Re: [Xen-devel] PV-vNUMA issue: topology is misinterpreted by the guest

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Fri, 2015-07-24 at 17:14 +0200, Juergen Gross wrote:
> On 07/24/2015 04:44 PM, Dario Faggioli wrote:

> > Ok. And I already have a question (as I lost track of things a bit).
> > What you just said about ACPI tables is certainly true for baremetal and
> > HVM guests, but for PV? At the time I was looking into it, together with
> > Elena, there were Linux patches being produced for the PV case, which
> > makes sense.
> > However, ISTR that both Wei and Elena mentioned recently that those
> > patches have not been upstreamed in Linux yet... Is that the case? Maybe
> > not all, but at least some of them are there? Because if not, I'm not
> > sure I see how a PV guest would even see a vNUMA topology (which it
> > does).

> I checked "bottom up", so when I found the acpi scan stuff I stopped
> searching how the kernel obtains numa info. During my search I found no
> clue of an pv-numa stuff in the kernel. And a quick "grep -i numa" in
> arch/x86/xen and drivers/xen didn't reveal anything. Same for a complete
> kernel source search for "vnuma".
> 
BTW, I've also been grepping, and I'm not seeing XENMEM_get_vnumainfo
being called anywhere either... Well, no wonder, we're seeing vNUMA
setup issues! If I did check for this before, I wouldn't even have
tested PV-vNUMA in the first place!! :-O

I actually wonder how _some_ of the vNUMA info get through!?!? :-O

IAC, all we're saying remains true, of course, and the CPUID issue will
still be there, if we don't fix it, when such a patch will be accepted.

Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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