RE: [Xen-devel] [timer/ticks related] dom0 hang during boot on large 1TB system

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> 04.01.10 23:07 >>>
>If there are known issues with 1TB of memory in this
>configuration, we'd like to understand them.  If 1Tb with
>32-bit dom0 is rife with hidden unresolvable problems,
>we'd like to make a clear support statement as to what the
>physical memory limit is.

I can't say there are known problems, but I'm convinced not everything
can work properly above the boundary of 168G. Nevertheless it is quite
possible that most or all of the normal (not error handling) code paths
work well. Page table walks e.g. during exceptions or kexec would be
problem candidates. And while my knowledge of the tools is rather
limited, libxc also has - iirc - several hard coded assumptions that might
not hold.

What is clear though is that you also depend on the memory distribution
across the (physical) address space: Contiguous (apart from the below-
4G hole) memory will likely represent little problems, but sparse memory
crossing the 44-bit boundary can't work in any case (since MFNs are
represented as 32-bit quantities in 32-bit Dom0).

Jan


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