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[Xen-devel] Re: mapcache broken?

On 10 Jan 2006, at 09:46, Leendert Van Doorn wrote:

Your map_domain_page mapcache cleanup from last night breaks VMX 32-bit,
but funny enough not VMX 64-bit.

The map_io_shared_page determines that there are 0 entries in the e820 map. The map itself doesn't appear to fail which probably means that a page full with 0's is mapped and this would indicate at a problem with the mapcache (this is just a conjecture, I haven't actually added to code to test this,
I only had 10min to look at this).

Yeah, I realised this might be a problem for VMX last night. Problem is that certain pagetables get map_domain_page()'ed for the lifetime of the guest, and are expected to then be mapped in all address spaces. Now the mapcache is per domain, this 'trick' won't work.

A new shadow mode should not do such long-term mappings. I'll see if I can come up with a temporary solution for current shadow mode (maybe reintroduce ioremap()...).

 -- Keir

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