RE: [Xen-devel] Does it support to specify virtual function in guest for assigned device

["Han, Weidong" <weidong.han@xxxxxxxxx>]

Simon Horman wrote:
> On Tue, Sep 08, 2009 at 04:10:57PM +0800, Han, Weidong wrote:
>> Hi Simon,
>> 
>> You did lots of work on multiple functions passthrough. We can
>> specify virtual slot for assigned device like pci=[ '01:00.0@5' ].
>> Does it support to specify virtual function in guest for assigned
>> device? For example, I want to specify virtual bdf 00:05.1 for
>> device 01:00.1. 
> 
> Hi Weidong,
> 
> Yes, as of changeset "xend: pass-through: Extend multi-function
> mapping" (20012:3242351f9c67) is is possible to specify the virtual
> function. 
> 
> However, this is only possible for multi-function pass-through.
> When only a single function is passed through the virtual function
> will always be zero, because PCI devices must always have function 0
> present.
> 
> So the closest that you could do when passing through 01:00.1 is to
> get virtual function 00:05.0 by specifying '01:00.1@5'.
> 
> If you passed through another function of 01:00 at the same time as
> 01:00.1, say 01:00.0, then you could explicitly choose to have 01:00.1
> assigned to 00:05.1 and 01:00.0 assigned to 00:05.0 using
> '00:05.0=0,1=1@5'. 
> 
> Actually that would be the default as it is just an identity mapping,
> so the same result would be achieved by '00:05.0,1@5'. A more
> interesting case would be to reverse the mapping so 00:05.0 ->
> 01:00.1 and 00:05.1 -> 00:05.0, which could be achieved using
> '00:05.0=1,1=0@5'. 

Hi Simon,

Thanks for your detailed explanation. I need the option '00:05.0=0,1=1@5'. BTW, 
did you add these option explanation to any document? It is helpful if you do 
it.

Regards,
Weidong


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