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

On Mon, Jun 15, 2009 at 12:27:08PM +0300, Avi Kivity wrote:

On 06/15/2009 12:08 PM, Mark McLoughlin wrote:

quoted

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This last option makes sense to me: in a real world the user has
control over where he places the device on the bus, so why
not with qemu?
     

Yep, most people seem to agree that it makes sense to allow this, but
some believe it should only be via a machine description file, not the
command line.
   

I don't understand this opposition.  It's clear a machine config file is  
a long way in our future.  It's also clear lack of stable PCI addresses  
hurts us now.

quoted

However, the first problem is that it isn't a solution to the guest ABI
problem more generally.
   

pci_addr was never meant to bring world peace, just stable PCI  
addresses.  The other issues should be addressed separately.

quoted

And the second problem is that for e.g. libvirt to use it, it would have
to be possible to query qemu for what PCI slots were assigned to the
devices - libvirt would need to be able to parse 'info pci' and match
the devices listed with the devices specified on the command line.
   

If all devices (including vga, ide) are set up with pci_addr, then this  
is unneeded.

Right. I think it could be an all or nothing at all approach.

You do need to export available slot numbers from qemu.

Why would a slot be unavailable?