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

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 18 May 2005, at 23:18, Ian Pratt wrote:

> I think the best fix is to have the frame_table cover the whole of
> physical ram, and then mark non-ram pages in the frame_table.
>
> To save some memory, we could map the frame_table in virtual address
> space, then use __get_user when reading from it (a fault indicates a
> non-ram page too)
We already do this, and I initilialise every non-RAM e820 entry as an 
I/O area in the frame table. Actually, now I think about it, I/O 
mappings probably don't tend to appear in the e820... best fix is to 
initialise the frame table to all I/O, then override the RAM sections 
and the Xen section (to protect it).
I'll sort out a fix.

 -- Keir


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