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Re: NON FPU cpus - way to go

To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: NON FPU cpus - way to go
From: Jun Sun <jsun@mvista.com>
Date: Wed, 07 Feb 2001 11:37:00 -0800
Cc: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>, Florian Lohoff <flo@rfc822.org>, linux-mips@oss.sgi.com, ralf@oss.sgi.com
References: <E14QZie-00011I-00@the-village.bc.nu>
Sender: owner-linux-mips@oss.sgi.com
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.

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?

> 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. :-)

Jun

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