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Date: Sat, 13 Dec 2003 18:38:32 +0000
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Peter Horton <phorton@bitbox.co.uk>, linux-mips@linux-mips.org
Subject: Re: Kernel 2.4.23 on Cobalt Qube2 - area of problem
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From: Peter Horton <pdh@colonel-panic.org>
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On Sat, Dec 13, 2003 at 06:07:51PM +0100, Ralf Baechle wrote:
> On Fri, Dec 12, 2003 at 10:45:08AM +0000, Peter Horton wrote:
> 
> > More info on the random segmentation faults and data corruption on my Qube2.
> > 
> > 2.4.21 from CVS is the first kernel to exhibit the problem. I tracked it 
> > down to the cache handling changes that went in between 2.4.20 and 2.4.21.
> > 
> > By (not very scientifically) removing flush_dcache_page() and 
> > re-instating flush_page_to_ram() I managed to get the 2.4.21 kernel 
> > stable (see attached patch). Applying a similiar patch to 2.4.23 (CVS 
> > HEAD) allows me to run 2.4.23 too.
> > 
> > I don't know how to track the problem any further - the kernel's cache 
> > handling is a bit out of my league.
> > 
> > Anyone got a clue stick they can point me in the right direction with ?
> 
> Can you put a printk into c-r4k.c and print the value of the
> shm_align_mask variable?  I want to make sure it's got a sane value on
> your box.  Also the first few lines of your bootup messages with the
> processor and cache stuff would be useful.
> 

I've just tried changing pages_do_alias() to always return non-zero. The
resulting kernel is still unstable - segmentation faults when loading
shared libraries, signal 11 when compiling etc.

P.