Mirocom QXI interconnect
The Mirocom Quick Looped Interconnect (QXI) is the standard for Network-on-Chip interconnects within the Mirocom space.
Terminology
Ringstop:
A ringstop is an single interconnecting endpoint on a ringbus and is
responsible for handling time-division multiplexing of the ingress
passdown link and passdown injection to the egress passdown link.
Passdown link:
A passdown link is an connection that passes through one ringstop to
the next, forming a feedback loop that allows the bus to circularly
propagate packets.
Passdown injection:
Passdown injection allows for a node on the bus to inject its own packets
into a ringstop.
Architectural overview
The Mirocom QX1QXI fabric is a high-performance dual ring interconnect that incorporates
zero-relative addressing such that each node can be identified with a 5-bit region
identifier and addressed with a 27-bit offset, both of which are encoded in a 32-bit
physical addressaddress. (seeIn zra.txt).a typical configuration, one ring will be going clockwise and meant for requests
while the other ring goes counter clockwise and meant for data responses.
The QXI fabric is considered a Network-on-Chip that speaks QXI packets. A QXI packet frame encapsulates
metadata such as a CRC32 checksum, sequence number, packet kind, destination node, source node as well
as the packet payload and more.
Physical address format
offset region
+-------+-----+
| 31:5 | 4:0 | bits
+-------+-----+
High-level diagrammatic representation of a single ring
1 [PD_0]
[PDI_0] --> [RS_0] ---/----> [RS_1] <-- [PDI_1]
^ |_ 2 [PD_1]
|_4 |
| 3 [PD_1] V
[PDI_3] --> [RS_3] <-/------ [RS_2] <-- [PDI_2]
=========================
Where:
RS_N => Ringstop
PD_N => Passdown link
PDI_N => Passdown link injection