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  24           drivers that have been replaced by something else, and/or are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 source "usr/Kconfig"
 218
 219 config UID16
 220         bool "Enable 16-bit UID system calls" if EMBEDDED
 221         depends on ARM || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
 222         default y
 223         help
 224           This enables the legacy 16-bit UID syscall wrappers.
 225
 226 config VM86
 227         depends X86
 228         default y
 229         bool "Enable VM86 support" if EMBEDDED
 230         help
 231           This option is required by programs like DOSEMU to run 16-bit legacy
 232           code on X86 processors. It also may be needed by software like
 233           XFree86 to initialize some video cards via BIOS. Disabling this
 234           option saves about 6k.
 235
 236 config CC_OPTIMIZE_FOR_SIZE
 237         bool "Optimize for size (Look out for broken compilers!)"
 238         default y
 239         depends on ARM || H8300 || EXPERIMENTAL
 240         help
 241           Enabling this option will pass "-Os" instead of "-O2" to gcc
 242           resulting in a smaller kernel.
 243
 244           WARNING: some versions of gcc may generate incorrect code with this
 245           option.  If problems are observed, a gcc upgrade may be needed.
 246
 247           If unsure, say N.
 248
 249 menuconfig EMBEDDED
 250         bool "Configure standard kernel features (for small systems)"
 251         help
 252           This option allows certain base kernel options and settings
 253           to be disabled or tweaked. This is for specialized
 254           environments which can tolerate a "non-standard" kernel.
 255           Only use this if you really know what you are doing.
 256
 257 config KALLSYMS
 258          bool "Load all symbols for debugging/kksymoops" if EMBEDDED
 259          default y
 260          help
 261            Say Y here to let the kernel print out symbolic crash information and
 262            symbolic stack backtraces. This increases the size of the kernel
 263            somewhat, as all symbols have to be loaded into the kernel image.
 264
 265 config KALLSYMS_ALL
 266         bool "Include all symbols in kallsyms"
 267         depends on DEBUG_KERNEL && KALLSYMS
 268         help
 269            Normally kallsyms only contains the symbols of functions, for nicer
 270            OOPS messages.  Some debuggers can use kallsyms for other
 271            symbols too: say Y here to include all symbols, if you need them
 272            and you don't care about adding 300k to the size of your kernel.
 273
 274            Say N.
 275
 276 config KALLSYMS_EXTRA_PASS
 277         bool "Do an extra kallsyms pass"
 278         depends on KALLSYMS
 279         help
 280            If kallsyms is not working correctly, the build will fail with
 281            inconsistent kallsyms data.  If that occurs, log a bug report and
 282            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 283            Always say N here unless you find a bug in kallsyms, which must be
 284            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 285            you wait for kallsyms to be fixed.
 286
 287
 288 config HOTPLUG
 289         bool "Support for hot-pluggable devices" if EMBEDDED
 290         default y
 291         help
 292           This option is provided for the case where no hotplug or uevent
 293           capabilities is wanted by the kernel.  You should only consider
 294           disabling this option for embedded systems that do not use modules, a
 295           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 296
 297 config PRINTK
 298         default y
 299         bool "Enable support for printk" if EMBEDDED
 300         help
 301           This option enables normal printk support. Removing it
 302           eliminates most of the message strings from the kernel image
 303           and makes the kernel more or less silent. As this makes it
 304           very difficult to diagnose system problems, saying N here is
 305           strongly discouraged.
 306
 307 config BUG
 308         bool "BUG() support" if EMBEDDED
 309         default y
 310         help
 311           Disabling this option eliminates support for BUG and WARN, reducing
 312           the size of your kernel image and potentially quietly ignoring
 313           numerous fatal conditions. You should only consider disabling this
 314           option for embedded systems with no facilities for reporting errors.
 315           Just say Y.
 316
 317 config ELF_CORE
 318         default y
 319         bool "Enable ELF core dumps" if EMBEDDED
 320         help
 321           Enable support for generating core dumps. Disabling saves about 4k.
 322
 323 config BASE_FULL
 324         default y
 325         bool "Enable full-sized data structures for core" if EMBEDDED
 326         help
 327           Disabling this option reduces the size of miscellaneous core
 328           kernel data structures. This saves memory on small machines,
 329           but may reduce performance.
 330
 331 config FUTEX
 332         bool "Enable futex support" if EMBEDDED
 333         default y
 334         help
 335           Disabling this option will cause the kernel to be built without
 336           support for "fast userspace mutexes".  The resulting kernel may not
 337           run glibc-based applications correctly.
 338
 339 config EPOLL
 340         bool "Enable eventpoll support" if EMBEDDED
 341         default y
 342         help
 343           Disabling this option will cause the kernel to be built without
 344           support for epoll family of system calls.
 345
 346 config SHMEM
 347         bool "Use full shmem filesystem" if EMBEDDED
 348         default y
 349         depends on MMU
 350         help
 351           The shmem is an internal filesystem used to manage shared memory.
 352           It is backed by swap and manages resource limits. It is also exported
 353           to userspace as tmpfs if TMPFS is enabled. Disabling this
 354           option replaces shmem and tmpfs with the much simpler ramfs code,
 355           which may be appropriate on small systems without swap.
 356
 357 config CC_ALIGN_FUNCTIONS
 358         int "Function alignment" if EMBEDDED
 359         default 0
 360         help
 361           Align the start of functions to the next power-of-two greater than n,
 362           skipping up to n bytes.  For instance, 32 aligns functions
 363           to the next 32-byte boundary, but 24 would align to the next
 364           32-byte boundary only if this can be done by skipping 23 bytes or less.
 365           Zero means use compiler's default.
 366
 367 config CC_ALIGN_LABELS
 368         int "Label alignment" if EMBEDDED
 369         default 0
 370         help
 371           Align all branch targets to a power-of-two boundary, skipping
 372           up to n bytes like ALIGN_FUNCTIONS.  This option can easily
 373           make code slower, because it must insert dummy operations for
 374           when the branch target is reached in the usual flow of the code.
 375           Zero means use compiler's default.
 376
 377 config CC_ALIGN_LOOPS
 378         int "Loop alignment" if EMBEDDED
 379         default 0
 380         help
 381           Align loops to a power-of-two boundary, skipping up to n bytes.
 382           Zero means use compiler's default.
 383
 384 config CC_ALIGN_JUMPS
 385         int "Jump alignment" if EMBEDDED
 386         default 0
 387         help
 388           Align branch targets to a power-of-two boundary, for branch
 389           targets where the targets can only be reached by jumping,
 390           skipping up to n bytes like ALIGN_FUNCTIONS.  In this case,
 391           no dummy operations need be executed.
 392           Zero means use compiler's default.
 393
 394 config SLAB
 395         default y
 396         bool "Use full SLAB allocator" if EMBEDDED
 397         help
 398           Disabling this replaces the advanced SLAB allocator and
 399           kmalloc support with the drastically simpler SLOB allocator.
 400           SLOB is more space efficient but does not scale well and is
 401           more susceptible to fragmentation.
 402
 403 endmenu         # General setup
 404
 405 config TINY_SHMEM
 406         default !SHMEM
 407         bool
 408
 409 config BASE_SMALL
 410         int
 411         default 0 if BASE_FULL
 412         default 1 if !BASE_FULL
 413
 414 config SLOB
 415         default !SLAB
 416         bool
 417
 418 config OBSOLETE_INTERMODULE
 419         tristate
 420
 421 menu "Loadable module support"
 422
 423 config MODULES
 424         bool "Enable loadable module support"
 425         help
 426           Kernel modules are small pieces of compiled code which can
 427           be inserted in the running kernel, rather than being
 428           permanently built into the kernel.  You use the "modprobe"
 429           tool to add (and sometimes remove) them.  If you say Y here,
 430           many parts of the kernel can be built as modules (by
 431           answering M instead of Y where indicated): this is most
 432           useful for infrequently used options which are not required
 433           for booting.  For more information, see the man pages for
 434           modprobe, lsmod, modinfo, insmod and rmmod.
 435
 436           If you say Y here, you will need to run "make
 437           modules_install" to put the modules under /lib/modules/
 438           where modprobe can find them (you may need to be root to do
 439           this).
 440
 441           If unsure, say Y.
 442
 443 config MODULE_UNLOAD
 444         bool "Module unloading"
 445         depends on MODULES
 446         help
 447           Without this option you will not be able to unload any
 448           modules (note that some modules may not be unloadable
 449           anyway), which makes your kernel slightly smaller and
 450           simpler.  If unsure, say Y.
 451
 452 config MODULE_FORCE_UNLOAD
 453         bool "Forced module unloading"
 454         depends on MODULE_UNLOAD && EXPERIMENTAL
 455         help
 456           This option allows you to force a module to unload, even if the
 457           kernel believes it is unsafe: the kernel will remove the module
 458           without waiting for anyone to stop using it (using the -f option to
 459           rmmod).  This is mainly for kernel developers and desperate users.
 460           If unsure, say N.
 461
 462 config OBSOLETE_MODPARM
 463         bool
 464         default y
 465         depends on MODULES
 466         help
 467           You need this option to use module parameters on modules which
 468           have not been converted to the new module parameter system yet.
 469           If unsure, say Y.
 470
 471 config MODVERSIONS
 472         bool "Module versioning support"
 473         depends on MODULES
 474         help
 475           Usually, you have to use modules compiled with your kernel.
 476           Saying Y here makes it sometimes possible to use modules
 477           compiled for different kernels, by adding enough information
 478           to the modules to (hopefully) spot any changes which would
 479           make them incompatible with the kernel you are running.  If
 480           unsure, say N.
 481
 482 config MODULE_SRCVERSION_ALL
 483         bool "Source checksum for all modules"
 484         depends on MODULES
 485         help
 486           Modules which contain a MODULE_VERSION get an extra "srcversion"
 487           field inserted into their modinfo section, which contains a
 488           sum of the source files which made it.  This helps maintainers
 489           see exactly which source was used to build a module (since
 490           others sometimes change the module source without updating
 491           the version).  With this option, such a "srcversion" field
 492           will be created for all modules.  If unsure, say N.
 493
 494 config KMOD
 495         bool "Automatic kernel module loading"
 496         depends on MODULES
 497         help
 498           Normally when you have selected some parts of the kernel to
 499           be created as kernel modules, you must load them (using the
 500           "modprobe" command) before you can use them. If you say Y
 501           here, some parts of the kernel will be able to load modules
 502           automatically: when a part of the kernel needs a module, it
 503           runs modprobe with the appropriate arguments, thereby
 504           loading the module if it is available.  If unsure, say Y.
 505
 506 config STOP_MACHINE
 507         bool
 508         default y
 509         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 510         help
 511           Need stop_machine() primitive.
 512 endmenu
 513
 514 menu "Block layer"
 515 source "block/Kconfig"
 516 endmenu