Re: [Xen-devel] [PATCH 6/8] libxl: allow a generation ID to be specified at domain creation

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-06-27 at 12:35 +0100, David Vrabel wrote:
> On 27/06/14 12:16, Ian Campbell wrote:
> > On Wed, 2014-06-18 at 17:12 +0100, David Vrabel wrote:
> >> Toolstacks may specify a VM generation ID using the u.hvm.ms_vm_genid
> >> field in the libxl_domain_build_info structure, when creating a
> >> domain.
> >>
> >> The toolstack is responsible for providing the correct generation ID
> >> according to the Microsoft specification (e.g., generating new random
> >> ones with libxl_ms_vm_genid_generate() as appropriate when restoring).
> >>
> >> Although the specification requires that a ACPI Notify event is raised
> >> if the generation ID is changed, the generation ID is never changed
> >> when the domain is in a state to receive such an event (it's either
> >> newly created or suspended).
> >>
> >> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> > 
> > Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > 
> > And I intend to apply but one question:
> > 
> >> +bool libxl_ms_vm_genid_is_zero(const libxl_ms_vm_genid *id)
> >> +{
> >> +    static const libxl_ms_vm_genid zero;
> > 
> > Does this formally end up in .bss and is therefore definitely zero?
> 
> Yes.
> 
> K&R section A8.7 (initialization) makes no distinction between static
> variables of file or function scope.

Thanks.

> 
> > If it were global I'd have no doubt, but I'm not sure about it in this
> > scope.
> > 
> > Regardless, I'll assume for now that it is right. If not please send a
> > follow up with the necessary "= {0}".
> 
> I almost put this on but thought someone might nitpick and say it was
> unnecessary...

I would have been happy with it (as I'm now happy without). It serves a
purpose as documentation if nothing else...



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