EP80579 Datasheet, PDF (280/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
10.3.2
Note:
Note:
VGA and MDA Regions
Along with the memory space address regions described in Section 10.1.2, “VGA and
MDA Memory Spaces”, there are fixed I/O locations associated with both the VGA and
the MDA regions. Accesses to these addresses are routed to NSI by default, but this
behavior may be modified via the VGAEN, MDAP and MAE configuration settings. Refer
to the prior sections for the rules associated with the configuration settings of VGAEN,
MDAP and MAE.
The MDA region includes I/O space addresses 3B4h, 3B5h, 3B8h, 3B9h, 3BAh and
3BFh. The VGA region includes I/O space ranges 3B0-3BBh, and 3C0-3DFh. The PCI
Specification defines both MDA and VGA to be 10-bit address decode, thus all accesses
with A[9:0] matching any of these addresses are subject to the associated routing
rules. Address bits A[15:10] are ignored when the check against these fixed addresses
are applied.
The order of precedence for the routing checks is as follows:
• MAE = 0, MDA addresses will route to NSIif MDAP is set, overriding any VGAEN.
• MAE = 1, MDA addresses will route to the Peer device if MDAP is set, overriding any
VGAEN.
• MAE = 0, VGA addresses will route to the NSI.
• MAE = 1, VGA addresses will route to the PCI Express port with its VGAEN set, if
any.
• MAE = 0, MDA addresses which fall within VGA regions will route to the NSI if MDAP
is clear.
• MAE = 1, MDA addresses which fall within VGA regions will follow VGAEN if MDAP is
clear.
• Both VGA and MDA addresses default to NSI if MDAP and all VGAEN bits are clear.
Setting of MDAP or any of the VGAEN bits implies that the ISAEN bit is also set in all
virtual P2P bridges, because of the 10-bit decode requirement.
AIOC access to this space is not supported. Upstream attempted accesses to this space
are programming errors and will result in a master abort.
Intel^® EP80579 Integrated Processor Product Line Datasheet
280
August 2009
Order Number: 320066-003US