Re: FreeBSD guest on Linux KVM, some vtnet(4) packets don't arrive

> On 8. Apr 2026, at 17:13, Lexi Winter <[email protected]> wrote:
> 
> hello,
> 
> Miroslav Lachman wrote in <[email protected]>:
>> On 08/04/2026 16:38, Lexi Winter wrote:
>>> vtnet0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500
>> 
>> Can you try disabling rxcsum / txcsum? (add  -rxcsum -txcsum to
>> ifconfig_vtnet0 in rc.conf)
>> I had similar problem in the past on KVM hosted FreeBSD guest and this
>> solved the problem for me.
> 
> unfortunately i tried disabling tx and rx csum, LRO, and TSO, and this
> made no difference (you can see above that those flags are not set on
> vtnet0).
I expected this. Timo and myself fixed a couple of issues related to
offloading. Would be interested to fix any issues which may still exits.

Best regards
Michael
> 
> but i did notice a new oddity: even for network traffic that works, like
> ping to fe80::2 or an IPv4 ping, the traffic doesn't show in tcpdump.
> this is not the case on amd64 (main dc752c26b7e5) where tcpdump works
> fine on vtnet(4).
> 
> so possibly there are two separate issues here.  i'm currently
> installing a ppc64le guest, just in case this is an issue with
> endian translation on the Linux side.  (the host is ppc64le.)