From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: Re: Xen HVM cpuid problem Date: Tue, 13 May 2008 15:49:10 +0200 Message-ID: <200805131549.11121.Christoph.Egger@amd.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Tuesday 13 May 2008 14:56:00 Keir Fraser wrote: > All HVM guests receive a default configuration from libxc's > xc_cpuid_apply_policy(). You must update your tools if you have updated > your hypervisor to recent xen-unstable. Otherwise you will indeed get bog= us > CPUID behaviour. Tnx. Updating the tools fixed it. I should get used on updating the tools m= ore=20 regularly. Sorry for the noise. Christoph > > -- Keir > > On 13/5/08 13:41, "Christoph Egger" wrote: > > Hi Keir, > > > > For HVM guests, all cpuid Fn's going through domain_cpuid() > > iterate over the loop and then return 0 for all four registers. > > > > Guests OS's and cpuid tools in HVM which query for > > cpuid Fn 0000.0000 %eax and 8000.0000 %eax, see the value 0 and think, > > Xen emulates oldish 386/486 CPUs. > > > > This leads to strange boot failures, "your CPU does not support long > > mode" or "minimum required CPU is a 486DX CPU" when launching 32bit or > > 64bit HVM guests. > > > > To reproduce this, cpuid is NOT explicitely configured > > in the guest config file. > > > > BTW: Is there a reason for not handling cpuid in one central place? > > > > Christoph =2D-=20 AMD Saxony, Dresden, Germany Operating System Research Center Legal Information: AMD Saxony Limited Liability Company & Co. KG Sitz (Gesch=E4ftsanschrift): Wilschdorfer Landstr. 101, 01109 Dresden, Deutschland Registergericht Dresden: HRA 4896 vertretungsberechtigter Komplement=E4r: AMD Saxony LLC (Sitz Wilmington, Delaware, USA) Gesch=E4ftsf=FChrer der AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy