init/Kconfig

   1 config DEFCONFIG_LIST
   2         string
   3         depends on !UML
   4         option defconfig_list
   5         default "/lib/modules/$UNAME_RELEASE/.config"
   6         default "/etc/kernel-config"
   7         default "/boot/config-$UNAME_RELEASE"
   8         default "arch/$ARCH/defconfig"
   9
  10 menu "Code maturity level options"
  11
  12 config EXPERIMENTAL
  13         bool "Prompt for development and/or incomplete code/drivers"
  14         ---help---
  15           Some of the various things that Linux supports (such as network
  16           drivers, file systems, network protocols, etc.) can be in a state
  17           of development where the functionality, stability, or the level of
  18           testing is not yet high enough for general use. This is usually
  19           known as the "alpha-test" phase among developers. If a feature is
  20           currently in alpha-test, then the developers usually discourage
  21           uninformed widespread use of this feature by the general public to
  22           avoid "Why doesn't this work?" type mail messages. However, active
  23           testing and use of these systems is welcomed. Just be aware that it
  24           may not meet the normal level of reliability or it may fail to work
  25           in some special cases. Detailed bug reports from people familiar
  26           with the kernel internals are usually welcomed by the developers
  27           (before submitting bug reports, please read the documents
  28           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  29           <file:Documentation/BUG-HUNTING>, and
  30           <file:Documentation/oops-tracing.txt> in the kernel source).
  31
  32           This option will also make obsoleted drivers available. These are
  33           drivers that have been replaced by something else, and/or are
  34           scheduled to be removed in a future kernel release.
  35
  36           Unless you intend to help test and develop a feature or driver that
  37           falls into this category, or you have a situation that requires
  38           using these features, you should probably say N here, which will
  39           cause the configurator to present you with fewer choices. If
  40           you say Y here, you will be offered the choice of using features or
  41           drivers that are currently considered to be in the alpha-test phase.
  42
  43 config BROKEN
  44         bool
  45
  46 config BROKEN_ON_SMP
  47         bool
  48         depends on BROKEN || !SMP
  49         default y
  50
  51 config LOCK_KERNEL
  52         bool
  53         depends on SMP || PREEMPT
  54         default y
  55
  56 config INIT_ENV_ARG_LIMIT
  57         int
  58         default 32 if !UML
  59         default 128 if UML
  60         help
  61           Maximum of each of the number of arguments and environment
  62           variables passed to init from the kernel command line.
  63
  64 endmenu
  65
  66 menu "General setup"
  67
  68 config LOCALVERSION
  69         string "Local version - append to kernel release"
  70         help
  71           Append an extra string to the end of your kernel version.
  72           This will show up when you type uname, for example.
  73           The string you set here will be appended after the contents of
  74           any files with a filename matching localversion* in your
  75           object and source tree, in that order.  Your total string can
  76           be a maximum of 64 characters.
  77
  78 config LOCALVERSION_AUTO
  79         bool "Automatically append version information to the version string"
  80         default y
  81         help
  82           This will try to automatically determine if the current tree is a
  83           release tree by looking for git tags that belong to the current
  84           top of tree revision.
  85
  86           A string of the format -gxxxxxxxx will be added to the localversion
  87           if a git-based tree is found.  The string generated by this will be
  88           appended after any matching localversion* files, and after the value
  89           set in CONFIG_LOCALVERSION.
  90
  91           (The actual string used here is the first eight characters produced
  92           by running the command:
  93
  94             $ git rev-parse --verify HEAD
  95
  96           which is done within the script "scripts/setlocalversion".)
  97
  98 config SWAP
  99         bool "Support for paging of anonymous memory (swap)"
 100         depends on MMU && BLOCK
 101         default y
 102         help
 103           This option allows you to choose whether you want to have support
 104           for so called swap devices or swap files in your kernel that are
 105           used to provide more virtual memory than the actual RAM present
 106           in your computer.  If unsure say Y.
 107
 108 config SYSVIPC
 109         bool "System V IPC"
 110         ---help---
 111           Inter Process Communication is a suite of library functions and
 112           system calls which let processes (running programs) synchronize and
 113           exchange information. It is generally considered to be a good thing,
 114           and some programs won't run unless you say Y here. In particular, if
 115           you want to run the DOS emulator dosemu under Linux (read the
 116           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 117           you'll need to say Y here.
 118
 119           You can find documentation about IPC with "info ipc" and also in
 120           section 6.4 of the Linux Programmer's Guide, available from
 121           <http://www.tldp.org/guides.html>.
 122
 123 config IPC_NS
 124         bool "IPC Namespaces"
 125         depends on SYSVIPC
 126         default n
 127         help
 128           Support ipc namespaces.  This allows containers, i.e. virtual
 129           environments, to use ipc namespaces to provide different ipc
 130           objects for different servers.  If unsure, say N.
 131
 132 config SYSVIPC_SYSCTL
 133         bool
 134         depends on SYSVIPC
 135         depends on SYSCTL
 136         default y
 137
 138 config POSIX_MQUEUE
 139         bool "POSIX Message Queues"
 140         depends on NET && EXPERIMENTAL
 141         ---help---
 142           POSIX variant of message queues is a part of IPC. In POSIX message
 143           queues every message has a priority which decides about succession
 144           of receiving it by a process. If you want to compile and run
 145           programs written e.g. for Solaris with use of its POSIX message
 146           queues (functions mq_*) say Y here. To use this feature you will
 147           also need mqueue library, available from
 148           <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
 149
 150           POSIX message queues are visible as a filesystem called 'mqueue'
 151           and can be mounted somewhere if you want to do filesystem
 152           operations on message queues.
 153
 154           If unsure, say Y.
 155
 156 config BSD_PROCESS_ACCT
 157         bool "BSD Process Accounting"
 158         help
 159           If you say Y here, a user level program will be able to instruct the
 160           kernel (via a special system call) to write process accounting
 161           information to a file: whenever a process exits, information about
 162           that process will be appended to the file by the kernel.  The
 163           information includes things such as creation time, owning user,
 164           command name, memory usage, controlling terminal etc. (the complete
 165           list is in the struct acct in <file:include/linux/acct.h>).  It is
 166           up to the user level program to do useful things with this
 167           information.  This is generally a good idea, so say Y.
 168
 169 config BSD_PROCESS_ACCT_V3
 170         bool "BSD Process Accounting version 3 file format"
 171         depends on BSD_PROCESS_ACCT
 172         default n
 173         help
 174           If you say Y here, the process accounting information is written
 175           in a new file format that also logs the process IDs of each
 176           process and it's parent. Note that this file format is incompatible
 177           with previous v0/v1/v2 file formats, so you will need updated tools
 178           for processing it. A preliminary version of these tools is available
 179           at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
 180
 181 config TASKSTATS
 182         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 183         depends on NET
 184         default n
 185         help
 186           Export selected statistics for tasks/processes through the
 187           generic netlink interface. Unlike BSD process accounting, the
 188           statistics are available during the lifetime of tasks/processes as
 189           responses to commands. Like BSD accounting, they are sent to user
 190           space on task exit.
 191
 192           Say N if unsure.
 193
 194 config TASK_DELAY_ACCT
 195         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 196         depends on TASKSTATS
 197         help
 198           Collect information on time spent by a task waiting for system
 199           resources like cpu, synchronous block I/O completion and swapping
 200           in pages. Such statistics can help in setting a task's priorities
 201           relative to other tasks for cpu, io, rss limits etc.
 202
 203           Say N if unsure.
 204
 205 config TASK_XACCT
 206         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 207         depends on TASKSTATS
 208         help
 209           Collect extended task accounting data and send the data
 210           to userland for processing over the taskstats interface.
 211
 212           Say N if unsure.
 213
 214 config TASK_IO_ACCOUNTING
 215         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 216         depends on TASK_XACCT
 217         help
 218           Collect information on the number of bytes of storage I/O which this
 219           task has caused.
 220
 221           Say N if unsure.
 222
 223 config UTS_NS
 224         bool "UTS Namespaces"
 225         default n
 226         help
 227           Support uts namespaces.  This allows containers, i.e.
 228           vservers, to use uts namespaces to provide different
 229           uts info for different servers.  If unsure, say N.
 230
 231 config AUDIT
 232         bool "Auditing support"
 233         depends on NET
 234         help
 235           Enable auditing infrastructure that can be used with another
 236           kernel subsystem, such as SELinux (which requires this for
 237           logging of avc messages output).  Does not do system-call
 238           auditing without CONFIG_AUDITSYSCALL.
 239
 240 config AUDITSYSCALL
 241         bool "Enable system-call auditing support"
 242         depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
 243         default y if SECURITY_SELINUX
 244         help
 245           Enable low-overhead system-call auditing infrastructure that
 246           can be used independently or with another kernel subsystem,
 247           such as SELinux.  To use audit's filesystem watch feature, please
 248           ensure that INOTIFY is configured.
 249
 250 config IKCONFIG
 251         tristate "Kernel .config support"
 252         ---help---
 253           This option enables the complete Linux kernel ".config" file
 254           contents to be saved in the kernel. It provides documentation
 255           of which kernel options are used in a running kernel or in an
 256           on-disk kernel.  This information can be extracted from the kernel
 257           image file with the script scripts/extract-ikconfig and used as
 258           input to rebuild the current kernel or to build another kernel.
 259           It can also be extracted from a running kernel by reading
 260           /proc/config.gz if enabled (below).
 261
 262 config IKCONFIG_PROC
 263         bool "Enable access to .config through /proc/config.gz"
 264         depends on IKCONFIG && PROC_FS
 265         ---help---
 266           This option enables access to the kernel configuration file
 267           through /proc/config.gz.
 268
 269 config CPUSETS
 270         bool "Cpuset support"
 271         depends on SMP
 272         help
 273           This option will let you create and manage CPUSETs which
 274           allow dynamically partitioning a system into sets of CPUs and
 275           Memory Nodes and assigning tasks to run only within those sets.
 276           This is primarily useful on large SMP or NUMA systems.
 277
 278           Say N if unsure.
 279
 280 config SYSFS_DEPRECATED
 281         bool "Create deprecated sysfs files"
 282         default y
 283         help
 284           This option creates deprecated symlinks such as the
 285           "device"-link, the <subsystem>:<name>-link, and the
 286           "bus"-link. It may also add deprecated key in the
 287           uevent environment.
 288           None of these features or values should be used today, as
 289           they export driver core implementation details to userspace
 290           or export properties which can't be kept stable across kernel
 291           releases.
 292
 293           If enabled, this option will also move any device structures
 294           that belong to a class, back into the /sys/class heirachy, in
 295           order to support older versions of udev.
 296
 297           If you are using a distro that was released in 2006 or later,
 298           it should be safe to say N here.
 299
 300 config RELAY
 301         bool "Kernel->user space relay support (formerly relayfs)"
 302         help
 303           This option enables support for relay interface support in
 304           certain file systems (such as debugfs).
 305           It is designed to provide an efficient mechanism for tools and
 306           facilities to relay large amounts of data from kernel space to
 307           user space.
 308
 309           If unsure, say N.
 310
 311 config BLK_DEV_INITRD
 312         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 313         depends on BROKEN || !FRV
 314         help
 315           The initial RAM filesystem is a ramfs which is loaded by the
 316           boot loader (loadlin or lilo) and that is mounted as root
 317           before the normal boot procedure. It is typically used to
 318           load modules needed to mount the "real" root file system,
 319           etc. See <file:Documentation/initrd.txt> for details.
 320
 321           If RAM disk support (BLK_DEV_RAM) is also included, this
 322           also enables initial RAM disk (initrd) support and adds
 323           15 Kbytes (more on some other architectures) to the kernel size.
 324
 325           If unsure say Y.
 326
 327 if BLK_DEV_INITRD
 328
 329 source "usr/Kconfig"
 330
 331 endif
 332
 333 config CC_OPTIMIZE_FOR_SIZE
 334         bool "Optimize for size (Look out for broken compilers!)"
 335         default y
 336         depends on ARM || H8300 || EXPERIMENTAL
 337         help
 338           Enabling this option will pass "-Os" instead of "-O2" to gcc
 339           resulting in a smaller kernel.
 340
 341           WARNING: some versions of gcc may generate incorrect code with this
 342           option.  If problems are observed, a gcc upgrade may be needed.
 343
 344           If unsure, say N.
 345
 346 config SYSCTL
 347         bool
 348
 349 menuconfig EMBEDDED
 350         bool "Configure standard kernel features (for small systems)"
 351         help
 352           This option allows certain base kernel options and settings
 353           to be disabled or tweaked. This is for specialized
 354           environments which can tolerate a "non-standard" kernel.
 355           Only use this if you really know what you are doing.
 356
 357 config UID16
 358         bool "Enable 16-bit UID system calls" if EMBEDDED
 359         depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
 360         default y
 361         help
 362           This enables the legacy 16-bit UID syscall wrappers.
 363
 364 config SYSCTL_SYSCALL
 365         bool "Sysctl syscall support" if EMBEDDED
 366         default y
 367         select SYSCTL
 368         ---help---
 369           sys_sysctl uses binary paths that have been found challenging
 370           to properly maintain and use.  The interface in /proc/sys
 371           using paths with ascii names is now the primary path to this
 372           information.
 373
 374           Almost nothing using the binary sysctl interface so if you are
 375           trying to save some space it is probably safe to disable this,
 376           making your kernel marginally smaller.
 377
 378           If unsure say Y here.
 379
 380 config KALLSYMS
 381          bool "Load all symbols for debugging/ksymoops" if EMBEDDED
 382          default y
 383          help
 384            Say Y here to let the kernel print out symbolic crash information and
 385            symbolic stack backtraces. This increases the size of the kernel
 386            somewhat, as all symbols have to be loaded into the kernel image.
 387
 388 config KALLSYMS_ALL
 389         bool "Include all symbols in kallsyms"
 390         depends on DEBUG_KERNEL && KALLSYMS
 391         help
 392            Normally kallsyms only contains the symbols of functions, for nicer
 393            OOPS messages.  Some debuggers can use kallsyms for other
 394            symbols too: say Y here to include all symbols, if you need them
 395            and you don't care about adding 300k to the size of your kernel.
 396
 397            Say N.
 398
 399 config KALLSYMS_EXTRA_PASS
 400         bool "Do an extra kallsyms pass"
 401         depends on KALLSYMS
 402         help
 403            If kallsyms is not working correctly, the build will fail with
 404            inconsistent kallsyms data.  If that occurs, log a bug report and
 405            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 406            Always say N here unless you find a bug in kallsyms, which must be
 407            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 408            you wait for kallsyms to be fixed.
 409
 410
 411 config HOTPLUG
 412         bool "Support for hot-pluggable devices" if EMBEDDED
 413         default y
 414         help
 415           This option is provided for the case where no hotplug or uevent
 416           capabilities is wanted by the kernel.  You should only consider
 417           disabling this option for embedded systems that do not use modules, a
 418           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 419
 420 config PRINTK
 421         default y
 422         bool "Enable support for printk" if EMBEDDED
 423         help
 424           This option enables normal printk support. Removing it
 425           eliminates most of the message strings from the kernel image
 426           and makes the kernel more or less silent. As this makes it
 427           very difficult to diagnose system problems, saying N here is
 428           strongly discouraged.
 429
 430 config BUG
 431         bool "BUG() support" if EMBEDDED
 432         default y
 433         help
 434           Disabling this option eliminates support for BUG and WARN, reducing
 435           the size of your kernel image and potentially quietly ignoring
 436           numerous fatal conditions. You should only consider disabling this
 437           option for embedded systems with no facilities for reporting errors.
 438           Just say Y.
 439
 440 config ELF_CORE
 441         default y
 442         bool "Enable ELF core dumps" if EMBEDDED
 443         help
 444           Enable support for generating core dumps. Disabling saves about 4k.
 445
 446 config BASE_FULL
 447         default y
 448         bool "Enable full-sized data structures for core" if EMBEDDED
 449         help
 450           Disabling this option reduces the size of miscellaneous core
 451           kernel data structures. This saves memory on small machines,
 452           but may reduce performance.
 453
 454 config FUTEX
 455         bool "Enable futex support" if EMBEDDED
 456         default y
 457         select RT_MUTEXES
 458         help
 459           Disabling this option will cause the kernel to be built without
 460           support for "fast userspace mutexes".  The resulting kernel may not
 461           run glibc-based applications correctly.
 462
 463 config EPOLL
 464         bool "Enable eventpoll support" if EMBEDDED
 465         default y
 466         help
 467           Disabling this option will cause the kernel to be built without
 468           support for epoll family of system calls.
 469
 470 config SHMEM
 471         bool "Use full shmem filesystem" if EMBEDDED
 472         default y
 473         depends on MMU
 474         help
 475           The shmem is an internal filesystem used to manage shared memory.
 476           It is backed by swap and manages resource limits. It is also exported
 477           to userspace as tmpfs if TMPFS is enabled. Disabling this
 478           option replaces shmem and tmpfs with the much simpler ramfs code,
 479           which may be appropriate on small systems without swap.
 480
 481 config VM_EVENT_COUNTERS
 482         default y
 483         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
 484         help
 485           VM event counters are needed for event counts to be shown.
 486           This option allows the disabling of the VM event counters
 487           on EMBEDDED systems.  /proc/vmstat will only show page counts
 488           if VM event counters are disabled.
 489
 490 choice
 491         prompt "Choose SLAB allocator"
 492         default SLAB
 493         help
 494            This option allows to select a slab allocator.
 495
 496 config SLAB
 497         bool "SLAB"
 498         help
 499           The regular slab allocator that is established and known to work
 500           well in all environments. It organizes chache hot objects in
 501           per cpu and per node queues. SLAB is the default choice for
 502           slab allocator.
 503
 504 config SLUB
 505         depends on EXPERIMENTAL && !ARCH_USES_SLAB_PAGE_STRUCT
 506         bool "SLUB (Unqueued Allocator)"
 507         help
 508            SLUB is a slab allocator that minimizes cache line usage
 509            instead of managing queues of cached objects (SLAB approach).
 510            Per cpu caching is realized using slabs of objects instead
 511            of queues of objects. SLUB can use memory efficiently
 512            way and has enhanced diagnostics.
 513
 514 config SLOB
 515 #
 516 #       SLOB cannot support SMP because SLAB_DESTROY_BY_RCU does not work
 517 #       properly.
 518 #
 519         depends on EMBEDDED && !SMP && !SPARSEMEM
 520         bool "SLOB (Simple Allocator)"
 521         help
 522            SLOB replaces the SLAB allocator with a drastically simpler
 523            allocator.  SLOB is more space efficient that SLAB but does not
 524            scale well (single lock for all operations) and is more susceptible
 525            to fragmentation. SLOB it is a great choice to reduce
 526            memory usage and code size for embedded systems.
 527
 528 endchoice
 529
 530 endmenu         # General setup
 531
 532 config RT_MUTEXES
 533         boolean
 534         select PLIST
 535
 536 config TINY_SHMEM
 537         default !SHMEM
 538         bool
 539
 540 config BASE_SMALL
 541         int
 542         default 0 if BASE_FULL
 543         default 1 if !BASE_FULL
 544
 545 menu "Loadable module support"
 546
 547 config MODULES
 548         bool "Enable loadable module support"
 549         help
 550           Kernel modules are small pieces of compiled code which can
 551           be inserted in the running kernel, rather than being
 552           permanently built into the kernel.  You use the "modprobe"
 553           tool to add (and sometimes remove) them.  If you say Y here,
 554           many parts of the kernel can be built as modules (by
 555           answering M instead of Y where indicated): this is most
 556           useful for infrequently used options which are not required
 557           for booting.  For more information, see the man pages for
 558           modprobe, lsmod, modinfo, insmod and rmmod.
 559
 560           If you say Y here, you will need to run "make
 561           modules_install" to put the modules under /lib/modules/
 562           where modprobe can find them (you may need to be root to do
 563           this).
 564
 565           If unsure, say Y.
 566
 567 config MODULE_UNLOAD
 568         bool "Module unloading"
 569         depends on MODULES
 570         help
 571           Without this option you will not be able to unload any
 572           modules (note that some modules may not be unloadable
 573           anyway), which makes your kernel slightly smaller and
 574           simpler.  If unsure, say Y.
 575
 576 config MODULE_FORCE_UNLOAD
 577         bool "Forced module unloading"
 578         depends on MODULE_UNLOAD && EXPERIMENTAL
 579         help
 580           This option allows you to force a module to unload, even if the
 581           kernel believes it is unsafe: the kernel will remove the module
 582           without waiting for anyone to stop using it (using the -f option to
 583           rmmod).  This is mainly for kernel developers and desperate users.
 584           If unsure, say N.
 585
 586 config MODVERSIONS
 587         bool "Module versioning support"
 588         depends on MODULES
 589         help
 590           Usually, you have to use modules compiled with your kernel.
 591           Saying Y here makes it sometimes possible to use modules
 592           compiled for different kernels, by adding enough information
 593           to the modules to (hopefully) spot any changes which would
 594           make them incompatible with the kernel you are running.  If
 595           unsure, say N.
 596
 597 config MODULE_SRCVERSION_ALL
 598         bool "Source checksum for all modules"
 599         depends on MODULES
 600         help
 601           Modules which contain a MODULE_VERSION get an extra "srcversion"
 602           field inserted into their modinfo section, which contains a
 603           sum of the source files which made it.  This helps maintainers
 604           see exactly which source was used to build a module (since
 605           others sometimes change the module source without updating
 606           the version).  With this option, such a "srcversion" field
 607           will be created for all modules.  If unsure, say N.
 608
 609 config KMOD
 610         bool "Automatic kernel module loading"
 611         depends on MODULES
 612         help
 613           Normally when you have selected some parts of the kernel to
 614           be created as kernel modules, you must load them (using the
 615           "modprobe" command) before you can use them. If you say Y
 616           here, some parts of the kernel will be able to load modules
 617           automatically: when a part of the kernel needs a module, it
 618           runs modprobe with the appropriate arguments, thereby
 619           loading the module if it is available.  If unsure, say Y.
 620
 621 config STOP_MACHINE
 622         bool
 623         default y
 624         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 625         help
 626           Need stop_machine() primitive.
 627 endmenu
 628
 629 menu "Block layer"
 630 source "block/Kconfig"
 631 endmenu