AMD CS5535 - Manual (Page 25)

AMD Geode™ GX Processor/CS5535 Companion Device GeodeROM Porting Guide 25
Initialization 32430C
4.5 Miscellaneous Initializations
In addition to the previous processor initializations, the graphics card(s) must also be initialized.
4.5.1 Initialize Graphics Subsystem
There are two different modes: CRT and TFT. Graphics initialization needs to identify which kind of support is required by
reading an MSR in the Video Processor.
Entry Conditions:
4 GB descriptor in FS core register.
GeodeLink descriptors initialized.
VSA initialized.
First MB of DRAM functional.
Interrupts enabled.
DMA initialized.
PCI bus functional.
Procedure:
4.5.1.1 Monochrome Support
GeodeROM includes the appropriate INT 10h support for monochrome video adapters.
SoftVG needs an extra hole at B000h-B7FFh when a mono card is present.
4.5.1.2 Dual Monitor Support
GeodeROM provides dual monitor support. GeodeROM assumes that the external card is the primary graphics card and
that the XpressGRAPHICS™ system is secondary.
IF THEN
Jump to PCI graphics BIOS for initialization.
ELSEIF THEN
Jump to ISA graphics BIOS for initialization.
ELSE THEN
Initialize SoftVGA during VSA initialization
Jump to integrated graphics BIOS for initialization
ENDIF