Receive buffer reordering – Altera IP Compiler for PCI Express User Manual
Page 180
8–4
Chapter 8: Transaction Layer Protocol (TLP) Details
Receive Buffer Reordering
IP Compiler for PCI Express User Guide
August 2014
Altera Corporation
■
The transaction layer sends all memory and I/O requests, as well as completions
generated by the application layer and passed to the transmit interface, to the PCI
Express link.
■
The IP core can generate and transmit power management, interrupt, and error
signaling messages automatically under the control of dedicated signals.
Additionally, the IP core can generate MSI requests under the control of the
dedicated signals.
Receive Buffer Reordering
The receive datapath implements a receive buffer reordering function that allows
posted and completion transactions to pass non-posted transactions (as allowed by
PCI Express ordering rules) when the application layer is unable to accept additional
non-posted transactions.
The application layer dynamically enables the RX buffer reordering by asserting the
rx_mask
signal. The rx_mask signal masks non-posted request transactions made to
the application interface so that only posted and completion transactions are
presented to the application.
lists the transaction ordering rules.
Table 8–2. Transaction Ordering Rules (Part 1 of 2)
Row Pass Column
Posted Request
Non Posted Request
Completion
Memory Write or
Message
Request
Read Request
I/O or Cfg Write
Request
Read Completion
I/O or Cfg Write
Completion
Spec
Core
Spec
Core
Spec
Core
Spec
Core
Spec
Core
Posted
Memory Write or
Message
Request
Y/N
N
N
yes
yes
yes
yes
Y/N
Y
N
N
No
No
NonPos
ted
Read Request
No
No
Y/N
Yes
Y/N
Yes
Y/N
No
Y/N
No
I/O or
Configuration
Write Request
No
No
Y/N
Yes
Y/N
Yes
Y/N
No
Y/N
No