From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: softtsc for PV guests Date: Fri, 21 Aug 2009 16:02:18 -0700 Message-ID: <4A8F277A.7080103@goop.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: 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 Cc: "Xen-Devel (E-mail)" List-Id: xen-devel@lists.xenproject.org On 08/21/09 15:17, Dan Magenheimer wrote: > I'm starting to play with implementing softtsc for > PV guests, but am not adequately familiar with the low > level x86 instruction set or emulation code in Xen. > > The attached patch seems to work fine for awhile. > Dom0 begins the boot process and the printk added > to traps.c observes more than 256K TSC traps (mostly > in the BogoMIPS calculation) and continues on loading > drivers etc but eventually freezes after: > The Xen clocksource uses rdtsc extensively for timing; emulating it would be a bad idea. I guess it would make some sense to emulate usermode rdtsc, but it shouldn't affect kernel rdtscs. > device-mapper: ioctl: 4.7.0-ioctl (2006-06-24) initialised: dm-devel@redhat.com > kjournald starting. Commit interval 5 seconds > EXT3-fs: mounted filesystem with ordered data mode. > > Any ideas on what might be stopping the dom0 boot? > How dead is the system? Does it respond to sysrq-p? 'q' or '0' on the Xen console? J