Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755347Ab2K2VGW (ORCPT ); Thu, 29 Nov 2012 16:06:22 -0500 Received: from mga11.intel.com ([192.55.52.93]:35161 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754154Ab2K2VGV (ORCPT ); Thu, 29 Nov 2012 16:06:21 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,186,1355126400"; d="scan'208";a="255238718" Message-ID: <50B7CE4C.80201@linux.intel.com> Date: Thu, 29 Nov 2012 13:06:20 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Borislav Petkov , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Linus Torvalds , Linux Kernel Mailing List , Mario Gzuk Subject: Re: [PATCH 8/8] x86, cleanups: Simplify sync_core() in the case of no CPUID References: <1354132230-21854-1-git-send-email-hpa@linux.intel.com> <1354132230-21854-9-git-send-email-hpa@linux.intel.com> <20121128204158.GC14635@liondog.tnic> <50B6A8F3.5000407@zytor.com> <20121129091317.GA21084@liondog.tnic> In-Reply-To: <20121129091317.GA21084@liondog.tnic> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 676 Lines: 23 On 11/29/2012 01:13 AM, Borislav Petkov wrote: > > RCX gets correctly cleaned to 0 and *then* we call CPUID. > > And the asm output is the same except that RCX gets correctly cleaned up > before calling CPUID. > > So what am I missing? > It doesn't matter in that context, as the surrounding MSR references have barriers, but what I'm refering to is the "memory" barrier. The value of ECX doesn't matter when EAX=1. -hpa -- 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/