VGA-Compatible Miniport's SvgaHwIoPortXxx

VGA-compatible miniport drivers in x86-based machines replace the system-supplied VGA miniport driver. Therefore, VGA-compatible miniports must have a set of SvgaHwIoPortXxx functions to support full-screen MS-DOS applications as the system-supplied VGA miniport driver does.

The designer of a new VGA-compatible SVGA miniport driver should adapt one of the system-supplied SVGA miniport's SvgaHwIoPortXxx functions to the adapter's features. As already mentioned in VGA-compatible x86 Based Miniports, miniport drivers for other types of adapters in x86-based machines can have a set of SvgaHwIoPortXxx routines and provide the same support at the discretion of the miniport designer or if the miniport cannot be loaded while the system VGA miniport is loaded.