From owner-freebsd-embedded@FreeBSD.ORG Sun Jan 20 15:13:03 2008 Return-Path: Delivered-To: freebsd-embedded@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1006516A418 for ; Sun, 20 Jan 2008 15:13:02 +0000 (UTC) (envelope-from bms@incunabulum.net) Received: from out3.smtp.messagingengine.com (out3.smtp.messagingengine.com [66.111.4.27]) by mx1.freebsd.org (Postfix) with ESMTP id AEAE713C468 for ; Sun, 20 Jan 2008 15:13:02 +0000 (UTC) (envelope-from bms@incunabulum.net) Received: from compute2.internal (compute2.internal [10.202.2.42]) by out1.messagingengine.com (Postfix) with ESMTP id 59F6C8B46A; Sun, 20 Jan 2008 09:54:14 -0500 (EST) Received: from heartbeat2.messagingengine.com ([10.202.2.161]) by compute2.internal (MEProxy); Sun, 20 Jan 2008 09:54:14 -0500 X-Sasl-enc: 6N+o+lPvnDN2sRubyzPULIVWS8sDbfvPVxl8nOPsR38e 1200840853 Received: from empiric.lon.incunabulum.net (82-35-112-254.cable.ubr07.dals.blueyonder.co.uk [82.35.112.254]) by mail.messagingengine.com (Postfix) with ESMTP id 6C1D81085A; Sun, 20 Jan 2008 09:54:12 -0500 (EST) Message-ID: <47936091.2030701@incunabulum.net> Date: Sun, 20 Jan 2008 14:54:09 +0000 From: Bruce M Simpson User-Agent: Thunderbird 2.0.0.6 (X11/20070928) MIME-Version: 1.0 To: Bruce Evans References: <47929883.1070003@incunabulum.net> <20080120152510.P14810@delplex.bde.org> In-Reply-To: <20080120152510.P14810@delplex.bde.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-embedded@FreeBSD.org Subject: FPU emulation X-BeenThere: freebsd-embedded@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Dedicated and Embedded Systems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 20 Jan 2008 15:13:03 -0000 [Cc: to -embedded] [Re: RDC R8610 x86 SOC, equally applicable to MIPS cores] Bruce Evans wrote: > > libc/softfloat is probably the best practical way to support these. It > has higher quality than the FreeBSD FPU emulator and is hopefully easy > to configure. It was used by arm. Not sure if it still is, or what > happened to gcc support for soft-float after I stopped using it when > I got a 486. Even in 1988, soft-float was painful to configure because > almost everyone assumed hardware or emulator support for x86s. Thanks for the advice. It looks current but I'd have to fire up -msoft-float to check. My understanding is that gcc did not always support -msoft-float for i386, and several Linux distributions have patches floating around to support it on i386. Moreover, it appears that the i387 version of libm is a hardcoded dependency in buildworld for ARCH=i386. I'm not 100% sure what the best way is to deal with this is. It seems reasonable that floating point can't be used in the kernel for these targets, however, someone is bound to trip over this -- I wonder if soft-float can be used in kernel or with threaded apps -- it looks that way, as I see no 'statics' in any of the library code. Thanks again BMS