Re: [PATCH] Xen/i386 cleanups - AGP bus/phys cleanups

[Tupshin Harper <tupshin@tupshin.com>]

Paul Mackerras wrote:

>Rik van Riel writes:
>
>  
>
>>Thing is, the rest of the kernel uses virt_to_phys for
>>two different things.  Only one of them has to do with
>>the real physical address, the other is about getting
>>the page frame number.
>>    
>>
>
>So fix the places that are using virt_to_phys to get the page frame
>number to use virt_to_pfn instead. :)
>
>  
>
>>On native x86, x86-64 and others, the page frame number
>>and physical address are directly related to each other.
>>Under Xen, however, the two are different - and the
>>AGPGART really needs to have the physical address ;)
>>    
>>
>
>If Xen is letting the kernel program the GART, you just lost any
>memory isolation between partitions you might have been trying to
>enforce. :)
>  
>
Since xen only lets the  dom0 (privileged domain) program the GART, all 
of the domU's  (non-privileged domains) are still isolated from each other.

-Tupshin