From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759491Ab2EIOQO (ORCPT ); Wed, 9 May 2012 10:16:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49285 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758294Ab2EIOQK (ORCPT ); Wed, 9 May 2012 10:16:10 -0400 Message-ID: <4FAA7C06.1060209@redhat.com> Date: Wed, 09 May 2012 16:15:34 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120425 Thunderbird/12.0 MIME-Version: 1.0 To: "H. Peter Anvin" CC: Jarkko Sakkinen , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, Michal Marek , Sam Ravnborg , Joseph Cihula , Shane Wang Subject: Re: [PATCH 04/23] x86, realmode: Move reboot_32.S to unified realmode code References: <1336501366-28617-1-git-send-email-jarkko.sakkinen@intel.com> <1336501366-28617-5-git-send-email-jarkko.sakkinen@intel.com> <4FAA18F1.6080508@redhat.com> <4FAA76E7.1070807@linux.intel.com> In-Reply-To: <4FAA76E7.1070807@linux.intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 09/05/2012 15:53, H. Peter Anvin ha scritto: >> > It's true that it doesn't matter much but still it is a >> > regression. And it doesn't cause any kind of overhead >> > or bloat to fix this. >> > > However, the big thing is that we jump to the BIOS with caches off. I > personally think it is the wrong thing to do (we don't jump to the real > reset vector anyway) but it is what has been tested for a long time. I'm not sure I understand. The code has andl $0x60000000, %edx ; clear ET/PE jz 2f ... 2: andb $0x10, %dl ; clear CD/WT, %edx is always 0 What I've suggested is: testl $0x60000000, %edx jz 2f ... 2: andb $0x10, %dl ; clear PE only What would jump to the BIOS with caches on is: testl $0x60000000, %edx jz 2f ... 2: andl $0x10, %edx ; Clear CD/WT/PE Am I missing something? Paolo