Re: [Xen-devel] [PATCH v6 01/14] iommu: introduce the concept of BFN...

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Tuesday, September 4, 2018 4:33 PM
> >
> > bus address is commonly used along with physical/virtual address, to
> > represent different views between devices and CPU. From that angle
> > I think BFN is a clear term in this context. btw it is not necessary to
> > differentiate GBFN and MBFN since there is only one BFN view per
> > device.
> 
> Sure, but you neglect the presence of one or more IOMMUs when
> you say "between devices and CPU". There addresses prior to and
> after IOMMU translation are distinct, and while the one before the
> translation matches the device view, the one after translation does
> not necessarily match the CPU view. Hence there are two "bus"
> frame numbers here - one representing the device view, and the
> other representing the IOMMU (output) view.
> 

I didn't get. the output address from IOMMU is the one sent to
memory controller, same as the one sent from CPU.

Thanks
Kevin

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel