Re: FreeBSD guest on Linux KVM, some vtnet(4) packets don't arrive
Date: Sat, 11 Apr 2026 12:09:27 UTC
> On 10. Apr 2026, at 23:34, Adrian Chadd <adrian@freebsd.org> wrote: > > On Fri, 10 Apr 2026 at 13:40, Michael Tuexen > <michael.tuexen@lurchi.franken.de> wrote: >> >>> On 10. Apr 2026, at 12:21, Lexi Winter <ivy@FreeBSD.org> wrote: >>> >>> Lexi Winter wrote in <adilBIOdjleUAkC5@amaryllis.le-fay.org>: >>>> the problem seems to be due to choice of cipher: >>>> >>>> % ssh -oCiphers=aes256-gcm@openssh.com root@ppc64-main.vm.le-fay.org >>>> Fssh_ssh_dispatch_run_fatal: Connection to fd00:0:0:1::b port 22: message authentication code incorrect >>>> >>>> % ssh -oCiphers=chacha20-poly1305@openssh.com root@ppc64-main.vm.le-fay.org >>>> Last login: Fri Apr 10 08:17:20 2026 from tansy.le-fay.org >>>> >>>> if AES is broken, that would also explain why TLS doesn't work. >>>> >>>> unfortunately while trying to rebuild world i ran into an unrelated >>>> panic[0], so i'll need to find a workaround for that before i can >>>> test more. >>> >>> i was able to cross-build current main (82ff1c334b97) on another system >>> and copy it over, which seems to have fixed the issue with TLS and SSH. >>> >>> i need to do some final setup on the VM and then i'll try to do some >>> more testing for the original vtnet/tcpdump problem, which is still >>> present. >> Hi Ivy, >> >> is this really a vtnet/tcpdump problem? On my PPC64 VM, tcpdump does not >> show any packets on vtnet0 or lo0. On bare metal, tcpdump does not show >> any packets on lo0 or bge2. >> >> So I guess, this has nothing to do with vtnet. > > There's likely a bunch of weird broken stuff that we need to fix. > > I'm pretty sure tcpdump worked fine in December last year on > ppc64le/ppc64be since I was doing > general fixing of stuff there. > > Let's file some ppc64 bugs and get them triaged/debugged. I bet the > "why's tcpdump not working?" > problem is triagable with dtrace/fbt points. Some more testing: 1. 15.0 shows the same behavior as CURRENT 2. It is not that tcpdump is not working at all, it just shows the packets in a batch after some time. Use ping -s 16000 127.0.0.1 and you see what I mean. Just using ping requires you to wait substantially longer. So it seems that tcpdump gets the packets on PPC64 only when some buffer is full. Best regards Michael > > > > -adrian