Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761226AbXIUQWU (ORCPT ); Fri, 21 Sep 2007 12:22:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754547AbXIUQWO (ORCPT ); Fri, 21 Sep 2007 12:22:14 -0400 Received: from ns1.suse.de ([195.135.220.2]:32971 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758508AbXIUQWN (ORCPT ); Fri, 21 Sep 2007 12:22:13 -0400 To: "Maciej W. Rozycki" Cc: Peter Fordham , linux-kernel@vger.kernel.org Subject: Re: fpu IO port reservation (arch/i386) References: From: Andi Kleen Date: 21 Sep 2007 18:22:12 +0200 In-Reply-To: Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 954 Lines: 21 "Maciej W. Rozycki" writes: > Hi Peter, > > > Does anybody know why we reserve this range of IO ports for 'fpu'? > > AFAIK from all the IO maps I can find on the internet for various x86 > > chipsets only 0x00f0 is actaully ever used. > > There are two ports used: 0xf0 is the busy latch reset and 0xf1 is the > coprocessor reset. They are legacy ports resulting from the interesting > way the FPU has been wired by IBM in their PC design. Was it really needed on 386s? I didn't think there was a IBM 386 PC. > None of them is > used by Linux for i486 and newer systems, which can support the FPU in its > native configuration. I can remove it from x86-64 at least. -Andi - 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/