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  24           drivers that have been replaced by something else, and/or are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 SLAB
 358         default y
 359         bool "Use full SLAB allocator" if EMBEDDED
 360         help
 361           Disabling this replaces the advanced SLAB allocator and
 362           kmalloc support with the drastically simpler SLOB allocator.
 363           SLOB is more space efficient but does not scale well and is
 364           more susceptible to fragmentation.
 365
 366 endmenu         # General setup
 367
 368 config TINY_SHMEM
 369         default !SHMEM
 370         bool
 371
 372 config BASE_SMALL
 373         int
 374         default 0 if BASE_FULL
 375         default 1 if !BASE_FULL
 376
 377 config SLOB
 378         default !SLAB
 379         bool
 380
 381 config OBSOLETE_INTERMODULE
 382         tristate
 383
 384 menu "Loadable module support"
 385
 386 config MODULES
 387         bool "Enable loadable module support"
 388         help
 389           Kernel modules are small pieces of compiled code which can
 390           be inserted in the running kernel, rather than being
 391           permanently built into the kernel.  You use the "modprobe"
 392           tool to add (and sometimes remove) them.  If you say Y here,
 393           many parts of the kernel can be built as modules (by
 394           answering M instead of Y where indicated): this is most
 395           useful for infrequently used options which are not required
 396           for booting.  For more information, see the man pages for
 397           modprobe, lsmod, modinfo, insmod and rmmod.
 398
 399           If you say Y here, you will need to run "make
 400           modules_install" to put the modules under /lib/modules/
 401           where modprobe can find them (you may need to be root to do
 402           this).
 403
 404           If unsure, say Y.
 405
 406 config MODULE_UNLOAD
 407         bool "Module unloading"
 408         depends on MODULES
 409         help
 410           Without this option you will not be able to unload any
 411           modules (note that some modules may not be unloadable
 412           anyway), which makes your kernel slightly smaller and
 413           simpler.  If unsure, say Y.
 414
 415 config MODULE_FORCE_UNLOAD
 416         bool "Forced module unloading"
 417         depends on MODULE_UNLOAD && EXPERIMENTAL
 418         help
 419           This option allows you to force a module to unload, even if the
 420           kernel believes it is unsafe: the kernel will remove the module
 421           without waiting for anyone to stop using it (using the -f option to
 422           rmmod).  This is mainly for kernel developers and desperate users.
 423           If unsure, say N.
 424
 425 config OBSOLETE_MODPARM
 426         bool
 427         default y
 428         depends on MODULES
 429         help
 430           You need this option to use module parameters on modules which
 431           have not been converted to the new module parameter system yet.
 432           If unsure, say Y.
 433
 434 config MODVERSIONS
 435         bool "Module versioning support"
 436         depends on MODULES
 437         help
 438           Usually, you have to use modules compiled with your kernel.
 439           Saying Y here makes it sometimes possible to use modules
 440           compiled for different kernels, by adding enough information
 441           to the modules to (hopefully) spot any changes which would
 442           make them incompatible with the kernel you are running.  If
 443           unsure, say N.
 444
 445 config MODULE_SRCVERSION_ALL
 446         bool "Source checksum for all modules"
 447         depends on MODULES
 448         help
 449           Modules which contain a MODULE_VERSION get an extra "srcversion"
 450           field inserted into their modinfo section, which contains a
 451           sum of the source files which made it.  This helps maintainers
 452           see exactly which source was used to build a module (since
 453           others sometimes change the module source without updating
 454           the version).  With this option, such a "srcversion" field
 455           will be created for all modules.  If unsure, say N.
 456
 457 config KMOD
 458         bool "Automatic kernel module loading"
 459         depends on MODULES
 460         help
 461           Normally when you have selected some parts of the kernel to
 462           be created as kernel modules, you must load them (using the
 463           "modprobe" command) before you can use them. If you say Y
 464           here, some parts of the kernel will be able to load modules
 465           automatically: when a part of the kernel needs a module, it
 466           runs modprobe with the appropriate arguments, thereby
 467           loading the module if it is available.  If unsure, say Y.
 468
 469 config STOP_MACHINE
 470         bool
 471         default y
 472         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 473         help
 474           Need stop_machine() primitive.
 475 endmenu
 476
 477 menu "Block layer"
 478 source "block/Kconfig"
 479 endmenu