From: David Gibson <david@gibson.dropbear.id.au>
To: linuxppc-embedded@lists.linuxppc.org
Subject: Re: 4xx - a question and a patch
Date: Wed, 5 Sep 2001 11:04:51 +1000 [thread overview]
Message-ID: <20010905110451.A599@zax> (raw)
In-Reply-To: <3B95307D.1BE64A98@mvista.com>
On Tue, Sep 04, 2001 at 03:50:21PM -0400, Dan Malek wrote:
>
> David Gibson wrote:
> >
> > First the question: is there a good reason that set_dec() is a no-op
> > on 4xx, rather than setting the PIT?
>
> Yes. The PIT is far from a perfect approximation of the decrementer.
> When you "set the PIT" you actually set the reload register, not the
> value that is decrementing.
The 405gp manual implies that an mtspr to the PIT writes both the
decrementing value and the reload register. Is this a hardware /
documentation bug? Could the PIT be used this way if auto-reload was
disabled?
> > Second a patch - the below adds floating point emulation to the 4xx.
>
> Got it. Thanks. Since we now have libraries built specially for
> processors without floating point, emulation isn't necessary. Try
> them out.
Sure, but it's still useful to be able to run binaries copied from
"normal" PPC machines.
--
David Gibson | For every complex problem there is a
david@gibson.dropbear.id.au | solution which is simple, neat and
| wrong. -- H.L. Mencken
http://www.ozlabs.org/people/dgibson
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2001-09-05 1:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-30 7:52 4xx - a question and a patch David Gibson
2001-08-30 8:54 ` HHL 2.0 Journeyman and SuSE Linux Steven Scholz
2001-08-30 16:21 ` Tom Rini
2001-08-31 7:48 ` Steven Scholz
2001-09-04 19:50 ` 4xx - a question and a patch Dan Malek
2001-09-05 1:04 ` David Gibson [this message]
2001-09-05 4:18 ` Dan Malek
2001-09-05 4:41 ` David Gibson
2001-09-05 15:34 ` Dan Malek
2001-09-06 1:06 ` David Gibson
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