Severely broken bhyve console

[Mark Raynsford]

Hello!

For reasons I'm unable to explain, my ability to access the nmdm
consoles of bhyve guests has suddenly broken. It may have been caused
by a recent 11.2 update - I keep this machine on 11.2-RELEASE plus
freebsd-update patches but, as it's not a publically accessible machine,
I rarely reboot for updates unless absolutely necessary.

I can use "sudo cu -l /dev/nmdm*B" to connect to a particular bhyve
guest's console, but as this video shows, the console is effectively
unusable:

https://ataxia.io7m.com/2019/08/20/broken_terminal.ogv

In that video, I connect to /dev/nmdm57B when the guest is shut down. I
start the guest in a separate terminal (not pictured) and wait for it
to boot into the Debian installer. I don't touch the keys until the
title bar becomes visible. At that point, touching the arrow keys or
the return key results in chaos.

It doesn't seem to be terminal-specific; I'm ssh'd into the host
machine, and have tried various different terminals and $TERM settings
to no effect. It doesn't seem to be guest-specific; I'm running
FreeBSD, Debian, and OpenBSD guests and they now all show this
behaviour. The guests themselves don't appear to be in any distress, I
can ssh into the guests and everything is working correctly.

The host:

# uname -a
FreeBSD cranberry.int.arc7.info 11.2-RELEASE-p13 FreeBSD
11.2-RELEASE-p13 #0: Tue Aug  6 06:41:33 UTC 2019
root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64

I'd appreciate any help on this.

-- 
Mark Raynsford | http://www.io7m.com

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 228 bytes
Desc: OpenPGP digital signature
URL: <http://lists.freebsd.org/pipermail/freebsd-virtualization/attachments/20190820/7a2b7e03/attachment.sig>