On 28.08.2023 23:52, Stefano Stabellini wrote: > On Mon, 28 Aug 2023, Jan Beulich wrote: >> On 26.08.2023 00:21, Stefano Stabellini wrote: >>> Coming to unsigned int, it should be 32-bit on all supported arches, >> >> But this isn't a requirement, even if we're using "unsigned int" in the >> C declarations / definitions: If "unsigned int" was wider, all we'd >> demand is that hypercall entry code (likely written in assembly anyway) >> zero-extend incoming values suitably to fit whatever "unsigned int" is. >> Which is no different to Andrew (aiui) suggesting to use "unsigned >> long" instead: That'll too require suitable zero-extension up front. > > What you wrote assumes that "unsigned int" can only be 32-bit or wider, > such as 64-bit. However, I think that by the C standard there is no > guarantee. For instance, it could be smaller, e.g. 16-bit.
Of course, but in Xen (just like e.g. Linux does) we inherently assume sizeof(int) >= 4. Jan
