Re: [RFC PATCH] virtio: change config to guest endian.

[Hollis Blanchard <hollisb@us.ibm.com>]

On Tuesday 22 April 2008 17:13:01 Anthony Liguori wrote:
> Hollis Blanchard wrote:
> > On Tuesday 22 April 2008 16:05:38 Rusty Russell wrote:
> >   
> >> On Wednesday 23 April 2008 06:29:14 Hollis Blanchard wrote:
> >>     
> >>> On Tuesday 22 April 2008 09:31:35 Rusty Russell wrote:
> >>>       
> >>>> We may still regret not doing *everything* little-endian, but this
> >>>> doesn't make it worse.
> >>>>         
> >>> Hmm, why *don't* we just do everything LE, including the ring?
> >>>       
> >> Mainly because when requirements are in doubt, simplicity wins, I think.
> >>     
> >
> > Well, I think the definition of simplicity is up for debate in this 
> > case... "LE everywhere" is much simpler than "it depends", IMHO.
> 
> You couldn't use the vringfd direct ring mapping optimization in KVM for 
> PPC without teaching the kernel to access a vring in LE format.  I'm 
> pretty sure the later would get rejected on LKML anyway for vringfd as a 
> generic mechanism.

You mean vringfd for use cases other than virtual IO drivers? I have a poor 
imagination; can you give some examples?

Even then, it should be possible to have VIO drivers use a different set of 
accessors, just like there are swapping and non-swapping accessors for real 
IO, so I still don't see the problem.

-- 
Hollis Blanchard
IBM Linux Technology Center

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