VirtualBox mangles memory

[Martin Birgmeier]

In https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=195970, Larry
Rosenman suggested setting net.graph.maxdata=8192. I set it to 4096, and
the problem seems to have gone away (I am currently testing, and it has
not failed so far).

This is actually mentioned in
https://wiki.freebsd.org/VirtualBox/Tuning, but I would never have
guessed that the standard network stack is affected by setting this
tunable: I am not copying anything in/out of the VB client, but rather
run a completely independent regular IPv4 transfer alongside it. Maybe
the description there could be expanded accordingly.

Anyway, thanks to Larry for pointing me in the right direction.

-- Martin