Re: [GIT PULL] pidfd updates

[Linus Torvalds]

On Fri, Apr 28, 2023 at 1:40 AM David Laight <David.Laight@xxxxxxxxxx> wrote:
>
> It is definitely architecture dependant.
> x86-64 and arm-64 will return two 64bit values in registers.
> x86-32 and arm-32 return two 32bit values on stack.

Yes, but I think the "return value in two registers" is the generic
thing. At least gcc has very special code to deal with a two-register
return value.

And yes, those registers will then obviously be different sizes on
different architectures, but a tuple like a '(ptr,fd)' thing will fit
regardless.

We very much do depend on this kind of pattern generating reasonable
code in some parts of the kernel.

               Linus