IDT 89HPES48T12G2, User Manual

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IDT Theory of Operation
PES48T12G2 User Manual 8 - 5 April 5, 2013
Notes
Figure 8.3 ACS Upstream Forwarding Example
When multiple ACS checks are enabled, they are prioritized as described below. Table 8.4 shows the
prioritization for ACS checks associated with the reception of request TLPs. Table 8.5 shows the prioritiza-
tion for ACS checks associated with the reception of completion TLPs.
ACS Check Priority Comment
ACS Source Validation 4
(Highest)
Applicable to request TLPs received by a down-
stream port on its ingress link.
ACS Translation Block-
ing 3 Applicable to memory request TLPs received by
a downstream port on its ingress link.
ACS Upstream For-
warding 2 Applicable to request or completion TLPs
received by the downstream port on its ingress
link that target the port’s egress link. This is not
considered a peer-to-peer transfer.
ACS Peer-to-Peer
Request Redirect 1
(Lowest)
Applicable to peer-to-peer request TLPs only
Subject to the interaction rules in Section 6.12.3
of the PCI Express 2.0 Specification.
ACS Peer-to-Peer
Egress Control
ACS Direct Translated
Peer-to-Peer
Table 8.4 Prioritization of ACS Checks for Request TLPs
Intended TLP Route
ACS Re-directed Route
Virtual PCI Bus
P2P
Bridge
Upstream
Port
P2P
Bridge
P2P
Bridge
Downstream Ports
ACS Upstream
Forwarding