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xen-devel
Re: [Xen-devel] x86-64's contig_initmem_init
On 30 Aug 2005, at 15:07, Keir Fraser wrote:
The tail part of the initial mapping has no special handling on i386
nor on x86_64. It just gets freed up when we free from 0 up to
max_pfn, and it never gets reserved (the reserved region precisely
covers kernel text/data and initial page tables).
Actually, that could be another bug on x86/64 -- I may need to
truncate the initial mapping, or we may be ending up with spurious
extra writable mappings to some pages... I'll take a look and see if
this is the case.
Okay, I see what you mean. init_memory_mapping() sets start_pfn to
something after the domain-builder-provided mapping. So we probably
lose around 4MB of RAM per domain on x86/64.... that'll have to be
fixed. I didn't originally write this code, btw. ;-)
i386 does not have this concept of an initial/kernel mapping separate
from the 1:1 mapping of all phys mem. So this particular problem cannot
occur.
-- Keir
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