From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758065AbYEDUZS (ORCPT ); Sun, 4 May 2008 16:25:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756346AbYEDUZG (ORCPT ); Sun, 4 May 2008 16:25:06 -0400 Received: from mga10.intel.com ([192.55.52.92]:50813 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752679AbYEDUZE (ORCPT ); Sun, 4 May 2008 16:25:04 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.27,435,1204531200"; d="scan'208";a="324393440" Message-ID: <481E1B89.8020708@linux.intel.com> Date: Sun, 04 May 2008 22:24:41 +0200 From: Arjan van de Ven User-Agent: Thunderbird 2.0.0.12 (Windows/20080213) MIME-Version: 1.0 To: "H. Peter Anvin" CC: "Maciej W. Rozycki" , Thomas Gleixner , jamal , Suresh Siddha , Ingo Molnar , LKML , Jan Beulich Subject: Re: i387/FPU init issues... References: <1209810775.6972.37.camel@localhost> <481CA40A.7040906@zytor.com> <481CC5CD.8060205@zytor.com> In-Reply-To: <481CC5CD.8060205@zytor.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org H. Peter Anvin wrote: > Maciej W. Rozycki wrote: >> On Sat, 3 May 2008, H. Peter Anvin wrote: >> >>> Intel explicitly documents "all processors with family 6 or F." >> >> It depends (as usually with Intel) on what document you are looking >> at. Based on my short research, the instruction has been >> retroactively added >> to the list of supported opcodes. Even my somewhat dated P4 manual does >> not list it, never mind its predecessors. It could have been >> accidentally >> omitted or even buggy in some early members of the P6 family and this >> could have been the reason for not documenting it from the beginning (the >> case of FFREEP comes to mind). >> > > It has retroactively been added to the documented list for all P6 core > chips - that should mean it works on all of them. The most common > reason for not documenting something (other than various Pure Evil NDA > schemes) is that it hasn't been properly verified. However, > verification can be done a posteori. the other reason is that certain groups of "unknown" opcodes will act as NOP. Which for this purpose is .. exactly the right thing retroactive > > -hpa