Re: [Xen-devel] [PATCH] xen/x86: Force removal of memory range when not covered by MTRRs

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.02.13 at 14:47, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
>> >> Since when is E820_UNUSABLE memory being used as guest
>> >> memory? If that's indeed the case, that's the bug to fix. The
>> >> above data to me shows, however, that the range above
>> >> 228000000 is considered invalid. So then the question is why the
>> >> kernel tries to map that memory in the first place (the hypervisor
>> >> rejecting the attempt, despite Dom0 being privileged, seems
>> >> correct to me, as the range is also known not to be MMIO).
> 
> B/c it gets the E820 from the hypervisor, which shows that area as
> E820_UNUSABLE. And dom0 (or rather, the generic memory code) ends up
> creating pagetables for it.

That would be wrong even on native, and I don't see how that
would happen: memblock_add() gets called from
memblock_x86_fill() only for E820_RAM and E820_RESERVED_KERN
ranges.

Jan


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