QG82945GSE S LB2R Intel, QG82945GSE S LB2R Datasheet - Page 102

• Manufacturer Part Number: QG82945GSE S LB2R
• Description: GRAPHICS AND MEM CNTRL HUB; No. of Pins: 998; Package / Case: FCBGA; Interface Type: PCI, SATA, USB
• Manufacturer: Intel

5.1.25
102
LAC - Legacy Access Control
B/D/F/Type:
Address Offset:
Default Value:
Access:
Size:
This 8-bit register controls a fixed DRAM hole from 15-16 MB.
6:1
Bit
7
0
Access
R/W/L
R/W
RO
Default
Value
00h
0b
0b
Hole Enable (HEN):
This field enables a memory hole in DRAM space. The DRAM that
lies “behind” this space is not remapped.
0: No memory hole.
1: Memory hole from 15 MB to 16 MB.
Reserved
MDA Present (MDAP):
This bit works with the VGA Enable bits in the BCTRL register of
Device 1 to control the routing of CPU initiated transactions
targeting MDA compatible
I/O and memory address ranges.
This bit should not be set if Device 1's VGA Enable bit is not set.
If Device 1's VGA enable bit is not set, then accesses to IO
address range 03BCh-03BFh are forwarded to DMI.
If the VGA enable bit is set and MDA is not present, then accesses
to IO address range 03BCh-03BFh are forwarded to PCI Express-
G* if the address is within the corresponding IOBASE and
IOLIMIT, otherwise they are forwarded to DMI.
MDA resources are defined as the following:
Memory: 0B0000h - 0B7FFFh
I/O: 3B4h, 3B5h, 3B8h, 3B9h, 3BAh, 3BFh (including ISA address
aliases, A[15:10] are not used in decode).
Any I/O reference that includes the I/O locations listed above, or
their aliases, will be forwarded to DMI even if the reference
includes I/O locations not listed above.
The following table shows the behavior for all combinations of
MDA and VGA:
VAGEN
0
0
1
1
0/0/0/PCI
97h
00h
R/W/L; RO
8 bits
Host Bridge Device 0 - Configuration Registers (D0:F0)
MDAP
0
1
0
1
All references to MDA and VGA space
are routed to HI
Illegal Combination
All VGA and MDA references are routed
to PCI Express Graphics Attach
All VGA references are routed to PCI
Express Graphics Attach.MDA
references are routed to HI.
Description
Description
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