
Chapter 4
Registers
155
24674
Rev. 3.00
April 2003
AMD-8111 HyperTransport I/O Hub Data Sheet
AMD Preliminary Information
ROM Decode Control Register
DevB:0x43
Default:
00h.
Attribute:
Read-write.
SEGEN. ROM Segment Enables.
This register specifies the address space mapped to the BIOS
ROM on the LPC or PCI bus (see DevB:3x48[PCIBIOS]). Each bit specifies if the LPC or PCI bus is
enabled for BIOS. For each of these bits: 1=Enables an address range as a BIOS ROM access. 0=The
corresponding address range is not decoded as a BIOS ROM access and not forwarded to the LPC or
PCI bus. Writes to disabled segments are ignored and reads return all 0xF. The bits control the
following address ranges (the last column shows the translated LPC bus addresses):
Note:
The following ranges are always specified as BIOS address ranges. See DevB:0x80 for more
information about how access to BIOS spaces may be controlled.
Prefetchable Memory Control Register
DevB:0x44
Default:
0001h.
Attribute:
Read-write.
Bits
7
6
5
4
3
2
1
0
Size
Host Address Range[31:0]
FFC0_0000h
–
FFFF_FFFFh
FFB0_0000h
–
FFBF_FFFFh
000E_8000h
–
000E_FFFFh
000E_0000h
–
000E_7FFFh
000D_8000h
–
000D_FFFFh
000D_0000h
–
000D_7FFFh
000C_8000h
–
000C_FFFFh
000C_0000h
–
000C_7FFFh
Address translation for LPC bus
FFC0_0000h
–
FFFF_FFFFh
FFB0_0000h
–
FFBF_FFFFh
FFFE_8000h
–
FFFE_FFFFh
FFFE_0000h
–
FFFE_7FFFh
FFFD_8000h
–
FFFD_FFFFh
FFFD_0000h
–
FFFD_7FFFh
FFFC_8000h
–
FFFC_FFFFh
FFFC_0000h
–
FFFC_7FFFh
4 megabytes
1 megabyte
32K bytes
32K bytes
32K bytes
32K bytes
32K bytes
32K bytes
Size
Host Address Range[31:0]
FFFF_0000h
–
FFFF_FFFFh
000F_0000h
–
000F_FFFFh
Address translation for LPC bus
FFFF_0000h
–
FFFF_FFFFh
FFFF_0000h
–
FFFF_FFFFh
64K bytes
64K bytes
Bits
15:4
Description
TOM[31:20]. Top of memory bits[31:20].
This speci
fi
es the top of system memory. System memory
space is treated as prefetchable by the PCI bridge. It is de
fi
ned as follows:
System_memory = (PCI_address[31:20] <= TOM[31:20]);
Note: If ALLPF is set High, then TOM is ignored.
Reserved.
ALLPF. All of memory space (4 gigabytes) is prefetchable.
1=All 4 gigabytes of memory space is
prefetched by the PCI bridge; when memory read transactions with PCI command encoding of 6h are
initiated by PCI bus masters, then the data is prefetched, regardless of the address. 0=Only memory
read accesses with PCI command encoding of Ch or Eh, or memory accesses with PCI command
encoding 6h below the top of memory speci
fi
ed in the TOM
fi
eld of this register are prefetched.
3:1
0