[Xen-devel] Re: memsize for HVM save/restore

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 26/3/07 04:13, "Zhai, Edwin" <edwin.zhai@xxxxxxxxx> wrote:

> I don't think so.
> Besides locating PFNs, memsize is also used in QEMU for other purpose, such as
> bitmap allocation, dev init and map_foreign*. So memsize is a must for qemu
> init.
> 
> See following code in xc_hvm_build:
> if ( v_end > HVM_BELOW_4G_RAM_END )
>     shared_page_nr = (HVM_BELOW_4G_RAM_END >> PAGE_SHIFT) - 1;
> else
>     shared_page_nr = (v_end >> PAGE_SHIFT) - 1;
> 
> So it's impossible to get memsize by saved PFNs when restore a big memory
> guest.

It can use the new XENMEM_maximum_gpfn hypercall for bitmap allocation. I'm
not sure what memsize would have to do with dev init. The map_foreign* is
hidden behind mapcache which shouldn't need to know memsize (although if
it's an issue of sizing buckets I suppose it can use XENMEM_maximum_gpfn).

 -- Keir



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