linux-kernel - Re: i686 quirk for AMD Geode

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Message-ID: <4AF9E94D.5040601@zytor.com>
Date:	Tue, 10 Nov 2009 14:29:33 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Lennart Sorensen <lsorense@...lub.uwaterloo.ca>
CC:	Willy Tarreau <w@....eu>, Pavel Machek <pavel@....cz>,
	Avi Kivity <avi@...hat.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Matteo Croce <technoboy85@...il.com>,
	Sven-Haegar Koch <haegar@...net.de>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: i686 quirk for AMD Geode

On 11/10/2009 02:27 PM, Lennart Sorensen wrote:
> On Tue, Nov 10, 2009 at 01:19:30PM -0800, H. Peter Anvin wrote:
>> Willy, perhaps you can come up with a list of features you think should
>> be emulated, together with an explanation of why you opted for that list
>> of features and *did not* opt for others.
>>
>> Note: emulated FPU is a special subcase.  The FPU operations are
>> heavyweight enough that the overhead of trapping versus library calls is
>> relatively insignificant.
> 
> That doesn't seem to be the experience of the arm EABI versus the old
> arm ABI with kernel FPU emulation.  Using user space library calls for
> FPU is vastly faster than the trapping and kernel FPU emulation.

I don't believe we were talking about ARM.

	-hpa


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