Date: Mon, 2 Mar 2009 22:24:18 -0500 From: Justin Hibbits <jrh29@alumni.cwru.edu> To: freebsd-ppc@freebsd.org Subject: Re: graphics on G4 Message-ID: <20090303032418.GA1055@narn.knownspace> In-Reply-To: <20090302024918.GA1060@narn.knownspace> References: <20081023040422.EKQ11018@dommail.onthenet.com.au> <20081025024544.GA22527@narn.knownspace> <20090302024918.GA1060@narn.knownspace>
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On Sun, Mar 01, 2009 at 09:49:19PM -0500, Justin Hibbits wrote: > On Fri, Oct 24, 2008 at 10:45:44PM -0400, Justin Hibbits wrote: > > 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... I wrote a simple kernel module to print out BAT and segment registers, and the output immediately following boot is: register 528 = 0x1ffe register 529 = 0x12 register 530 = 0 register 531 = 0 register 532 = 0 register 533 = 0 register 534 = 0 register 535 = 0 register 536 = 0x1ffe register 537 = 0x12 register 538 = 0x80001ffe register 539 = 0x8000002a register 540 = 0xa0001ffe register 541 = 0xa000002a register 542 = 0x20001ffe register 543 = 0x20000012 segment register 0 = 0xfffff0 segment register 1 = 0xfffff0 segment register 2 = 0xfffff0 segment register 3 = 0xfffff0 segment register 4 = 0xfffff0 segment register 5 = 0xfffff0 segment register 6 = 0xfffff0 segment register 7 = 0xfffff0 segment register 8 = 0xfffff0 segment register 9 = 0xfffff0 segment register 10 = 0xfffff0 segment register 11 = 0xfffff0 segment register 12 = 0xe55e47 segment register 13 = 0xfffffd segment register 14 = 0xfffffe segment register 15 = 0xfffff0 Later, and I don't know precisely what is meant by "later", registers 540 and 541 get changed to 0x4......., which means the video memory gets un-BAT-mapped. This could be the cause of the hangs I've been seeing, but I don't know offhand how to further diagnose and fix this. - Justin
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