xfwm4 crashes on NetBSD 9.99.17 (was "Re: firefox dumping core after NetBSD upgrade")

["David H. Gutteridge" <david%gutteridge.ca@localhost>]

On Wed, 2019-10-16 at 12:10 +0100, Chavdar Ivanov wrote:
> On Wed, 16 Oct 2019 at 11:03, David H. Gutteridge <david%gutteridge.ca@localhost
> > wrote:
> 
> > FWIW, aside from Firefox (where I also see this issue), I've found
> > since the recent Mesa upgrade, Xfce4's window manager consistently
> > crashes during startup. These's a correlation with Firefox in the
> > backtrace:
> > 
> > Core was generated by `xfwm4'.
> > Program terminated with signal SIGSEGV, Segmentation fault.
> > (gdb) bt full
> > #0  debug_namespace_get (severity=MESA_DEBUG_SEVERITY_HIGH, id=1,
> > ns=0x79f288af02ef) at
> > /usr/xsrc/external/mit/MesaLib/dist/src/mesa/main/debug_output.c:393
> >         elem = 0x0
> >         node = 0x0
> >         state = 0
> >         node = <optimized out>
> >         state = <optimized out>
> >         elem = <optimized out>
> > #1  _mesa_debug_is_message_enabled (debug=0x79f288af77a0, 
> > source=source@entry=MESA_DEBUG_SOURCE_API, type=type@entry=MESA_DEBU
> > G_TYPE_ERROR, id=1,
> >     severity=severity@entry=MESA_DEBUG_SEVERITY_HIGH) at
> > /usr/xsrc/external/mit/MesaLib/dist/src/mesa/main/debug_output.c:623
> >         gstack = 0
> >         grp = 0x79f288af02ef
> >         nspace = 0x79f288af02ef
> > #2  0x000079f26fa440b0 in _mesa_error (ctx=ctx@entry=0x79f288ae5898,
> > error=error@entry=1282, fmtString=fmtString@entry=0
> > x79f271815ee4 "Inside glBegin/glEnd")
> >     at
> > /usr/xsrc/external/mit/MesaLib/dist/src/mesa/main/errors.c:311
> >         do_output = <optimized out>
> >         do_log = <optimized out>
> >         error_msg_id = 1
> > #3  0x000079f26fa5e256 in _mesa_GetString (name=7937) at
> > /usr/xsrc/external/mit/MesaLib/dist/src/mesa/main/getstring.c:124
> >         ctx = 0x79f288ae5898
> >         vendor = 0x79f271833414 "Brian Paul"
> >         renderer = 0x79f2718214ab "Mesa"
> > #4  0x000000000041b1b5 in ?? ()
> > No symbol table info available.
> > #5  0x0000000000442bb8 in ?? ()
> > No symbol table info available.
> > [...]
> > 
> > (I haven't had any time to look into this further, so I haven't
> > enabled
> > debugging symbols for xfwm4 itself.)
> > 
> > Regards,
> > 
> > Dave
>
> I also have xfwm4 crash, but only if there is .config/xfce4 directory.
> So far if I remove it, xfce4 works fine. Otherwise the trace appeared
> similar to the above.

I found that the file .config/xfce4/xfconf/xfce-perchannel-xml/xfwm4.xml
specifically relates to this problem. If I remove it alone, xfwm4 starts.
What's curious is that after each startup, that file gets automatically
regenerated, but the regenerated version of the file causes xfwm4 to
crash on the next startup cycle.

I also tried various vblank setting options in that config file, but none
have made a difference. Obviously there's more to this, but I haven't
narrowed it down.

Dave