Chapter 7
Recommended BIOS Settings
227
24081D—February 2002
AMD-761™ System Controller Software/BIOS Design Guide
Preliminary Information
Registers
----
Bits
Description
Initialized/
Required
Value
Actual
Value
Key
fcn( )
Notes
0x0x0xA0h
AGP Capability Identifier
31:24
Reserved
00h
r
23:20
Major_Rev
2h
r
19:16
Minor_Rev
0h
r
15:8
Next_Pointer
00h
r
Null = Final item on list
7:0
Cap_ID
02h
r
02h = AGP
0x0x0xA4h
AGP Status Register
31:24
Max_ReqQ_Depth
0Fh
r
Max # AGP Command
Requests
23:10
Reserved
00b 000h
r
9
SBA
1b
r
Side Band Addressing
Supported
8:6
Reserved
000b
r
5
R4G
0b
r
Fixed at 4 Gbytes Maximum
4
FW
yb
r
0x0x
0B4
[7]
1 = Fast Write Support
0 = Fast Write Not Supported
3
Reserved
0b
r
2:0
Rates
111b
r
AMD-761 system controller
supports 1x/2x/4x
0x0x0xA8h
AGP Command Register
31:10
Reserved
0000_0h
00b
r
9
SBA_Ena
Sideband addressing enable
yb
o
Set by operating system
agent,
not
BIOS.
0 = Disable, 1 = Enable
8
AGP_Ena
AGP operation enable
yb
o
Set by operating system
agent,
not
BIOS.
0 = Disable, 1 = Enable
7:6
Reserved
0b
r
5
Greater than 4G address
support
0b
r
0 = Disable, 1 = Enable
4
Fast_Writes
yb
o
0x0x0
B4[7]
0=Disabled, 1=Enabled
3
Reserved
0b
r
2:0
AGP data transfer mode
yyyb
o
001b=1x, 010b=2x,100b=4x
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