AMD-761 Datasheet, PDF (237/264 Pages) Advanced Micro Devices – AMD-761-TM System Controller Software/BIOS Design Guide

24081D—February 2002
Preliminary Information
AMD-761™ System Controller Software/BIOS Design Guide
Registers
-----
Bits
Description
11 Dis AGP Early Probe
10 Dis PCI Early Probe
9
Dis AGP arbiter pipelining
8
Southbridge lock disable
7
PM register enable
6
15-Mbytes hole enable
5
14-Mbytes hole enable
4
EV6 mode
3
Target latency timer disable
2
ApcPreEn
1
PciPreEn
0
ParkPCI
Initialized/
Required
Value
0b
0b
0b
0b
xb
xb
xb
1b
1b
0b
0b
0b
Actual
Value
Key fcn( )
Notes
1 = Disable early snoop
A
from AGP master running a
PCI cycle to memory
1 = Disable early probe
B
request for write cycles
from an external PCI master
A
1 = Disable AGP arbiter from
pipelining grants onto bus
1 = Disable flushing function
B
performed before granting
bus to the Southbridge
1 = Enables R/W accesses to
P
PM register at 0:0x18 BAR2
– AGP Power management
B
1 = Enable a memory hole
at 15-16 Mbytes
B
1 = Enable a memory hole
at 14-15 MBytes
1 = Enable PCI decoding in
EV6 mode. Used for
opening buffers in 640K to
B
1-Mbyte memory address
space. Legacy USB/SCSI
devices sometimes need
this capability.
0x0x ^{1 = Disable AMD-751™}
B
0x84 ^{system controller target}
latency timer on both PCI
[23] _{and AGP’s PCI interfaces}
1 = Disables AMD-751
system controller to prefetch
B
data from SDRAM when a
PCI master on AGP bus reads
from main memory
1 = Enables AMD-751
system controller to prefetch
B
data from SDRAM when a
PCI master on PCI bus reads
from main memory
0 = PCI arbiter parks on
B
processor accesses to PCI
1 = Enables parking on an
external PCI master
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
Chapter 7
Recommended BIOS Settings
225