From owner-freebsd-hackers Thu Nov 9 03:04:33 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id DAA06138 for hackers-outgoing; Thu, 9 Nov 1995 03:04:33 -0800 Received: from rah.star-gate.com (rah.star-gate.com [204.188.121.18]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id DAA06124 for ; Thu, 9 Nov 1995 03:04:25 -0800 Received: from rah.star-gate.com (localhost.v-site.net [127.0.0.1]) by rah.star-gate.com (8.6.12/8.6.9) with ESMTP id CAA03746; Thu, 9 Nov 1995 02:59:44 -0800 Message-Id: <199511091059.CAA03746@rah.star-gate.com> X-Mailer: exmh version 1.6.2 7/18/95 To: Luigi Rizzo cc: phk@critter.tfs.com (Poul-Henning Kamp), koshy@blr.novell.com, freebsd-hackers@freebsd.org Subject: Re: Load/Store using FPU regs ... In-reply-to: Your message of "Thu, 09 Nov 1995 11:25:53 +0100." <199511091025.LAA08155@labinfo.iet.unipi.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Thu, 09 Nov 1995 02:59:42 -0800 From: "Amancio Hasty Jr." Sender: owner-hackers@freebsd.org Precedence: bulk >>> Luigi Rizzo said: > > > Now, I'm not sure if this approach can be used across all processors. > > > Some FPU's could raise exceptions if illegal bit-patterns are loaded > > > into its registers. The x86 FPU in particular has very few registers > > > and a LIFO access pattern for loads and stores so I don't know if the > > > same trick would work well for it. > > > > Not to mention that you might not have a FPU. > > So what ? You still have the FPU emulator :) Just ignore Pohl's comment we can probably figure out a clever way to find out if we have a FPU . What would be nice to see is if there is indeed a performance gain by using the floating point instructions if there is for sure I will use it. Cheers, amancio