Re: [Xen-devel] [patch] more correct pfn_valid()

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 19 May 2005, at 09:14, Tian, Kevin wrote:

> For this part, I made a mistake to confuse domN and dom0. OK, for
> paravirtualized guest, there's actually no I/O range for domN, since 
> the
> front driver in domN will do all things to communicate with backend in
> Dom0. But what about a driver domain which has access to physical
> device, thus need real I/O address?
We rely on the driver using the dma_coherent/pci_consistent/bus_address 
macros for mapping device memory. Originally designed to handle IOMMUs, 
it is handy for us to determine places where code is handling real 
machine physical addresses rather than pseudophysical addresses. This 
gets groans of distaste from the kernel maintainers but has worked 
enormously well so far (AGP needed patching separately though).
 -- Keir


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