Re: problem unwinding past pthread_cond_wait() on x86 RedHat 9.0

[Daniel Jacobowitz <drow@mvista.com>]

On Tue, Oct 14, 2003 at 12:15:53PM -0400, Andrew Cagney wrote:
> >On Tue, Oct 14, 2003 at 08:46:49AM -0700, Joel Brobecker wrote:
> >
> >>> Joel, what happens if you type:
> >>> 
> >>> (gdb) x/i 0xffffe002
> >
> >>
> >>Something like "Cannot read memory at 0xffffe002" (already tried it :-).
> >>What is this address, BTW. I always wondered... Kernel code? Special
> >>address?
> >
> >
> >Search for "vsyscall DSO" in the gdb@ archives to learn more than you
> >ever wanted to know :)  Patches to fully support it are still pending.
> 
> No.
> 
> No matter how much you patch GDB, GDB isn't going to dig itself out of 
> thishole.  It's not able to access the code/data/whatever at that 
> address so it's never going to correctly unwind from it.
> 
> Kernel bug - incomplete functionality.

We're both right.  Patches for this are still pending.  They'll fix the
unwinding when using a 2.6 kernel which _does_ let the page be
accessed.  At that point I wouldn't be surprised if you folks at RH
published an errata kernel which let this work in RH9, or RH10 or
whatever it is now.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer