Technical data

4-4
Programming Model
4
Type 1 to Type 1 Forwarding
If the 21150 detects a Type 1 configuration transaction intended for a PCI
bus downstream from the secondary bus (i.e., another PCI bus on a PMC
adapter), the 21150 will forward the transaction unchanged to the
secondary bus. This transaction will eventually get translated to a Type 0
transaction or a Special Cycle by a downstream PCI-to-PCI bridge.
Special Cycles
Special Cycle transactions generated on the primary PCI bus are ignored
by the 21150. However, Special Cycle commands can be sent to the PMC
adapter using a Type 1 Configuration transaction. The 21150 will generate
a Special Cycle on the secondary bus when it detects a Type 1 transaction
on the primary bus with the following conditions:
Table 4-1. Secondary Device Number to IDSEL Mapping
Device
Number
(Hex)
Secondary AD(31:16)
(Binary)
AD Bit
Used as
IDSEL#
Purpose
0-1 0000_0000_0000_0001 -
0000_0000_0000_0010
- Implemented by 21150 but not
used
2 0000_0000_0000_0100 18 PMC 1 IDSEL#
(Slot 1 on PMCspan-001/-002)
3 0000_0000_0000_1000 19 PMC 2 IDSEL#
(Slot 2 on PMCspan-001/-002)
4 0000_0000_0001_0000 20 PMC 3 IDSEL#
(Slot 1 on PMCspan-010)
5 0000_0000_0010_0000 21 PMC 4 IDSEL#
(Slot 2 on PMCspan-010)
6 - F 0000_0000_0100_0000 -
1000_0000_0000_0000
22 - 31 Implemented by 21150 but not
used
10 - 1E 0000_0000_0000_0000 None Not implemented by 21150
1F Special Cycle Data - Special Cycles for PMC