xorg.conf(5)




INTRODUCTION

       Xorg  supports several mechanisms for supplying/obtaining configuration
       and run-time parameters: command line options,  environment  variables,
       the   xorg.conf   configuration   file,  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  parame-
       ters  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  mod-
       ule  specific  configuration  parameters  are described in the relevant
       driver or module manual page.


DESCRIPTION

       Xorg uses a configuration file called xorg.conf for its initial  setup.
       This  configuration  file  is searched for in the following places when
       the server is started as a normal user:

           /etc/X11/<cmdline>
           /usr/X11R6/etc/X11/<cmdline>
           /etc/X11/$XORGCONFIG
           /usr/X11R6/etc/X11/$XORGCONFIG
           /etc/X11/xorg.conf-4
           /etc/X11/xorg.conf
           /etc/xorg.conf
           /usr/X11R6/etc/X11/xorg.conf.<hostname>
           /usr/X11R6/etc/X11/xorg.conf-4
           /usr/X11R6/etc/X11/xorg.conf
           /usr/X11R6/lib/X11/xorg.conf.<hostname>
           /usr/X11R6/lib/X11/xorg.conf-4
           /usr/X11R6/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/X11R6/etc/X11/<cmdline>
           $XORGCONFIG
           /etc/X11/$XORGCONFIG
           /usr/X11R6/etc/X11/$XORGCONFIG
           $HOME/xorg.conf
           /etc/X11/xorg.conf-4
           /etc/X11/xorg.conf
           /etc/xorg.conf
           /usr/X11R6/etc/X11/xorg.conf.<hostname>

       present in any order.  Each section has the form:

           Section  "SectionName"
               SectionEntry
               ...
           EndSection

       The section names are:

           Files          File pathnames
           ServerFlags    Server flags
           Module         Dynamic module loading
           InputDevice    Input device 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  compati-
       bility  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 usu-
       ally 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 ServerLay-
       out 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-insensi-
       tive, 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
           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 may  be  either  absolute  directory

                  /usr/X11R6/lib/X11/fonts/misc/
                  /usr/X11R6/lib/X11/fonts/TTF/
                  /usr/X11R6/lib/X11/fonts/Type1/
                  /usr/X11R6/lib/X11/fonts/CID/
                  /usr/X11R6/lib/X11/fonts/75dpi/
                  /usr/X11R6/lib/X11/fonts/100dpi/

              The recommended font path contains the following font path  ele-
              ments:

                  /usr/X11R6/lib/X11/fonts/local/
                  /usr/X11R6/lib/X11/fonts/misc/
                  /usr/X11R6/lib/X11/fonts/75dpi/:unscaled
                  /usr/X11R6/lib/X11/fonts/100dpi/:unscaled
                  /usr/X11R6/lib/X11/fonts/Type1/
                  /usr/X11R6/lib/X11/fonts/CID/
                  /usr/X11R6/lib/X11/fonts/Speedo/
                  /usr/X11R6/lib/X11/fonts/75dpi/
                  /usr/X11R6/lib/X11/fonts/100dpi/

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

       RGBPath "path"
              sets the path name for the RGB color database.  When this  entry
              is  not  specified  in the config file, the server falls back to
              the compiled-in default RGB path, which is:

                  /usr/X11R6/lib/X11/rgb

       Note that an implicit .txt is added to this path if the server was com-
       piled to use text rather than binary format RGB color databases.

       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 speci-
              fied.  Multiple ModulePath entries may be  specified,  and  they
              will be concatenated to build the module search path used by the
              server.


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  compati-
       bility  purposes  some  of  the old style entries are still recognised.
       Those old style entries are not documented here, and using them is dis-
       couraged.  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  "Default-
              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 operat-
              ing 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 Ctrl+Alt+Backspace sequence.  That
              sequence  is  normally  used to terminate the Xorg server.  When
              this option is enabled, that key sequence has no special meaning
              and is passed to clients.  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 "DisableModInDev"  "boolean"
              This  disables  the parts of the Xorg-Misc extension that can be
              used to modify the input device settings dynamically.   Default:
              that functionality is enabled.

       Option "AllowNonLocalModInDev"  "boolean"
              This  allows  a  client  to connect from another host and change
              keyboard and mouse settings in  the  running  server.   Default:
              off.

       Option "AllowMouseOpenFail"  "boolean"
              This  allows  the  server  to  start up even if the mouse device
              can't be opened/initialised.  Default: false.

       Option "VTInit"  "command"
              Runs command after the VT used by the server  has  been  opened.
              The  command  string  is passed to "/bin/sh -c", and is run with
              the real user's id with stdin and stdout set  to  the  VT.   The
              enabled.

       Option "BlankTime"  "time"
              sets  the  inactivity  timeout  for  the  blanking  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: 20 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: 30 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: 40 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 "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 "PC98"  "boolean"
              Specify that the machine is  a  Japanese  PC-98  machine.   This
              should  not be enabled for anything other than the Japanese-spe-
              cific PC-98 architecture.  Default: auto-detected.

       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 "AllowDeactivateGrabs" "boolean"
              This  option  enables  the use of the Ctrl+Alt+Keypad-Divide key

       Option "HandleSpecialKeys" "when"
              This option controls when the server uses the builtin handler to
              process special key combinations (such  as  Ctrl+Alt+Backspace).
              Normally  the  XKEYBOARD extension keymaps will provide mappings
              for each of the special key combinations, so the builtin handler
              is  not  needed unless the XKEYBOARD extension is disabled.  The
              value of when can be Always, Never, or WhenNeeded.  Default: Use
              the  builtin  handler  only if needed.  The server will scan the
              keymap for a mapping to the Terminate action and, if found,  use
              XKEYBOARD  for processing actions, otherwise the builtin handler
              will be used.


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 types of modules normally loaded in this section  are
       Xorg server extension modules, and font rasteriser 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  com-
       monly  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" prefix, or the ".a", ".o", or ".so"
              suffixes.

              Example: the Type 1 font rasteriser can be loaded with the  fol-
              lowing entry:

                  Load "type1"

       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 Xorg-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, input, extensions, fonts, and internal


INPUTDEVICE SECTION

       The  config  file  may  have multiple InputDevice sections.  There will
       normally be at least two: one for the core (primary) keyboard, and  one
       of the core pointer.  If either of these two is missing, a default con-
       figuration for the missing ones will be used.   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 sec-
       tions.  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 refer-
       ences.  The  most  commonly  used  input  drivers  are  "keyboard"  and
       "mouse".

       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
       "keyboard" or "kbd") driver is used.  The  final  fallback  is  to  use
       built-in default configurations.

       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 "CorePointer"
              When  this  is  set,  the  input device is installed as the core
              (primary) pointer  device.   There  must  be  exactly  one  core
              pointer.  If this option is not set here, or in the ServerLayout
              section, or from the -pointer  command  line  option,  then  the
              first  input  device  that  is  capable  of being used as a core
              pointer will be selected as the core pointer.   This  option  is
              implicitly set when the obsolete Pointer section is used.

       Option "CoreKeyboard"
              When  this  is  set,  the input device is to be installed as the

       Option "HistorySize"  "number"
           Sets the motion history size.  Default: 0.

       Option "SendDragEvents"  "boolean"
              ???


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  mod-
       ule  "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 Xorg server with the -scan-
              pci command line option.

              chipset type.  Don't specify it unless the driver-specific docu-
              mentation 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  give, 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 rat-
              ing 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  documen-
              tation 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-spe-
              cific documentation should indicate when it might be needed.

       BiosBase  baseaddress
              This optional entry specifies the base address of the video BIOS

       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.

       TextClockFreq  freq
              This optional entry specifies the pixel clock frequency that  is
              used  for  the regular text mode.  The frequency is specified in
              MHz.  This is rarely used.

       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  nor-
       mally  be  at least one, for the monitor being used, but a default con-
       figuration 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 provides information about the  specifications  of  the
       monitor,  monitor-specific  Options,  and  information  about the video
       modes to use with the monitor.   Specifying  video  modes  is  optional
       because  the  server  now  has  a built-in list of VESA standard modes.
       When modes are specified explicitly in the Monitor  section  (with  the
       Modes,  ModeLine,  or  UseModes keywords), built-in modes with the same
       names are not included.  Built-in modes with different names are,  how-
              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 spec-
              ifications 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 spec-
              ifications 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 mod-
              esection-id.  This make 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 ter-
              minated 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
                  ally, 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  sup-
                  plied  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.   Gener-
                  ally,  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.  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,  hsync-
              start, 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  characteris-
              tics  of  the mode.  Interlace indicates that the mode is inter-
              laced.  DoubleScan indicates a mode where each scanline is  dou-
              bled.   +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.   Addition-
              ally,  on some hardware, +CSync and -CSync may be used to select
              the composite sync polarity.  The HSkew and VScan  options  men-
              tioned  above  in  the  Modes entry description can also be used
              here.

       Options
              Some Option flags that may be useful to include in Monitor  sec-
              tions (when needed) include "DPMS", and "SyncOnGreen".


           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  sec-
       tion.


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"
               Monitor    "monid"
               entries
               ...
               SubSection "Display"
                  entries
                  ...
               EndSubSection
               ...
           EndSection

       The  Identifier  and  Device  entries  are  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 mandatory entry specifies the Device section to be used for
              this  screen.   This  is what ties a specific graphics card to a
              screen.  The device-id must match the  Identifier  of  a  Device
              section in the config file.

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

              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.

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

       Option "Accel"
              Enables XAA (X  Acceleration  Architecture),  a  mechanism  that
              makes  video  cards'  2D  hardware acceleration available to the
              Xorg server.  This option is on by default, but it may be neces-
              sary  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 "BiosLocation" "address"
              Set  the  location  of  the  BIOS  for the Int10 module. One may
              select a BIOS of another card for posting or the  legacy  V_BIOS
              range  located  at  0xc0000 or an alternative address (BUS_ISA).
              This is only useful under very special circumstances and  should
              be used with extreme care.

       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.

       Option "NoMTRR"
              Disables MTRR (Memory Type Range Register) support, a feature of
              modern  processors which can improve video performance by a fac-
              tor of up to 2.5.  Some hardware has  buggy  MTRR  support,  and
              some  video  drivers  have  been  known to exhibit problems when
              MTRR's are used.

       Option "XaaNoCPUToScreenColorExpandFill"
              Disables accelerated rectangular  expansion  blits  from  source
              patterns  stored  in  system memory (using a memory-mapped aper-
              ture).

       Option "XaaNoColor8x8PatternFillRect"
              Disables accelerated fills of a rectangular region with a  full-
              color pattern.
              terns from system memory to video memory (using a  memory-mapped
              aperture).

       Option "XaaNoMono8x8PatternFillRect"
              Disables  accelerated fills of a rectangular region with a mono-
              chrome pattern.

       Option "XaaNoMono8x8PatternFillTrap"
              Disables accelerated fills of a trapezoidal region with a  mono-
              chrome pattern.

       Option "XaaNoOffscreenPixmaps"
              Disables  accelerated  draws  into  pixmaps  stored in offscreen
              video memory.

       Option "XaaNoPixmapCache"
              Disables caching of patterns in offscreen video memory.

       Option "XaaNoScanlineCPUToScreenColorExpandFill"
              Disables accelerated rectangular  expansion  blits  from  source
              patterns stored in system memory (one scan line at a time).

       Option "XaaNoScanlineImageWriteRect"
              Disables  accelerated  transfers  of full-color rectangular pat-
              terns from system memory to video memory (one  scan  line  at  a
              time).

       Option "XaaNoScreenToScreenColorExpandFill"
              Disables  accelerated  rectangular  expansion  blits from source
              patterns stored in offscreen video memory.

       Option "XaaNoScreenToScreenCopy"
              Disables accelerated copies of rectangular regions from one part
              of video memory to another part of video memory.

       Option "XaaNoSolidBresenhamLine"
              Disables accelerated solid Bresenham line draws.

       Option "XaaNoSolidFillRect"
              Disables accelerated solid-color fills of rectangles.

       Option "XaaNoSolidFillTrap"
              Disables  accelerated solid-color fills of Bresenham trapezoids.

       Option "XaaNoSolidHorVertLine"
              Disables accelerated solid horizontal and vertical line draws.

       Option "XaaNoSolidTwoPointLine"
              Disables accelerated solid  line  draws  between  two  arbitrary
              points.

       Each  Screen section may optionally contain one or more Display subsec-

       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 driver sup-
              port 8, 15, 16 and 24.  Some also support 1 and/or 4,  and  some
              may  support other values (like 30).  Note: depth means the num-
              ber 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 subsec-
              tion  is to be used for.  This entry is only needed when provid-
              ing 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  combina-
              tions  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 resolu-
              Ctrl+Alt+Keypad-Plus and to the previous mode with Ctrl+Alt+Key-
              pad-Minus.  When this entry is omitted, the valid  modes  refer-
              enced  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 Stat-
              icColor):

                  StaticGray
                  GrayScale
                  StaticColor
                  PseudoColor

              The visual type available for the depth 1 (monochrome) is  Stat-
              icGray.

       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 docu-
              mentation.  Some of the latter are described above in  the  sec-
              tion  about  the  Screen  section, and they may also be included

       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 num-
              bering starts from 0, and must be  consecutive.   The  position-
              information  field  describes the way multiple screens are posi-
              tioned.  There are a number of different ways that this informa-
              tion 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 Xorg (4.2 and earlier) don't recognise the Abso-
                  lute keyword, so it's safest to just specify the coordinates
                  without it.

              RightOf   "screen-id"

              LeftOf    "screen-id"

              Above     "screen-id"

              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 Input-
              Device 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.

       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 configu-
       ration 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 sec-
       tion can be found on-line at <http://dri.freedesktop.org/>.
       fbdev(4),  glide(4),  glint(4),  i128(4),  i740(4),  i810(4), imstt(4),
       mga(4),   neomagic(4),   nv(4),   r128(4),   rendition(4),   savage(4),
       s3virge(4), siliconmotion(4), sis(4), sunbw2(4), suncg14(4), suncg3(4),
       suncg6(4),  sunffb(4),  sunleo(4),  suntcx(4),  tdfx(4),  tga(4),  tri-
       dent(4), tseng(4), v4l(4), vesa(4), vga(4), vmware(4),


AUTHORS

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



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