Re: [Xen-devel] [Experimental PATCH] PCI and IO device emulation

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 30 Sep 2005, at 18:14, Stefan Berger wrote:

> Access to PCI config space is protected by spinlocks. First one writes 
> bus/device/function and address into the config register then one 
> reads or writes from/to the data register affecting the previously 
> given address. To properly protect access to the config space it 
> really should be done in a common place and accessed in the same way 
> by domain 0 and any other domain.
That's orthogonal to whether we emulate or have an explicit hypercall. 
Yes, dom0 would have to use the same interface as the domUs.
> I don't think you would like to move ownership of the IO-APIC to Xen 
> and let Xen do that part of the setup.  Therefore, I would build a 
> request list for domain 0 to do the necessary setup for those devices 
> it does not see and provide the HV with the necessary information 
> (like machine physical interrupt) it needs to properly route the IRQs 
> to a domain that is accessing a device. This would require an 
> additional module in the domain 0 kernel and some more hypercalls.
Seems simpler just to get dom0 to do the final setup when it builds the 
driver domain.
 -- Keir


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