[Ksummit-2012-discuss] PCI breakout session

H. Peter Anvin hpa at zytor.com
Mon Jun 18 17:02:32 UTC 2012

On 06/18/2012 03:28 AM, Michael S. Tsirkin wrote:
>> I'd say don't do it :-) Or rather try to give each device in the VM its
>> own dedicated virtual host bridge & bus :-)
> This only makes the problem of resource allocation worse.
> For example for IO this means you waste 4K of space per device. Since
> x86 only uses 16 bit IO addresses, this allows up to 16 devices.

OK, maybe this is a crazy idea, but we could do an extension to the PCI
standard to allow I/O address space to be subdivided finer than 4K.  We
could even try to push it at the PCI-SIG; it might be useful for some
PCI-Express configurations, since PCI-Express has exactly the same issue.


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