From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760971Ab3BJPMK (ORCPT ); Sun, 10 Feb 2013 10:12:10 -0500 Received: from terminus.zytor.com ([198.137.202.10]:50606 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759294Ab3BJPMH (ORCPT ); Sun, 10 Feb 2013 10:12:07 -0500 User-Agent: K-9 Mail for Android In-Reply-To: <20130210083616.GA4878@pd.tnic> References: <20130209231351.GB5556@pd.tnic> <1360451762-10175-1-git-send-email-bp@alien8.de> <5117236D.5000607@zytor.com> <20130210083616.GA4878@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH 2/5 -v2.1] x86: Detect CPUID support early at boot From: "H. Peter Anvin" Date: Sun, 10 Feb 2013 07:10:56 -0800 To: Borislav Petkov CC: X86 ML , LKML , Borislav Petkov Message-ID: <168505a3-2aba-4d4a-b1e7-d37c79ae306c@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sure it does... it takes time. Borislav Petkov wrote: >On Sat, Feb 09, 2013 at 08:34:53PM -0800, H. Peter Anvin wrote: >> I wouldn't really call it a "side effect". Perhaps the right thing >> here is to say something like "we want to start out with %eflags >> unambiguously clear". >> >> (Note also we have had to CLD earlier because we have already copied >> the command line.) > >Ok, let's make it even more verbose so that people know in the future: > >"... we want to start out with EFLAGS unambiguously clear. That means >DF >in particular (even though we have cleared it earlier after copying the >command line) because GCC expects it." > >How does that sound? > >Also, I was wondering about the whole reasoning behind that: do you >know >why DF=0 is a GCC requirement? I mean, nothing hurts GCC from issuing a >CLD each time? > >Thanks. -- Sent from my mobile phone. Please excuse brevity and lack of formatting.