Linux powerpc new system call instruction and ABI

[Segher Boessenkool]

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 :-)

> New system calls just should be made to not return
> error numbers.

Which sometimes is a difficult / non-natural / clumsy thing to do.


Segher