Re: [kvm-devel] [Qemu-devel] Re: [PATCH 1/6] Use correct types to enable > 2G support

[Anthony Liguori]

Ian Jackson wrote:
> Anthony Liguori writes ("[Qemu-devel] Re: [kvm-devel] [PATCH 1/6] Use correct types to 
> enable > 2G support"):
>   
> > The alternative is to change all the places that assume phys_ram_base + 
> > PA which I don't like very much.
> >     
>
> We would ideally like to do this for Xen, at least in the places we
> care about.  (Xen uses less of the qemu tree than KVM, I think.)
>   

Support for the map cache in the Xen tree is a rather big change that 
I'm not going to attempt to support it in this patch series.

I'd rather preserve the phys_ram_base + PA assumption because it allows 
us to be able to do support > 1 page DMA operations for our virtual IO 
drivers.  If you break the assumption that physically contiguous memory 
in the guest is virtual contiguous memory in the host, things get pretty 
ugly.

Regards,

Anthony Liguori

> In Xen, the guest memory is not in general mapped into the host qemu's
> address space.
>
> Ian.
>
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