Intel D425 AU80610006252AA User Manual

152  

Datasheet  

MMIO 
Address 
Register 

Index 0  3  00000000h 

RW; 

MMIO Data 
Register 

Data 4  7 00000000h 

RW; 

B/D/F/Type: 0/2/0/PCI 

IO 

Address Offset: 

0-3h 

Default Value: 

00000000h 

Access: RW; 

Size: 32 

bits 

MMIO_INDEX: A 32 bit IO write to this port loads the offset of the MMIO register or 

offset into the GTT that needs to be accessed. An IO Read returns the current value of 
this register. An 8/16 bit IO write to this register is completed by the CPU UNCORE 

but does not update this register. 

This mechanism to access internal graphics MMIO registers must not be used to 
access VGA IO registers which are mapped through the MMIO space. VGA registers 

must be accessed directly through the dedicated VGA IO ports. 

 

 

31:2 RW 00000000h 

Register/GTT Offset (REGGTTO):  
This field selects any one of the DWORD 
registers within the MMIO register space 
of Device #2 if the target is MMIO 
Registers. 
This field selects a GTT offset if the 
target is the GTT. 

1:0 RW  00b 

•  00: MMIO Registers 
•  01: GTT 
•  1X: Reserved