re. pr188261 - any way I can investigate further?

[Karl Pielorz]

Hi,

I submitted a PR a while ago (pr188261) - or now, Bugzilla 
<https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=188261>

I've updated this recently - as I found doing 'ifconfig xn0 -txcsum' on a 
"client" will fix the issue, for just that client - but I'm still unable to 
fix the 'router' VM in such a way as all clients don't need a fix.

I have a test system setup with all this now (and all of 9.2-S, 10-S, and 
11-Current have the issue) - is anyone able to point me in the right 
direction of what I can do to investigate this further? (i.e. debug things, 
packet captures, etc. etc.)

We could really do with getting this fixed - we use FreeBSD as routers on a 
few systems - as as they move to Xen we end up having to either setup 2 
pools (and be very, very careful about what machines we put on each) in 
order to avoid this - or face running them in HVM mode for which the 
performance is very, very poor.

-Karl