Re: [Xen-devel] [PATCH][v2] Hybrid extension support in Xen

[Sheng Yang <sheng@xxxxxxxxxxxxxxx>]

On Tuesday 02 February 2010 19:22:21 Ian Campbell wrote:
> On Tue, 2010-02-02 at 08:16 +0000, Sheng Yang wrote:
> > +/* Reserve 128KB for grant table */
> > +#define GNTTAB_MEMBASE     0xfbfe0000
> > +#define GNTTAB_MEMSIZE     0x20000
> 
> Why is this necessary? Isn't the grant table contained within one of the
> BARS on the virtual PCI device? What needs grant tables for prior to the
> kernel finding the PCI device which necessitates hardcoding these
> addresses in both guest and hypervisor?
> 
Thanks for so quick and detail comments. :)

And this one is purposed, because we don't want to depends on QEmu. As you 
see, we now have PV drivers, QEmu is an alternative way to provide device 
model now. We think that still involving QEmu as a requirement is somehow 
strange. So this reserved region is there, to drop the dependence with QEmu to 
provide PV driver(PV driver depends on QEmu is still strange, right?).

-- 
regards
Yang, Sheng

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