Re: [Xen-devel] [edk2] Passing Xen memory map and resource map to OVMF

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Nov 13, 2013 at 08:03:39AM +0100, Gerd Hoffmann wrote:
>   Hi,
> 
> > > The first thing that comes in mind is to reuse E820 table for memory map
> > > plus some extra fields for io / mmio resources. But I guess UEFI is the
> > > new world so stuffs like E820 from old world will be less popular. Any
> > > suggestion on existing table / data structure I can use?
> 
> What io/mmio ressources do you need to pass on?
> 

MMIO holes, IO range created by hvmloader.

OVMF should make use of that information instead of creating MMIO holes
etc of its own. See OvmfPkg/PlatformPei/Platform.c:MemMapInitialization.

> > As far as I can see, qemu exports an fw_cfg table called "etc/e820". See
> > qemu commit
> > 
> > commit 7d67110f2d9a6a2d6b5215a948abc95d07258735
> > Author: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> > Date:   Fri Oct 18 11:31:54 2013 +0200
> > 
> >     pc: add etc/e820 fw_cfg file
> 
> New in qemu 1.7  Was added exactly to deal with the 1TB limitation and
> also to allow for non-contiguous memory (not implemented yet in qemu,
> but if numa support is extended some day to support that we are fine
> interface-wise).
> 

This is probably too new for us. We're still fighting a regression in
1.6.

Wei.

> > Does this work when qemu is used in combination with Xen?
> 
> It should, might need windup in the xen machine type though (not fully
> sure how much code is shared between normal and xen machine types).
> 
> cheers,
>   Gerd
> 

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