Re: [Xen-devel] sparse M2P table

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 17/09/2009 06:42, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:

> I'm working on similar staff also, mainly because of memory hotplug requires
> such support. Maybe I can base my work on your work :-)
> 
> 256G is not enough if memory hotplug is enabled. In some platform, user can
> set the start address for hotpluged memory and the default value is 1024G.
> That means 4M memory will be used for the L3 table entries (1024 * 4K).

Jan doesn't mean that the M2P only addresses up to 256G; he means that the
M2P itself can be up to 256G in size! I.e., it will be able to address up to
128TB :-)

The only structure in Xen that I think doesn't just work with expanding its
virtual memory allocation and sparse-mapping is the '1:1 memory mapping'.
Because to address such large sparse memory maps, the virtual memory
allocation would be too large. So I'm guessing the '1:1 memory map' area
will end up divided into say 1TB strips with phys_to_virt() executing a
radix-tree lookup to map physical address ranges onto those
dynamically-allocated strips.

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel