From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olaf Hering Subject: Re: Question re live migrate on Xen 4.2 re different cpu capabilities Date: Thu, 7 Feb 2013 16:11:26 +0100 Message-ID: <20130207151126.GA31180@aepfle.de> References: <8B93B6FC00D1EC219B83AEDB@nimrod.local> <20130207091907.GA5540@aepfle.de> <1360230421.32479.46.camel@zakaz.uk.xensource.com> <496E7A8DB9DCF257D29E10F2@nimrod.local> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <496E7A8DB9DCF257D29E10F2@nimrod.local> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Alex Bligh Cc: Ian Campbell , Xen Devel List-Id: xen-devel@lists.xenproject.org On Thu, Feb 07, Alex Bligh wrote: > >You can also level down an entire host using the cpuid_mask_* command > >line options described in > >http://xenbits.xen.org/docs/unstable/misc/xen-command-line.html > > Thanks - that's really helpful. Looking at the documentation for cpuid= > I can't see an obvious way of saying 'mask everything except the > least common denominator of features' using the libxl method, without > having prior knowledge of what each version of xen supports. I'm not > even clear how to do this on the xend method (obviously I want to > pass long bitstrings of zeros, but how many?). Am I missing something? cpuid= is what the guest sees, so its not so much a feature of Xen itself but what the host cpu provides. I'm not sure if Xen can emulate certain important bits. The wikipedia CPUID entry has a list what each bit means. Olaf