RE: [Xen-devel] sparse M2P table

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> 17.09.09 11:05 >>>
>Can you elaborate it a bit? For example, considering system with following
>memory layout: 1G ~ 3G, 1024G ~ 1028G, 1056G~1060G, I did't catch
>you algrithom :$

That would be (assuming it really starts a 0)

0000000000000000-00000000bfffffff
0000010000000000-00000100ffffffff
0000010800000000-00000108ffffffff

right? The common non-top zero bits are 36-39, which would reduce the
virtual address space needed for the 1:1 mapping and frame table
approximately by a factor of 16 (with the remaining gaps dealt with by
leaving holes in these tables' mappings).

Actually, this tells me that I shouldn't simply use the first range of non-
top zero bits, but the largest one (currently, I would use bits 32-34).

But, to be clear, for the purposes of memory hotplug, the SRAT is what
the parameters get determined from, not the E820 (since these
parameters, other than the upper boundaries, must not change post-
boot).

Jan


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