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

[Gleb Natapov]

On Sun, Feb 13, 2011 at 10:56:30AM -0600, Anthony Liguori wrote:
> >>
> >>qemu -device i440fx,id=nb -device piix3,id=sb,chipset=nb -device
> >>ioapic,id=ioapic,chipset=sb -device
> >>cpu,ioapic=ioapic,northbridge=nb
> >>
> >>Is not all that unreasonable and presents a fully functioning PC.
> >
> >Sure.  And -M blah is a shortcut.
> 
> Exactly.  Or better yet, blah is a config file that contains
> 
> [device "nb"]
> driver=i440fx
> 
You are trying to model how particular (very ancient) HW looked like,
instead of emulating guest visible functionality, but is dead end since
things are changing constantly. Northbridge functionality moves onto
cpu for instance. What CPU i440fx was designed for? Pentium?  What if
user runs QEMU with emulated CPU that in real life has internal memory
controller? Does you config have sense for such setup? Should we allow
to specify only Pentium CPU since this is how real HW worked?

> [device "sb"]
> driver=piix3
And piix3 refers to piix3.cfg which describe devices that present on the
chipset.

> chipset=nb
> 
> [device "ioapic"]
> driver=ioapic
> chipset=sb
Here, for instance, IOAPIC is included in a chipset for a long time
now. Why user should care that piix3 didn't have it. How this detail
changes qemu functionality? If it doesn't why should we expose it?

> 
> [device "cpu"]
> driver=cpu
> ioapic=ioapic
Why ioapic here? Doesn't cpu talks to ioapic via northbridge?

> northbridge=nb
> 

--
                        Gleb.