From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753848AbYECUHd (ORCPT ); Sat, 3 May 2008 16:07:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752470AbYECUH0 (ORCPT ); Sat, 3 May 2008 16:07:26 -0400 Received: from terminus.zytor.com ([198.137.202.10]:55702 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752344AbYECUHZ (ORCPT ); Sat, 3 May 2008 16:07:25 -0400 Message-ID: <481CC5CD.8060205@zytor.com> Date: Sat, 03 May 2008 13:06:37 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: "Maciej W. Rozycki" CC: Thomas Gleixner , jamal , Suresh Siddha , Arjan van de Ven , Ingo Molnar , LKML , Jan Beulich Subject: Re: i387/FPU init issues... References: <1209810775.6972.37.camel@localhost> <481CA40A.7040906@zytor.com> In-Reply-To: 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 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. -hpa