Re: [RFC PATCH 00/17] virtual-bus

[Avi Kivity]

Gregory Haskins wrote:
> Avi Kivity wrote:
>   
> > Gregory Haskins wrote:
> >     
> > > Rusty Russell wrote:
> > >  
> > >       
> > > > On Thursday 02 April 2009 21:36:07 Gregory Haskins wrote:
> > > >      
> > > >         
> > > > > You do not need to know when the packet is copied (which I currently
> > > > > do).  You only need it for zero-copy (of which I would like to
> > > > > support,
> > > > > but as I understand it there are problems with the reliability of
> > > > > proper
> > > > > callback (i.e. skb->destructor).
> > > > >           
> > > > >           
> > > > But if you have a UP guest,
> > > >     
> > > >         
> > > I assume you mean UP host ;)
> > >
> > >   
> > >       
> > I think Rusty did mean a UP guest, and without schedule-and-forget.
> >     
> That doesnt make sense to me, tho.  All the testing I did was a UP
> guest, actually.  Why would I be constrained to run without the
> scheduling unless the host was also UP?
>   

You aren't constrained.  And your numbers show it works.

> > The problem is that we already have virtio guest drivers going several
> > kernel versions back, as well as Windows drivers.  We can't keep
> > changing the infrastructure under people's feet.
> >     
>
> Well, IIUC the virtio code itself declares the ABI as unstable, so there
> technically *is* an out if we really wanted one.  But I certainly
> understand the desire to not change this ABI if at all possible, and
> thus the resistance here.
>   

virtio is a stable ABI.

> However, theres still the possibility we can make this work in an ABI
> friendly way with cap-bits, or other such features.  For instance, the
> virtio-net driver could register both with pci and vbus-proxy and
> instantiate a device with a slightly different ops structure for each or
> something.  Alternatively we could write a host-side shim to expose vbus
> devices as pci devices or something like that.
>   

Sounds complicated...

--
error compiling committee.c: too many arguments to function

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