kern/51675: radeondrmkms wedge with supertuxkart

[dholland%netbsd.org@localhost]

>Number:         51675
>Category:       kern
>Synopsis:       radeondrmkms wedge with supertuxkart
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 29 23:55:00 +0000 2016
>Originator:     David A. Holland
>Release:        NetBSD 7.99.42 (20161125)
>Organization:
>Environment:
System: NetBSD valkyrie 7.99.42 NetBSD 7.99.42 (VALKYRIE) #20: Fri Nov 25 18:33:19 EST 2016  dholland@valkyrie:/usr/src/sys/arch/amd64/compile/VALKYRIE amd64
Architecture: x86_64
Machine: amd64
>Description:

Now that we think 50349 is fixed I updated another machine with the
same radeon card to -current, and discovered that supertuxkart wedges
the X server and/or console.

In particular, when you open supertuxkart and start a race, the X
server hangs cold. It doesn't seem to wedge the rest of the system,
although my options for investigating the wedge state are somewhat
limited at the moment.

Once when I did this supertuxkart cored instead, which is maybe/maybe
not a different issue.

While poking around I found that running teapot from MesaDemos dumps
core, as does glxgears; running with env RADEON_THREAD=FALSE (as
suggested in 49838) to disable the thread in the gallium driver makes
glxgears run, but not teapot. (This much requires a fix to the gallium
driver build, or it doesn't load; but that's been committed.)

I haven't tried the thread thing with supertuxkart yet, but I will
next go.

>How-To-Repeat:

>Fix: