Re: [Xen-devel] Correct DTB compatibility for xen /hypervisor node?

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 31 Jan 2013, Ian Campbell wrote:
> On Wed, 2013-01-30 at 16:49 +0000, Stefano Stabellini wrote:
> > On Mon, 28 Jan 2013, Ian Campbell wrote:
> > > Looks like we have both 4.2 and 4.3 in use. Which should it be?
> > > 
> > > $ rgrep xen-4 arch/arm Documentation/
> > > arch/arm/boot/dts/xenvm-4.2.dts:          compatible = "xen,xen-4.2", 
> > > "xen,xen";
> > > Documentation/devicetree/bindings/arm/xen.txt:    compatible = 
> > > "xen,xen-4.3", "xen,xen";
> > > 
> > > FWIW I've always used 4.2 in my own DTB files.
> > > 
> > > Strictly speaking the API is the Xen 3.x API, but that doesn't seem
> > > terribly relevant.
> > 
> > I have always used 4.2 too.
> > Even though the one in xen.txt is just an example it might be worth
> > updating with xen-4.2 to avoid confusions.
> 
> Or maybe we should update to 4.3 everywhere.
> 
> > > I suppose arch_get_xen_caps ought to return something consistent?
> > 
> > Right.
> > 
> > From my point of view, it would be useful to return a string
> > that expresses the current hypervisor version (xen-4.3 from the Xen 4.3
> > release, xen-4.4 from the Xen 4.4 release and so on) rather than xen-3.0.
> > I would do the same in the compatibility node of the DTS.
> 
> Remember that the capability string returned by the hypervisor is not
> exposing the version of the hypervisor -- it is exposing the version of
> the Hypervisor *ABI*, which is a subtly different thing.
> 
> I think we should follow the hypervisor version until we freeze the ABI,
> at which point we hardcode whichever version we froze at?

That's reasonable, but we shouldn't be afraid of bumping that number.

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