Re: [rfc, s390] [gdb part] Support extended register sets

["Ulrich Weigand" <uweigand at de dot ibm dot com>]

Tom Tromey wrote:
> >>>>> "Ulrich" == Ulrich Weigand <uweigand@de.ibm.com> writes:
> 
> Ulrich> Since I'm already at it, the patch also adds another register,
> Ulrich> which is unrelated to system call restarting, but also has been
> Ulrich> added to the kernel a while ago and is not yet supported in GDB:
> 
> Ulrich>  last_break: presented as a new register set NT_S390_LAST_BREAK,
> Ulrich>  always size 8 bytes; holds the address of the last branch
> Ulrich>  instruction
> 
> Nice.  Jan had an idea for a way this would be useful to gdb:
> 
> http://sourceware.org/bugzilla/show_bug.cgi?id=11705

Yes, the Intel BTS is something similar (except that on S/390 the feature
is always on, on systems where it is supported, and it stores just a
single branch, not multiple of them).

I guess if GDB core ever makes use of this information, we need to define
a platform interface to make it available.  For now, my patch simply shows
the data as a register value on S/390 ...


I've checked the patch set in now.

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com