Re: [PATCH][HVM] pass-through PCI device hotplug support

["Zhai, Edwin" <edwin.zhai@intel.com>]

On Fri, Jan 25, 2008 at 01:40:54AM +0000, Daniel P. Berrange wrote:
> > 
> > I had the same idea at the beginning, but change mind due to some concerns:
> > 
> > xxx-attach/detach are used for _PV_ driver, but dpci is not the case.
> > If pci PV driver support hotplug in future, we get a complicated code path to 
> > handle both PV and dpci's hotplug.
> 
> I don't buy that argument. You can still just have completely separate
> codepaths inside XenD if you really need to - just switch on different
> impls in the main RPC dispatcher...
> 
>  def pci_attach()
>     if dom.is_hvm():
>        pci_attach_hvm()
>     else
>        pci_attach_pv()
> 
> Every part of Xen where we expose the user to a difference between HVM
> vs PV is a point of pain. We should ensure that use of HVM & PV is as 
> near as possible, identical from a user's view.

If we support PV driver in HVM guest with hotplug, the code path become more 
complicated:(

Anyway it's a trade off. I can change to pci_attach/detach for a simple user 
interface with complicated implementation.


> 
> > So do we have plan to support PCI PV driver hotplug? If no, we can use 
> > pci-attach/detach.
> 
> >From the user's point of view they are attaching & detaching PCI devices, 
> and they should not have to use separate commands to do the same operation
> for PV vs HVM.
> 
> Regards,
> Dan.
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> 

-- 
best rgds,
edwin