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Date: Fri, 21 Mar 2003 08:42:41 +1000
From: Peter Grehan <grehan@freebsd.org>
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To: Andrew Gallatin <gallatin@cs.duke.edu>
Cc: Jake Burkholder <jake@locore.ca>, src-committers@freebsd.org,
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Subject: Re: cvs commit: src/sys/powerpc/powerpc fpu.c genassym.c swtch.S trap.c
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> Yes.  At least on the alpha, gcc uses the floating point
> registers/instructions extensively.  So even a process which isn't
> intentionally using floating point will likely take a FEN trap.

 Although I've not seen it, this does appear to be the case with PPC as well,
judging by a recent NetBSD thread:

  http://mail-index.netbsd.org/port-powerpc/2003/03/17/0001.html

> From what I can see, NetBSD still seems to be using lazy FP though.

 They do the full-blown lazy save/restore and MP IPI stuff on PPC. It might
be worth it for Altivec, since it's an additional 32 x 128 bits of context
to save.

later,

Peter.

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