Hi. I've also developed a polling VF driver and I'm also seeing this 4-descriptor problem. I'm confused by the description in the latest XL710 Datasheet to workaround it. Since you appear to have found a fix, I'm wondering if you can help me. Specifically the datasheet says:
8.3.3.1.4.2:
Enable interrupts internally in the QINT_RQCTL register of the queue and map it to an MSI-X interrupt that is guaranteed to be inactive by the operating system....
The QINT_RQCTL register is in the PF, but the queue involved is obviously in my VF, so it's not clear to me that there IS a QINT_RQCTL register associated with my queue. Do you know what the answer is? Could you send me the details of your fix that worked?
Regards,
Clive