RE: [PATCH v3 6/6] KVM: x86: allow defining return-0 static calls

[David Laight]

> I guess something with returning u64 made 32 compiler unhappy.
> 
> I suspect that __static_call_return0 returns long, which means it returns
> 32 bit value on 32 bit system.
> 
> Maybe we can make it return u64. I don't know if that will break something else though.

32 bit system will return a 64bit value in %edx:%eax.
Since %rdx is a scratch register (caller saved) it is fine.

Is __statc_call_return0() ever used to return a NULL pointer?
ISTR some ABI (maybe m68k ones) that returned pointers and
integers in different registers.
Plausibly that was only 35 years ago.

	David

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