Writing NFB graphical adapter drivers

Writing NFB graphical adapter drivers

This topic describes how to use the X Link Kit to create a dynamically-loaded graphics driver that interfaces with the SVR5, SCO OpenServer 5 or AIX 5L X server. The process described here uses the NFB interface and is most appropriate for intelligent graphics adapters that implement a BitBlt or CopyArea routine on the card and can do fills. Further optimization is possible for cards that have Bresenham Line drawing capabilities or some sort of stipple operation, hardware support for tiling operations, and hardware cursors.

The NFB driver handles handles the graphics rendering for the chip or chip set on the graphics adapter. It must also have graphical information about how to switch back and forth from graphics mode to text mode on this graphic adapter. For SVR5 and SCO OpenServer 5, this is provided in a grafinfo(DSP/4dsp) file; for AIX 5L, this is provided by the vga driver with the NFB_GRAFINFO driver definitions that are added to the ODM database.

The X server uses monitor information to determine the physical dimensions of your screen so that fonts and other records are displayed in the correct size. In most cases, the generic monitor size (such as Other 17 inch) is adequate. On SVR5 and SCO OpenServer 5 systems, you can create a moninfo(DSP/4dsp) file if you have a specialized monitor that is not already supported. If an NFB driver for your chip or chip set is already supported, you may not need to write a whole new graphics driver. Instead, you can modify the specific graphical information. For SVR5 and SCO OpenServer 5, this is defined in the grafinfo(DSP/4dsp) file; for AIX 5L, this is defined in the ODM database as discussed in UNRESOLVED XREF-0.