Once you have given a description of your monitor and graphics
hardware you need to specify how they are to be used by the servers.
This is done with the "Screen" sections in the XF86Config
file. You need to supply a Screen section for each of the server
driver types you will be using.
The driver types are "SVGA" (XF86_SVGA), "VGA16" (XF86_VGA16), "VGA2"
(XF86_Mono), "MONO" (XF86_Mono, XF86_VGA16), and "ACCEL" (XF86_S3,
XF86_Mach32, XF86_Mach8, XF86_Mach64, XF86_8514, XF86_P9000, XF86_AGX,
XF86_W32).
Each Screen section specifies which Monitor description and Device
description are to be used.
The Screen sections include one or more "Display" subsections. One Display subsection may be provided for each depth that the server supports. In the Display subsection you can specify the size of the virtual screen the server will use. The virtual screen allows you to have a "root window" larger than can be displayed on your monitor (e.g. you can have an 800x600 display, but a 1280x1024 virtual size). The Virtual keyword is used to specify this size. Note that many of the new accelerated server use non-displayed memory for caching. It is not desirable to use all of your memory for virtual display, as this leaves none for caching, and this can cost as much as 30-40% of your server performance.
The last thing you specify in Display subsection is the display modes. These are the physical display resolutions that the server will use. The name is arbitrary, but must match something in the appropriate Monitor section. In general, these names are the display resolution (e.g. "1024x768"), but need not be. You can list as many as desired; the first is the default/starting display, and you can cycle through the list with Ctrl-Alt-Keypad+ or Ctrl-Alt-Keypad- hotkey sequences.
That's it. Now you're ready to test out your new XFree86 installation.