System Address Map
3.11.1
Legacy VGA and I/O Range Decode Rules
The legacy 128 KB VGA memory range 000A_0000h-000B_FFFFh can be mapped to
IGD (Device 2), to PCI Express (Device 1), and/or to the DMI Interface depending on
the programming of the VGA steering bits. Priority for VGA mapping is constant in that
the GMCH always decodes internally mapped devices first. Internal to the GMCH,
decode precedence is always given to IGD. The GMCH always positively decodes
internally mapped devices, namely the IGD and PCI-Express. Subsequent decoding of
regions mapped to PCI Express or the DMI Interface depends on the Legacy VGA
configurations bits (VGA Enable and MDAP).
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Datasheet
INTEL [ INTEL ]
