From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754995AbYGVSdX (ORCPT ); Tue, 22 Jul 2008 14:33:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751542AbYGVSdO (ORCPT ); Tue, 22 Jul 2008 14:33:14 -0400 Received: from srv5.dvmed.net ([207.36.208.214]:37247 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750961AbYGVSdO (ORCPT ); Tue, 22 Jul 2008 14:33:14 -0400 Message-ID: <488627E2.2060101@garzik.org> Date: Tue, 22 Jul 2008 14:33:06 -0400 From: Jeff Garzik User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: "H. Peter Anvin" CC: "Luis R. Rodriguez" , linux kernel , "H. Peter Anvin" , Ivan Seskar , jfm3 , Sujith Subject: Re: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot References: <43e72e890807210614y58065d75j5b2fb3c5ebe6180a@mail.gmail.com> <48848DDF.6010903@zytor.com> <43e72e890807210701w6d7f5638w5fdbea76a1cf1c0b@mail.gmail.com> <48851AC2.8030007@zytor.com> <43e72e890807212147p5d19cfact17e719abb338378c@mail.gmail.com> <488614A3.1060400@garzik.org> <48862526.7060704@zytor.com> In-Reply-To: <48862526.7060704@zytor.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.4 (----) X-Spam-Report: SpamAssassin version 3.2.5 on srv5.dvmed.net summary: Content analysis details: (-4.4 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org H. Peter Anvin wrote: > Jeff Garzik wrote: >>> >>> Thanks for taking a look at this. So well, it would be a >>> misconfiguration bug by the distribution then to try to support a >>> generic 686 kernel wihtout GENERIC then. >> >> Well, it may be intentional -- some distros simply exclude support for >> the lower-volume VIA processors, since that might imply building their >> "generic 686 kernel" sans CMOV and some other instructions, and >> changing the compiler's instruction scheduling to something less >> optimal for the majority. :/ >> > > X86_GENERIC shouldn't disable CMOV? I said "generic 686 kernel" not a specific Kconfig option (for reasons stated below), which is a bit different. > We're only referring specifically to the family == 6 VIA processors here. To be specific, I was merely saying that VIA processors where c->x86_model==6 may lack CMOV. I have not kept track of what current Kconfig options will set, but in the past it was quite easy to build a "generic 686 kernel" that required CMOV and thus excluded these VIA processors. Distros in the past often wound up intentionally -not- supporting some of these VIA processors, because they did not want to create a non-CMOV kernel. (This policy obviously excluded older x86 as well) If these things have been addressed recently (< 12-18 months) then all good. Jeff