Date: Fri, 24 Oct 2008 22:45:44 -0400 From: Justin Hibbits <jrh29@alumni.cwru.edu> To: freebsd-ppc@freebsd.org Subject: Re: graphics on G4 Message-ID: <20081025024544.GA22527@narn.knownspace> In-Reply-To: <20081023040422.EKQ11018@dommail.onthenet.com.au> References: <20081023040422.EKQ11018@dommail.onthenet.com.au>
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On Thu, Oct 23, 2008 at 04:04:22AM +1000, Peter Grehan wrote: > Hi Nathan, > > >One thing that worries me about our PMAP layer could cause > >this. This machine has a lot of RAM. What happens if we have > >physical or device memory in the same range as kmem VAs? > >It seems like trying to modify it through the BAT map (as > >zero/copy page, /dev/mem and friends do) will overwrite > >random bits of KVA instead... > > Apple h/w seems to use 0-2G for RAM, and 2G and up for MMIO. > G5's can then use > 4G for additional RAM. I've not seen a > system that has a conflict with the 2 seg's used for KVA, but > I wouldn't say it's not possible. > > Justin - can you drop into OFW, do a 'dev screen' and > '.properties', and list the 'address' property ? > > later, > > Peter. The address property is a0008000, from ofw. This seems like a rather odd address, being 8 pages inside the 2.5GB memory space. - Justin
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