Re: [Xen-devel] [PATCH][VTD] enable integrated graphics passthrough for Calpella and Sandybridge

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 14 Jun 2010, Isaku Yamahata wrote:
> On Fri, Jun 11, 2010 at 12:08:29PM +0100, Stefano Stabellini wrote:
> > On Tue, 8 Jun 2010, Kay, Allen M wrote:
> > > Isaku,
> > > 
> > > Thanks for the feedback.
> > > 
> > > > pci_{read, write}_block() would be better than
> > > > switch(len) case 1: case 2: case4:...
> > > 
> > > Done!
> > > 
> > > > Is it really necessary to move PCIBus and PCIBridge to the header file?
> > > > Doesn't pci_bridge_init() work?
> > > 
> > > I changed to code to utilize pci_bridge_init().  However, I still need to 
> > > move
> > > PCIBus and PCIBridge defines to the header file.  The alternative is to 
> > > pollute
> > > pc.c with graphics passthrough specific code.
> > > 
> > > > Overriding pci config read/write methods of i440fx would be much cleaner
> > > > than hooking pci_data_read/write. (pass igd_pci_read/write to 
> > > > pci_register_device() in i440fx_init() in hw/piix_pci.c instead of NULL)
> > > 
> > > Doing this resulted in a lot of duplicated code and also force code path 
> > > to change
> > > even when IGD passthrough is not used.  To do it correctly, I also need to
> > > put in IGD or PASSTHROGH awareness in piix_pci.c.  For now, I'm going to 
> > > keep
> > > the original patch.
> > > 
> > 
> > I see.
> > 
> > Even though the patch is an improvement over what we currently have in
> > qemu-xen, it is still not acceptable in upstream qemu as it is.
> > Considering that we are pretty close to have the merge complete, I think
> > it worth trying to come up with something cleaner.
> > 
> > Isaku, you are the latest one to touch the pci_host code in qemu, do you
> > have any other suggestion?
> 
> How about the following patch which is on top of the v2 patch?
> I did only compile test, but I think it's enough to show my idea.
> 
> For PCI bridge, I have a patches to clean up/enhance the implementation and
> I'm planning to push to the qemu upstream soon.
> 

I think this looks much better, thanks Isaku!

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