Re: Linux powerpc new system call instruction and ABI

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:

quoted

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