Re: Configuration vs. compat hints [was Re: [Qemu-devel] [PATCHv3 03/13] qemu: add routines to manage PCI capabilities]

Michael S. Tsirkin
2009-06-15T11:36:55Z

On Mon, Jun 15, 2009 at 02:14:15PM +0300, Gleb Natapov wrote:
> On Mon, Jun 15, 2009 at 02:07:53PM +0300, Michael S. Tsirkin wrote:
> > On Mon, Jun 15, 2009 at 01:52:13PM +0300, Gleb Natapov wrote:
> > > On Mon, Jun 15, 2009 at 01:46:53PM +0300, Michael S. Tsirkin wrote:
> > > > On Mon, Jun 15, 2009 at 01:44:56PM +0300, Gleb Natapov wrote:
> > > > > On Mon, Jun 15, 2009 at 01:32:49PM +0300, Michael S. Tsirkin wrote:
> > > > > > > You do need to export available slot numbers from qemu.
> > > > > >
> > > > > > Why would a slot be unavailable?
> > > > > >
> > > > > Because it does not exist?
> > > >
> > > > We can create a slot with any number, can't we?
> > > What do you mean? If the mobo has 4 slots you can't create fifth.
> > > KVM describes 32 slots in the BIOS.
> >
> > Do you mean the KVM kernel module here? I don't know much about the
> No I don't mean KVM kernel module here.
>
> > BIOS. Can't qemu control the number of slots declared?
> >
> Qemu represents HW, BIOS drives this HW. They should be in sync on such
> important issues like pci slot configuration.

As a simple solution, let's stick to 32 slots per bus. That's the
maximum that the PCI spec allows, anyway.

> Even if QEMU can control the number of slots declared (which it can't
> easily do), it will be able to do it only on startup (before BIOS
> runs).

That's OK - this is when the machine description is read.

> The way to have dynamic
> number of slots may be pci bridge emulation. Not sure what is needed
> from BIOS for that.

Since bridge can be hot-plugged, probably nothing?
But we don't necessarily need dynamic number of slots IMO.

>
> --
> Gleb.

--
MST