AMD-761 Datasheet, PDF (240/264 Pages) Advanced Micro Devices – AMD-761-TM System Controller Software/BIOS Design Guide

Preliminary Information
AMD-761™ System Controller Software/BIOS Design Guide
24081D—February 2002
Registers
-----
Bits
Description
Initialized/
Required
Value
Actual
Value
Key
fcn( )
Notes
0x0x0xACh
AGP Virtual Address Space
Size Register
31:17 Reserved
yyyb 000h
16
VGA_IA_En
xb
15:4 Reserved
000h
VA_Size
3:1
xxxb
AGP aperture size
0
GARTEna
xb
AGP aperture base address enable
r
0 = No ISA aliasing on
address [15:0]
B
1 = Force AMD-751™
system controller to alias
ISA address [15:0]
r
000 = 32 Mbytes
001 = 64 Mbytes
010 = 128 Mbytes
011 = 256 Mbytes
A
100 = 512 Mbytes
101 = 1 Gbyte
110 = 2 Gbytes
128 Mbytes recommended
0 = Disable register
A
1 = Enable register 0:0x10
(BAR0) and start GART
0x0x0xB0h Gart/AGP Mode Control
31:21 Reserved
20
Reserved
00h 000b
0b
19
NonGART Snoop
0b
18
Reserved
0b
17
GART page directory cache enable
0b
16
GART Index Scheme control
yb
15:0 Reserved
00h
r
B
Debug/Performance register
B
0 = Disable probes
1 = Enable probes
B
Debug/Performance
B
register
0 = Disable, 1 = Enable
o
0 = 2-Level, 1 = 1-Level Mode
r
KEY:
B= Mandatory BIOS function
A= AGP setup by BIOS
c = Calculated/set by AMD-761™ internal logic
P= Power management setup by BIOS o = Setup by OS or OS driver F = Performance enhancement set by BIOS
r = Hardcoded and reserved
u = PCI operational user interface E = Elective BIOS function
228
Recommended BIOS Settings
Chapter 7