Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 22 Mar 2001 16:24:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 22 Mar 2001 16:24:50 -0500 Received: from router-100M.swansea.linux.org.uk ([194.168.151.17]:50953 "EHLO the-village.bc.nu") by vger.kernel.org with ESMTP id ; Thu, 22 Mar 2001 16:24:34 -0500 Subject: Re: Incorrect mdelay() results on Power Managed Machines x86 To: twoller@crystal.cirrus.com (Woller, Thomas) Date: Thu, 22 Mar 2001 21:26:34 +0000 (GMT) Cc: linux-kernel@vger.kernel.org ('linux-kernel@vger.kernel.org') In-Reply-To: <973C11FE0E3ED41183B200508BC7774C0124F06D@csexchange.crystal.cirrus.com> from "Woller, Thomas" at Mar 22, 2001 02:29:48 PM X-Mailer: ELM [version 2.5 PL1] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: From: Alan Cox Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > Problem: Certain Laptops (IBM Thinkpads is where i see the issue) reduce the > CPU frequency based upon whether the unit is on battery power or direct > power. When the Linux kernel boots up, then the cpu_khz (time.c) value is This is commonly done using the speedstep feature on intel cpus. Speedstep can generate events so the OS knows about it but Intel are not telling people about how this works. > Appreciate any responses or thoughts on the subject, Boot with the 'notsc' option is one approach. We certainly could recalibrate the clock if we could get events out of ACPI, APM or some other source. Maybe someone at IBM knows something on the thinkpad front here. If there is for example an additional apm event or irq we can enable for the thinkpads to see the speed change we can make it work - 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/