Re: [Xen-devel] Re: Dom0 Panics/lockups

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 18 Jun 2006, at 22:44, Shaun wrote:

> Here's a xm info, hope that gives you everything you need.  What does 
> this
> lowmem_emergency_pool=16M do and why is it needed?  Is the problem a 
> memory
> issue?  This host has 8GB, 1GB allocated to dom0 and about 6GB 
> allocated to
> DomU's
When running in PAE mode you need a supply of memory below 4GB as each 
process needs its root page table to be located below 4GB. Xen isn't 
very careful about ensuring it doesn't give away all that memory and, 
if you run out, you get crashes of the type you've been seeing. The fix 
is to specifically reserve some of that low memory so that it is only 
given out when that type of memory is specifically requested.
This limitation is gone from the xen-unstable tree (future Xen 3.0.3).

 -- Keir


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