24888 Rev 3.03 - July 12, 2004 AMD-8151
TM
AGP Tunnel Data Sheet
17
AGP Device Graphic Virtual Memory Aperture Register DevA:0x10
It is expected that the state of this register is copied into the host by software. This register controls no hard-
ware in the IC.
Default: 0000 0000 0000 0008h Attribute: See below.
AGP Device Subsystem ID and Subsystem Vendor ID Register DevA:0x2C
Default: 0000 0000h Attribute: Read; write once.
AGP Capabilities Pointer DevA:0x34
Default: 0000 00A0h Attribute: Read only.
Bits Description
63:32 APBARHI. Read-write. Aperture base address register high. Note: bits[63:40] are required to be
programmed low; setting any of these bits high results in undefined behavior. Note: if
DevA:0x10[64BIT]=0, then these bits are read only, all zero.
31:22 APBARLO. Aperture base address register low. These bits are a combination of read-write and read-
only zero, based on the state of DevA:0xB4[APSIZE]; see that register for details.
21:4 Reserved.
3 Read only. This bit is fixed at its default value to indicate that this register points prefetchable space.
2 64BIT: 64-bit pointer. Read; write once. 1=DevA:0x10 is a 64-bit pointer. 0=DevA:0x10 is a 32-bit
pointer; bits[63:32] are reserved.
1:0 Read only. These bits are fixed at their default value to indicate that this register points memory space.
Bits Description
31:16 Subsystem ID. This field controls no hardware.
15:0 Subsystem vendor ID. This field controls no hardware.
Bits Description
31:8 Reserved.
7:0 Capabilities pointer. Specifies the offset in DevA:0 address space for the AGP capabilities block.
