From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: use of scratchpad registers Date: Mon, 25 Mar 2013 10:12:57 -0400 Message-ID: <20130325141257.GH11546@phenom.dumpdata.com> References: <51502FEA02000078000C8088@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <51502FEA02000078000C8088@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel List-Id: xen-devel@lists.xenproject.org On Mon, Mar 25, 2013 at 10:07:22AM +0000, Jan Beulich wrote: > Konrad, > > in a response on thread "High CPU temp, suspend problem - xen > 4.1.5-pre, linux 3.7.x", you say > > "There are some BIOSes out there that I know that use the > scratchpad registers in IOH (so depending on the platform that > can be 0:0e.1 , Reg 0x84). If Xen or Linux touch it then the > P-states and C-states that the BIOS generates are buggy", > > which makes me assume you have knowledge on why and where > Xen or Linux would touch these registers. It is my understanding > that these registers should be left alone by Xen, and be used by > Linux only in ways consistent between native and running on top > of Xen (i.e. through the same specific driver). > > However, we've been having a report of there being a difference > in behavior, which so far we weren't able to narrow down the > origin of. Hence, if you know details here, I'd very much > appreciate if you could share them. Of course. Let me email the group that had let me know about this scratchpad registers and see if they narrowed down _who_ was poking at that. Once I get that information - or if they are comfortable responding in a public forum, I will post it here ASAP. > > Thanks, Jan > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel >