[Xen-devel] Re: [RFC] fix xen_in_range()

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 23/04/2009 00:53, "Cihula, Joseph" <joseph.cihula@xxxxxxxxx> wrote:

> Unfortunately, the frametable is only contiguous in the virtual address space,
> so one can't simply take __pa() of its start and end.  And since it is quite
> large, iterating through each page to gets its phys addr adds a perceptible
> delay when that check has to be done for each page of physical memory (as is
> the case in the only caller, the VT-d routine that maps memory for dom0).  But
> it also appears that we can't convert the phys addr arguments into their virt
> addrs to compare with the contiguous frametable range because they will
> convert to the DIRECTMAP va's instead.

The frametable is allocated in aligned 2MB chunks. So you can check at that
granularity rather than 4kB.

 -- Keir



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