kern/54005: X server vt switching stops audio

[dholland%eecs.harvard.edu@localhost]

>Number:         54005
>Category:       kern
>Synopsis:       X server vt switching stops audio
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Feb 23 01:30:01 +0000 2019
>Originator:     David Holland
>Release:        NetBSD 8.99.27 (~20181215)
>Organization:
>Environment:
System: NetBSD macaran 8.99.27 NetBSD 8.99.27 (MACARAN) #51: Mon Dec 17 15:38:55 EST 2018 dholland@macaran:/usr/src/sys/arch/amd64/compile/MACARAN amd64
Architecture: x86_64
Machine: amd64
>Description:

Just now I was working in one X server and playing music from youtube
(in a browser) in another; switching from the youtube X server to the
other one caused audio output to stop. It did not resume when I
switched back, but generating a bell in an xterm unstuck it.

It was not immediately clear if audio data posted while it was stuck
was blocked, queued, or discarded.

>How-To-Repeat:

The problem has not repeated and is probably not readily repeatable.

>Fix:

It boggles me a bit that this is even possible, because virtual
consoles and the X server are pretty much independent of audio, so if
anyone can figure out what linkage is involved that's probably at
least the first 95%.

(Note that hw.hdafg1.multiuser was already set to 1 to make this
arrangement work at all.)