QP Setup Is Performed in a Defined Sequence
After the initial creation of a QP (or if the QP has been commanded to re-enter the Reset state via the Modify QP verb), software incrementally advances it through a defined series of states until it is fully operational:
Immediately after creation, the QP is in the Reset state. It does not have sufficient information either to send messages or to receive them.
Using the Modify QP verb, software supplies the QP with additional information (see “Initialized State” on page 240) and transitions it to the Initialized state. At this point:
- RQ WR posting is enabled, but not RQ WQE processing.
- SQ WR posting and processing are still disabled.
Using the Modify QP verb, software supplies the QP with additional information [see “Ready to Receive State” on page 244] and transitions it to the Ready To Receive (RTR) state. At this point:
- RQ posting and processing are now enabled. The RQ Logic can handle inbound messages.
- SQ posting and processing are still disabled.
Using the Modify QP verb, software supplies the QP with additional information [see “Ready to Send State” on page 247] and transitions it to the Ready To Send (RTS) state. This is the fully operational state. At this point:
- WRs can be posted to both the SQ and RQ.
- WQEs on both queues are processed.