From: Andi Kleen <andi@firstfloor.org>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Peter Fordham <peter.fordham@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: fpu IO port reservation (arch/i386)
Date: 21 Sep 2007 18:22:12 +0200 [thread overview]
Message-ID: <p73y7f07zuz.fsf@bingen.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64N.0709211440380.2724@blysk.ds.pg.gda.pl>
"Maciej W. Rozycki" <macro@linux-mips.org> writes:
> Hi Peter,
>
> > Does anybody know why we reserve this range of IO ports for 'fpu'?
> > AFAIK from all the IO maps I can find on the internet for various x86
> > chipsets only 0x00f0 is actaully ever used.
>
> There are two ports used: 0xf0 is the busy latch reset and 0xf1 is the
> coprocessor reset. They are legacy ports resulting from the interesting
> way the FPU has been wired by IBM in their PC design.
Was it really needed on 386s? I didn't think there was a IBM 386 PC.
> None of them is
> used by Linux for i486 and newer systems, which can support the FPU in its
> native configuration.
I can remove it from x86-64 at least.
-Andi
next prev parent reply other threads:[~2007-09-21 16:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-21 13:22 fpu IO port reservation (arch/i386) Peter Fordham
2007-09-21 13:52 ` Maciej W. Rozycki
2007-09-21 16:22 ` Andi Kleen [this message]
2007-09-21 16:52 ` Maciej W. Rozycki
2007-09-21 19:30 ` Andi Kleen
2007-09-24 11:42 ` Maciej W. Rozycki
2007-09-28 19:33 ` Bill Davidsen
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