Linux powerpc new system call instruction and ABI

[Joakim Tjernlund]

On Wed, 2021-05-19 at 09:38 -0500, Segher Boessenkool wrote:
> On Wed, May 19, 2021 at 06:42:40PM +1000, Nicholas Piggin wrote:
> > Excerpts from Joakim Tjernlund's message of May 19, 2021 6:08 pm:
> > > I always figured the ppc way was superior. It begs the question if not the other archs should
> > > change instead?
> > 
> > It is superior in some ways, not enough to be worth being different.
> 
> The PowerPC syscall ABI *requires* using cr0.3 for indicating errors,
> you will have to do that whether you conflate the concepts of return
> code and error indicator or not!
> 
> > Other archs are unlikely to change because it would be painful for
> > not much benefit.
> 
> Other archs cannot easily change for much the same reason :-)

Really? I figured you could just add extra error indication in kernel syscall I/F.
Eventually user space could migrate to the new indication.

 Jocke