bug#22058: 25.1.50; emacs_backtrace.txt

[Eli Zaretskii]

> Date: Mon, 30 Nov 2015 08:22:44 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: jwiegley@gmail.com, 22058@debbugs.gnu.org
> 
> > A good rule of thumb is: if the backtrace includes this pair of lines:
> > 
> > > Exception 0xc0000005 at this address:
> > > 774374f6
> > 
> > and if the address starts with 7, then we will not be able to convert
> > it to any meaningful address in the Emacs application code.  (The
> > exception code does not need to be 0xc0000005, although it usually
> > is.)
> 
> Excellent.  Wish I'd have known that long ago.

I didn't know that myself until a few of those were processed by
Juanma.

> How about mentioning this in (emacs) `Crashing'?

It's not universal.  The borderline value depends on the build.

> Or perhaps the code that creates the emacs_backtrace.txt file could
> just print a message in such a case, saying that no useful backtrace
> file could be created?

It doesn't know enough to do that.  That code does the minimum
necessary to display the addresses, to avoid the danger of triggering
another exception.