFILING || PERF_COUNTERS)
 954         depends on HAVE_PERF_EVENTS
 955         select ANON_INODES
 956         help
 957           Enable kernel support for various performance events provided
 958           by software and hardware.
 959
 960           Software events are supported either built-in or via the
 961           use of generic tracepoints.
 962
 963           Most modern CPUs support performance events via performance
 964           counter registers. These registers count the number of certain
 965           types of hw events: such as instructions executed, cachemisses
 966           suffered, or branches mis-predicted - without slowing down the
 967           kernel or applications. These registers can also trigger interrupts
 968           when a threshold number of events have passed - and can thus be
 969           used to profile the code that runs on that CPU.
 970
 971           The Linux Performance Event subsystem provides an abstraction of
 972           these software and hardware event capabilities, available via a
 973           system call and used by the "perf" utility in tools/perf/. It
 974           provides per task and per CPU counters, and it provides event
 975           capabilities on top of those.
 976
 977           Say Y if unsure.
 978
 979 config EVENT_PROFILE
 980         bool "Tracepoint profiling sources"
 981         depends on PERF_EVENTS && EVENT_TRACING
 982         default y
 983         help
 984          Allow the use of tracepoints as software performance events.
 985
 986          When this is enabled, you can create perf events based on
 987          tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
 988          found in debugfs://tracing/events/*/*/id. (The -e/--events
 989          option to the perf tool can parse and interpret symbolic
 990          tracepoints, in the subsystem:tracepoint_name format.)
 991
 992 config PERF_COUNTERS
 993         bool "Kernel performance counters (old config option)"
 994         depends on HAVE_PERF_EVENTS
 995         help
 996           This config has been obsoleted by the PERF_EVENTS
 997           config option - please see that one for details.
 998
 999           It has no effect on the kernel whether you enable
1000           it or not, it is a compatibility placeholder.
1001
1002           Say N if unsure.
1003
1004 config DEBUG_PERF_USE_VMALLOC
1005         default n
1006         bool "Debug: use vmalloc to back perf mmap() buffers"
1007         depends on PERF_EVENTS && DEBUG_KERNEL
1008         select PERF_USE_VMALLOC
1009         help
1010          Use vmalloc memory to back perf mmap() buffers.
1011
1012          Mostly useful for debugging the vmalloc code on platforms
1013          that don't require it.
1014
1015          Say N if unsure.
1016
1017 endmenu
1018
1019 config VM_EVENT_COUNTERS
1020         default y
1021         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1022         help
1023           VM event counters are needed for event counts to be shown.
1024           This option allows the disabling of the VM event counters
1025           on EMBEDDED systems.  /proc/vmstat will only show page counts
1026           if VM event counters are disabled.
1027
1028 config PCI_QUIRKS
1029         default y
1030         bool "Enable PCI quirk workarounds" if EMBEDDED
1031         depends on PCI
1032         help
1033           This enables workarounds for various PCI chipset
1034           bugs/quirks. Disable this only if your target machine is
1035           unaffected by PCI quirks.
1036
1037 config SLUB_DEBUG
1038         default y
1039         bool "Enable SLUB debugging support" if EMBEDDED
1040         depends on SLUB && SYSFS
1041         help
1042           SLUB has extensive debug support features. Disabling these can
1043           result in significant savings in code size. This also disables
1044           SLUB sysfs support. /sys/slab will not exist and there will be
1045           no support for cache validation etc.
1046
1047 config COMPAT_BRK
1048         bool "Disable heap randomization"
1049         default y
1050         help
1051           Randomizing heap placement makes heap exploits harder, but it
1052           also breaks ancient binaries (including anything libc5 based).
1053           This option changes the bootup default to heap randomization
1054           disabled, and can be overridden at runtime by setting
1055           /proc/sys/kernel/randomize_va_space to 2.
1056
1057           On non-ancient distros (post-2000 ones) N is usually a safe choice.
1058
1059 choice
1060         prompt "Choose SLAB allocator"
1061         default SLUB
1062         help
1063            This option allows to select a slab allocator.
1064
1065 config SLAB
1066         bool "SLAB"
1067         help
1068           The regular slab allocator that is established and known to work
1069           well in all environments. It organizes cache hot objects in
1070           per cpu and per node queues.
1071
1072 config SLUB
1073         bool "SLUB (Unqueued Allocator)"
1074         help
1075            SLUB is a slab allocator that minimizes cache line usage
1076            instead of managing queues of cached objects (SLAB approach).
1077            Per cpu caching is realized using slabs of objects instead
1078            of queues of objects. SLUB can use memory efficiently
1079            and has enhanced diagnostics. SLUB is the default choice for
1080            a slab allocator.
1081
1082 config SLOB
1083         depends on EMBEDDED
1084         bool "SLOB (Simple Allocator)"
1085         help
1086            SLOB replaces the stock allocator with a drastically simpler
1087            allocator. SLOB is generally more space efficient but
1088            does not perform as well on large systems.
1089
1090 endchoice
1091
1092 config MMAP_ALLOW_UNINITIALIZED
1093         bool "Allow mmapped anonymous memory to be uninitialized"
1094         depends on EMBEDDED && !MMU
1095         default n
1096         help
1097           Normally, and according to the Linux spec, anonymous memory obtained
1098           from mmap() has it's contents cleared before it is passed to
1099           userspace.  Enabling this config option allows you to request that
1100           mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1101           providing a huge performance boost.  If this option is not enabled,
1102           then the flag will be ignored.
1103
1104           This is taken advantage of by uClibc's malloc(), and also by
1105           ELF-FDPIC binfmt's brk and stack allocator.
1106
1107           Because of the obvious security issues, this option should only be
1108           enabled on embedded devices where you control what is run in
1109           userspace.  Since that isn't generally a problem on no-MMU systems,
1110           it is normally safe to say Y here.
1111
1112           See Documentation/nommu-mmap.txt for more information.
1113
1114 config PROFILING
1115         bool "Profiling support (EXPERIMENTAL)"
1116         help
1117           Say Y here to enable the extended profiling support mechanisms used
1118           by profilers such as OProfile.
1119
1120 #
1121 # Place an empty function call at each tracepoint site. Can be
1122 # dynamically changed for a probe function.
1123 #
1124 config TRACEPOINTS
1125         bool
1126
1127 source "arch/Kconfig"
1128
1129 config SLOW_WORK
1130         default n
1131         bool
1132         help
1133           The slow work thread pool provides a number of dynamically allocated
1134           threads that can be used by the kernel to perform operations that
1135           take a relatively long time.
1136
1137           An example of this would be CacheFiles doing a path lookup followed
1138           by a series of mkdirs and a create call, all of which have to touch
1139           disk.
1140
1141           See Documentation/slow-work.txt.
1142
1143 config SLOW_WORK_DEBUG
1144         bool "Slow work debugging through debugfs"
1145         default n
1146         depends on SLOW_WORK && DEBUG_FS
1147         help
1148           Display the contents of the slow work run queue through debugfs,
1149           including items currently executing.
1150
1151           See Documentation/slow-work.txt.
1152
1153 endmenu         # General setup
1154
1155 config HAVE_GENERIC_DMA_COHERENT
1156         bool
1157         default n
1158
1159 config SLABINFO
1160         bool
1161         depends on PROC_FS
1162         depends on SLAB || SLUB_DEBUG
1163         default y
1164
1165 config RT_MUTEXES
1166         boolean
1167
1168 config BASE_SMALL
1169         int
1170         default 0 if BASE_FULL
1171         default 1 if !BASE_FULL
1172
1173 menuconfig MODULES
1174         bool "Enable loadable module support"
1175         help
1176           Kernel modules are small pieces of compiled code which can
1177           be inserted in the running kernel, rather than being
1178           permanently built into the kernel.  You use the "modprobe"
1179           tool to add (and sometimes remove) them.  If you say Y here,
1180           many parts of the kernel can be built as modules (by
1181           answering M instead of Y where indicated): this is most
1182           useful for infrequently used options which are not required
1183           for booting.  For more information, see the man pages for
1184           modprobe, lsmod, modinfo, insmod and rmmod.
1185
1186           If you say Y here, you will need to run "make
1187           modules_install" to put the modules under /lib/modules/
1188           where modprobe can find them (you may need to be root to do
1189           this).
1190
1191           If unsure, say Y.
1192
1193 if MODULES
1194
1195 config MODULE_FORCE_LOAD
1196         bool "Forced module loading"
1197         default n
1198         help
1199           Allow loading of modules without version information (ie. modprobe
1200           --force).  Forced module loading sets the 'F' (forced) taint flag and
1201           is usually a really bad idea.
1202
1203 config MODULE_UNLOAD
1204         bool "Module unloading"
1205         help
1206           Without this option you will not be able to unload any
1207           modules (note that some modules may not be unloadable
1208           anyway), which makes your kernel smaller, faster
1209           and simpler.  If unsure, say Y.
1210
1211 config MODULE_FORCE_UNLOAD
1212         bool "Forced module unloading"
1213         depends on MODULE_UNLOAD && EXPERIMENTAL
1214         help
1215           This option allows you to force a module to unload, even if the
1216           kernel believes it is unsafe: the kernel will remove the module
1217           without waiting for anyone to stop using it (using the -f option to
1218           rmmod).  This is mainly for kernel developers and desperate users.
1219           If unsure, say N.
1220
1221 config MODVERSIONS
1222         bool "Module versioning support"
1223         help
1224           Usually, you have to use modules compiled with your kernel.
1225           Saying Y here makes it sometimes possible to use modules
1226           compiled for different kernels, by adding enough information
1227           to the modules to (hopefully) spot any changes which would
1228           make them incompatible with the kernel you are running.  If
1229           unsure, say N.
1230
1231 config MODULE_SRCVERSION_ALL
1232         bool "Source checksum for all modules"
1233         help
1234           Modules which contain a MODULE_VERSION get an extra "srcversion"
1235           field inserted into their modinfo section, which contains a
1236           sum of the source files which made it.  This helps maintainers
1237           see exactly which source was used to build a module (since
1238           others sometimes change the module source without updating
1239           the version).  With this option, such a "srcversion" field
1240           will be created for all modules.  If unsure, say N.
1241
1242 endif # MODULES
1243
1244 config INIT_ALL_POSSIBLE
1245         bool
1246         help
1247           Back when each arch used to define their own cpu_online_map and
1248           cpu_possible_map, some of them chose to initialize cpu_possible_map
1249           with all 1s, and others with all 0s.  When they were centralised,
1250           it was better to provide this option than to break all the archs
1251           and have several arch maintainers pursuing me down dark alleys.
1252
1253 config STOP_MACHINE
1254         bool
1255         default y
1256         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1257         help
1258           Need stop_machine() primitive.
1259
1260 source "block/Kconfig"
1261
1262 config PREEMPT_NOTIFIERS
1263         bool
1264
1265 source "kernel/Kconfig.locks"