Re: Shared memory and event channel

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Feb 23, 2010 at 09:38:26AM +0000, Ian Campbell wrote:
> On Mon, 2010-02-22 at 22:16 +0000, Ritu kaur wrote:
> > 
> > All I need to  is access NIC registers via domU's(network controller
> > will still be working normally). Using PCI passthrough solves the
> > problem for a domU, however, it doesn't solve when multiple domU's
> > wanting to read NIC registers(ex. statistics).  
> 
> Direct access to hardware registers and availability of the device to
> multiple guest domains are mutually exclusive configurations under Xen
> (in the absence of additional technologies such as SR-IOV).
> 
> The paravirtual front and back devices contain no hardware specific
> functionality, in this configuration all hardware specific knowledge is
> contained in the driver in domain 0. Guests use regular L2 or L3
> mechanisms such as bridging, NAT or routing to obtain a path to the
> physical hardware but they are never aware of that physical hardware.
> 
> PCI passthrough allows a guest direct access to a PCI device but this is
> obviously incompatible with access from multiple guests (again, unless
> you have SR-IOV or something similar)

What if the netback was set be able to work in guest mode? This way you
could export it out to the guests?