Re: [PATCH v4 04/17] x86/acrn: Introduce hypercall interfaces

Segher Boessenkool
2020-10-01T00:05:10Z

On Wed, Sep 30, 2020 at 09:42:40PM +0200, Peter Zijlstra wrote:
> > Looks like yes. You can even check different GCC versions via the
> > dropdown in the top right.
>
> That only tells me it compiles it, not if that (IMO) weird construct is
> actually guaranteed to work as expected.
>
> I'd almost dive into the GCC archives to read the back-story to this
> 'feature', it just seems to weird to me. A well, for another day that.

It was documented in 1996 (<https://gcc.gnu.org/g:c1f7febfcb10>), the
feature is older than that though.

In 2004 (in <https://gcc.gnu.org/g:805c33df1366>) the documentation for
this was made more explicit (it has been rewritten since, but it still
says the same thing).

Segher