Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753311Ab2HFGol (ORCPT ); Mon, 6 Aug 2012 02:44:41 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:38793 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753041Ab2HFGoj (ORCPT ); Mon, 6 Aug 2012 02:44:39 -0400 Message-Id: <501F83F20200007800092C1C@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.0 Date: Mon, 06 Aug 2012 07:44:34 +0100 From: "Jan Beulich" To: , "H. Peter Anvin" Cc: "Ingo Molnar" , "Matt Fleming" , , Subject: Re: [Regression] "x86-64/efi: Use EFI to deal with platform wall clock" prevents my machine from booting References: <20120805172903.5f8bb24c@zougloub.eu> <501EF3A2.20200@zytor.com> In-Reply-To: <501EF3A2.20200@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1712 Lines: 43 >>> On 06.08.12 at 00:28, "H. Peter Anvin" wrote: > On 08/05/2012 02:29 PM, Jérôme Carretero wrote: >> Hi, >> >> My PC (AMD Bulldozer + Asus SABERTOOTH 990FX) booted fine from UEFI >> and it broke between v3.5 and v3.6-rc1. >> Other machines with old BIOSes booted fine so I looked into EFI-related >> patches trying to revert them, because I didn't know what else to do. >> >> Bingo, bacef661: x86-64/efi: Use EFI to deal with platform wall clock. >> >> At the moment I reverted this commit after v3.6-rc1-133-g42a579a, >> and it boots fine. >> >> This really not my domain so tell me if I can help testing. >> > > Thank you... we were aware of the problem but had not been able to > reproduce it, so we had hoped someone would bisect or otherwise identify > the faulty patch. Faulty? Without technical detail I'd be careful with this, as there's too many broken EFI implementation around. The only change that has a (very low) potential for causing problems by itself is the earlier calling of efi_enter_virtual_mode(), which was requested/recommended by Matthew. I am e.g. (meanwhile) aware of (Intel) systems that use floating point instructions in the UEFI runtime code, which is clearly a violation of the spec; having the kernel continue to be not spec compliant is a questionable tradeoff. In any case, without having seen _how_ things break I don't think a decision should be taken if/how to address this (apparent) regression. Jan -- 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/