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

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

On Thu, Jan 24, 2008 at 06:06:56PM +0000, Daniel P. Berrange wrote:
> > 
> > "xm dpci-remove" hot remove the specified vtd device by the ID, like:
> > xm dpci-remove EdwinHVMDomainVtd 0
> > 
> > "xm dpci-insert" hot add a new vtd device, like '03:00.0':
> > xm dpci-insert EdwinHVMDomainVtd 3 0 0
> 
> IMHO we shouldn't have a 'd' on the front of the command names. VT-d is a 
> vendor specific implementation whose nomenculture doesn't need to be exposed

'd' means directly assigned device, which is generic including VT-d and other 
pass-through device..

Anyway, it's not so important.

> to users. In addition the existing block & network hotplug commands use
> 'attach' and 'detach' for their command names. So for sake of consistency
> I'd recommend command names of:
> 
>   pci-list
>   pci-attach
>   pci-detach

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.

So do we have plan to support PCI PV driver hotplug? If no, we can use 
pci-attach/detach.

> 
> I think it is useful to use the same unique naming & data for both attach and
> detach operations. So if we use a (bus,slot,func) triple for attachment, I
> think we should use the same (bus,slot,func) triple for detachment too,
> rather than having to make apps / users lookup the dynamically-allocated
> 'ID' value for the device.

yes, dynamical ID is not easily for use.
How about using some fixed 'ID' for hot remove, just like vbd/vnif(they also 
use 
different naming&data for attach/detach)?


> 
> Regards,
> Dan.
> -- 
> |=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
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-- 
best rgds,
edwin

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