init/Kconfig

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  32           drivers that have been replaced by something else, and/or are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