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Date:   Sun, 31 Jan 2010 08:55:03 -0800
From:   Guenter Roeck <guenter.roeck@ericsson.com>
To:     "Maciej W. Rozycki" <macro@linux-mips.org>
CC:     David Daney <ddaney@caviumnetworks.com>,
        Ralf Baechle <ralf@linux-mips.org>,
        "linux-mips@linux-mips.org" <linux-mips@linux-mips.org>
Subject: Re: Kernel crash in 2.6.32.6 / bcm1480 with 16k page size
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References: <20100129132406.GD5685@linux-mips.org> <20100129151220.GA3882@ericsson.com> <4B6316D2.1060006@caviumnetworks.com> <20100129180619.GA20113@linux-mips.org> <20100129183926.GB9895@ericsson.com> <4B632F60.4000604@caviumnetworks.com> <20100129192532.GA11123@ericsson.com> <4B6336F1.8070208@caviumnetworks.com> <20100129195801.GC11123@ericsson.com> <alpine.LFD.2.00.1001310907320.31764@eddie.linux-mips.org>
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On Sun, Jan 31, 2010 at 04:10:10AM -0500, Maciej W. Rozycki wrote:
> On Fri, 29 Jan 2010, Guenter Roeck wrote:
> 
> > > I suspect you are hitting a maximum valid address bits limit and getting 
> > > the Address Exception.  Limiting VMALLOC_END so that you don't hit the 
> > > limit seems to be the solution.  I don't have the manual for the sibyte, 
> > > so I don't know what the limit is.  The architecture specification 
> > > doesn't state a fixed limit, although it tells what should happen when 
> > > the limit is reached.
> > > 
> > You mean there might be a CPU-specific limit ? I hope not - that would be quite messy.
> 
>  The size of the address space can be probed via CP0 registers (for MIPS 
> architecture processors that is).  No need to add any CPU dependencies 
> (except from legacy 64-bit MIPS processors perhaps).
> 
That would help. Do you happen to know which CP0 register(s) to look for ? 
I browsed through the MIPS 5K and 20Kc manuals, but didn't find it.

Guenter