Re: [Xen-devel] [PATCH] hvmloader: write extra memory in CMOS

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Nov 12, 2013 at 02:13:26PM +0000, Jan Beulich wrote:
> >>> On 12.11.13 at 15:00, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> > On Tue, Nov 12, 2013 at 01:56:02PM +0000, Jan Beulich wrote:
> >> >>> On 12.11.13 at 14:39, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> >> > On Tue, Nov 12, 2013 at 01:21:36PM +0000, Jan Beulich wrote:
> >> >> >>> On 12.11.13 at 13:37, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> >> >> > However in some CMOS maps I found those bytes are marked as reserved.
> >> >> 
> >> >> Exactly. The question is whether some _other_ BIOSes then use
> >> >> these register for other purposes...
> >> >> 
> >> > 
> >> > So I think now the solution is to make this code OVMF only, are you fine
> >> > with this?
> >> 
> >> Yes, provided you widen the location to at least 4 bytes.
> >> 
> > 
> > I'm afraid I cannot widen the location (not for technical reason). It's
> > a conventional protocol used by these non traditional BIOSes. It doesn't
> > make sense to change Xen only, right?
> 
> Maybe, maybe not. But those other BIOSes must have some
> understanding of how to support >1Tb systems?
> 

Presumably yes. But that's another topic.

My point is widening this field to 4 bytes would not make them support
more than 1TB of RAM, at least not in canonical way.

Wei.

> Jan

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