Re: [Qemu-devel] [PATCH] vfio-pci: Add KVM INTx acceleration

[Michael S. Tsirkin]

On Tue, Oct 16, 2012 at 09:13:15AM -0600, Alex Williamson wrote:
> > There's no chance we ship e.g. q35 by mistake without this API: since
> > there is no way this specific assert can be missed in even basic
> > testing:
> > 
> > So I see it differently:
> > 
> > As coded here:
> >     chipset authors get lazy and do not implement API.
> >     bad performance for all users.
> > 
> > With assert:
> >     chipset authors implement necessary API.
> >     good performance for all users.
> 
> I prefer a carrot, not a whip.  Thanks,
> 
> Alex
> 

It's not just that.
Problem is performance testing/fixing is hard.
Catching and fixing asserts is easy.
So working around buggy qemu code really backfires
as it reverses the motivation for writing well performing
code. History proves me right: for each API change where
we implemented a fallback old code stayed around for years.

-- 
MST