From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756362AbYEKDD4 (ORCPT ); Sat, 10 May 2008 23:03:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754261AbYEKDDq (ORCPT ); Sat, 10 May 2008 23:03:46 -0400 Received: from smtp1.betherenow.co.uk ([87.194.0.68]:55615 "HELO smtp1.betherenow.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754170AbYEKDDp (ORCPT ); Sat, 10 May 2008 23:03:45 -0400 From: Alistair John Strachan To: Andrew Morton Subject: Re: [PATCH] x86: enable hpet=force for AMD SB400 Date: Sun, 11 May 2008 04:02:20 +0100 User-Agent: KMail/1.9.9 Cc: Thomas Gleixner , andreas.herrmann3@amd.com, mingo@elte.hu, hpa@zytor.com, linux-kernel@vger.kernel.org References: <20080509094911.GG5023@alberich.amd.com> <20080509165501.a0fdb29d.akpm@linux-foundation.org> In-Reply-To: <20080509165501.a0fdb29d.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200805110402.20327.alistair@devzero.co.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 10 May 2008 00:55:01 Andrew Morton wrote: > On Sat, 10 May 2008 01:42:30 +0200 (CEST) > > Thomas Gleixner wrote: > > On Fri, 9 May 2008, Andrew Morton wrote: > > > On Fri, 9 May 2008 11:49:11 +0200 > > > > > > Andreas Herrmann wrote: > > > > x86: enable hpet=force for ATI SB400 > > > > > > Sigh. > > > > > > > Add quirk to allow forced usage of HPET on ATI SB400. > > > > I stumbled over machines where HPET is enabled but not reported > > > > by BIOS. > > > > > > Is there no way in which we can probe for or identify this condition, > > > rather than hoping that the user will find out about this boot option? > > > > I'd love to have a sane solution for that, but looking at the rate of > > HPET wreckage since we increased the usage of HPET I'm happy to have > > this as an opt in thingy. > > Well we don't have to auto-enable the hpet. Simply adding a loud "you > should try the hpet=force option" printk would help a lot of people. I'm a bit confused about the policy here: if we look at the Intel chipset overrides for HPET, they conditionally enable the HPET _without_ the hpet=force option if you have a chipset on the whitelist. If Intel can do this on their chipsets, why is this not being done for the ATI chipsets for which (presumably) AMD have specs? One thing I'd considered was that HPET isn't actually used very often on Intel chipsets because on most recent Intel CPUs the TSC is stable, but I think either the Intel quirk should be consistent with the hpet=force usage, or "known correct" HPET overrides should just always be applied. -- Cheers, Alistair. 137/1 Warrender Park Road, Edinburgh, UK.