Re: [Xen-devel] Source of guest-physical address in PCI BAR for HVM domain?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

I see there's been a small email thread on this topic now, but I want to
point out that the code that configures the PCI BARs initially is not in the
rombios code but is in the hvmloader code. See
tools/formware/hvmloader/hvmloader.c:pci_setup().

 -- Keir

On 4/1/08 16:35, "David Stone" <unclestoner@xxxxxxxxx> wrote:

> I understand that eventually it would be the HVM guest OS that would
> write to the PCI configuration IO port which would get caught be Xen
> and passed along to qemu.  But, this is happending early in the boot
> process before the guest OS proper is even running.  My understanding
> of how PCI systems work is that the BIOS first configures (a subset
> of) the PCI devices, and then the once the real OS is initializing it
> can re-configure any PCI devices it wants to.  Can someone tell me if
> this is correct?
> 
> If so, shouldn't the early PCI configuration from the BIOS be coming
> from qemu itself?  My understanding is that qemu emulates a BIOS for
> HVM domains.



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