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  24           drivers that have been replaced by something else, and/or are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 CLEAN_COMPILE
  35         bool "Select only drivers expected to compile cleanly" if EXPERIMENTAL
  36         default y
  37         help
  38           Select this option if you don't even want to see the option
  39           to configure known-broken drivers.
  40
  41           If unsure, say Y
  42
  43 config BROKEN
  44         bool
  45         depends on !CLEAN_COMPILE
  46         default y
  47
  48 config BROKEN_ON_SMP
  49         bool
  50         depends on BROKEN || !SMP
  51         default y
  52
  53 config LOCK_KERNEL
  54         bool
  55         depends on SMP || PREEMPT
  56         default y
  57
  58 config INIT_ENV_ARG_LIMIT
  59         int
  60         default 32 if !USERMODE
  61         default 128 if USERMODE
  62         help
  63           Maximum of each of the number of arguments and environment
  64           variables passed to init from the kernel command line.
  65
  66 endmenu
  67
  68 menu "General setup"
  69
  70 config LOCALVERSION
  71         string "Local version - append to kernel release"
  72         help
  73           Append an extra string to the end of your kernel version.
  74           This will show up when you type uname, for example.
  75           The string you set here will be appended after the contents of
  76           any files with a filename matching localversion* in your
  77           object and source tree, in that order.  Your total string can
  78           be a maximum of 64 characters.
  79
  80 config LOCALVERSION_AUTO
  81         bool "Automatically append version information to the version string"
  82         default y
  83         help
  84           This will try to automatically determine if the current tree is a
  85           release tree by looking for git tags that
  86           belong to the current top of tree revision.
  87
  88           A string of the format -gxxxxxxxx will be added to the localversion
  89           if a git based tree is found.  The string generated by this will be
  90           appended after any matching localversion* files, and after the value
  91           set in CONFIG_LOCALVERSION
  92
  93           Note: This requires Perl, and a git repository, but not necessarily
  94           the git or cogito tools to be installed.
  95
  96 config SWAP
  97         bool "Support for paging of anonymous memory (swap)"
  98         depends on MMU
  99         default y
 100         help
 101           This option allows you to choose whether you want to have support
 102           for socalled swap devices or swap files in your kernel that are
 103           used to provide more virtual memory than the actual RAM present
 104           in your computer.  If unsure say Y.
 105
 106 config SYSVIPC
 107         bool "System V IPC"
 108         depends on MMU
 109         ---help---
 110           Inter Process Communication is a suite of library functions and
 111           system calls which let processes (running programs) synchronize and
 112           exchange information. It is generally considered to be a good thing,
 113           and some programs won't run unless you say Y here. In particular, if
 114           you want to run the DOS emulator dosemu under Linux (read the
 115           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 116           you'll need to say Y here.
 117
 118           You can find documentation about IPC with "info ipc" and also in
 119           section 6.4 of the Linux Programmer's Guide, available from
 120           <http://www.tldp.org/guides.html>.
 121
 122 config POSIX_MQUEUE
 123         bool "POSIX Message Queues"
 124         depends on NET && EXPERIMENTAL
 125         ---help---
 126           POSIX variant of message queues is a part of IPC. In POSIX message
 127           queues every message has a priority which decides about succession
 128           of receiving it by a process. If you want to compile and run
 129           programs written e.g. for Solaris with use of its POSIX message
 130           queues (functions mq_*) say Y here. To use this feature you will
 131           also need mqueue library, available from
 132           <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
 133
 134           POSIX message queues are visible as a filesystem called 'mqueue'
 135           and can be mounted somewhere if you want to do filesystem
 136           operations on message queues.
 137
 138           If unsure, say Y.
 139
 140 config BSD_PROCESS_ACCT
 141         bool "BSD Process Accounting"
 142         help
 143           If you say Y here, a user level program will be able to instruct the
 144           kernel (via a special system call) to write process accounting
 145           information to a file: whenever a process exits, information about
 146           that process will be appended to the file by the kernel.  The
 147           information includes things such as creation time, owning user,
 148           command name, memory usage, controlling terminal etc. (the complete
 149           list is in the struct acct in <file:include/linux/acct.h>).  It is
 150           up to the user level program to do useful things with this
 151           information.  This is generally a good idea, so say Y.
 152
 153 config BSD_PROCESS_ACCT_V3
 154         bool "BSD Process Accounting version 3 file format"
 155         depends on BSD_PROCESS_ACCT
 156         default n
 157         help
 158           If you say Y here, the process accounting information is written
 159           in a new file format that also logs the process IDs of each
 160           process and it's parent. Note that this file format is incompatible
 161           with previous v0/v1/v2 file formats, so you will need updated tools
 162           for processing it. A preliminary version of these tools is available
 163           at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
 164
 165 config SYSCTL
 166         bool "Sysctl support"
 167         ---help---
 168           The sysctl interface provides a means of dynamically changing
 169           certain kernel parameters and variables on the fly without requiring
 170           a recompile of the kernel or reboot of the system.  The primary
 171           interface consists of a system call, but if you say Y to "/proc
 172           file system support", a tree of modifiable sysctl entries will be
 173           generated beneath the /proc/sys directory. They are explained in the
 174           files in <file:Documentation/sysctl/>.  Note that enabling this
 175           option will enlarge the kernel by at least 8 KB.
 176
 177           As it is generally a good thing, you should say Y here unless
 178           building a kernel for install/rescue disks or your system is very
 179           limited in memory.
 180
 181 config AUDIT
 182         bool "Auditing support"
 183         depends on NET
 184         default y if SECURITY_SELINUX
 185         help
 186           Enable auditing infrastructure that can be used with another
 187           kernel subsystem, such as SELinux (which requires this for
 188           logging of avc messages output).  Does not do system-call
 189           auditing without CONFIG_AUDITSYSCALL.
 190
 191 config AUDITSYSCALL
 192         bool "Enable system-call auditing support"
 193         depends on AUDIT && (X86 || PPC || PPC64 || ARCH_S390 || IA64 || UML || SPARC64)
 194         default y if SECURITY_SELINUX
 195         help
 196           Enable low-overhead system-call auditing infrastructure that
 197           can be used independently or with another kernel subsystem,
 198           such as SELinux.
 199
 200 config HOTPLUG
 201         bool "Support for hot-pluggable devices" if !ARCH_S390
 202         default ARCH_S390
 203         help
 204           This option is provided for the case where no in-kernel-tree
 205           modules require HOTPLUG functionality, but a module built
 206           outside the kernel tree does. Such modules require Y here.
 207
 208 config KOBJECT_UEVENT
 209         bool "Kernel Userspace Events" if EMBEDDED
 210         depends on NET
 211         default y
 212         help
 213           This option enables the kernel userspace event layer, which is a
 214           simple mechanism for kernel-to-user communication over a netlink
 215           socket.
 216           The goal of the kernel userspace events layer is to provide a simple
 217           and efficient events system, that notifies userspace about kobject
 218           state changes. This will enable applications to just listen for
 219           events instead of polling system devices and files.
 220           Hotplug events (kobject addition and removal) are also available on
 221           the netlink socket in addition to the execution of /sbin/hotplug if
 222           CONFIG_HOTPLUG is enabled.
 223
 224           Say Y, unless you are building a system requiring minimal memory
 225           consumption.
 226
 227 config IKCONFIG
 228         bool "Kernel .config support"
 229         ---help---
 230           This option enables the complete Linux kernel ".config" file
 231           contents to be saved in the kernel. It provides documentation
 232           of which kernel options are used in a running kernel or in an
 233           on-disk kernel.  This information can be extracted from the kernel
 234           image file with the script scripts/extract-ikconfig and used as
 235           input to rebuild the current kernel or to build another kernel.
 236           It can also be extracted from a running kernel by reading
 237           /proc/config.gz if enabled (below).
 238
 239 config IKCONFIG_PROC
 240         bool "Enable access to .config through /proc/config.gz"
 241         depends on IKCONFIG && PROC_FS
 242         ---help---
 243           This option enables access to the kernel configuration file
 244           through /proc/config.gz.
 245
 246 config CPUSETS
 247         bool "Cpuset support"
 248         depends on SMP
 249         help
 250           This option will let you create and manage CPUSETs which
 251           allow dynamically partitioning a system into sets of CPUs and
 252           Memory Nodes and assigning tasks to run only within those sets.
 253           This is primarily useful on large SMP or NUMA systems.
 254
 255           Say N if unsure.
 256
 257 source "usr/Kconfig"
 258
 259 config CC_OPTIMIZE_FOR_SIZE
 260         bool "Optimize for size (Look out for broken compilers!)"
 261         default y
 262         depends on ARM || H8300 || EXPERIMENTAL
 263         help
 264           Enabling this option will pass "-Os" instead of "-O2" to gcc
 265           resulting in a smaller kernel.
 266
 267           WARNING: some versions of gcc may generate incorrect code with this
 268           option.  If problems are observed, a gcc upgrade may be needed.
 269
 270           If unsure, say N.
 271
 272 menuconfig EMBEDDED
 273         bool "Configure standard kernel features (for small systems)"
 274         help
 275           This option allows certain base kernel options and settings
 276           to be disabled or tweaked. This is for specialized
 277           environments which can tolerate a "non-standard" kernel.
 278           Only use this if you really know what you are doing.
 279
 280 config KALLSYMS
 281          bool "Load all symbols for debugging/kksymoops" if EMBEDDED
 282          default y
 283          help
 284            Say Y here to let the kernel print out symbolic crash information and
 285            symbolic stack backtraces. This increases the size of the kernel
 286            somewhat, as all symbols have to be loaded into the kernel image.
 287
 288 config KALLSYMS_ALL
 289         bool "Include all symbols in kallsyms"
 290         depends on DEBUG_KERNEL && KALLSYMS
 291         help
 292            Normally kallsyms only contains the symbols of functions, for nicer
 293            OOPS messages.  Some debuggers can use kallsyms for other
 294            symbols too: say Y here to include all symbols, if you need them
 295            and you don't care about adding 300k to the size of your kernel.
 296
 297            Say N.
 298
 299 config KALLSYMS_EXTRA_PASS
 300         bool "Do an extra kallsyms pass"
 301         depends on KALLSYMS
 302         help
 303            If kallsyms is not working correctly, the build will fail with
 304            inconsistent kallsyms data.  If that occurs, log a bug report and
 305            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 306            Always say N here unless you find a bug in kallsyms, which must be
 307            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 308            you wait for kallsyms to be fixed.
 309
 310
 311 config PRINTK
 312         default y
 313         bool "Enable support for printk" if EMBEDDED
 314         help
 315           This option enables normal printk support. Removing it
 316           eliminates most of the message strings from the kernel image
 317           and makes the kernel more or less silent. As this makes it
 318           very difficult to diagnose system problems, saying N here is
 319           strongly discouraged.
 320
 321 config BUG
 322         bool "BUG() support" if EMBEDDED
 323         default y
 324         help
 325           Disabling this option eliminates support for BUG and WARN, reducing
 326           the size of your kernel image and potentially quietly ignoring
 327           numerous fatal conditions. You should only consider disabling this
 328           option for embedded systems with no facilities for reporting errors.
 329           Just say Y.
 330
 331 config BASE_FULL
 332         default y
 333         bool "Enable full-sized data structures for core" if EMBEDDED
 334         help
 335           Disabling this option reduces the size of miscellaneous core
 336           kernel data structures. This saves memory on small machines,
 337           but may reduce performance.
 338
 339 config FUTEX
 340         bool "Enable futex support" if EMBEDDED
 341         default y
 342         help
 343           Disabling this option will cause the kernel to be built without
 344           support for "fast userspace mutexes".  The resulting kernel may not
 345           run glibc-based applications correctly.
 346
 347 config EPOLL
 348         bool "Enable eventpoll support" if EMBEDDED
 349         default y
 350         help
 351           Disabling this option will cause the kernel to be built without
 352           support for epoll family of system calls.
 353
 354 config SHMEM
 355         bool "Use full shmem filesystem" if EMBEDDED
 356         default y
 357         depends on MMU
 358         help
 359           The shmem is an internal filesystem used to manage shared memory.
 360           It is backed by swap and manages resource limits. It is also exported
 361           to userspace as tmpfs if TMPFS is enabled. Disabling this
 362           option replaces shmem and tmpfs with the much simpler ramfs code,
 363           which may be appropriate on small systems without swap.
 364
 365 config CC_ALIGN_FUNCTIONS
 366         int "Function alignment" if EMBEDDED
 367         default 0
 368         help
 369           Align the start of functions to the next power-of-two greater than n,
 370           skipping up to n bytes.  For instance, 32 aligns functions
 371           to the next 32-byte boundary, but 24 would align to the next
 372           32-byte boundary only if this can be done by skipping 23 bytes or less.
 373           Zero means use compiler's default.
 374
 375 config CC_ALIGN_LABELS
 376         int "Label alignment" if EMBEDDED
 377         default 0
 378         help
 379           Align all branch targets to a power-of-two boundary, skipping
 380           up to n bytes like ALIGN_FUNCTIONS.  This option can easily
 381           make code slower, because it must insert dummy operations for
 382           when the branch target is reached in the usual flow of the code.
 383           Zero means use compiler's default.
 384
 385 config CC_ALIGN_LOOPS
 386         int "Loop alignment" if EMBEDDED
 387         default 0
 388         help
 389           Align loops to a power-of-two boundary, skipping up to n bytes.
 390           Zero means use compiler's default.
 391
 392 config CC_ALIGN_JUMPS
 393         int "Jump alignment" if EMBEDDED
 394         default 0
 395         help
 396           Align branch targets to a power-of-two boundary, for branch
 397           targets where the targets can only be reached by jumping,
 398           skipping up to n bytes like ALIGN_FUNCTIONS.  In this case,
 399           no dummy operations need be executed.
 400           Zero means use compiler's default.
 401
 402 endmenu         # General setup
 403
 404 config TINY_SHMEM
 405         default !SHMEM
 406         bool
 407
 408 config BASE_SMALL
 409         int
 410         default 0 if BASE_FULL
 411         default 1 if !BASE_FULL
 412
 413 menu "Loadable module support"
 414
 415 config MODULES
 416         bool "Enable loadable module support"
 417         help
 418           Kernel modules are small pieces of compiled code which can
 419           be inserted in the running kernel, rather than being
 420           permanently built into the kernel.  You use the "modprobe"
 421           tool to add (and sometimes remove) them.  If you say Y here,
 422           many parts of the kernel can be built as modules (by
 423           answering M instead of Y where indicated): this is most
 424           useful for infrequently used options which are not required
 425           for booting.  For more information, see the man pages for
 426           modprobe, lsmod, modinfo, insmod and rmmod.
 427
 428           If you say Y here, you will need to run "make
 429           modules_install" to put the modules under /lib/modules/
 430           where modprobe can find them (you may need to be root to do
 431           this).
 432
 433           If unsure, say Y.
 434
 435 config MODULE_UNLOAD
 436         bool "Module unloading"
 437         depends on MODULES
 438         help
 439           Without this option you will not be able to unload any
 440           modules (note that some modules may not be unloadable
 441           anyway), which makes your kernel slightly smaller and
 442           simpler.  If unsure, say Y.
 443
 444 config MODULE_FORCE_UNLOAD
 445         bool "Forced module unloading"
 446         depends on MODULE_UNLOAD && EXPERIMENTAL
 447         help
 448           This option allows you to force a module to unload, even if the
 449           kernel believes it is unsafe: the kernel will remove the module
 450           without waiting for anyone to stop using it (using the -f option to
 451           rmmod).  This is mainly for kernel developers and desperate users.
 452           If unsure, say N.
 453
 454 config OBSOLETE_MODPARM
 455         bool
 456         default y
 457         depends on MODULES
 458         help
 459           You need this option to use module parameters on modules which
 460           have not been converted to the new module parameter system yet.
 461           If unsure, say Y.
 462
 463 config MODVERSIONS
 464         bool "Module versioning support (EXPERIMENTAL)"
 465         depends on MODULES && EXPERIMENTAL
 466         help
 467           Usually, you have to use modules compiled with your kernel.
 468           Saying Y here makes it sometimes possible to use modules
 469           compiled for different kernels, by adding enough information
 470           to the modules to (hopefully) spot any changes which would
 471           make them incompatible with the kernel you are running.  If
 472           unsure, say N.
 473
 474 config MODULE_SRCVERSION_ALL
 475         bool "Source checksum for all modules"
 476         depends on MODULES
 477         help
 478           Modules which contain a MODULE_VERSION get an extra "srcversion"
 479           field inserted into their modinfo section, which contains a
 480           sum of the source files which made it.  This helps maintainers
 481           see exactly which source was used to build a module (since
 482           others sometimes change the module source without updating
 483           the version).  With this option, such a "srcversion" field
 484           will be created for all modules.  If unsure, say N.
 485
 486 config KMOD
 487         bool "Automatic kernel module loading"
 488         depends on MODULES
 489         help
 490           Normally when you have selected some parts of the kernel to
 491           be created as kernel modules, you must load them (using the
 492           "modprobe" command) before you can use them. If you say Y
 493           here, some parts of the kernel will be able to load modules
 494           automatically: when a part of the kernel needs a module, it
 495           runs modprobe with the appropriate arguments, thereby
 496           loading the module if it is available.  If unsure, say Y.
 497
 498 config STOP_MACHINE
 499         bool
 500         default y
 501         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 502         help
 503           Need stop_machine() primitive.
 504 endmenu
 505
 506 menu "Block layer"
 507 source "block/Kconfig"
 508 endmenu