Re: [PATCH/RFA] Don't gdbarch_init for core files

[Michael Snyder <msnyder at redhat dot com>]

Andrew Cagney wrote:
> 
> > How about this?
> >
> >       * corelow.c (core_open): If the core's arch is known and
> >       different from the current, reinitialize gdbarch based on
> >       the core file.
> >
> 
> Hmm, thing is:
> 
> > -  set_gdbarch_from_file (core_bfd);
> > +  /* If the core's arch is known and different from the current,
> > +     reinitialize gdbarch based on the core file.  */
> > +
> > +  current_arch_info = gdbarch_bfd_arch_info (current_gdbarch);
> > +  if (core_bfd->arch_info->arch != bfd_arch_unknown
> > +      && core_bfd->arch_info->arch != current_arch_info->arch)
> > +    set_gdbarch_from_file (core_bfd);
> 
> is [almost] no different to deleting the call - GDB isn't yet built with
> multiple architectures so the two architectures will always be identical.

Will they?  What if, for instance, gdb defaults to sparc32, but
the corefile is sparc64?

> Looking at the date/author of the original patch [and making a wild
> guess], I think the original change was related to debugging 32 bit core
> files on a SPARC64 system.  Michael?

Correct.  And I think the worrisome case is when there is no symbol
file.

> For the moment, bfd's compatible() might be the best test (does it give
> the effect you're looking for?).  The other approach is to enhance the
> relevant architecture vectors so that they don't change the architecture
> for cases like this.  I think, eventually, the ABI/OS stuff will help
> solve this problem.  Anway, what ever the change, it will need plenty
> comments :-)
> 
> enjoy,
> Andrew