Intel D425 AU80610006252AA User Manual

Datasheet 

 147 

B/D/F/Type: 0/2/1/PCI 

Address Offset: 

60-61h 

Default Value: 

0000h 

Access:  

RO; 

Size: 16 

bits 

15:0 RO 

0000h  Reserved R/W (): 

B/D/F/Type: 0/2/1/PCI 

Address Offset: 

62h 

Default Value: 

02h 

Access:  

RO; 

Size: 8 

bits 

This register determines the size of the graphics memory aperture in function 0 and in 
the trusted space. Only the system BIOS will write this register based on pre- boot 
address allocation efforts, but the graphics may read this register to determine the 

correct aperture size. System BIOS needs to save this value on boot so that it can 

reset it correctly during S3 resume. 

 

 

7:4 RO  0h 

Reserved R/W ():  
 Scratch Bits Only --  Have no physical effect on 
hardware 

3 RO  0b 

2:1 RO  01b 

Untrusted Aperture Size (LHSAS):  
00: Reserved 
01:  512 MB. Bit 28 and 27 of GMADR are 
read-only, allowing 512 MB of address space to 
be mapped. Bits 18 and 17 of GTTADR are read-
only. The untrusted GTT is 512KB. 
10:  256 MB. Bit 28 of GMADR is read-write 
and bit 27 of GMADR is read-only, limiting the 
address space to 256MB. Bit 18 of GTTADR is 
read-write and bit 17 of GTTADR is read-only. 
The untrusted GTT is 256KB. 
11:  128 MB.  Bits 28 and 27 of GMADR are 
read-write, allowing 128 MB of address space to 
be mapped. Bits 18 and 17 of GTTADR are read-
write. The untrusted GTT is 128KB. 
BIOS Requirement: Graphics driver