Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261244AbUCHVJZ (ORCPT ); Mon, 8 Mar 2004 16:09:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261239AbUCHVJZ (ORCPT ); Mon, 8 Mar 2004 16:09:25 -0500 Received: from 1-2-2-1a.has.sth.bostream.se ([82.182.130.86]:2763 "EHLO K-7.stesmi.com") by vger.kernel.org with ESMTP id S261244AbUCHVJV (ORCPT ); Mon, 8 Mar 2004 16:09:21 -0500 Message-ID: <404CE0FC.8070900@stesmi.com> Date: Mon, 08 Mar 2004 22:09:16 +0100 From: Stefan Smietanowski User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7a) Gecko/20040219 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Bjoern Schmidt CC: linux-kernel@vger.kernel.org Subject: Re: fsb of older cpu References: <404C4D32.1080609@uni-paderborn.de> <200403081714.04182.bernd.schubert@pci.uni-heidelberg.de> <404CD4E7.5050105@uni-paderborn.de> In-Reply-To: <404CD4E7.5050105@uni-paderborn.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1211 Lines: 36 >>> Hello, >>> is there a way to measure/change the fsb of a PII/233/Tonga/440BX while >>> running linux? Google has no answer... >> >> >> >> This is the only one I know about, but it has support for a few >> boards/pll's only. >> >> http://home.iprimus.com.au/mccvals/mvpll/ >> >> Hope it helps, >> Bernd > > > Hello and thank you for your answer. I determined that this cpu has a > fsb of > 66MHz. The reason for my question was that i want to underclock the cpu. > I think it would be better to change the multiplier instead of changing > the fsb. > Therefore i read the msr register 0x02ah, tilted bit 27 and wrote it > back, but > the cpu clock is still the same. Why does that not work? Is it possible to > change the multiplier at runtime at all? > I'm no expert on the subject but as I recall the processor sets the internal clock (derived from fsb+multiplier) on startup so no matter what you do do the running cpu it won't change it. // Stefan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/