[mythtv] Backend crash when tuning to an invalid channel with HD-PVR

Daniel Kristjansson danielk at cuymedia.net
Tue Feb 22 13:01:50 UTC 2011


On Tue, 2011-02-22 at 01:19 -0800, Ian Forde wrote:
> On Mon, 2011-02-21 at 16:14 -0500, Daniel Kristjansson wrote:
> > On Mon, 2011-02-21 at 12:25 -0800, Ian Forde wrote:
> > > I've finally gotten around to testing the scenario again where what I
> > > thought was a valid channel on my cable lineup isn't recognized by my
> > > DCT-6200.  Instead of tuning to channel 840 as requested, it tunes to
> > > 847, which is not a channel that I currently receive.  Yes - that's a
> > > lineup issue, but the thing is that the backend crashes.
> > > 
> > > So I followed the instructions on http://www.mythtv.org/wiki/Debugging
> > > and got a backtrace... (pasted at the bottom)
> > > 
> > > For now I'm just going to remove the channels from my lineup, but I'm
> > > hoping this helps somebody...
> > 
> > You are missing the part that tells us where the crash occurred. It
> > should have told you which thread faulted when you loaded the coredump
> > or when it crashed if you ran mythbackend under gdb.
> 
> That's strange, because I pasted the entire output from gdb from "thread
> apply all bt".  I was under the impression that the info was in there.
> Should I rebuild as a profile build and reproduce the crash?  Or would
> the output from the backend log (of the crash earlier today) suffice?

The part about where it crashed would have been printed before you
got the prompt. From the backtrace it looks like it hit an assert
in nVidia's OpenGL library, which doesn't make any sense for the
backend. OpenGL is a graphics library which shouldn't be used in
by the backend.

A full debug build rather than a profile build would probably be
more informative. The part where the assert happened didn't have
a full backtrace back to a MythTV piece of code; hopefully a full
debug build would provide that.

-- Daniel



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