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Re: [Xen-devel] question about domU memory mapping

On 27 Jul 2005, at 17:15, Xin Zhao wrote:

WHy some kernel virtual addresses cannot be virt_to_machine'd? Any
restriction on that?

Addresses from vmalloc, kmap and fixmap are not in the 1:1 virtual-physical kernel address space. To find the corresponding physical address for such a virtual address you must walk the pagetables.

Module structures are vmalloc'ed on i386, so you cannot use virt_to_machine.

If your code is Xen-specific (no need to work on native i386) then you can use the arbitrary_virt_to_machine() function that only xenlinux provides.

 -- Keir

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