linux-kernel - Re: FP in kernelspace

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Message-ID: <44CCCE72.8030808@argo.co.il>
Date:	Sun, 30 Jul 2006 18:21:22 +0300
From:	Avi Kivity <avi@...o.co.il>
To:	Arjan van de Ven <arjan@...radead.org>
CC:	Jiri Slaby <jirislaby@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: FP in kernelspace

Arjan van de Ven wrote:
>
> > > So 2 questions are:
> > > 1) howto FP in kernel
> > >
> > kernel_fpu_begin();
> > c = d * 3.14;
> > kernel_fpu_end();
> >
>
> unfortunately this only works for MMX not for real fpu (due to exception
> handling uglies)
>

Perhaps there should be a comment to that effect?  Neither the code nor 
Documentation/preemt-locking (which mentions the fpu) says anything 
about this little fact.

It's also broken for x86-64, which uses sse for floating point, not the 
x87 fpu.

-- 
error compiling committee.c: too many arguments to function

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