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  24           drivers that have been replaced by something else, and/or are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" if EMBEDDED
 155         default y
 156         ---help---
 157           The sysctl interface provides a means of dynamically changing
 158           certain kernel parameters and variables on the fly without requiring
 159           a recompile of the kernel or reboot of the system.  The primary
 160           interface consists of a system call, but if you say Y to "/proc
 161           file system support", a tree of modifiable sysctl entries will be
 162           generated beneath the /proc/sys directory. They are explained in the
 163           files in <file:Documentation/sysctl/>.  Note that enabling this
 164           option will enlarge the kernel by at least 8 KB.
 165
 166           As it is generally a good thing, you should say Y here unless
 167           building a kernel for install/rescue disks or your system is very
 168           limited in memory.
 169
 170 config AUDIT
 171         bool "Auditing support"
 172         depends on NET
 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.  To use audit's filesystem watch feature, please
 187           ensure that INOTIFY is configured.
 188
 189 config IKCONFIG
 190         bool "Kernel .config support"
 191         ---help---
 192           This option enables the complete Linux kernel ".config" file
 193           contents to be saved in the kernel. It provides documentation
 194           of which kernel options are used in a running kernel or in an
 195           on-disk kernel.  This information can be extracted from the kernel
 196           image file with the script scripts/extract-ikconfig and used as
 197           input to rebuild the current kernel or to build another kernel.
 198           It can also be extracted from a running kernel by reading
 199           /proc/config.gz if enabled (below).
 200
 201 config IKCONFIG_PROC
 202         bool "Enable access to .config through /proc/config.gz"
 203         depends on IKCONFIG && PROC_FS
 204         ---help---
 205           This option enables access to the kernel configuration file
 206           through /proc/config.gz.
 207
 208 config CPUSETS
 209         bool "Cpuset support"
 210         depends on SMP
 211         help
 212           This option will let you create and manage CPUSETs which
 213           allow dynamically partitioning a system into sets of CPUs and
 214           Memory Nodes and assigning tasks to run only within those sets.
 215           This is primarily useful on large SMP or NUMA systems.
 216
 217           Say N if unsure.
 218
 219 config RELAY
 220         bool "Kernel->user space relay support (formerly relayfs)"
 221         help
 222           This option enables support for relay interface support in
 223           certain file systems (such as debugfs).
 224           It is designed to provide an efficient mechanism for tools and
 225           facilities to relay large amounts of data from kernel space to
 226           user space.
 227
 228           If unsure, say N.
 229
 230 source "usr/Kconfig"
 231
 232 config UID16
 233         bool "Enable 16-bit UID system calls" if EMBEDDED
 234         depends on ARM || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
 235         default y
 236         help
 237           This enables the legacy 16-bit UID syscall wrappers.
 238
 239 config VM86
 240         depends X86
 241         default y
 242         bool "Enable VM86 support" if EMBEDDED
 243         help
 244           This option is required by programs like DOSEMU to run 16-bit legacy
 245           code on X86 processors. It also may be needed by software like
 246           XFree86 to initialize some video cards via BIOS. Disabling this
 247           option saves about 6k.
 248
 249 config CC_OPTIMIZE_FOR_SIZE
 250         bool "Optimize for size (Look out for broken compilers!)"
 251         default y
 252         depends on ARM || H8300 || EXPERIMENTAL
 253         help
 254           Enabling this option will pass "-Os" instead of "-O2" to gcc
 255           resulting in a smaller kernel.
 256
 257           WARNING: some versions of gcc may generate incorrect code with this
 258           option.  If problems are observed, a gcc upgrade may be needed.
 259
 260           If unsure, say N.
 261
 262 menuconfig EMBEDDED
 263         bool "Configure standard kernel features (for small systems)"
 264         help
 265           This option allows certain base kernel options and settings
 266           to be disabled or tweaked. This is for specialized
 267           environments which can tolerate a "non-standard" kernel.
 268           Only use this if you really know what you are doing.
 269
 270 config KALLSYMS
 271          bool "Load all symbols for debugging/kksymoops" if EMBEDDED
 272          default y
 273          help
 274            Say Y here to let the kernel print out symbolic crash information and
 275            symbolic stack backtraces. This increases the size of the kernel
 276            somewhat, as all symbols have to be loaded into the kernel image.
 277
 278 config KALLSYMS_ALL
 279         bool "Include all symbols in kallsyms"
 280         depends on DEBUG_KERNEL && KALLSYMS
 281         help
 282            Normally kallsyms only contains the symbols of functions, for nicer
 283            OOPS messages.  Some debuggers can use kallsyms for other
 284            symbols too: say Y here to include all symbols, if you need them
 285            and you don't care about adding 300k to the size of your kernel.
 286
 287            Say N.
 288
 289 config KALLSYMS_EXTRA_PASS
 290         bool "Do an extra kallsyms pass"
 291         depends on KALLSYMS
 292         help
 293            If kallsyms is not working correctly, the build will fail with
 294            inconsistent kallsyms data.  If that occurs, log a bug report and
 295            turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
 296            Always say N here unless you find a bug in kallsyms, which must be
 297            reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 298            you wait for kallsyms to be fixed.
 299
 300
 301 config HOTPLUG
 302         bool "Support for hot-pluggable devices" if EMBEDDED
 303         default y
 304         help
 305           This option is provided for the case where no hotplug or uevent
 306           capabilities is wanted by the kernel.  You should only consider
 307           disabling this option for embedded systems that do not use modules, a
 308           dynamic /dev tree, or dynamic device discovery.  Just say Y.
 309
 310 config PRINTK
 311         default y
 312         bool "Enable support for printk" if EMBEDDED
 313         help
 314           This option enables normal printk support. Removing it
 315           eliminates most of the message strings from the kernel image
 316           and makes the kernel more or less silent. As this makes it
 317           very difficult to diagnose system problems, saying N here is
 318           strongly discouraged.
 319
 320 config BUG
 321         bool "BUG() support" if EMBEDDED
 322         default y
 323         help
 324           Disabling this option eliminates support for BUG and WARN, reducing
 325           the size of your kernel image and potentially quietly ignoring
 326           numerous fatal conditions. You should only consider disabling this
 327           option for embedded systems with no facilities for reporting errors.
 328           Just say Y.
 329
 330 config ELF_CORE
 331         default y
 332         bool "Enable ELF core dumps" if EMBEDDED
 333         help
 334           Enable support for generating core dumps. Disabling saves about 4k.
 335
 336 config BASE_FULL
 337         default y
 338         bool "Enable full-sized data structures for core" if EMBEDDED
 339         help
 340           Disabling this option reduces the size of miscellaneous core
 341           kernel data structures. This saves memory on small machines,
 342           but may reduce performance.
 343
 344 config FUTEX
 345         bool "Enable futex support" if EMBEDDED
 346         default y
 347         help
 348           Disabling this option will cause the kernel to be built without
 349           support for "fast userspace mutexes".  The resulting kernel may not
 350           run glibc-based applications correctly.
 351
 352 config EPOLL
 353         bool "Enable eventpoll support" if EMBEDDED
 354         default y
 355         help
 356           Disabling this option will cause the kernel to be built without
 357           support for epoll family of system calls.
 358
 359 config SHMEM
 360         bool "Use full shmem filesystem" if EMBEDDED
 361         default y
 362         depends on MMU
 363         help
 364           The shmem is an internal filesystem used to manage shared memory.
 365           It is backed by swap and manages resource limits. It is also exported
 366           to userspace as tmpfs if TMPFS is enabled. Disabling this
 367           option replaces shmem and tmpfs with the much simpler ramfs code,
 368           which may be appropriate on small systems without swap.
 369
 370 config SLAB
 371         default y
 372         bool "Use full SLAB allocator" if EMBEDDED
 373         help
 374           Disabling this replaces the advanced SLAB allocator and
 375           kmalloc support with the drastically simpler SLOB allocator.
 376           SLOB is more space efficient but does not scale well and is
 377           more susceptible to fragmentation.
 378
 379 endmenu         # General setup
 380
 381 config TINY_SHMEM
 382         default !SHMEM
 383         bool
 384
 385 config BASE_SMALL
 386         int
 387         default 0 if BASE_FULL
 388         default 1 if !BASE_FULL
 389
 390 config SLOB
 391         default !SLAB
 392         bool
 393
 394 menu "Loadable module support"
 395
 396 config MODULES
 397         bool "Enable loadable module support"
 398         help
 399           Kernel modules are small pieces of compiled code which can
 400           be inserted in the running kernel, rather than being
 401           permanently built into the kernel.  You use the "modprobe"
 402           tool to add (and sometimes remove) them.  If you say Y here,
 403           many parts of the kernel can be built as modules (by
 404           answering M instead of Y where indicated): this is most
 405           useful for infrequently used options which are not required
 406           for booting.  For more information, see the man pages for
 407           modprobe, lsmod, modinfo, insmod and rmmod.
 408
 409           If you say Y here, you will need to run "make
 410           modules_install" to put the modules under /lib/modules/
 411           where modprobe can find them (you may need to be root to do
 412           this).
 413
 414           If unsure, say Y.
 415
 416 config MODULE_UNLOAD
 417         bool "Module unloading"
 418         depends on MODULES
 419         help
 420           Without this option you will not be able to unload any
 421           modules (note that some modules may not be unloadable
 422           anyway), which makes your kernel slightly smaller and
 423           simpler.  If unsure, say Y.
 424
 425 config MODULE_FORCE_UNLOAD
 426         bool "Forced module unloading"
 427         depends on MODULE_UNLOAD && EXPERIMENTAL
 428         help
 429           This option allows you to force a module to unload, even if the
 430           kernel believes it is unsafe: the kernel will remove the module
 431           without waiting for anyone to stop using it (using the -f option to
 432           rmmod).  This is mainly for kernel developers and desperate users.
 433           If unsure, say N.
 434
 435 config MODVERSIONS
 436         bool "Module versioning support"
 437         depends on MODULES
 438         help
 439           Usually, you have to use modules compiled with your kernel.
 440           Saying Y here makes it sometimes possible to use modules
 441           compiled for different kernels, by adding enough information
 442           to the modules to (hopefully) spot any changes which would
 443           make them incompatible with the kernel you are running.  If
 444           unsure, say N.
 445
 446 config MODULE_SRCVERSION_ALL
 447         bool "Source checksum for all modules"
 448         depends on MODULES
 449         help
 450           Modules which contain a MODULE_VERSION get an extra "srcversion"
 451           field inserted into their modinfo section, which contains a
 452           sum of the source files which made it.  This helps maintainers
 453           see exactly which source was used to build a module (since
 454           others sometimes change the module source without updating
 455           the version).  With this option, such a "srcversion" field
 456           will be created for all modules.  If unsure, say N.
 457
 458 config KMOD
 459         bool "Automatic kernel module loading"
 460         depends on MODULES
 461         help
 462           Normally when you have selected some parts of the kernel to
 463           be created as kernel modules, you must load them (using the
 464           "modprobe" command) before you can use them. If you say Y
 465           here, some parts of the kernel will be able to load modules
 466           automatically: when a part of the kernel needs a module, it
 467           runs modprobe with the appropriate arguments, thereby
 468           loading the module if it is available.  If unsure, say Y.
 469
 470 config STOP_MACHINE
 471         bool
 472         default y
 473         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
 474         help
 475           Need stop_machine() primitive.
 476 endmenu
 477
 478 menu "Block layer"
 479 source "block/Kconfig"
 480 endmenu