Table of Contents
Advertisement
IDT Multicast
Notes
PES48H12G2 User Manual
Only posted memory write TLPs and address routed message TLPs can be multicast TLPs. The primary
determinant of whether or not a memory write or address routed message TLP is a multicast TLP is its
address and the address associated with multicast address regions. A multicast address region may
overlap a non-multicast address region.
– Multicast TLPs that target a multicast address region are routed to all multicast group members
while other TLPs, such as non-posted reads, may be routed to only one, possibly different, desti-
nation.
Multicast TLPs are posted TLPs and have the same ordering requirements as other posted TLPs. There
are no new multicast TLP ordering rules.
The maximum number of multicast groups supported in an implementation is contained in the Max Multi-
cast Groups (MAXGROUP) field in the Multicast Capability (MCCAP) register. The number of multicast
groups that are actually enabled is determined by the value in the Number of Multicast Groups
(NUMGROUP) field in the Multicast Control (MCCTL) register.
As illustrated in Figure 14.1, multicast TLP group membership is determined by address. Associated
with each multicast group is an address region. Posted memory write and address routed message TLPs
whose address is equal to that associated with a multicast group when the Multicast Enable (MEN) bit is set
are defined to be multicast TLPs associated with that group.
Muticast Base Address
The multicast address region associated with a TLP is determined as follows. Multicast group address
regions are laid out contiguously in memory from low to high starting with multicast group zero. The number
of regions is determined by the value of the NUMGROUP field in the MCCTL register.
– There are no address regions allocated for multicast group numbers that are greater than that
enabled by the NUMGROUP field in the MCCTL register.
The size of each multicast group address region is determined by the value of the Index Position
(INDEXPOS) field in the Multicast Base Address Low (MCBARL) register. The size of each multicast group
INDEXPOS
region is equal to 2
.
0x0000_0000_0000_0000
Multicast Group 0
2
INDEXPOS
Multicast Group 1
Multicast Group 2
Multicast Group 3
...
Multicast Group x
0xFFFF_FFFF_FFFF_FFFF
Figure 14.1 Multicast Group Address Ranges
14 - 2
(NUMGROUP + 1) * 2
INDEXPOS
April 5, 2013
Advertisement
Table of Contents
