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

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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