Re: [uml-user] host/guest setup to debug with frame pointers

[Jeff D. <jd...@ad...>]

On Mon, Aug 01, 2005 at 06:07:17PM -0700, Alexei Potashnik wrote:
> Basically, I was able to bring up and successfully use guest in any
> of the above combinations. But when I try to bring it up under
> gdb, I get various problems.
> 
> I follow instruction from UML site for debugging:
> ddd gdb &
> ./linux debug gdb-pid=<gdb-pid>
> then in gdb "att 1" and "c".
> 
> With FC4 host/2.6.12 guest all of the above would succeed. But as soon as I
> interrupt execution or it stops on a breakpoint, it's impossible to 
> continue...
> gdb just freezes.
> 
> With FC3 host/2.6.11 guest, gdb would freeze right after "att 1".
> 
> Other combinations of host/guest would produce one of the above results.

You might try the latest 2.6.13-pre.  That has skas0 which simplifies the
debugging situation - you just gdb the thing.

tt mode has had increasing problems with gdb over time.  UML "knows" things 
about how gdb works, and gdb has changed so that these things aren't true
any more.  This is why the debug window hangs with newer gdbs.

For best results, disable CONFIG_MODE_TT.  This disables the exec of itself
that UML does early on, and which confuses gdb.

				Heff