init/Kconfig

   1 menu "Code maturity level options"
   2
   3 config EXPERIMENTAL
   4         bool "Prompt for development and/or incomplete code/drivers"
   5         ---help---
   6           Some of the various things that Linux supports (such as network
   7           drivers, file systems, network protocols, etc.) can be in a state
   8           of development where the functionality, stability, or the level of
   9           testing is not yet high enough for general use. This is usually
  10           known as the "alpha-test" phase among developers. If a feature is
  11           currently in alpha-test, then the developers usually discourage
  12           uninformed widespread use of this feature by the general public to
  13           avoid "Why doesn't this work?" type mail messages. However, active
  14           testing and use of these systems is welcomed. Just be aware that it
  15           may not meet the normal level of reliability or it may fail to work
  16           in some special cases. Detailed bug reports from people familiar
  17           with the kernel internals are usually welcomed by the developers
  18           (before submitting bug reports, please read the documents
  19           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  20           <file:Documentation/BUG-HUNTING>, and
  21           <file:Documentation/oops-tracing.txt> in the kernel source).
  22
  23           This option will also make obsoleted drivers available. These are
  24           drivers that have been replaced by something else, and/or are
  25           scheduled to be removed in a future kernel release.
  26
  27           Unless you intend to help test and develop a feature or driver that
  28           falls into this category, or you have a situation that requires
  29           using these features, you should probably say N here, which will
  30           cause the configurator to present you with fewer choices. If
  31           you say Y here, you will be offered the choice of using features or
  32           drivers that are currently considered to be in the alpha-test phase.
  33
  34 config BROKEN
  35         bool
  36
  37 config BROKEN_ON_SMP
  38         bool
  39         depends on BROKEN || !SMP
  40         default y
  41
  42 config LOCK_KERNEL
  43         bool
  44         depends on SMP || PREEMPT
  45         default y
  46
  47 config INIT_ENV_ARG_LIMIT
  48         int
  49         default 32 if !USERMODE
  50         default 128 if USERMODE
  51         help
  52           Maximum of each of the number of arguments and environment
  53           variables passed to init from the kernel command line.
  54
  55 endmenu
  56
  57 menu "General setup"
  58
  59 config LOCALVERSION
  60         string "Local version - append to kernel release"
  61         help
  62           Append an extra string to the end of your kernel version.
  63           This will show up when you type uname, for example.
  64           The string you set here will be appended after the contents of
  65           any files with a filename matching localversion* in your
  66           object and source tree, in that order.  Your total string can
  67           be a maximum of 64 characters.
  68
  69 config LOCALVERSION_AUTO
  70         bool "Automatically append version information to the version string"
  71         default y
  72         help
  73           This will try to automatically determine if the current tree is a
  74           release tree by looking for git tags that
  75           belong to the current top of tree revision.
  76
  77           A string of the format -gxxxxxxxx will be added to the localversion
  78           if a git based tree is found.  The string generated by this will be
  79           appended after any matching localversion* files, and after the value
  80           set in CONFIG_LOCALVERSION
  81
  82           Note: This requires Perl, and a git repository, but not necessarily
  83           the git or cogito tools to be installed.
  84
  85 config SWAP
  86         bool "Support for paging of anonymous memory (swap)"
  87         depends on MMU
  88         default y
  89         help
  90           This option allows you to choose whether you want to have support
  91           for so called swap devices or swap files in your kernel that are
  92           used to provide more virtual memory than the actual RAM present
  93           in your computer.  If unsure say Y.
  94
  95 config SYSVIPC
  96         bool "System V IPC"
  97         ---help---
  98           Inter Process Communication is a suite of library functions and
  99           system calls which let processes (running programs) synchronize and
 100           exchange information. It is generally considered to be a good thing,
 101           and some programs won't run unless you say Y here. In particular, if
 102           you want to run the DOS emulator dosemu under Linux (read the
 103           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 104           you'll need to say Y here.
 105
 106           You can find documentation about IPC with "info ipc" and also in
 107           section 6.4 of the Linux Programmer's Guide, available from
 108           <http://www.tldp.org/guides.html>.
 109
 110 config POSIX_MQUEUE
 111         bool "POSIX Message Queues"
 112         depends on NET && EXPERIMENTAL
 113         ---help---
 114           POSIX variant of message queues is a part of IPC. In POSIX message
 115           queues every message has a priority which decides about succession
 116           of receiving it by a process. If you want to compile and run
 117           programs written e.g. for Solaris with use of its POSIX message
 118           queues (functions mq_*) say Y here. To use this feature you will
 119           also need mqueue library, available from
 120           <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
 121
 122           POSIX message queues are visible as a filesystem called 'mqueue'
 123           and can be mounted somewhere if you want to do filesystem
 124           operations on message queues.
 125
 126           If unsure, say Y.
 127
 128 config BSD_PROCESS_ACCT
 129         bool "BSD Process Accounting"
 130         help
 131           If you say Y here, a user level program will be able to instruct the
 132           kernel (via a special system call) to write process accounting
 133           information to a file: whenever a process exits, information about
 134           that process will be appended to the file by the kernel.  The
 135           information includes things such as creation time, owning user,
 136           command name, memory usage, controlling terminal etc. (the complete
 137           list is in the struct acct in <file:include/linux/acct.h>).  It is
 138           up to the user level program to do useful things with this
 139           information.  This is generally a good idea, so say Y.
 140
 141 config BSD_PROCESS_ACCT_V3
 142         bool "BSD Process Accounting version 3 file format"
 143         depends on BSD_PROCESS_ACCT
 144         default n
 145         help
 146           If you say Y here, the process accounting information is written
 147           in a new file format that also logs the process IDs of each
 148           process and it's parent. Note that this file format is incompatible
 149           with previous v0/v1/v2 file formats, so you will need updated tools
 150           for processing it. A preliminary version of these tools is available
 151           at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
 152
 153 config SYSCTL
 154         bool "Sysctl support"
 155         ---help---
 156           The sysctl interface provides a means of dynamically changing
 157           certain kernel parameters and variables on the fly without requiring
 158           a recompile of the kernel or reboot of the system.  The primary
 159           interface consists of a system call, but if you say Y to "/proc
 160           file system support", a tree of modifiable sysctl entries will be
 161           generated beneath the /proc/sys directory. They are explained in the
 162           files in <file:Documentation/sysctl/>.  Note that enabling this
 163           option will enlarge the kernel by at least 8 KB.
 164
 165           As it is generally a good thing, you should say Y here unless
 166           building a kernel for install/rescue disks or your system is very
 167           limited in memory.
 168
 169 config AUDIT
 170         bool "Auditing support"
 171         depends on NET
 172         help
 173           Enable auditing infrastructure that can be used with another
 174           kernel subsystem, such as SELinux (which requires this for
 175           logging of avc messages output).  Does not do system-call
 176           auditing without CONFIG_AUDITSYSCALL.
 177
 178 config AUDITSYSCALL
 179         bool "Enable system-call auditing support"
 180         depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
 181         default y if SECURITY_SELINUX
 182         help
 183           Enable low-overhead system-call auditing infrastructure that
 184           can be used independently or with another kernel subsystem,
 185           such as SELinux.
 186
 187 config IKCONFIG
 188         bool "Kernel .config support"
 189         ---help---
 190           This option enables the complete Linux kernel ".config" file
 191           contents to be saved in the kernel. It provides documentation
 192           of which kernel options are used in a running kernel or in an
 193           on-disk kernel.  This information can be extracted from the kernel
 194           image file with the script scripts/extract-ikconfig and used as
 195           input to rebuild the current kernel or to build another kernel.
 196           It can also be extracted from a running kernel by reading
 197           /proc/config.gz if enabled (below).
 198
 199 config IKCONFIG_PROC
 200         bool "Enable access to .config through /proc/config.gz"
 201         depends on IKCONFIG && PROC_FS
 202         ---help---
 203           This option enables access to the kernel configuration file
 204           through /proc/config.gz.
 205
 206 config CPUSETS
 207         bool "Cpuset support"
 208         depends on SMP
 209         help
 210           This option will let you create and manage CPUSETs which
 211           allow dynamically partitioning a system into sets of CPUs and
 212           Memory Nodes and assigning tasks to run only within those sets.
 213           This is primarily useful on large SMP or NUMA systems.
 214
 215           Say N if unsure.
 216
 217 config RELAY
 218         bool "Kernel->user space relay support (formerly relayfs)"
 219         help
 220           This option enables support for relay interface support in
 221           certain file systems (such as debugfs).
 222           It is designed to provide an efficient mechanism for tools and
 223           facilities to relay large amounts of data from kernel space to
 224           user space.
 225
 226           If unsure, say N.
 227
 228 source "usr/Kconfig"
 229
 230 config UID16
 231         bool "Enable 16-bit UID system calls" if EMBEDDED
 232         depends on ARM || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
 233         default y
 234         help
 235           This enables the legacy 16-bit UID syscall wrappers.
 236
 237 config VM86
 238         depends X86
 239         default y
 240         bool "Enable VM86 support" if EMBEDDED
 241         help
 242           This option is required by programs like DOSEMU to run 16-bit legacy
 243           code on X86 processors. It also may be needed by software like
 244           XFree86 to initialize some video cards via BIOS. Disabling this
 245           option saves about 6k.
 246
 247 config CC_OPTIMIZE_FOR_SIZE
 248         bool "Optimize for size (Look out for broken compilers!)"
 249         default y
 250         depends on ARM || H8300 || EXPERIMENTAL
 251         help
 252           Enabling this option will pass "-Os" instead of "-O2" to gcc
 253           resulting in a smaller kernel.
 254
 255           WARNING: some versions of gcc may generate incorrect code with this
 256           option.  If problems are observed, a gcc upgrade may be needed.
 257
 258           If unsure, say N.
 259
 260 menuconfig EMBEDDED
 261         bool "Configure standard kernel features (for small systems)"
 262         help
 263           This option allows certain base kernel options and settings
 264           to be disabled or tweaked. This is for specialized
 265           environments which can tolerate a "non-standard" kernel.
 266           Only use this if you really know what you are doing.
 267
 268 config KALLSYMS
 269          bool "Load all symbols for debugging/kksymoops" if EMBEDDED
 270          default y
 271          help
 272            Say Y here to let the kernel print out symbolic crash information and
 273            symbolic stack backtraces. This increases the size of the kernel
 274            somewhat, as all symbols have to be loaded into the kernel image.
 275
 276 config KALLSYMS_ALL
 277         bool "Include all symbols in kallsyms"
 278         depends on DEBUG_KERNEL && KALLSYMS
 279         help
 280            Normally kallsyms only contains the symbols of functions, for nicer
 281            OOPS messages.  Some debuggers can use kallsyms for other
 282            symbols too: say Y here to include all symbols, if you need them
 283            and you don't care about adding 300k to the size of your kernel.
 284
 285            Say N.
 286
 287 config KALLSYMS_EXTRA_PASS
 288         bool "Do an extra kallsyms pass"
 289         depends on KALLSYMS
 290         help
 291            If kallsyms is not working correctly, the build will fail with
 292            inconsistent kallsyms data.  If that occurs, log a bug report and
 293            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 294            Always say N here unless you find a bug in kallsyms, which must be
 295            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 296            you wait for kallsyms to be fixed.
 297
 298
 299 config HOTPLUG
 300         bool "Support for hot-pluggable devices" if EMBEDDED
 301         default y
 302         help
 303           This option is provided for the case where no hotplug or uevent
 304           capabilities is wanted by the kernel.  You should only consider
 305           disabling this option for embedded systems that do not use modules, a
 306           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 307
 308 config PRINTK
 309         default y
 310         bool "Enable support for printk" if EMBEDDED
 311         help
 312           This option enables normal printk support. Removing it
 313           eliminates most of the message strings from the kernel image
 314           and makes the kernel more or less silent. As this makes it
 315           very difficult to diagnose system problems, saying N here is
 316           strongly discouraged.
 317
 318 config BUG
 319         bool "BUG() support" if EMBEDDED
 320         default y
 321         help
 322           Disabling this option eliminates support for BUG and WARN, reducing
 323           the size of your kernel image and potentially quietly ignoring
 324           numerous fatal conditions. You should only consider disabling this
 325           option for embedded systems with no facilities for reporting errors.
 326           Just say Y.
 327
 328 config ELF_CORE
 329         default y
 330         bool "Enable ELF core dumps" if EMBEDDED
 331         help
 332           Enable support for generating core dumps. Disabling saves about 4k.
 333
 334 config BASE_FULL
 335         default y
 336         bool "Enable full-sized data structures for core" if EMBEDDED
 337         help
 338           Disabling this option reduces the size of miscellaneous core
 339           kernel data structures. This saves memory on small machines,
 340           but may reduce performance.
 341
 342 config FUTEX
 343         bool "Enable futex support" if EMBEDDED
 344         default y
 345         help
 346           Disabling this option will cause the kernel to be built without
 347           support for "fast userspace mutexes".  The resulting kernel may not
 348           run glibc-based applications correctly.
 349
 350 config EPOLL
 351         bool "Enable eventpoll support" if EMBEDDED
 352         default y
 353         help
 354           Disabling this option will cause the kernel to be built without
 355           support for epoll family of system calls.
 356
 357 config SHMEM
 358         bool "Use full shmem filesystem" if EMBEDDED
 359         default y
 360         depends on MMU
 361         help
 362           The shmem is an internal filesystem used to manage shared memory.
 363           It is backed by swap and manages resource limits. It is also exported
 364           to userspace as tmpfs if TMPFS is enabled. Disabling this
 365           option replaces shmem and tmpfs with the much simpler ramfs code,
 366           which may be appropriate on small systems without swap.
 367
 368 config CC_ALIGN_FUNCTIONS
 369         int "Function alignment" if EMBEDDED
 370         default 0
 371         help
 372           Align the start of functions to the next power-of-two greater than n,
 373           skipping up to n bytes.  For instance, 32 aligns functions
 374           to the next 32-byte boundary, but 24 would align to the next
 375           32-byte boundary only if this can be done by skipping 23 bytes or less.
 376           Zero means use compiler's default.
 377
 378 config CC_ALIGN_LABELS
 379         int "Label alignment" if EMBEDDED
 380         default 0
 381         help
 382           Align all branch targets to a power-of-two boundary, skipping
 383           up to n bytes like ALIGN_FUNCTIONS.  This option can easily
 384           make code slower, because it must insert dummy operations for
 385           when the branch target is reached in the usual flow of the code.
 386           Zero means use compiler's default.
 387
 388 config CC_ALIGN_LOOPS
 389         int "Loop alignment" if EMBEDDED
 390         default 0
 391         help
 392           Align loops to a power-of-two boundary, skipping up to n bytes.
 393           Zero means use compiler's default.
 394
 395 config CC_ALIGN_JUMPS
 396         int "Jump alignment" if EMBEDDED
 397         default 0
 398         help
 399           Align branch targets to a power-of-two boundary, for branch
 400           targets where the targets can only be reached by jumping,
 401           skipping up to n bytes like ALIGN_FUNCTIONS.  In this case,
 402           no dummy operations need be executed.
 403           Zero means use compiler's default.
 404
 405 config SLAB
 406         default y
 407         bool "Use full SLAB allocator" if EMBEDDED
 408         help
 409           Disabling this replaces the advanced SLAB allocator and
 410           kmalloc support with the drastically simpler SLOB allocator.
 411           SLOB is more space efficient but does not scale well and is
 412           more susceptible to fragmentation.
 413
 414 endmenu         # General setup
 415
 416 config TINY_SHMEM
 417         default !SHMEM
 418         bool
 419
 420 config BASE_SMALL
 421         int
 422         default 0 if BASE_FULL
 423         default 1 if !BASE_FULL
 424
 425 config SLOB
 426         default !SLAB
 427         bool
 428
 429 config OBSOLETE_INTERMODULE
 430         tristate
 431
 432 menu "Loadable module support"
 433
 434 config MODULES
 435         bool "Enable loadable module support"
 436         help
 437           Kernel modules are small pieces of compiled code which can
 438           be inserted in the running kernel, rather than being
 439           permanently built into the kernel.  You use the "modprobe"
 440           tool to add (and sometimes remove) them.  If you say Y here,
 441           many parts of the kernel can be built as modules (by
 442           answering M instead of Y where indicated): this is most
 443           useful for infrequently used options which are not required
 444           for booting.  For more information, see the man pages for
 445           modprobe, lsmod, modinfo, insmod and rmmod.
 446
 447           If you say Y here, you will need to run "make
 448           modules_install" to put the modules under /lib/modules/
 449           where modprobe can find them (you may need to be root to do
 450           this).
 451
 452           If unsure, say Y.
 453
 454 config MODULE_UNLOAD
 455         bool "Module unloading"
 456         depends on MODULES
 457         help
 458           Without this option you will not be able to unload any
 459           modules (note that some modules may not be unloadable
 460           anyway), which makes your kernel slightly smaller and
 461           simpler.  If unsure, say Y.
 462
 463 config MODULE_FORCE_UNLOAD
 464         bool "Forced module unloading"
 465         depends on MODULE_UNLOAD && EXPERIMENTAL
 466         help
 467           This option allows you to force a module to unload, even if the
 468           kernel believes it is unsafe: the kernel will remove the module
 469           without waiting for anyone to stop using it (using the -f option to
 470           rmmod).  This is mainly for kernel developers and desperate users.
 471           If unsure, say N.
 472
 473 config OBSOLETE_MODPARM
 474         bool
 475         default y
 476         depends on MODULES
 477         help
 478           You need this option to use module parameters on modules which
 479           have not been converted to the new module parameter system yet.
 480           If unsure, say Y.
 481
 482 config MODVERSIONS
 483         bool "Module versioning support"
 484         depends on MODULES
 485         help
 486           Usually, you have to use modules compiled with your kernel.
 487           Saying Y here makes it sometimes possible to use modules
 488           compiled for different kernels, by adding enough information
 489           to the modules to (hopefully) spot any changes which would
 490           make them incompatible with the kernel you are running.  If
 491           unsure, say N.
 492
 493 config MODULE_SRCVERSION_ALL
 494         bool "Source checksum for all modules"
 495         depends on MODULES
 496         help
 497           Modules which contain a MODULE_VERSION get an extra "srcversion"
 498           field inserted into their modinfo section, which contains a
 499           sum of the source files which made it.  This helps maintainers
 500           see exactly which source was used to build a module (since
 501           others sometimes change the module source without updating
 502           the version).  With this option, such a "srcversion" field
 503           will be created for all modules.  If unsure, say N.
 504
 505 config KMOD
 506         bool "Automatic kernel module loading"
 507         depends on MODULES
 508         help
 509           Normally when you have selected some parts of the kernel to
 510           be created as kernel modules, you must load them (using the
 511           "modprobe" command) before you can use them. If you say Y
 512           here, some parts of the kernel will be able to load modules
 513           automatically: when a part of the kernel needs a module, it
 514           runs modprobe with the appropriate arguments, thereby
 515           loading the module if it is available.  If unsure, say Y.
 516
 517 config STOP_MACHINE
 518         bool
 519         default y
 520         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 521         help
 522           Need stop_machine() primitive.
 523 endmenu
 524
 525 menu "Block layer"
 526 source "block/Kconfig"
 527 endmenu