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  24           drivers that have been replaced by something else, and/or are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         default y if SECURITY_SELINUX
 173         help
 174           Enable auditing infrastructure that can be used with another
 175           kernel subsystem, such as SELinux (which requires this for
 176           logging of avc messages output).  Does not do system-call
 177           auditing without CONFIG_AUDITSYSCALL.
 178
 179 config AUDITSYSCALL
 180         bool "Enable system-call auditing support"
 181         depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
 182         default y if SECURITY_SELINUX
 183         help
 184           Enable low-overhead system-call auditing infrastructure that
 185           can be used independently or with another kernel subsystem,
 186           such as SELinux.
 187
 188 config IKCONFIG
 189         bool "Kernel .config support"
 190         ---help---
 191           This option enables the complete Linux kernel ".config" file
 192           contents to be saved in the kernel. It provides documentation
 193           of which kernel options are used in a running kernel or in an
 194           on-disk kernel.  This information can be extracted from the kernel
 195           image file with the script scripts/extract-ikconfig and used as
 196           input to rebuild the current kernel or to build another kernel.
 197           It can also be extracted from a running kernel by reading
 198           /proc/config.gz if enabled (below).
 199
 200 config IKCONFIG_PROC
 201         bool "Enable access to .config through /proc/config.gz"
 202         depends on IKCONFIG && PROC_FS
 203         ---help---
 204           This option enables access to the kernel configuration file
 205           through /proc/config.gz.
 206
 207 config CPUSETS
 208         bool "Cpuset support"
 209         depends on SMP
 210         help
 211           This option will let you create and manage CPUSETs which
 212           allow dynamically partitioning a system into sets of CPUs and
 213           Memory Nodes and assigning tasks to run only within those sets.
 214           This is primarily useful on large SMP or NUMA systems.
 215
 216           Say N if unsure.
 217
 218 source "usr/Kconfig"
 219
 220 config UID16
 221         bool "Enable 16-bit UID system calls" if EMBEDDED
 222         depends on ARM || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
 223         default y
 224         help
 225           This enables the legacy 16-bit UID syscall wrappers.
 226
 227 config VM86
 228         depends X86
 229         default y
 230         bool "Enable VM86 support" if EMBEDDED
 231         help
 232           This option is required by programs like DOSEMU to run 16-bit legacy
 233           code on X86 processors. It also may be needed by software like
 234           XFree86 to initialize some video cards via BIOS. Disabling this
 235           option saves about 6k.
 236
 237 config CC_OPTIMIZE_FOR_SIZE
 238         bool "Optimize for size (Look out for broken compilers!)"
 239         default y
 240         depends on ARM || H8300 || EXPERIMENTAL
 241         help
 242           Enabling this option will pass "-Os" instead of "-O2" to gcc
 243           resulting in a smaller kernel.
 244
 245           WARNING: some versions of gcc may generate incorrect code with this
 246           option.  If problems are observed, a gcc upgrade may be needed.
 247
 248           If unsure, say N.
 249
 250 menuconfig EMBEDDED
 251         bool "Configure standard kernel features (for small systems)"
 252         help
 253           This option allows certain base kernel options and settings
 254           to be disabled or tweaked. This is for specialized
 255           environments which can tolerate a "non-standard" kernel.
 256           Only use this if you really know what you are doing.
 257
 258 config KALLSYMS
 259          bool "Load all symbols for debugging/kksymoops" if EMBEDDED
 260          default y
 261          help
 262            Say Y here to let the kernel print out symbolic crash information and
 263            symbolic stack backtraces. This increases the size of the kernel
 264            somewhat, as all symbols have to be loaded into the kernel image.
 265
 266 config KALLSYMS_ALL
 267         bool "Include all symbols in kallsyms"
 268         depends on DEBUG_KERNEL && KALLSYMS
 269         help
 270            Normally kallsyms only contains the symbols of functions, for nicer
 271            OOPS messages.  Some debuggers can use kallsyms for other
 272            symbols too: say Y here to include all symbols, if you need them
 273            and you don't care about adding 300k to the size of your kernel.
 274
 275            Say N.
 276
 277 config KALLSYMS_EXTRA_PASS
 278         bool "Do an extra kallsyms pass"
 279         depends on KALLSYMS
 280         help
 281            If kallsyms is not working correctly, the build will fail with
 282            inconsistent kallsyms data.  If that occurs, log a bug report and
 283            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 284            Always say N here unless you find a bug in kallsyms, which must be
 285            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 286            you wait for kallsyms to be fixed.
 287
 288
 289 config HOTPLUG
 290         bool "Support for hot-pluggable devices" if EMBEDDED
 291         default y
 292         help
 293           This option is provided for the case where no hotplug or uevent
 294           capabilities is wanted by the kernel.  You should only consider
 295           disabling this option for embedded systems that do not use modules, a
 296           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 297
 298 config PRINTK
 299         default y
 300         bool "Enable support for printk" if EMBEDDED
 301         help
 302           This option enables normal printk support. Removing it
 303           eliminates most of the message strings from the kernel image
 304           and makes the kernel more or less silent. As this makes it
 305           very difficult to diagnose system problems, saying N here is
 306           strongly discouraged.
 307
 308 config BUG
 309         bool "BUG() support" if EMBEDDED
 310         default y
 311         help
 312           Disabling this option eliminates support for BUG and WARN, reducing
 313           the size of your kernel image and potentially quietly ignoring
 314           numerous fatal conditions. You should only consider disabling this
 315           option for embedded systems with no facilities for reporting errors.
 316           Just say Y.
 317
 318 config ELF_CORE
 319         default y
 320         bool "Enable ELF core dumps" if EMBEDDED
 321         help
 322           Enable support for generating core dumps. Disabling saves about 4k.
 323
 324 config BASE_FULL
 325         default y
 326         bool "Enable full-sized data structures for core" if EMBEDDED
 327         help
 328           Disabling this option reduces the size of miscellaneous core
 329           kernel data structures. This saves memory on small machines,
 330           but may reduce performance.
 331
 332 config FUTEX
 333         bool "Enable futex support" if EMBEDDED
 334         default y
 335         help
 336           Disabling this option will cause the kernel to be built without
 337           support for "fast userspace mutexes".  The resulting kernel may not
 338           run glibc-based applications correctly.
 339
 340 config EPOLL
 341         bool "Enable eventpoll support" if EMBEDDED
 342         default y
 343         help
 344           Disabling this option will cause the kernel to be built without
 345           support for epoll family of system calls.
 346
 347 config SHMEM
 348         bool "Use full shmem filesystem" if EMBEDDED
 349         default y
 350         depends on MMU
 351         help
 352           The shmem is an internal filesystem used to manage shared memory.
 353           It is backed by swap and manages resource limits. It is also exported
 354           to userspace as tmpfs if TMPFS is enabled. Disabling this
 355           option replaces shmem and tmpfs with the much simpler ramfs code,
 356           which may be appropriate on small systems without swap.
 357
 358 config CC_ALIGN_FUNCTIONS
 359         int "Function alignment" if EMBEDDED
 360         default 0
 361         help
 362           Align the start of functions to the next power-of-two greater than n,
 363           skipping up to n bytes.  For instance, 32 aligns functions
 364           to the next 32-byte boundary, but 24 would align to the next
 365           32-byte boundary only if this can be done by skipping 23 bytes or less.
 366           Zero means use compiler's default.
 367
 368 config CC_ALIGN_LABELS
 369         int "Label alignment" if EMBEDDED
 370         default 0
 371         help
 372           Align all branch targets to a power-of-two boundary, skipping
 373           up to n bytes like ALIGN_FUNCTIONS.  This option can easily
 374           make code slower, because it must insert dummy operations for
 375           when the branch target is reached in the usual flow of the code.
 376           Zero means use compiler's default.
 377
 378 config CC_ALIGN_LOOPS
 379         int "Loop alignment" if EMBEDDED
 380         default 0
 381         help
 382           Align loops to a power-of-two boundary, skipping up to n bytes.
 383           Zero means use compiler's default.
 384
 385 config CC_ALIGN_JUMPS
 386         int "Jump alignment" if EMBEDDED
 387         default 0
 388         help
 389           Align branch targets to a power-of-two boundary, for branch
 390           targets where the targets can only be reached by jumping,
 391           skipping up to n bytes like ALIGN_FUNCTIONS.  In this case,
 392           no dummy operations need be executed.
 393           Zero means use compiler's default.
 394
 395 config SLAB
 396         default y
 397         bool "Use full SLAB allocator" if EMBEDDED
 398         help
 399           Disabling this replaces the advanced SLAB allocator and
 400           kmalloc support with the drastically simpler SLOB allocator.
 401           SLOB is more space efficient but does not scale well and is
 402           more susceptible to fragmentation.
 403
 404 endmenu         # General setup
 405
 406 config TINY_SHMEM
 407         default !SHMEM
 408         bool
 409
 410 config BASE_SMALL
 411         int
 412         default 0 if BASE_FULL
 413         default 1 if !BASE_FULL
 414
 415 config SLOB
 416         default !SLAB
 417         bool
 418
 419 config OBSOLETE_INTERMODULE
 420         tristate
 421
 422 menu "Loadable module support"
 423
 424 config MODULES
 425         bool "Enable loadable module support"
 426         help
 427           Kernel modules are small pieces of compiled code which can
 428           be inserted in the running kernel, rather than being
 429           permanently built into the kernel.  You use the "modprobe"
 430           tool to add (and sometimes remove) them.  If you say Y here,
 431           many parts of the kernel can be built as modules (by
 432           answering M instead of Y where indicated): this is most
 433           useful for infrequently used options which are not required
 434           for booting.  For more information, see the man pages for
 435           modprobe, lsmod, modinfo, insmod and rmmod.
 436
 437           If you say Y here, you will need to run "make
 438           modules_install" to put the modules under /lib/modules/
 439           where modprobe can find them (you may need to be root to do
 440           this).
 441
 442           If unsure, say Y.
 443
 444 config MODULE_UNLOAD
 445         bool "Module unloading"
 446         depends on MODULES
 447         help
 448           Without this option you will not be able to unload any
 449           modules (note that some modules may not be unloadable
 450           anyway), which makes your kernel slightly smaller and
 451           simpler.  If unsure, say Y.
 452
 453 config MODULE_FORCE_UNLOAD
 454         bool "Forced module unloading"
 455         depends on MODULE_UNLOAD && EXPERIMENTAL
 456         help
 457           This option allows you to force a module to unload, even if the
 458           kernel believes it is unsafe: the kernel will remove the module
 459           without waiting for anyone to stop using it (using the -f option to
 460           rmmod).  This is mainly for kernel developers and desperate users.
 461           If unsure, say N.
 462
 463 config OBSOLETE_MODPARM
 464         bool
 465         default y
 466         depends on MODULES
 467         help
 468           You need this option to use module parameters on modules which
 469           have not been converted to the new module parameter system yet.
 470           If unsure, say Y.
 471
 472 config MODVERSIONS
 473         bool "Module versioning support"
 474         depends on MODULES
 475         help
 476           Usually, you have to use modules compiled with your kernel.
 477           Saying Y here makes it sometimes possible to use modules
 478           compiled for different kernels, by adding enough information
 479           to the modules to (hopefully) spot any changes which would
 480           make them incompatible with the kernel you are running.  If
 481           unsure, say N.
 482
 483 config MODULE_SRCVERSION_ALL
 484         bool "Source checksum for all modules"
 485         depends on MODULES
 486         help
 487           Modules which contain a MODULE_VERSION get an extra "srcversion"
 488           field inserted into their modinfo section, which contains a
 489           sum of the source files which made it.  This helps maintainers
 490           see exactly which source was used to build a module (since
 491           others sometimes change the module source without updating
 492           the version).  With this option, such a "srcversion" field
 493           will be created for all modules.  If unsure, say N.
 494
 495 config KMOD
 496         bool "Automatic kernel module loading"
 497         depends on MODULES
 498         help
 499           Normally when you have selected some parts of the kernel to
 500           be created as kernel modules, you must load them (using the
 501           "modprobe" command) before you can use them. If you say Y
 502           here, some parts of the kernel will be able to load modules
 503           automatically: when a part of the kernel needs a module, it
 504           runs modprobe with the appropriate arguments, thereby
 505           loading the module if it is available.  If unsure, say Y.
 506
 507 config STOP_MACHINE
 508         bool
 509         default y
 510         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 511         help
 512           Need stop_machine() primitive.
 513 endmenu
 514
 515 menu "Block layer"
 516 source "block/Kconfig"
 517 endmenu