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

Michael S. Tsirkin
2009-06-15T10:31:43Z

On Mon, Jun 15, 2009 at 12:43:48PM +0300, Avi Kivity wrote:
> On 06/14/2009 12:50 PM, Michael S. Tsirkin wrote:
>> On Fri, Jun 12, 2009 at 05:48:23PM +0100, Mark McLoughlin wrote:
>>
>>> However, in order to retain compat for that SCSI device (e.g. ensuring
>>> the PCI address doesn't change as other devices are added an removed),
>>> we're back to the same problem ... either:
>>>
>>> 1) Use '-drive file=foo.img,if=scsi,pci_addr=foo'; in order to figure
>>> out what address to use, libvirt would need to query qemu for what
>>> address was originally allocated to device or it would do all the
>>> PCI address allocation itself ...
>>>
>>
>> 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?
>>
>
> Yes, the user build the machine using the command line and monitor (or,
> in 2017, the machine configuration file), then turns on the power.
> Command line options are the parts lying around when we start.
>
> btw, -drive needs to be separated:
>
> -controller type=lsi1234,pci_addr=foobar,name=blah
> -drive file=foo.img,controller=blah,index=0
> -drive file=bar.img,controller=blah,index=1
>
> Drives to not have pci addresses.

Maybe we need a generic 'bus options' flag.