PEX 8532 Transparent Mode Port Registers
PLX Technology, Inc.
Register 11-8. 1Ch Secondary Status, I/O Limit, and I/O Base (All Ports)
Serial
Default
Bit(s)
Description
Type
EEPROM
I/O Base
I/O Base Addressing Capability
3:0
RO
Yes
Yes
1h
Fh
1h = 32-bit Address decoding is supported
Other values are not allowed.
I/O Base Address[15:12]
The PEX 8532 ports use their I/O Base and I/O Limit registers to determine
the address range of I/O transactions to forward from the primary interface
to the secondary interface or vice versa.
I/O Base Address[15:12] bits specify the corresponding PEX 8532 port I/O Base
Address[15:12]. The PEX 8532 assumes I/O Base Address[11:0] = 000h.
7:4
RW
For 16-bit I/O addressing, the PEX 8532 assumes Address[31:16] = 0000h.
For 32-bit addressing, the PEX 8532 decodes Address[31:0], and uses
the I/O Base Upper 16 Bits and I/O Limit Upper 16 Bits.
I/O Limit
I/O Limit Addressing Capability
1h = 32-bit Address decoding is supported
Other values are not allowed.
11:8
RO
Yes
1h
I/O Limit Address[15:12]
The PEX 8532 ports use their I/O Base and I/O Limit registers to determine the
Address range of I/O transactions to forward from the primary interface to the
secondary interface or vice versa.
I/O Limit Address[15:12] specify the corresponding PEX 8532 port I/O Limit
Address[15:12]. The PEX 8532 assumes Address bits [11:0] of the I/O Limit
Address are FFFh.
15:12
RW
Yes
0h
For 16-bit I/O addressing, the PEX 8532 decodes Address bits [31:16]
and assumes Address bits [31:16] of the I/O Limit Address are 0000h.
For 32-bit addressing, the PEX 8532 decodes Address bits [31:0],
and uses the I/O Base Upper 16 Bits and I/O Limit Upper 16 Bits.
If the I/O Limit Address is less than the I/O Base Address, the PEX 8532 does
not forward I/O transactions from the corresponding port primary/upstream bus
to its secondary/downstream bus. However, the PEX 8532 forwards all I/O
transactions from the secondary bus of the corresponding port to its primary bus.
160
ExpressLane PEX 8532AA/BA/BB/BC 8-Port/32-Lane Versatile PCI Express Switch Data Book
Copyright © 2007 by PLX Technology, Inc. All Rights Reserved – Version 1.6
PLX [ PLX TECHNOLOGY ]
