Re: [RFC] use realmode code to reserve end-of-conventional-memoryto 1MB

[H. Peter Anvin]

Eduardo Habkost wrote:
> > > I am aware that it would take more work to tell all kernel code that it
> > > shouldn't look for BIOS data on this region when running as a domU guest,
> > > but it seems that it would be a better solution.
> > No, the right thing is for Xen to not try to map RAM in this area.
>
> Why? If the Xen host is telling us there is valid RAM in this area,
> why can't we use it?
>
> Existing Xen hosts use those physical address ranges for RAM. We can't
> fix this on the e820 map on the guest side without making otherwise-valid
> RAM unused.

x86 has a number of historical assumptions, both in kernel and in 
userspace (consider dmidecode!)  Trying to go against them is a losing 
proposition, *AND* a headache for the maintainers, which will have to 
consider "oh yes, and Xen does this dumb thing which goes against what 
all the hardware does."

	-hpa
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