Re: [Xen-devel] [rfc 00/18] ioemu: use devfn instead of slots as the unit for passthrough

[Simon Horman <horms@xxxxxxxxxxxx>]

On Tue, Feb 24, 2009 at 01:29:48AM +0000, Ian Pratt wrote:
> > > That thought crossed my mind too, I will investigate further.
> > > But I think that ideally it would need to be expanded to 143
> > > as the first 16 GSI are currently reserved for ISA.
> > 
> > Can't xend or qemu do a search of PCI slot space to pick a virtual
> > devfn:intx that doesn't conflict (or that purposely does conflict, if
> > there are any cases where you want that)? 32 non-legacy GSIs should be 
> > enough
> > to avoid any aliasing if a bit of effort is put in to avoid it.
> 
> One related issue we need to think about is how we can get some sort of
> consistency over how devices are assigned to slots, so it's possible to
> add a new device and not have all existing ones re-numbered (hence
> causing the OS to hiccup).

I'm not clear on how this renumbering occurs? Are you talking
about renumbering of vslots, gsi, or something else?

> Giving devices (both emulated and PT) an optional order parameter in the
> config file which is used to determine the order with which they are
> allocated resources is probably sufficient.

One of the patches in this series sorts pass-through devices
before they are inserted. My approach was to do this inside ioemu.

http://lists.xensource.com/archives/html/xen-devel/2009-02/msg00603.html

-- 
Simon Horman
  VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
  H: www.vergenet.net/~horms/             W: www.valinux.co.jp/en


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