Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757981Ab1CaOly (ORCPT ); Thu, 31 Mar 2011 10:41:54 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:38022 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757711Ab1CaOlx (ORCPT ); Thu, 31 Mar 2011 10:41:53 -0400 Date: Thu, 31 Mar 2011 15:41:03 +0100 From: Alan Cox To: "H. Peter Anvin" Cc: Ingo Molnar , Len Brown , x86@kernel.org, linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, Len Brown , Linus Torvalds , Andrew Morton , Thomas Gleixner Subject: Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag Message-ID: <20110331154103.70d88899@lxorguk.ukuu.org.uk> In-Reply-To: <4D948D86.2050607@zytor.com> References: <67e90d97e0a77df4acd0c75e1bacc7714e011f3e.1301550524.git.len.brown@intel.com> <20110331061247.GA24786@elte.hu> <20110331081800.GH5938@elte.hu> <20110331102355.17d30a38@lxorguk.ukuu.org.uk> <20110331092721.GA16570@elte.hu> <20110331103320.5a72ff8c@lxorguk.ukuu.org.uk> <20110331093528.GA19288@elte.hu> <4D948D86.2050607@zytor.com> X-Mailer: Claws Mail 3.7.8 (GTK+ 2.22.0; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1617 Lines: 37 On Thu, 31 Mar 2011 07:19:50 -0700 "H. Peter Anvin" wrote: > On 03/31/2011 02:35 AM, Ingo Molnar wrote: > > > > * Alan Cox wrote: > > > >>> Btw., we used to auto-detect broken HLT systems IIRC - but that got lost > >>> already. We should at least honor the boot parameter. > >> > >> I don't believe we ever auto detected them or found a way to do so. That > >> was why the HLT message was printed before hlt was executed. > > > > Yeah - the CPU hang was unrecoverably deep so no auto-detection was possible. > > > > That's seriously ancient stuff - still, keeping the boot option around (<10 > > lines of code) does not hurt anyone. > > > > What it was was bad power supplies or low-capacitance, high-inductance > power distribution that happened to work with MS-DOS which always burned > the CPU at 100% and therefore left the power draw relatively consistent > current. A proper OS putting the CPU in HLT produced a lot more high > frequency noise on the power busses, with disastrous results without > proper bypass. And also chipset errata in some cases - eg some revisions of the CS5510 hung the box solid if a CPU hlt occurred during an IDE transfer. I don't think any CS5510s are still around although I've had mail from someone with a CS5520 in use not that long ago so who knows! The joy of ancient history. -- 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/