In D17987#389775, @v.maffione_gmail.com wrote:

The truth is that netmap not setting the IFCAP_NETMAP flag in ifp->if_capabilities after r307394 is a mistake that we did not notice so far.
It got introduced by refactoring, 3 years ago (see https://github.com/luigirizzo/netmap/commit/5d0796f93a1107eb14422c7b8ea416f7fd750a2e).
Sorry for that, it was unintended.
I just happened to notice that and fix it.

The cxgbe part of this diff reverts r309725. The commit message for r309725 indicates the changes were made to catch up with r307394, which was the a netmap update. Can you confirm that various releases of netmap have had different behavior regarding if_capabilities? If netmap has finally settled on handling the caps this way then I have no objection to one last catch-up in the driver.

lazy_tx_credit_flush in the driver is supposed to avoid the situation you described. Try setting it to 1 if it isn't already and see if that helps.

+Vincenzo for the netmap_kern.h part.

How about using __aligned(CACHE_LINE_SIZE) like the rest of the driver and let the compiler figure out the padding?

Can you provide exact steps to reproduce the problem that you described? I get an EAGAIN (as expected) and not a panic if I try to enable netmap when the link is down.

In D17843#381477, @ae wrote:

Hi, I have a report, that cxgbe driver doesn't take into account packets, that are received from mirrored port. So, when you run netstat -hw 1 -I cxl0 you will see no packets, but tcpdump will show them. It seems a bit confusing. I didn't checked this, so I might be wrong.

What version of FreeBSD is this? I think this is already fixed in 12.0.