Re: [PATCH] hvmloader: write extra memory in CMOS

Wei Liu
Tue, 12 Nov 2013 12:01:52 -0000

On Tue, Nov 12, 2013 at 06:52:59AM -0500, Konrad Rzeszutek Wilk
wrote:
> Wei Liu <wei.liu2@citrix.com> wrote:
> >Some firmware, such as OVMF relies on this value to get the size of
> >extra memory above 4GB.
> >
> >Seabios in Xen doesn''t need this as it gets e820 directly from
Xen.
> >Rombios doesn''t read this value.
>
> I was looking at this some time ago for the GPU. I think a better way
> is to take advantage that the e820 can be retrieved from the
> hypervisor (used to be only for PV - but with thr PVH patches it works
> on HVM too). There is code from Gordan that also takes advantage of
> e820_hole.
>
> Anyhow why don''t we plumb in the libxl the standard memory layout
and
> query for that?
>
> Or use xenstore?

I''m hacking a prototype to plumb through necessary information to OVMF.
It takes much longer to properly upstream the new protocol.

In any case this patch is something nice to have. We can never know when
firmware decides to consult this value.


Wei.