From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1THZft-0002uh-7t for mharc-grub-devel@gnu.org; Fri, 28 Sep 2012 08:28:09 -0400 Received: from eggs.gnu.org ([208.118.235.92]:52671) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1THZfq-0002uK-VR for grub-devel@gnu.org; Fri, 28 Sep 2012 08:28:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1THZfl-0003xv-LK for grub-devel@gnu.org; Fri, 28 Sep 2012 08:28:06 -0400 Received: from mail.kernelconcepts.de ([212.60.202.196]:40454) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1THZfl-0003xD-D8 for grub-devel@gnu.org; Fri, 28 Sep 2012 08:28:01 -0400 Received: from [192.168.2.135] by mail.kernelconcepts.de with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from ) id 1THZfI-0004Gl-TH for grub-devel@gnu.org; Fri, 28 Sep 2012 14:27:32 +0200 Message-ID: <506597CE.9030703@kernelconcepts.de> Date: Fri, 28 Sep 2012 14:27:58 +0200 From: Nils Faerber Organization: kernel concepts GbR User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120827 Thunderbird/15.0 MIME-Version: 1.0 To: The development of GNU GRUB Subject: CPU MSR register "tweak" module? X-Enigmail-Version: 1.4.4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 212.60.202.196 X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Sep 2012 12:28:08 -0000 Hello! Recently I purchased an AMD E-450 based netbook - my first AMD CPU for a long time. As expected Grub works perfectly on it - as does the Debian Linux I did install. Many AMD CPUs, and some Intel CPUs maybe too, can be tweaked for way lower power consumption by modifying the CPU MSR registers to lower the core voltage and eventually also the frequency (per P-state). The drawback of this is that the new values are lost upon reboot or suspend-to-disk. And additionally some of the Linux kernel drivers that get loaded or re-initialised during boot/resume pick up those values from those registers before user-space can re-setup them. So I was wondering if there is a possibility to configure Grub in a way that it will set-up specific registers with specific values. Ideally using the Grub config file... a small table with register/value pairs would be enough and they can just be written to the MSR registers without additional magic, so such a function should be pretty easy to implement - if it does not exist yet. I did search through the docs and also had a brief look at the Grub source but could not find something like that. Cheers nils -- kernel concepts GmbH Tel: +49-271-771091-12 Sieghuetter Hauptweg 48 D-57072 Siegen Mob: +49-176-21024535 http://www.kernelconcepts.de