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Re: [Xen-devel] [PATCH] Register PV driver product numbers 4 and 5.

  • To: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
  • From: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
  • Date: Thu, 3 Oct 2013 16:56:10 +0000
  • Accept-language: en-GB, en-US
  • Cc: "xen-devel@xxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxx>
  • Delivery-date: Thu, 03 Oct 2013 16:56:47 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>
  • Thread-index: AQHOvc7FzDecMxsZd0qHLWtPHPHvL5ni2RIAgAAvuUD//+T+AIAAPAFg///lfwCAACZKkA==
  • Thread-topic: [Xen-devel] [PATCH] Register PV driver product numbers 4 and 5.

> -----Original Message-----
> I'm not sure I understand what you are trying to say.
> How does a driver which expects the blacklist protocol work with
> xen_pvdevice which doesn't implement that protocol?

It's a bit confusing, I agree. Referring back to previous threads though, all 
HVM systems are assumed to have the xen platform PCI device (as there is no way 
to turn it off if youâre using machine type xenfv), thus the fixed IO ports 
that implement the blacklisting protocol are assumed to always be present. 
Because the ports are fixed and always present the PV drivers don't have to 
care which device they are binding to - they talk to the same IO ports 
> Or are does a driver which works with xen_platform not work with
> xen_pvdevice and vice versa? Or do the drivers have to contain code to
> determine which they are running against and only do the unplug against
> xen_platform?
> I'm a bit surprised xen_platform doesn't implement the unplug protocol,
> I thought it was just a xen_platform with parameterised vendor id etc.
> > > >  if anyone cares to implement it for product number 5 but, as I said,
> > > > I don't anticipate the need for it.
> > >
> > > So product 5 is intended to be the same thing no matter whether you use
> > > xen_platform or xen_pvdevice and no matter which vendor/device ID is
> > > configured? You can only make this true for Citrix vendor ids I think,
> > > or do you intend this to be binding for everyone?
> > >
> >
> > The whole point of having this header file is that it is the canonical
> > list of product codes;
> In which namespace is my question.
> Do the drivers using these 4 and 5 codes work with xen_platform and/or
> xen_pvdevice?
> xen_pvdevice doesn't implement the unplug protocol AFAICT, so the list
> of product codes seems to be pretty irrelevant to it.

Indeed, as I explained above the unplug protocol is controlled entirely by 
xen_platform and this header file refers only to that namespace.


> >  it should apply to everyone. That is why I'm reserving 4 and 5 - to
> > make sure that no-one else tries to use them.
> Ian.

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