From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joshua West Subject: Re: Migrate/Save of 32-bit domU Broken on Xen 3.1.2 64-bit dom0 Date: Fri, 18 Jan 2008 18:32:39 -0500 Message-ID: <47913717.5040201@brandeis.edu> References: <20080118161753234.00000001968@djm-pc> <4791364C.50004@brandeis.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4791364C.50004@brandeis.edu> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "dan.magenheimer@oracle.com" Cc: Kurt Hackel , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org Joshua West wrote: > Hi Dan, > > Dan Magenheimer wrote: >> Joshua -- >> >> Why do you need so much memory on dom0? Are you thinking >> that the total memory available to guests is limited to >> what dom0 has? Or are you running some memory-hungry >> applications on dom0? >> > > Hmm, I thought that a 32-bit dom0 system can only have up to 16GB of > memory available to it and its domU's -- and a 64-bit dom0 can have a > max of 32GB. I only allocate ~512MB of memory to the dom0's > themselves. "xm info" shows us the rest of whats available for use by > domU's. > > Thus, even if I have 32GB of RAM in a server, the total memory that > will be used in dom0 + all domU's can only add up to 16GB. Am I just > plain old wrong? > >> Note that 64-bit Xen + 32-bit Dom0 will support both 32-bit >> and 64-bit domU's. (Oracle VM uses this configuration by >> default on 64-bit capable machines.) And save/restore/migration >> has been tested to work for this (with the patch Kurt posted). >> > > Interesting. For some reason I thought that the Hypervisor had to > match the dom0's kernel. So you're saying that if I compile the Xen > Hypervisor as 64-bit and my dom0 + domU's both as 32-bit, I can reach > the full capacity of my servers with respect to RAM (32GB) instead of > being limited to 16GB? (And this only works with Kurt's patches?). Sorry about this second question. Looks like you already answered it in your first message :-/ I'm going to give it a whirl (64-bit Xen Hypervisor, 32-bit dom0, 64-bit and 32-bit domU's -- all with Kurt's patches). Thanks. > >> Dan > > -- Joshua West Systems Engineer Brandeis University http://www.brandeis.edu