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NAME

       xorg.conf, xorg.conf.d - configuration files for Xorg X server

INTRODUCTION

       Xorg  supports  several mechanisms for supplying/obtaining configuration and run-time parameters: command
       line options, environment variables, the xorg.conf and xorg.conf.d configuration  files,  auto-detection,
       and fallback defaults. When the same information is supplied in more than one way, the highest precedence
       mechanism is used. The list of mechanisms is ordered from highest precedence to lowest. Note that not all
       parameters  can be supplied via all methods. The available command line options and environment variables
       (and some defaults) are described in the Xserver(1) and Xorg(1) manual  pages.  Most  configuration  file
       parameters, with their defaults, are described below. Driver and module specific configuration parameters
       are described in the relevant driver or module manual page.

DESCRIPTION

       Xorg uses a configuration file called xorg.conf and files ending in the suffix .conf from  the  directory
       xorg.conf.d  for  its  initial  setup.  The xorg.conf configuration file is searched for in the following
       places when the server is started as a normal user:

           /etc/X11/<cmdline>
           /usr/etc/X11/<cmdline>
           /etc/X11/$XORGCONFIG
           /usr/etc/X11/$XORGCONFIG
           /etc/X11/xorg.conf
           /etc/xorg.conf
           /usr/etc/X11/xorg.conf.<hostname>
           /usr/etc/X11/xorg.conf
           /usr/lib/X11/xorg.conf.<hostname>
           /usr/lib/X11/xorg.conf

       where <cmdline> is a relative path (with no “..” components) specified  with  the  -config  command  line
       option,  $XORGCONFIG  is  the  relative  path  (with  no  “..”  components) specified by that environment
       variable, and <hostname> is the machine's hostname as reported by gethostname(3).

       When the Xorg server is started by the “root” user, the config file search locations are as follows:

           <cmdline>
           /etc/X11/<cmdline>
           /usr/etc/X11/<cmdline>
           $XORGCONFIG
           /etc/X11/$XORGCONFIG
           /usr/etc/X11/$XORGCONFIG
           /etc/X11/xorg.conf
           /etc/xorg.conf
           /usr/etc/X11/xorg.conf.<hostname>
           /usr/etc/X11/xorg.conf
           /usr/lib/X11/xorg.conf.<hostname>
           /usr/lib/X11/xorg.conf

       where <cmdline> is the path specified with the -config command line option  (which  may  be  absolute  or
       relative),  $XORGCONFIG  is the path specified by that environment variable (absolute or relative), $HOME
       is the path specified by that environment variable (usually the home directory), and  <hostname>  is  the
       machine's hostname as reported by gethostname(3).

       Additional  configuration  files are searched for in the following directories when the server is started
       as a normal user:

           /etc/X11/<cmdline>
           /etc/X11/<cmdline>
           /etc/X11/xorg.conf.d
           /etc/X11/xorg.conf.d

       where <cmdline> is a relative path (with no “..” components) specified with the -configdir  command  line
       option.

       When the Xorg server is started by the “root” user, the config directory search locations are as follows:

           <cmdline>
           /etc/X11/<cmdline>
           /etc/X11/<cmdline>
           /etc/X11/xorg.conf.d
           /etc/X11/xorg.conf.d

       where  <cmdline>  is the path specified with the -configdir command line option (which may be absolute or
       relative).

       Finally, configuration files will also be searched for in a directory reserved for system use.   This  is
       to separate configuration files from the vendor or 3rd party packages from those of local administration.
       These files are found in the following directory:

           /usr/share/X11/xorg.conf.d

       The xorg.conf and xorg.conf.d files are composed of a number of sections which  may  be  present  in  any
       order, or omitted to use default configuration values.  Each section has the form:

           Section  "SectionName"
               SectionEntry
               ...
           EndSection

       The section names are:

           Files          File pathnames
           ServerFlags    Server flags
           Module         Dynamic module loading
           Extensions     Extension enabling
           InputDevice    Input device description
           InputClass     Input class description
           OutputClass    Output class description
           Device         Graphics device description
           VideoAdaptor   Xv video adaptor description
           Monitor        Monitor description
           Modes          Video modes descriptions
           Screen         Screen configuration
           ServerLayout   Overall layout
           DRI            DRI-specific configuration
           Vendor         Vendor-specific configuration

       The  following  obsolete  section  names  are still recognised for compatibility purposes.  In new config
       files, the InputDevice section should be used instead.

           Keyboard       Keyboard configuration
           Pointer        Pointer/mouse configuration

       The old XInput section is no longer recognised.

       The ServerLayout sections are at the highest level.  They bind together the input and output devices that
       will  be used in a session.  The input devices are described in the InputDevice sections.  Output devices
       usually consist of multiple independent components  (e.g.,  a  graphics  board  and  a  monitor).   These
       multiple components are bound together in the Screen sections, and it is these that are referenced by the
       ServerLayout section.  Each Screen section binds together a graphics board and a monitor.   The  graphics
       boards are described in the Device sections, and the monitors are described in the Monitor sections.

       Config  file  keywords  are  case-insensitive,  and  “_” characters are ignored.  Most strings (including
       Option names) are also case-insensitive, and insensitive to white space and “_” characters.

       Each config file entry usually takes up a single line in the file.  They consist of a keyword,  which  is
       possibly  followed  by one or more arguments, with the number and types of the arguments depending on the
       keyword.  The argument types are:

           Integer     an integer number in decimal, hex or octal
           Real        a floating point number
           String      a string enclosed in double quote marks (")

       Note: hex integer values must be prefixed with “0x”, and octal values with “0”.

       A special keyword called Option may be used to provide  free-form  data  to  various  components  of  the
       server.   The Option keyword takes either one or two string arguments.  The first is the option name, and
       the optional second argument is the option value.  Some commonly used option value types include:

           Integer     an integer number in decimal, hex or octal
           Real        a floating point number
           String      a sequence of characters
           Boolean     a boolean value (see below)
           Frequency   a frequency value (see below)

       Note that all Option values, not just strings, must be enclosed in quotes.

       Boolean options may optionally have a value specified.  When no value is specified, the option's value is
       TRUE.  The following boolean option values are recognised as TRUE:

           1, on, true, yes

       and the following boolean option values are recognised as FALSE:

           0, off, false, no

       If an option name is prefixed with "No", then the option value is negated.

       Example: the following option entries are equivalent:

           Option "Accel"   "Off"
           Option "NoAccel"
           Option "NoAccel" "On"
           Option "Accel"   "false"
           Option "Accel"   "no"

       Frequency  option  values  consist  of  a real number that is optionally followed by one of the following
       frequency units:

           Hz, k, kHz, M, MHz

       When the unit name is omitted, the correct units will be determined from the value and  the  expectations
       of  the  appropriate range of the value.  It is recommended that the units always be specified when using
       frequency option values to avoid any errors in determining the value.

FILES SECTION

       The Files section is used to specify some path names required by the server.  Some  of  these  paths  can
       also  be  set from the command line (see Xserver(1) and Xorg(1)).  The command line settings override the
       values specified in the config file.  The Files section is optional, as are all of the entries  that  may
       appear in it.

       The entries that can appear in this section are:

       FontPath "path"
              sets  the  search path for fonts.  This path is a comma separated list of font path elements which
              the Xorg server searches for font databases.  Multiple FontPath entries may be specified, and they
              will  be  concatenated  to  build  up  the fontpath used by the server.  Font path elements can be
              absolute directory paths, catalogue directories or a font server identifier. The  formats  of  the
              later two are explained below:

              Catalogue directories:

                  Catalogue  directories can be specified using the prefix catalogue: before the directory name.
                  The directory can then be populated with symlinks pointing to the real font directories, using
                  the following syntax in the symlink name:

                      <identifier>:[attribute]:pri=<priority>

                  where  <identifier>  is  an alphanumeric identifier, [attribute] is an attribute which will be
                  passed to the underlying FPE and <priority> is a number  used  to  order  the  fontfile  FPEs.
                  Examples:

                      75dpi:unscaled:pri=20 -> /usr/share/X11/fonts/75dpi
                      gscript:pri=60 -> /usr/share/fonts/default/ghostscript
                      misc:unscaled:pri=10 -> /usr/share/X11/fonts/misc

              Font server identifiers:

                  Font server identifiers have the form:

                      <trans>/<hostname>:<port-number>

                  where  <trans>  is  the  transport  type  to use to connect to the font server (e.g., unix for
                  UNIX-domain sockets or tcp for a TCP/IP connection), <hostname> is the hostname of the machine
                  running  the  font  server,  and  <port-number>  is  the  port  number that the font server is
                  listening on (usually 7100).

              When this entry is not specified in the config file, the server  falls  back  to  the  compiled-in
              default  font  path,  which  contains  the following font path elements (which can be set inside a
              catalogue directory):

                  /usr/share/fonts/X11/misc/
                  /usr/share/fonts/X11/TTF/
                  /usr/share/fonts/X11/OTF/
                  /usr/share/fonts/X11/Type1/
                  /usr/share/fonts/X11/100dpi/
                  /usr/share/fonts/X11/75dpi/

              Font path elements that are found to be invalid are removed from the font  path  when  the  server
              starts up.

       ModulePath "path"
              sets  the  search  path  for loadable Xorg server modules.  This path is a comma separated list of
              directories which the Xorg server searches for loadable modules loading in  the  order  specified.
              Multiple  ModulePath  entries  may be specified, and they will be concatenated to build the module
              search path used by the server.  The default module path is

                  /usr/lib/xorg/modules

       XkbDir "path"
              sets the base directory for keyboard layout files.  The -xkbdir command line option can be used to
              override this.  The default directory is

                  /usr/share/X11/xkb

SERVERFLAGS SECTION

       In  addition  to  options  specific to this section (described below), the ServerFlags section is used to
       specify some global Xorg server options.  All of the entries in this section are  Options,  although  for
       compatibility  purposes  some of the old style entries are still recognised.  Those old style entries are
       not documented here, and using them is discouraged.  The ServerFlags section  is  optional,  as  are  the
       entries that may be specified in it.

       Options  specified  in  this  section  (with  the  exception  of the "DefaultServerLayout" Option) may be
       overridden by  Options  specified  in  the  active  ServerLayout  section.   Options  with  command  line
       equivalents  are  overridden  when their command line equivalent is used.  The options recognised by this
       section are:

       Option "DefaultServerLayout"  "layout-id"
              This specifies the default ServerLayout section to use in the absence of the -layout command  line
              option.

       Option "NoTrapSignals"  "boolean"
              This  prevents  the  Xorg  server  from  trapping  a range of unexpected fatal signals and exiting
              cleanly.  Instead, the Xorg server will die and drop core where the fault occurred.   The  default
              behaviour  is  for  the  Xorg  server to exit cleanly, but still drop a core file.  In general you
              never want to use this option unless you are debugging an Xorg server problem and know how to deal
              with the consequences.

       Option "DontVTSwitch"  "boolean"
              This  disallows  the  use  of  the  Ctrl+Alt+Fn  sequence  (where Fn refers to one of the numbered
              function keys).  That sequence is normally  used  to  switch  to  another  "virtual  terminal"  on
              operating  systems  that have this feature.  When this option is enabled, that key sequence has no
              special meaning and is passed to clients.  Default: off.

       Option "DontZap"  "boolean"
              This disallows the  use  of  the  Terminate_Server  XKB  action  (usually  on  Ctrl+Alt+Backspace,
              depending  on XKB options).  This action is normally used to terminate the Xorg server.  When this
              option is enabled, the action has no effect.  Default: off.

       Option "DontZoom"  "boolean"
              This disallows the use of the Ctrl+Alt+Keypad-Plus  and  Ctrl+Alt+Keypad-Minus  sequences.   These
              sequences  allows  you  to  switch  between  video  modes.  When this option is enabled, those key
              sequences have no special meaning and are passed to clients.  Default: off.

       Option "DisableVidModeExtension"  "boolean"
              This disables the parts of the VidMode extension used by the xvidtune client that can be  used  to
              change the video modes.  Default: the VidMode extension is enabled.

       Option "AllowNonLocalXvidtune"  "boolean"
              This allows the xvidtune client (and other clients that use the VidMode extension) to connect from
              another host.  Default: off.

       Option "AllowMouseOpenFail"  "boolean"
              This tells the mousedrv(4) and vmmouse(4) drivers to not report failure if the mouse device  can't
              be opened/initialised.  It has no effect on the evdev(4) or other drivers.  Default: false.

       Option "BlankTime"  "time"
              sets  the inactivity timeout for the blank phase of the screensaver.  time is in minutes.  This is
              equivalent to the Xorg server's -s flag, and the value can be changed at  run-time  with  xset(1).
              Default: 10 minutes.

       Option "StandbyTime"  "time"
              sets the inactivity timeout for the standby phase of DPMS mode.  time is in minutes, and the value
              can be changed at run-time with xset(1).  Default: 10 minutes.  This is  only  suitable  for  VESA
              DPMS  compatible  monitors, and may not be supported by all video drivers.  It is only enabled for
              screens that have the "DPMS" option set (see the MONITOR section below).

       Option "SuspendTime"  "time"
              sets the inactivity timeout for the suspend phase of DPMS mode.  time is in minutes, and the value
              can  be  changed  at  run-time with xset(1).  Default: 10 minutes.  This is only suitable for VESA
              DPMS compatible monitors, and may not be supported by all video drivers.  It is only  enabled  for
              screens that have the "DPMS" option set (see the MONITOR section below).

       Option "OffTime"  "time"
              sets the inactivity timeout for the off phase of DPMS mode.  time is in minutes, and the value can
              be changed at run-time with xset(1).  Default: 10 minutes.  This is only suitable  for  VESA  DPMS
              compatible  monitors,  and  may  not  be  supported  by all video drivers.  It is only enabled for
              screens that have the "DPMS" option set (see the MONITOR section below).

       Option "MaxClients"  "integer"
              Set the maximum number of clients allowed to connect to the X server.  Acceptable values  are  64,
              128, 256 or 512.

       Option "Pixmap"  "bpp"
              This  sets the pixmap format to use for depth 24.  Allowed values for bpp are 24 and 32.  Default:
              32 unless driver constraints don't allow this (which is rare).  Note: some  clients  don't  behave
              well when this value is set to 24.

       Option "NoPM"  "boolean"
              Disables  something  to  do  with  power management events.  Default: PM enabled on platforms that
              support it.

       Option "Xinerama"  "boolean"
              enable or disable XINERAMA extension.  Default is disabled.

       Option "IndirectGLX" "boolean"
              enable or disable indirect GLX contexts. Indirect GLX contexts are disabled by default.

       Option "DRI2" "boolean"
              enable or disable DRI2. DRI2 is disabled by default.

       Option "GlxVisuals" "string"
              This option controls how many GLX visuals the GLX modules sets up.  The default value is  typical,
              which  will  setup  up a typical subset of the GLXFBConfigs provided by the driver as GLX visuals.
              Other options are minimal, which will set up the minimal set allowed by the GLX specification  and
              all which will setup GLX visuals for all GLXFBConfigs.

       Option "UseDefaultFontPath" "boolean"
              Include  the  default  font path even if other paths are specified in xorg.conf. If enabled, other
              font paths are included as well. Enabled by default.

       Option "IgnoreABI" "boolean"
              Allow modules built for a different, potentially incompatible version of the  X  server  to  load.
              Disabled by default.

       Option "AutoAddDevices" "boolean"
              If  this  option is disabled, then no devices will be added from the HAL or udev backends. Enabled
              by default.

       Option "AutoEnableDevices" "boolean"
              If this option is disabled, then the devices will be added  (and  the  DevicePresenceNotify  event
              sent), but not enabled, thus leaving policy up to the client.  Enabled by default.

       Option "AutoAddGPU" "boolean"
              If  this  option  is disabled, then no GPU devices will be added from the udev backend. Enabled by
              default. (May need to be disabled to setup Xinerama).

       Option "AutoBindGPU"  "boolean"
              If enabled then secondary GPUs will be automatically set up as output-sinks  and  offload-sources.
              Making  e.g. laptop outputs connected only to the secondary GPU directly available for use without
              needing to run "xrandr --setprovideroutputsource". Enabled by default.

       Option "Log" "string"
              This option controls whether the log  is  flushed  and/or  synced  to  disk  after  each  message.
              Possible values are flush or sync.  Unset by default.

MODULE SECTION

       The  Module  section  is  used  to  specify  which Xorg server modules should be loaded.  This section is
       ignored when the Xorg server is built in static form.  The  type  of  modules  normally  loaded  in  this
       section  are  Xorg  server extension modules.  Most other module types are loaded automatically when they
       are needed via other mechanisms.  The Module section is optional, as are all of the entries that  may  be
       specified in it.

       Entries in this section may be in two forms.  The first and most commonly used form is an entry that uses
       the Load keyword, as described here:

       Load  "modulename"
              This instructs the server to load the module called modulename.  The module name given  should  be
              the  module's  standard  name, not the module file name.  The standard name is case-sensitive, and
              does not include the “lib” or “cyg” prefixes, or the “.so” or “.dll” suffixes.

              Example: the DRI extension module can be loaded with the following entry:

                  Load "dri"

       Disable  "modulename"
              This instructs the server to not load the module called modulename.  Some modules  are  loaded  by
              default  in  the  server,  and this overrides that default. If a Load instruction is given for the
              same module, it overrides the Disable instruction and the module is loaded. The module name  given
              should  be the module's standard name, not the module file name. As with the Load instruction, the
              standard name is case-sensitive, and does not include the "lib" prefix,  or  the  ".a",  ".o",  or
              ".so" suffixes.

       The  second  form  of  entry  is  a  SubSection,  with the subsection name being the module name, and the
       contents of the SubSection being Options that are passed to the module when it is loaded.

       Example: the extmod module (which contains a miscellaneous group of server  extensions)  can  be  loaded,
       with the XFree86-DGA extension disabled by using the following entry:

           SubSection "extmod"
              Option  "omit XFree86-DGA"
           EndSubSection

       Modules  are  searched for in each directory specified in the ModulePath search path, and in the drivers,
       extensions, input, internal, and multimedia subdirectories of each of those directories.  In addition  to
       this, operating system specific subdirectories of all the above are searched first if they exist.

       To see what extension modules are available, check the extensions subdirectory under:

           /usr/lib/xorg/modules

       The  “extmod”,  “dbe”,  “dri”, “dri2”, “glx”, and “record” extension modules are loaded automatically, if
       they are present, unless disabled with "Disable" entries.  It is  recommended  that  at  very  least  the
       “extmod”  extension  module be loaded.  If it isn't, some commonly used server extensions (like the SHAPE
       extension) will not be available.

EXTENSIONS SECTION

       The Extensions section is used to specify which X11 protocol extensions should be  enabled  or  disabled.
       The Extensions section is optional, as are all of the entries that may be specified in it.

       Entries  in  this  section  are  listed  as Option statements with the name of the extension as the first
       argument, and a boolean value as the second.  The extension name is case-sensitive, and matches the  form
       shown in the output of "Xorg -extension ?".

              Example: the MIT-SHM extension can be disabled with the following entry:

                  Section "Extensions"
                      Option "MIT-SHM" "Disable"
                  EndSection

INPUTDEVICE SECTION

       The config file may have multiple InputDevice sections.  Recent X servers employ HAL or udev backends for
       input device enumeration and input hotplugging. It  is  usually  not  necessary  to  provide  InputDevice
       sections  in  the  xorg.conf if hotplugging is in use (i.e. AutoAddDevices is enabled). If hotplugging is
       enabled, InputDevice sections using the mouse, kbd and vmmouse driver will be ignored.

       If hotplugging is disabled, there will normally be at least two: one for the core (primary) keyboard  and
       one  for  the  core  pointer.  If either of these two is missing, a default configuration for the missing
       ones will be used. In the absence of an explicitly specified core input  device,  the  first  InputDevice
       marked  as CorePointer (or CoreKeyboard) is used.  If there is no match there, the first InputDevice that
       uses  the  “mouse”  (or  “kbd”)  driver  is  used.   The  final  fallback  is  to  use  built-in  default
       configurations.  Currently the default configuration may not work as expected on all platforms.

       InputDevice sections have the following format:

           Section "InputDevice"
               Identifier "name"
               Driver     "inputdriver"
               options
               ...
           EndSection

       The  Identifier  and  Driver  entries  are  required  in all InputDevice sections.  All other entries are
       optional.

       The Identifier entry specifies the unique name for this input device.  The  Driver  entry  specifies  the
       name of the driver to use for this input device.  When using the loadable server, the input driver module
       "inputdriver" will be loaded for each active InputDevice section.  An InputDevice section  is  considered
       active  if  it  is  referenced by an active ServerLayout section, if it is referenced by the -keyboard or
       -pointer command line options, or if it is selected implicitly as the core pointer or keyboard device  in
       the  absence  of  such  explicit  references.  The most commonly used input drivers are evdev(4) on Linux
       systems, and kbd(4) and mousedrv(4) on other platforms.

       InputDevice sections recognise some driver-independent  Options,  which  are  described  here.   See  the
       individual input driver manual pages for a description of the device-specific options.

       Option "AutoServerLayout"  "boolean"
              Always  add  the  device  to  the  ServerLayout  section used by this instance of the server. This
              affects implied layouts as well as explicit layouts specified in the configuration and/or  on  the
              command line.

       Option "CorePointer"
              Deprecated, see Floating

       Option "CoreKeyboard"
              Deprecated, see Floating

       Option "AlwaysCore"  "boolean"
              Deprecated, see Floating

       Option "SendCoreEvents"  "boolean"
              Deprecated, see Floating

       Option "Floating"  "boolean"
              When  enabled,  the  input device is set up floating and does not report events through any master
              device or control a cursor. The device is only available to clients using the  X  Input  Extension
              API.  This  option is disabled by default.  The options CorePointer, CoreKeyboard, AlwaysCore, and
              SendCoreEvents, are the inverse of option Floating (i.e.  SendCoreEvents  "on"  is  equivalent  to
              Floating "off" ).

              This  option  controls  the  startup  behavior only, a device may be reattached or set floating at
              runtime.

       Option "TransformationMatrix" "a b c d e f g h i"
              Specifies the 3x3 transformation matrix for absolute input devices. The input device will be bound
              to the area given in the matrix.  In most configurations, "a" and "e" specify the width and height
              of the area the device is bound to, and "c" and "f" specify the x and y offset of the  area.   The
              value  range  is  0 to 1, where 1 represents the width or height of all root windows together, 0.5
              represents half the area, etc. The values represent a 3x3 matrix, with the first, second and third
              group  of  three  values representing the first, second and third row of the matrix, respectively.
              The identity matrix is "1 0 0 0 1 0 0 0 1".

   POINTER ACCELERATION
       For pointing devices, the following options control how the pointer is accelerated  or  decelerated  with
       respect  to  physical device motion. Most of these can be adjusted at runtime, see the xinput(1) man page
       for details. Only the most important acceleration options are discussed here.

       Option "AccelerationProfile"  "integer"
              Select the profile. In layman's terms, the profile constitutes the "feeling" of the  acceleration.
              More  formally, it defines how the transfer function (actual acceleration as a function of current
              device velocity and acceleration controls) is constructed. This is mainly  a  matter  of  personal
              preference.

              0      classic (mostly compatible)
             -1      none (only constant deceleration is applied)
              1      device-dependent
              2      polynomial (polynomial function)
              3      smooth linear (soft knee, then linear)
              4      simple (normal when slow, otherwise accelerated)
              5      power (power function)
              6      linear (more speed, more acceleration)
              7      limited (like linear, but maxes out at threshold)

       Option "ConstantDeceleration"  "real"
              Makes  the  pointer  go  deceleration  times  slower  than normal. Most useful for high-resolution
              devices. A value between 0 and 1 will speed up the pointer.

       Option "AdaptiveDeceleration"  "real"
              Allows to actually decelerate  the  pointer  when  going  slow.  At  most,  it  will  be  adaptive
              deceleration times slower. Enables precise pointer placement without sacrificing speed.

       Option "AccelerationScheme"  "string"
              Selects the scheme, which is the underlying algorithm.

              predictable   default algorithm (behaving more predictable)
              lightweight   old acceleration code (as specified in the X protocol spec)
              none          no acceleration or deceleration

       Option "AccelerationNumerator"  "integer"

       Option "AccelerationDenominator"  "integer"
              Set  numerator  and  denominator of the acceleration factor. The acceleration factor is a rational
              which, together with threshold, can be used to tweak profiles to suit the users needs. The  simple
              and  limited  profiles use it directly (i.e. they accelerate by the factor), for other profiles it
              should hold that a higher  acceleration  factor  leads  to  a  faster  pointer.  Typically,  1  is
              unaccelerated and values up to 5 are sensible.

       Option "AccelerationThreshold"  "integer"
              Set  the  threshold,  which  is roughly the velocity (usually device units per 10 ms) required for
              acceleration to become effective. The precise effect varies with the profile however.

INPUTCLASS SECTION

       The config file may have multiple InputClass sections.  These sections  are  optional  and  are  used  to
       provide  configuration  for a class of input devices as they are automatically added. An input device can
       match more than one InputClass section. Each class can override settings from a previous class, so it  is
       best to arrange the sections with the most generic matches first.

       InputClass sections have the following format:

           Section "InputClass"
               Identifier  "name"
               entries
               ...
               options
               ...
           EndSection

       The Identifier entry is required in all InputClass sections.  All other entries are optional.

       The Identifier entry specifies the unique name for this input class.  The Driver entry specifies the name
       of the driver to use for this input device.  After all classes  have  been  examined,  the  "inputdriver"
       module from the first Driver entry will be enabled when using the loadable server.

       When  an  input  device  is  automatically  added, its characteristics are checked against all InputClass
       sections. Each section can contain optional entries to narrow the match of the  class.  If  none  of  the
       optional  entries appear, the InputClass section is generic and will match any input device. If more than
       one of these entries appear, they all must match for the configuration to apply.

       There are two types of match entries used in InputClass sections. The first allows various tokens  to  be
       matched  against attributes of the device. An entry can be constructed to match attributes from different
       devices by separating arguments with a '|' character. Multiple entries of the same type may  be  supplied
       to add multiple matching conditions on the same attribute. For example:

           Section "InputClass"
               Identifier   "My Class"
               # product string must contain example and
               # either gizmo or gadget
               MatchProduct "example"
               MatchProduct "gizmo|gadget"
               NoMatchDriver "drivername"
               ...
           EndSection

       MatchProduct  "matchproduct"
              This  entry  can  be  used to check if the substring "matchproduct" occurs in the device's product
              name.

       MatchVendor  "matchvendor"
              This entry can be used to check if the substring "matchvendor" occurs in the device's vendor name.

       MatchDevicePath "matchdevice"
              This entry can be used to check if the device file matches the "matchdevice" pathname pattern.

       MatchOS "matchos"
              This entry can be used to check if the operating system  matches  the  case-insensitive  "matchos"
              string. This entry is only supported on platforms providing the uname(2) system call.

       MatchPnPID "matchpnp"
              The device's Plug and Play (PnP) ID can be checked against the "matchpnp" shell wildcard pattern.

       MatchUSBID "matchusb"
              The  device's  USB  ID  can  be  checked  against the "matchusb" shell wildcard pattern. The ID is
              constructed as lowercase hexadecimal numbers separated by a ':'. This is the same  format  as  the
              lsusb(8) program.

       MatchDriver "matchdriver"
              Check  the  case-sensitive  string  "matchdriver"  against  the currently configured driver of the
              device. Ordering of sections using this entry is important since it  will  not  match  unless  the
              driver has been set by the config backend or a previous InputClass section.

       MatchTag "matchtag"
              This  entry  can  be  used  to check if tags assigned by the config backend matches the "matchtag"
              pattern. A match is found if at least one of the tags given in "matchtag" matches at least one  of
              the tags assigned by the backend.

       MatchLayout "matchlayout"
              Check  the  case-sensitive string "matchlayout" against the currently active ServerLayout section.
              The empty string "" matches an implicit layout which appears if  no  named  ServerLayout  sections
              have been found.

       The  above  directives  have  equivalents  for  negative matching with the NoMatchProduct, NoMatchVendor,
       NoMatchDevicePath, NoMatchOS, NoMatchPnPID, NoMatchUSBID, NoMatchDriver,  NoMatchTag,  and  NoMatchLayout
       directives. These NoMatch directives match if the subsequent match is not met by the device.

       The  second type of entry is used to match device types. These entries take a boolean argument similar to
       Option entries.

       MatchIsKeyboard     "bool"

       MatchIsPointer      "bool"

       MatchIsJoystick     "bool"

       MatchIsTablet       "bool"

       MatchIsTabletPad    "bool"

       MatchIsTouchpad     "bool"

       MatchIsTouchscreen  "bool"

       When an input device has been matched to the InputClass section, any Option entries are  applied  to  the
       device. One InputClass specific Option is recognized. See the InputDevice section above for a description
       of the remaining Option entries.

       Option "Ignore" "boolean"
              This optional entry specifies that the device should be ignored entirely, and  not  added  to  the
              server. This can be useful when the device is handled by another program and no X events should be
              generated.

OUTPUTCLASS SECTION

       The config file may have multiple OutputClass sections.  These sections are  optional  and  are  used  to
       provide  configuration  for  a class of output devices as they are automatically added.  An output device
       can match more than one OutputClass section.  Each class can override settings from a previous class,  so
       it is best to arrange the sections with the most generic matches first.

       OutputClass sections have the following format:

           Section "OutputClass"
               Identifier  "name"
               entries
               ...
           EndSection

       The Identifier entry is required in all OutputClass sections.  All other entries are optional.

       The  Identifier  entry  specifies  the unique name for this output class.  The Driver entry specifies the
       name of the driver  to  use  for  this  output  device.   After  all  classes  have  been  examined,  the
       "outputdriver" module from the first Driver entry will be enabled when using the loadable server.

       When  an  output  device  is automatically added, its characteristics are checked against all OutputClass
       sections.  Each section can contain optional entries to narrow the match of the class.  If  none  of  the
       optional  entries  appear,  the OutputClass section is generic and will match any output device.  If more
       than one of these entries appear, they all must match for the configuration to apply.

       The following list of tokens can  be  matched  against  attributes  of  the  device.   An  entry  can  be
       constructed to match attributes from different devices by separating arguments with a '|' character.

       For example:

           Section "OutputClass"
               Identifier   "My Class"
               # kernel driver must be either foo or bar
               MatchDriver "foo|bar"
               ...
           EndSection

       MatchDriver "matchdriver"
              Check the case-sensitive string "matchdriver" against the kernel driver of the device.

DEVICE SECTION

       The  config file may have multiple Device sections.  There must be at least one, for the video card being
       used.

       Device sections have the following format:

           Section "Device"
               Identifier "name"
               Driver     "driver"
               entries
               ...
           EndSection

       The Identifier and Driver entries are required in all Device sections.  All other entries are optional.

       The Identifier entry specifies the unique name for this graphics device.  The Driver entry specifies  the
       name  of  the  driver to use for this graphics device.  When using the loadable server, the driver module
       "driver" will be loaded for each active Device section.  A Device section is considered active if  it  is
       referenced by an active Screen section.

       Device sections recognise some driver-independent entries and Options, which are described here.  Not all
       drivers make use of these driver-independent entries, and many of those that do don't require them to  be
       specified  because the information is auto-detected.  See the individual graphics driver manual pages for
       further information about this, and for a description of the device-specific options.  Note that most  of
       the  Options  listed  here  (but not the other entries) may be specified in the Screen section instead of
       here in the Device section.

       BusID  "bus-id"
              This specifies the bus location of the graphics card.  For PCI/AGP cards, the  bus-id  string  has
              the  form  PCI:bus:device:function (e.g., “PCI:1:0:0” might be appropriate for an AGP card).  This
              field is usually optional in single-head configurations when using the primary graphics card.   In
              multi-head configurations, or when using a secondary graphics card in a single-head configuration,
              this entry is mandatory.  Its main purpose is to make an unambiguous connection between the device
              section and the hardware it is representing.  This information can usually be found by running the
              pciaccess tool scanpci.

       Screen  number
              This option is mandatory for cards where a single PCI entity  can  drive  more  than  one  display
              (i.e., multiple CRTCs sharing a single graphics accelerator and video memory).  One Device section
              is required for each head, and this parameter determines which head each of  the  Device  sections
              applies  to.   The  legal values of number range from 0 to one less than the total number of heads
              per entity.  Most drivers require that the primary screen (0) be present.

       Chipset  "chipset"
              This usually optional entry specifies the chipset used on the graphics board.  In most cases  this
              entry  is  not required because the drivers will probe the hardware to determine the chipset type.
              Don't specify it unless the driver-specific documentation recommends that you do.

       Ramdac  "ramdac-type"
              This optional entry specifies the type of RAMDAC used on the graphics board.  This is only used by
              a  few  of  the  drivers,  and in most cases it is not required because the drivers will probe the
              hardware to determine the RAMDAC type where possible.  Don't specify it unless the driver-specific
              documentation recommends that you do.

       DacSpeed  speed

       DacSpeed  speed-8 speed-16 speed-24 speed-32
              This  optional  entry  specifies  the  RAMDAC speed rating (which is usually printed on the RAMDAC
              chip).  The speed is in MHz.  When one value is given, it applies to all framebuffer pixel  sizes.
              When  multiple  values  are  given,  they  apply  to  the framebuffer pixel sizes 8, 16, 24 and 32
              respectively.  This is not used by many drivers, and only needs to be  specified  when  the  speed
              rating  of  the RAMDAC is different from the defaults built in to driver, or when the driver can't
              auto-detect the correct defaults.  Don't  specify  it  unless  the  driver-specific  documentation
              recommends that you do.

       Clocks  clock ...
              specifies  the pixel that are on your graphics board.  The clocks are in MHz, and may be specified
              as a floating point number.  The value is stored internally to the nearest kHz.  The  ordering  of
              the  clocks  is  important.   It  must  match the order in which they are selected on the graphics
              board.  Multiple Clocks lines may be specified, and each is concatenated to form the  list.   Most
              drivers do not use this entry, and it is only required for some older boards with non-programmable
              clocks.  Don't specify this entry unless the driver-specific documentation  explicitly  recommends
              that you do.

       ClockChip  "clockchip-type"
              This  optional  entry  is  used  to  specify  the  clock chip type on graphics boards which have a
              programmable clock generator.  Only a few Xorg drivers  support  programmable  clock  chips.   For
              details, see the appropriate driver manual page.

       VideoRam  mem
              This  optional  entry  specifies  the amount of video ram that is installed on the graphics board.
              This is measured in kBytes.  In most cases this is not required because the Xorg server probes the
              graphics board to determine this quantity.  The driver-specific documentation should indicate when
              it might be needed.

       BiosBase  baseaddress
              This optional entry specifies the base address of the video BIOS for the VGA board.  This  address
              is  normally  auto-detected,  and  should  only  be specified if the driver-specific documentation
              recommends it.

       MemBase  baseaddress
              This optional entry specifies the memory base address of a graphics board's linear  frame  buffer.
              This  entry  is  not  used by many drivers, and it should only be specified if the driver-specific
              documentation recommends it.

       IOBase  baseaddress
              This optional entry specifies the IO base address.  This entry is not used by many drivers, and it
              should only be specified if the driver-specific documentation recommends it.

       ChipID  id
              This  optional  entry  specifies  a numerical ID representing the chip type.  For PCI cards, it is
              usually the device ID.  This can be used to override the auto-detection, but that should  only  be
              done when the driver-specific documentation recommends it.

       ChipRev  rev
              This  optional  entry  specifies the chip revision number.  This can be used to override the auto-
              detection, but that should only be done when the driver-specific documentation recommends it.

       MatchSeat  seat-id
              Only apply this Device section if X server was started with -seat seat-id option.

       Option "ModeDebug" "boolean"
              Enable printing of additional debugging information about modesetting to the server log.

       Options
              Option flags may be specified in the Device sections.  These include driver-specific  options  and
              driver-independent  options.  The former are described in the driver-specific documentation.  Some
              of the latter are described below in the section about the Screen section, and they  may  also  be
              included here.

VIDEOADAPTOR SECTION

       Nobody wants to say how this works.  Maybe nobody knows ...

MONITOR SECTION

       The  config  file  may  have  multiple  Monitor sections.  There should normally be at least one, for the
       monitor being used, but a default configuration will be created when one isn't specified.

       Monitor sections have the following format:

           Section "Monitor"
               Identifier "name"
               entries
               ...
           EndSection

       The only mandatory entry in a Monitor section is the Identifier entry.

       The Identifier entry specifies the unique name for this monitor.  The Monitor  section  may  be  used  to
       provide  information  about  the specifications of the monitor, monitor-specific Options, and information
       about the video modes to use with the monitor.

       With RandR 1.2-enabled drivers, monitor sections may be tied to  specific  outputs  of  the  video  card.
       Using  the  name  of the output defined by the video driver plus the identifier of a monitor section, one
       associates a monitor section with an output by adding an option to the Device section  in  the  following
       format:

       Option "Monitor-outputname" "monitorsection"

       (for example, Option "Monitor-VGA" "VGA monitor" for a VGA output)

       In  the  absence  of specific association of monitor sections to outputs, if a monitor section is present
       the server will  associate  it  with  an  output  to  preserve  compatibility  for  previous  single-head
       configurations.

       Specifying  video  modes is optional because the server will use the DDC or other information provided by
       the monitor to automatically configure the list of modes available.  When modes are specified  explicitly
       in  the  Monitor  section  (with  the Mode, ModeLine, or UseModes keywords), built-in modes with the same
       names are not included.  Built-in modes with different names are,  however,  still  implicitly  included,
       when they meet the requirements of the monitor.

       The entries that may be used in Monitor sections are described below.

       VendorName  "vendor"
              This optional entry specifies the monitor's manufacturer.

       ModelName  "model"
              This optional entry specifies the monitor's model.

       HorizSync  horizsync-range
              gives  the  range(s) of horizontal sync frequencies supported by the monitor.  horizsync-range may
              be a comma separated list of either discrete values or ranges of values.  A range of values is two
              values  separated by a dash.  By default the values are in units of kHz.  They may be specified in
              MHz or Hz if MHz or Hz is added to the end of the line.  The data given here is used by  the  Xorg
              server to determine if video modes are within the specifications of the monitor.  This information
              should be available in the monitor's handbook.  If this entry  is  omitted,  a  default  range  of
              28-33kHz is used.

       VertRefresh  vertrefresh-range
              gives  the  range(s)  of vertical refresh frequencies supported by the monitor.  vertrefresh-range
              may be a comma separated list of either discrete values or ranges of values.  A range of values is
              two  values separated by a dash.  By default the values are in units of Hz.  They may be specified
              in MHz or kHz if MHz or kHz is added to the end of the line.  The data given here is used  by  the
              Xorg  server  to  determine  if  video  modes  are within the specifications of the monitor.  This
              information should be available in the monitor's handbook.  If this entry is  omitted,  a  default
              range of 43-72Hz is used.

       DisplaySize  width height
              This  optional  entry  gives  the  width  and  height,  in millimetres, of the picture area of the
              monitor.  If given this is used to calculate the  horizontal  and  vertical  pitch  (DPI)  of  the
              screen.

       Gamma  gamma-value

       Gamma  red-gamma green-gamma blue-gamma
              This  is  an  optional entry that can be used to specify the gamma correction for the monitor.  It
              may be specified as either a single value or as three separate RGB values.  The values  should  be
              in  the  range  0.1  to  10.0,  and the default is 1.0.  Not all drivers are capable of using this
              information.

       UseModes  "modesection-id"
              Include the set of modes listed in the Modes section called modesection-id.  This makes all of the
              modes defined in that section available for use by this monitor.

       Mode  "name"
              This  is  an optional multi-line entry that can be used to provide definitions for video modes for
              the monitor.  In most cases this isn't necessary because the built-in set of VESA  standard  modes
              will  be sufficient.  The Mode keyword indicates the start of a multi-line video mode description.
              The mode description is terminated with the EndMode keyword.  The mode description consists of the
              following entries:

              DotClock  clock
                  is the dot (pixel) clock rate to be used for the mode.

              HTimings  hdisp hsyncstart hsyncend htotal
                  specifies the horizontal timings for the mode.

              VTimings  vdisp vsyncstart vsyncend vtotal
                  specifies the vertical timings for the mode.

              Flags  "flag" ...
                  specifies  an optional set of mode flags, each of which is a separate string in double quotes.
                  "Interlace" indicates that the mode is interlaced.  "DoubleScan" indicates a mode  where  each
                  scanline  is  doubled.   "+HSync" and "-HSync" can be used to select the polarity of the HSync
                  signal.  "+VSync" and "-VSync" can be used  to  select  the  polarity  of  the  VSync  signal.
                  "Composite"  can  be  used  to  specify  composite  sync  on hardware where this is supported.
                  Additionally, on some hardware, "+CSync" and "-CSync" may be used to select the composite sync
                  polarity.

              HSkew  hskew
                  specifies  the  number  of  pixels (towards the right edge of the screen) by which the display
                  enable signal is to be skewed.  Not all drivers  use  this  information.   This  option  might
                  become  necessary  to  override  the  default value supplied by the server (if any).  “Roving”
                  horizontal lines indicate this value needs to be increased.  If the last few pixels on a  scan
                  line appear on the left of the screen, this value should be decreased.

              VScan  vscan
                  specifies  the  number  of  times each scanline is painted on the screen.  Not all drivers use
                  this information.  Values less than 1 are treated as 1, which is the default.  Generally,  the
                  "DoubleScan" Flag mentioned above doubles this value.

       ModeLine  "name" mode-description
              This  entry  is a more compact version of the Mode entry, and it also can be used to specify video
              modes for the monitor.  This is a single line format for specifying video modes.   In  most  cases
              this isn't necessary because the built-in set of VESA standard modes will be sufficient.

              The  mode-description  is  in four sections, the first three of which are mandatory.  The first is
              the dot (pixel) clock.  This is a single number specifying the pixel clock rate for  the  mode  in
              MHz.   The  second  section  is  a  list of four numbers specifying the horizontal timings.  These
              numbers are the hdisp, hsyncstart, hsyncend, and htotal values.  The third section is  a  list  of
              four  numbers specifying the vertical timings.  These numbers are the vdisp, vsyncstart, vsyncend,
              and vtotal values.  The final section is a list of flags specifying other characteristics  of  the
              mode.   Interlace  indicates  that the mode is interlaced.  DoubleScan indicates a mode where each
              scanline is doubled.  +HSync and -HSync can be used to select the polarity of  the  HSync  signal.
              +VSync  and  -VSync can be used to select the polarity of the VSync signal.  Composite can be used
              to specify composite sync on hardware where this is supported.  Additionally,  on  some  hardware,
              +CSync  and -CSync may be used to select the composite sync polarity.  The HSkew and VScan options
              mentioned above in the Mode entry description can also be used here.

       Option "DPMS" "bool"
              This option controls whether the server should enable the DPMS extension for power management  for
              this screen.  The default is to enable the extension.

       Option "SyncOnGreen" "bool"
              This  option  controls whether the video card should drive the sync signal on the green color pin.
              Not all cards support this option, and most monitors do not require it.  The default is off.

       Option "Primary" "bool"
              This optional entry specifies that the monitor should be treated as the  primary  monitor.  (RandR
              1.2-supporting drivers only)

       Option "PreferredMode" "name"
              This  optional  entry  specifies a mode to be marked as the preferred initial mode of the monitor.
              (RandR 1.2-supporting drivers only)

       Option "ZoomModes" "name name ..."
              This optional entry specifies modes to be marked as zoom modes.  It is possible to switch  to  the
              next  and  previous  mode  via  Ctrl+Alt+Keypad-Plus  and Ctrl+Alt+Keypad-Minus.  All these keypad
              available modes are selected from the screen mode list.  This list is a copy of the  compatibility
              output  monitor  mode  list.   Since  this  output  is the output connected to the lowest dot-area
              monitor, as determined from its largest size mode, that monitor defines the available zoom  modes.
              (RandR 1.2-supporting drivers only)

       Option "Position" "x y"
              This  optional  entry  specifies  the  position  of  the  monitor  within  the  X  screen.  (RandR
              1.2-supporting drivers only)

       Option "LeftOf" "output"
              This optional entry specifies that the monitor should be positioned to the left of the output (not
              monitor) of the given name.  (RandR 1.2-supporting drivers only)

       Option "RightOf" "output"
              This  optional  entry  specifies  that the monitor should be positioned to the right of the output
              (not monitor) of the given name.  (RandR 1.2-supporting drivers only)

       Option "Above" "output"
              This optional entry specifies that the monitor should be positioned above the output (not monitor)
              of the given name.  (RandR 1.2-supporting drivers only)

       Option "Below" "output"
              This optional entry specifies that the monitor should be positioned below the output (not monitor)
              of the given name.  (RandR 1.2-supporting drivers only)

       Option "Enable" "bool"
              This optional entry specifies whether the monitor should be turned on at startup.  By default, the
              server will attempt to enable all connected monitors.  (RandR 1.2-supporting drivers only)

       Option "DefaultModes" "bool"
              This optional entry specifies whether the server should add supported default modes to the list of
              modes offered on this monitor. By default, the server will add  default  modes;  you  should  only
              disable  this  if you can guarantee that EDID will be available at all times, or if you have added
              custom modelines which the server can use.  (RandR 1.2-supporting drivers only)

       Option "MinClock" "frequency"
              This optional entry specifies the minimum dot clock, in kHz, that is supported by the monitor.

       Option "MaxClock" "frequency"
              This optional entry specifies the maximum dot clock, in kHz, that is supported by the monitor.

       Option "Ignore" "bool"
              This optional entry specifies that the monitor  should  be  ignored  entirely,  and  not  reported
              through  RandR.   This is useful if the hardware reports the presence of outputs that don't exist.
              (RandR 1.2-supporting drivers only)

       Option "Rotate" "rotation"
              This optional entry specifies the initial  rotation  of  the  given  monitor.   Valid  values  for
              rotation are "normal", "left", "right", and "inverted".  (RandR 1.2-supporting drivers only)

MODES SECTION

       The config file may have multiple Modes sections, or none.  These sections provide a way of defining sets
       of video modes independently of the Monitor sections.   Monitor  sections  may  include  the  definitions
       provided  in  these  sections  by  using  the UseModes keyword.  In most cases the Modes sections are not
       necessary because the built-in set of VESA standard modes will be sufficient.

       Modes sections have the following format:

           Section "Modes"
               Identifier "name"
               entries
               ...
           EndSection

       The Identifier entry specifies the unique name for this set of  mode  descriptions.   The  other  entries
       permitted  in  Modes  sections  are the Mode and ModeLine entries that are described above in the Monitor
       section.

SCREEN SECTION

       The config file may have multiple Screen sections.  There must be at least one, for  the  “screen”  being
       used.   A  “screen”  represents  the binding of a graphics device (Device section) and a monitor (Monitor
       section).  A Screen section is considered “active” if it is referenced by an active ServerLayout  section
       or by the -screen command line option.  If neither of those is present, the first Screen section found in
       the config file is considered the active one.

       Screen sections have the following format:

           Section "Screen"
               Identifier "name"
               Device     "devid"
               GPUDevice  "devid"
               Monitor    "monid"
               entries
               ...
               SubSection "Display"
                  entries
                  ...
               EndSubSection
               ...
           EndSection

       The Identifier entry is mandatory.  All others are optional.

       The Identifier entry specifies the unique name for this screen.  The Screen section provides  information
       specific  to  the  whole  screen, including screen-specific Options.  In multi-head configurations, there
       will be multiple active Screen sections, one for each head.  The entries available for this section are:

       Device  "device-id"
              This entry specifies the Device section to be used for this screen.  When multiple graphics  cards
              are  present,  this  is  what  ties  a  specific  card  to a screen.  The device-id must match the
              Identifier of a Device section in the config file.

       GPUDevice  "device-id"
              This entry specifies the Device section to be used as a secondary  GPU  device  for  this  screen.
              When multiple graphics cards are present, this is what ties a specific secondary card to a screen.
              The device-id must match the Identifier of a Device section  in  the  config  file.  This  can  be
              specified up to 4 times for a single screen.

       Monitor  "monitor-id"
              specifies  which  monitor  description  is  to  be used for this screen.  If a Monitor name is not
              specified, a default configuration is used.  Currently the default configuration may not  function
              as expected on all platforms.

       VideoAdaptor  "xv-id"
              specifies an optional Xv video adaptor description to be used with this screen.

       DefaultDepth  depth
              specifies  which color depth the server should use by default.  The -depth command line option can
              be used to override this.  If neither is specified, the default depth is driver-specific,  but  in
              most cases is 8.

       DefaultFbBpp  bpp
              specifies  which framebuffer layout to use by default.  The -fbbpp command line option can be used
              to override this.  In most cases the driver will chose the best default value for this.  The  only
              case where there is even a choice in this value is for depth 24, where some hardware supports both
              a packed 24 bit framebuffer layout and a sparse 32 bit framebuffer layout.

       MatchSeat  seat-id
              Only apply this Screen section if X server was started with -seat seat-id option.

       Options
              Various Option flags may be specified in the Screen section.  Some  are  driver-specific  and  are
              described  in  the  driver  documentation.   Others are driver-independent, and will eventually be
              described here.

       Option "Accel"
              Enables 2D hardware acceleration.  This option is on by default, but it may be necessary  to  turn
              it  off  if  there are bugs in the driver.  There are many options to disable specific accelerated
              operations, listed below.  Note that disabling an operation will have no effect if  the  operation
              is not accelerated (whether due to lack of support in the hardware or in the driver).

       Option "GlxVendorLibrary" "string"
              This  option  specifies  a  space-separated list of OpenGL vendor libraries to use for the screen.
              This may be used to select an alternate implementation for development,  debugging,  or  alternate
              feature sets.  Default: mesa.

       Option "InitPrimary" "boolean"
              Use  the Int10 module to initialize the primary graphics card.  Normally, only secondary cards are
              soft-booted using the Int10 module, as the primary card has already been initialized by  the  BIOS
              at boot time.  Default: false.

       Option "NoInt10" "boolean"
              Disables  the  Int10 module, a module that uses the int10 call to the BIOS of the graphics card to
              initialize it.  Default: false.

       Each Screen section may optionally contain one or more Display subsections.   Those  subsections  provide
       depth/fbbpp specific configuration information, and the one chosen depends on the depth and/or fbbpp that
       is being used for the screen.  The Display subsection format is described in the section below.

DISPLAY SUBSECTION

       Each Screen section may have multiple Display subsections.  The “active” Display subsection is the  first
       that  matches  the  depth  and/or  fbbpp values being used, or failing that, the first that has neither a
       depth or fbbpp value specified.  The Display subsections are optional.  When there isn't one that matches
       the  depth  and/or  fbbpp  values  being used, all the parameters that can be specified here fall back to
       their defaults.

       Display subsections have the following format:

               SubSection "Display"
                   Depth  depth
                   entries
                   ...
               EndSubSection

       Depth  depth
              This entry specifies what colour depth the Display subsection is to be used for.   This  entry  is
              usually  specified, but it may be omitted to create a match-all Display subsection or when wishing
              to match only against the FbBpp parameter.  The range of depth values that are allowed depends  on
              the  driver.   Most  drivers support 8, 15, 16 and 24.  Some also support 1 and/or 4, and some may
              support other values (like 30).  Note: depth means the number of bits in a pixel that are actually
              used  to  determine  the pixel colour.  32 is not a valid depth value.  Most hardware that uses 32
              bits per pixel only uses 24 of them to hold the colour information, which means  that  the  colour
              depth is 24, not 32.

       FbBpp  bpp
              This entry specifies the framebuffer format this Display subsection is to be used for.  This entry
              is only needed when providing depth 24 configurations that allow a choice between a 24 bpp  packed
              framebuffer  format and a 32bpp sparse framebuffer format.  In most cases this entry should not be
              used.

       Weight  red-weight green-weight blue-weight
              This optional entry specifies the relative RGB weighting to be used for a screen is being used  at
              depth  16  for  drivers  that allow multiple formats.  This may also be specified from the command
              line with the -weight option (see Xorg(1)).

       Virtual  xdim ydim
              This optional entry specifies the virtual screen resolution to be used.  xdim must be  a  multiple
              of  either  8  or  16 for most drivers, and a multiple of 32 when running in monochrome mode.  The
              given value will be rounded down if this is not the case.  Video modes which are too large for the
              specified  virtual  size  will  be  rejected.   If  this  entry is not present, the virtual screen
              resolution will be set to accommodate all the valid video modes given in the  Modes  entry.   Some
              drivers/hardware   combinations  do  not  support  virtual  screens.   Refer  to  the  appropriate
              driver-specific documentation for details.

       ViewPort  x0 y0
              This optional entry sets the upper left corner of the initial display.  This is only relevant when
              the virtual screen resolution is different from the resolution of the initial video mode.  If this
              entry is not given, then the initial display will be centered in the virtual display area.

       Modes  "mode-name" ...
              This optional entry specifies the list of video modes to use.  Each mode-name specified must be in
              double  quotes.   They must correspond to those specified or referenced in the appropriate Monitor
              section (including implicitly referenced built-in VESA standard modes).  The  server  will  delete
              modes  from this list which don't satisfy various requirements.  The first valid mode in this list
              will be the default display mode for startup.  The list of valid  modes  is  converted  internally
              into  a circular list.  It is possible to switch to the next mode with Ctrl+Alt+Keypad-Plus and to
              the previous mode with Ctrl+Alt+Keypad-Minus.   When  this  entry  is  omitted,  the  valid  modes
              referenced  by  the  appropriate Monitor section will be used.  If the Monitor section contains no
              modes, then the selection will be taken from the built-in VESA standard modes.

       Visual  "visual-name"
              This optional entry sets the default root visual type.   This  may  also  be  specified  from  the
              command  line  (see the Xserver(1) man page).  The visual types available for depth 8 are (default
              is PseudoColor):

                  StaticGray
                  GrayScale
                  StaticColor
                  PseudoColor
                  TrueColor
                  DirectColor

              The visual type available for the depths 15, 16 and 24 are (default is TrueColor):

                  TrueColor
                  DirectColor

              Not all drivers support DirectColor at these depths.

              The visual types available for the depth 4 are (default is StaticColor):

                  StaticGray
                  GrayScale
                  StaticColor
                  PseudoColor

              The visual type available for the depth 1 (monochrome) is StaticGray.

       Black  red green blue
              This optional entry allows the “black” colour to be specified.  This is only supported at depth 1.
              The default is black.

       White  red green blue
              This optional entry allows the “white” colour to be specified.  This is only supported at depth 1.
              The default is white.

       Options
              Option flags may be specified in the  Display  subsections.   These  may  include  driver-specific
              options  and  driver-independent  options.   The  former  are  described  in  the  driver-specific
              documentation.  Some of the latter are described above in the section about  the  Screen  section,
              and they may also be included here.

SERVERLAYOUT SECTION

       The config file may have multiple ServerLayout sections.  A “server layout” represents the binding of one
       or more screens (Screen sections) and one or more input devices (InputDevice sections) to form a complete
       configuration.   In  multi-head  configurations,  it  also specifies the relative layout of the heads.  A
       ServerLayout section is considered “active” if it is referenced by the -layout command line option or  by
       an  Option  "DefaultServerLayout"  entry in the ServerFlags section (the former takes precedence over the
       latter).  If those options are not used, the first ServerLayout section  found  in  the  config  file  is
       considered  the  active  one.   If no ServerLayout sections are present, the single active screen and two
       active (core) input devices are selected as described in the relevant sections above.

       ServerLayout sections have the following format:

           Section "ServerLayout"
               Identifier   "name"
               Screen       "screen-id"
               ...
               InputDevice  "idev-id"
               ...
               options
               ...
           EndSection

       Each ServerLayout section must have an Identifier entry and at least one Screen entry.

       The Identifier entry specifies the unique name for this server layout.  The ServerLayout section provides
       information  specific  to the whole session, including session-specific Options.  The ServerFlags options
       (described above) may be specified here, and ones given here override  those  given  in  the  ServerFlags
       section.

       The entries that may be used in this section are described here.

       Screen  screen-num "screen-id" position-information
              One  of  these entries must be given for each screen being used in a session.  The screen-id field
              is mandatory, and specifies  the  Screen  section  being  referenced.   The  screen-num  field  is
              optional,  and  may  be used to specify the screen number in multi-head configurations.  When this
              field is omitted, the screens will be numbered  in  the  order  that  they  are  listed  in.   The
              numbering  starts  from  0, and must be consecutive.  The position-information field describes the
              way multiple screens are positioned.  There are a number of different ways that  this  information
              can be provided:

              x y

              Absolute  x y
                  These  both  specify that the upper left corner's coordinates are (x,y).  The Absolute keyword
                  is optional.  Some older versions of XFree86 (4.2 and earlier) don't  recognise  the  Absolute
                  keyword, so it's safest to just specify the coordinates without it.

              RightOf   "screen-id"

              LeftOf    "screen-id"

              Above     "screen-id"

              Below     "screen-id"

              Relative  "screen-id" x y
                  These  give  the  screen's  location  relative to another screen.  The first four position the
                  screen immediately to the right, left, above or below the other screen.  When  positioning  to
                  the right or left, the top edges are aligned.  When positioning above or below, the left edges
                  are aligned.  The Relative form specifies the  offset  of  the  screen's  origin  (upper  left
                  corner) relative to the origin of another screen.

       InputDevice  "idev-id" "option" ...
              One  of  these entries should be given for each input device being used in a session.  Normally at
              least two are required, one each for the core pointer and keyboard devices.  If either of those is
              missing,  suitable  InputDevice  entries  are searched for using the method described above in the
              INPUTDEVICE section.  The idev-id field is mandatory, and specifies the name  of  the  InputDevice
              section  being  referenced.   Multiple option fields may be specified, each in double quotes.  The
              options permitted here are any that may also be given in the InputDevice sections.  Normally  only
              session-specific input device options would be used here.  The most commonly used options are:

                  "CorePointer"
                  "CoreKeyboard"
                  "SendCoreEvents"

              and  the  first two should normally be used to indicate the core pointer and core keyboard devices
              respectively.

       MatchSeat  seat-id
              Only apply this ServerLayout section if X server was started with -seat seat-id option.

       Options
              In addition to the following, any  option  permitted  in  the  ServerFlags  section  may  also  be
              specified  here.   When the same option appears in both places, the value given here overrides the
              one given in the ServerFlags section.

       Option "IsolateDevice"  "bus-id"
              Restrict device resets to the specified  bus-id.   See  the  BusID  option  (described  in  DEVICE
              SECTION,  above)  for  the  format  of the bus-id parameter.  This option overrides SingleCard, if
              specified.  At present, only PCI devices can be isolated in this manner.

       Option "SingleCard"  "boolean"
              As IsolateDevice, except that the bus ID of the first device in the layout is used.

       Here is an example of a ServerLayout section for a dual headed configuration with two mice:

           Section "ServerLayout"
               Identifier  "Layout 1"
               Screen      "MGA 1"
               Screen      "MGA 2" RightOf "MGA 1"
               InputDevice "Keyboard 1" "CoreKeyboard"
               InputDevice "Mouse 1"    "CorePointer"
               InputDevice "Mouse 2"    "SendCoreEvents"
               Option      "BlankTime"  "5"
           EndSection

DRI SECTION

       This optional section is used to provide  some  information  for  the  Direct  Rendering  Infrastructure.
       Details about the format of this section can be found on-line at <http://dri.freedesktop.org/>.

VENDOR SECTION

       The  optional  Vendor section may be used to provide vendor-specific configuration information.  Multiple
       Vendor sections may be present, and they may contain an Identifier entry and multiple Option flags.   The
       data therein is not used in this release.

SEE ALSO

       General: X(7), Xserver(1), Xorg(1), cvt(1), gtf(1).

       Not all modules or interfaces are available on all platforms.

       Display  drivers:  apm(4),  ati(4), chips(4), cirrus(4), cyrix(4), fbdev(4), glide(4), glint(4), i128(4),
       i740(4), imstt(4), intel(4), mga(4), neomagic(4), nv(4), openchrome(4), r128(4), radeon(4), rendition(4),
       savage(4),  s3virge(4), siliconmotion(4), sis(4), sisusb(4), sunbw2(4), suncg14(4), suncg3(4), suncg6(4),
       sunffb(4), sunleo(4), suntcx(4), tdfx(4), trident(4), tseng(4), vesa(4), vmware(4),  voodoo(4),  wsfb(4),
       xgi(4), xgixp(4).

       Input drivers: acecad(4), citron(4), elographics(4), evdev(4), fpit(4), joystick(4), kbd(4), mousedrv(4),
       mutouch(4), penmount(4), synaptics(4), vmmouse(4), void(4), wacom(4).

       Other modules and interfaces: exa(4), fbdevhw(4), v4l(4).

AUTHORS

       This manual page was largely rewritten by David Dawes <dawes@xfree86.org>.