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From: Andi Kleen <ak@suse.de>
Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg)
To: Jeff Garzik <jeff@garzik.org>
Subject: Re: A set of "standard" virtual devices?
Date: Mon, 2 Apr 2007 23:36:42 +0200
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Cc: virtualization@lists.linux-foundation.org,
       Jeremy Fitzhardinge <jeremy@goop.org>, "H. Peter Anvin" <hpa@zytor.com>,
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On Monday 02 April 2007 23:33:01 Jeff Garzik wrote:
> Andi Kleen wrote:
> >> How would that work in the case where virtualized guests don't have a
> >> visible PCI bus, and the virtual environment doesn't pretend to emulate
> >> a PCI bus?
> > 
> > If they emulated one with the appropiate device 
> > then distribution driver auto probing would just work transparently for them.
> 
> Yes, but, ideally with paravirtualization you should be able to avoid 
> the overhead of emulating many major classes of device (storage, 
> network, RNG, etc.) by developing a low-overhead passthrough interface 
> that does not involve PCI at all.

The implementation wouldn't need to use PCI at all. There wouldn't 
even need to be PCI like registers internally. Just a pci device
with an ID somewhere in sysfs. PCI with unique IDs
is just a convenient and well established key into the driver module
collection. Once you have the right driver it can do what it wants.

-Andi