Saving to 32 bits of GPRs in signal context

[Steve Munroe]

Segher Boessenkool <segher at kernel.crashing.org> wrote on 05/29/2007
08:12:24 AM:

> >> - how can an application know that it can use 64 bit registers and
> >> call
> >>   the optimized routines?
> >
> > I'd say use the 32 bits ABI, AT_HWCAP will tell you if you are running
> > on a 64 bits capable machine. You can then either use hand tuned code
> > at
> > runtime, or I think ld.so can load alternate libs based on the bits in
> > there.
>
> Or you can simply only install 64-bit binaries on 64-bit
> machines.
>
Yes exactly why make an incompatible ABI change to the powerp32 ABI, when
you can just use the existing 64-bit ABI.

Especially as you can only run what is proposed on 64-bit hardware!

We don't need another ABI change to powerpc32 (still recovering from the
-msecure-plt ABI change) and WE DONT NEED a 3rd ABI.

ABI changes ripple everywhere (not just GCC/GLIBC) including all debuggers
and performance tools. Believe me you really don't want this.



Steven J. Munroe
Linux on Power Toolchain Architect
IBM Corporation, Linux Technology Center