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  33           drivers that have been replaced by something else, and/or are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