On 10/12/20 5:31 AM, Edward Srouji wrote: > > On 10/8/2020 10:07 PM, Jason Gunthorpe wrote: >> On Fri, Oct 02, 2020 at 04:34:22PM -0500, Bob Pearson wrote: >>> I am currently trying to figure out why one of the pyverbs tests is failing. >>> >>> I added a check implementing C9-205 (p 419) of the IBA spec. I requires that a responder receiving a packet longer >>> than the receive buffer or the PMTU shall be silently dropped. I.e. a class D error. >>> >>> C9-205: Before executing the request, the responder shall validate the >>> Packet Length field of the LRH and the PadCnt of the BTH as described >>> in 9.8.3.2.2: Responder - Length Validation. >>> The following characteristics shall be validated: >>> • The Length fields shall be checked to confirm that there is sufficient >>> space available in the receive buffer specified by the receive WQE. >>> • The packet payload length must be between zero and PMTU bytes >>> inclusive in size. >>> If a packet is detected with an invalid length, the request shall be an invalid >>> request and it shall be silently dropped by the responder as specified in >>> Section 9.9.3 Responder Side Behavior on page 435. The responder then >>> waits for a new request packet. >>> >>> tests/test_cq_events.py passes PATH_MTU = 1024 in the modify QPs verb for RC and XRC but not UD. >>> This should be a required parameter as part of the primary destination address but is not getting >>> set for UD. The test then proceeds to send a 1024 byte payload to the destination and for UD hangs >>> waiting for the completion. >>> >>> I don't want to mess with these tests because I am a poor python coder. Is there some reason why it is >>> OK to not set the PMTU for UD QPs? >> Edward is the person to ask about the tests.. >> >> It seems like you are right and it should be set for UD too, if it is >> not set what is the default? >> >> Jason > > AFAIK PATH_MTU (when modifying a QP) is valid only for connected types (e.g. RC/UC etc.). It's not valid for UD. If you look at the code you may see that modify_qp does not update the PMTU according to the user attribute. > > There is a default PMTU set for UD (usually it's the maximum PMTU). > > Edward. > > Totally agree. Sorry for the wild goose chase.
