From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by oss.sgi.com id ; Wed, 7 Feb 2001 12:49:35 -0800 Received: from blackdog.wirespeed.com ([208.170.106.25]:32014 "EHLO blackdog.wirespeed.com") by oss.sgi.com with ESMTP id ; Wed, 7 Feb 2001 12:49:17 -0800 Received: from redhat.com (IDENT:joe@dhcp-4.wirespeed.com [172.16.17.4]) by blackdog.wirespeed.com (8.9.3/8.9.3) with ESMTP id OAA10922; Wed, 7 Feb 2001 14:36:54 -0600 Message-ID: <3A81B388.1090806@redhat.com> Date: Wed, 07 Feb 2001 14:43:52 -0600 From: Joe deBlaquiere Organization: Red Hat, Inc. User-Agent: Mozilla/5.0 (X11; U; Linux 2.2.16-22 i686; en-US; m18) Gecko/20001107 Netscape6/6.0 X-Accept-Language: en MIME-Version: 1.0 To: Jun Sun CC: Alan Cox , "Maciej W. Rozycki" , Florian Lohoff , linux-mips@oss.sgi.com, ralf@oss.sgi.com Subject: Re: NON FPU cpus - way to go References: <3A81A3DC.E75E6045@mvista.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mips@oss.sgi.com Precedence: bulk Return-Path: X-Orcpt: rfc822;linux-mips-outgoing Jun Sun wrote: > Alan Cox wrote: > >>> The i386 way seems reasonable, IMHO. Have a configure option to enable >>> an FPU emulator. Panic upon boot if no FP hardware is available and no >>> emulator is compiled in. >> >> Its an interesting question whether it belongs in the kernel or libc. >> Discuss ;) >> > > > I favor the libc approach as it is faster. You can still compile in the FP emulator just 'in case'... That way you leave it up to the application as to whether to do be quick or cheap. This also ensures binary portability (well, mostly, there's always .so ABI issues and the like...) > > Unfortunately I don't think glibc for MIPS can be configured with > --without-fp. I modified a patch to get glibc 2.0.6 working for no-fp config, > but it is not a clean one. Is anybody working on that for the latest glibc > 2.2? > > AFAIK, 2.0.7-20 (from Jay Carlson), 2.1.95 (from SGI), 2.2, and the current CVS can all be configured for soft float. >> Also we missed a trick on the x86 and I want to fix that one day, which is >> to have an __fpu ELF segment so if you boot an FPU emu kernel on an fpu >> box you regain 47K > > > Ironically for MIPS you MUST have the FPU emulater when the CPU actually has a > FPU. :-) > I'm confused here... why is this? -- Joe