Re: [Qemu-devel] KVM call minutes for Feb 8

[Gleb Natapov]

On Thu, Feb 10, 2011 at 01:51:14PM +0100, Anthony Liguori wrote:
> On 02/10/2011 12:13 PM, Gleb Natapov wrote:
> >
> >Which spec? Even in this discussion we completely mixed different
> >things. 440FX is not a chipset.
> 
> Yes, it is.  It's a single silicon package with a defined pinout.
> If you don't believe me, re-read the spec.
> 
> It's a MCM with the PIIX3 being internally connected.   The
> connection between the i440fx and PIIX3 happens to be PCI but that's
> not always the case.  Sometimes it's a proprietary bus.
> 
Which one? 29054901.pdf describes memory controller and PCI host bridge only.
 
> >Again you probably mean PIIX3. Even then removing unused ide will free
> >one more PCI slot for my cool virtio disk array. The things is, from
> >code point of view, it does not cost you extra to allow composition of
> >ide since it is just a regular PCI device and we need to support composing
> >those anyway.
> 
> If this is useful, and it doesn't break guests, you can always do
> -device i440fx,ide=off.  However, it's an exception where we're
> deviating from how hardware works.
> 
I don't care how command line will look like, but I do not see how you
will support ide=off without device composition unless you put ad-hoc
ifs all over your i440fx device code.

And I don't understand what do you mean by saying that this is not how
hardware works. Presence or absence of PCI device does not change how
hardware works.

> And that's okay, but the base modelling ought to follow real
> hardware closely with deviations being the exception.
> 
You keep saying this without explaining why. But with device composition
you will have exactly that, you will compose real chipsets using config
files, not code.

--
                        Gleb.