Re: [PATCHv2 RFC] virtio-spec: flexible configuration layout

[Sasha Levin <levinsasha928@gmail.com>]

On Wed, 2011-11-16 at 09:21 +0200, Michael S. Tsirkin wrote:
> On Wed, Nov 16, 2011 at 10:28:52AM +1030, Rusty Russell wrote:
> > On Fri, 11 Nov 2011 09:39:13 +0200, Sasha Levin <levinsasha928@gmail.com> wrote:
> > > On Fri, Nov 11, 2011 at 6:24 AM, Rusty Russell <rusty@rustcorp.com.au> wrote:
> > > > (2) There's no huge win in keeping the same layout.  Let's make some
> > > >    cleanups.  There are more users ahead of us then behind us (I
> > > >    hope!).
> > > 
> > > Actually, if we already do cleanups, here are two more suggestions:
> > > 
> > > 1. Make 64bit features a one big 64bit block, instead of having 32bits
> > > in one place and 32 in another.
> > > 2. Remove the reserved fields out of the config (the ones that were
> > > caused by moving the ISR and the notifications out).
> > 
> > Yes, those were exactly what I was thinking.  I left it vague because
> > there might be others you can see if we're prepared to abandon the
> > current format.
> > 
> > Cheers,
> > Rusty.
> 
> Yes but driver code doesn't get any cleaner by moving the fields.
> And in fact, the legacy support makes the code messier.
> What are the advantages?
> 

What about splitting the parts which handle legacy code and new code?
It'll make it easier playing with the new spec more freely and will also
make it easier removing legacy code in the future since you'll need to
simply delete a chunk of code instead of removing legacy bits out of
working code with a surgical knife.

-- 

Sasha.