User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 8: PCI Bus and HyperTransport Fabric Page
225
4.4.2 Broadcast Message
The only broadcast message the interface will generate is an EOI. No broadcast messages are
accepted.
4.4.3 Flush, 4.4.4 Fence
The interface will never generate a Flush or Fence command. They will be accepted and Flush
will result in a TgtDone return.
4.4.5 Atomic Read-Modify-Write
The Atomic Read-Modify-Write is neither generated nor accepted by the part.
4.5.2 Target Done
Target done is returned when a request has been sent from the HyperTransport interface to
the I/O Bridge. Inbound TargetDone responses cause the target done counter to increment
(making the completion visible to the processor).
4.7 Virtual Channels
The three standard Virtual Channels are supported. Since all writes within the part are posted,
the only writes that will be in the non-posted channel are configuration space writes.
4.9.4 Host Bridges
1. The interface supports the optional double-hosted memory space region as described in
Section: “Accessing the SiByte from a SiByte on a Double Hosted Chain” on page 212
.
Responses from the part always have the Bridge bit set (rather than the specified clear) and a
UnitID of zero.
2. Broadcasts are dropped.
3. Directed requests are accepted as described in the
Section: “Accessing the SiByte from
HyperTransport Devices” on page 210
4. This rule is not completely enforced. Responses with the Bridge bit set and a UnitID of zero
are treated as responses from a host on the far end of the link and compared to the outstanding
requests.
5. A SrcTag error is logged in the HyperTransport Error Status register (
) if a
responce is received with no matching request.
5 Interrupts
The interrupt usage follows the earlier HyperTransport specification which has now been
moved to the x86-specific appendix.
5.1 Interrupt Requests
The IntrInfo[55:32] bits are not supported. IntrInfo[31:2] are interpreted in a similar way to the
x86-specific model, as described in
Section: “HyperTransport Interrupts” on page 48
. Interrupt
messages can be generated using the special address range described in
Section: “HyperTransport End Of Interrupt (EOI) Signaling Space” on page 198
5.2 End of Interrupt
The interface ignores any EOI messages it receives. EOI messages are generated by software
as described in
Section: “HyperTransport End Of Interrupt (EOI) Signaling
.