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Re: [Xen-devel] [PATCH] enforce dom0 cpus and balloon out memory

To: aq <aquynh@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] enforce dom0 cpus and balloon out memory
From: Ryan Harper <ryanh@xxxxxxxxxx>
Date: Fri, 29 Jul 2005 10:17:20 -0500
Cc: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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* aq <aquynh@xxxxxxxxx> [2005-07-29 09:01]:
> This patch does 2 jobs:
> - Enforce the number of CPUs dom0 will take. See the new variable
> "dom0-cpus" in xend-config.sxp (you will want to set this variable to
> 1 on SMP systems)

You could use vcpu-hotplug to drop the extra cpus from dom0 instead of
writing directly into sysfs.  The only stopper to that approach is the
fact that dom0's self.channel is not initialized when xend starts and
subsequently doesn't send the control message.  Channels are initialized
when a domain is built, but since dom0 is built by xen, the routine
which sets up channels isn't called for dom0.  Haven't found a good place
for xend to initialized the channel for dom0 yet either.

See vcpu_hotplug() in xen/xend/XendDomInfo.py

Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253

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