Created attachment 217546 [details]
hw.em.sbp off by default
The iflib rewrite changed sysctl hw.em.sbp default to on but it is still documented as off by default. This coupled with #248869 caused error counters for the affected NICs to report lots of errors as compared to FreeBSD 11 and below.
This also affects CURRENT and is present since 12.0, but marking this as a 12.1-RELEASE issue.
Patch is attached to restore the previous behaviour, but maybe the documentation should be changed instead.
I'm not sure about this one; I agree that either the code or the documentation should change, but I don't know if we should change the default back, for 13.0 or 12.2.
I also don't know why it changed from 11, either. We at Intel didn't do the 1G driver conversion to iflib. (and I'm not even supposed to be maintaining it!)
I am unsure too. The only issue I see is that some applications VLANs with Netmap only work in device promisc mode and having this enabled by default might decrease performance which is hard to track down to this "debug" sysctl.