From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 5 Sep 2001 11:04:51 +1000 From: David Gibson To: linuxppc-embedded@lists.linuxppc.org Subject: Re: 4xx - a question and a patch Message-ID: <20010905110451.A599@zax> References: <20010830175217.H858@zax> <3B95307D.1BE64A98@mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <3B95307D.1BE64A98@mvista.com> Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: 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/