Re: [Xen-users] High Memory Support on systems >1GB

["John A. Sullivan III" <jsullivan@xxxxxxxxxxxxxxxxxxx>]

On Fri, 2006-01-13 at 14:38 +0000, Mark Williamson wrote:
> > On a Xen 2.0.7 host with between one and four GB of RAM but no single
> > domain larger than 880MB, how should kernel High Memory Support be
> > configured? Should it be off since no domain kernel is using more than
> > 880?
> 
> Xen will support all your memory (unless there's a big memory hole, causing 
> some of it to be mapped above 4Gig).  Domains only need highmem4g if they're 
> going to individually use more than 880.
> 
> > Should dom0 have it enabled to manage all the memory?
> 
> Nope, Xen manages all the memory, so you should be fine.
> 
> > Should all  
> > the domains have it since they are drawing on a pool larger than 880 MB?
> 
> Nope.  But...
> 
> *if* you need PAE, then Xen and all domains do need to use PAE.
> 
> > Is the answer the same for Xen 3.0? Thanks - John
> 
> Yes. (and PAE is Xen 3 only).
> 
> Cheers,
> Mark
> 
Thanks very much.  So just to make completely sure I understand, on a
physical host with between 880 MB and 4 GB of RAM, if no single domain,
privileged or unprivileged requires more than 880 MB of RAM, no domain
kernel needs high memory support enabled.  If any domain, privileged or
unprivileged, will use more than 880 MB, then that kernel and only that
kernel needs high memory support enabled.  Correct? - John
-- 
John A. Sullivan III
Open Source Development Corporation
+1 207-985-7880
jsullivan@xxxxxxxxxxxxxxxxxxx

Financially sustainable open source development
http://www.opensourcedevel.com


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