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Date:      Mon, 29 Jan 2001 07:20:55 +1100
From:      Peter Jeremy <peter.jeremy@alcatel.com.au>
To:        freebsd-alpha@freebsd.org
Subject:   Multia problems
Message-ID:  <20010129072055.X52423@gsmx07.alcatel.com.au>

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I have a Multia VX40 that is displaying normal `dodgy hardware'
symptoms - specifically random segmentation violations whilst trying
to make world.

Having poked around, I've found that writing 0x0000000000000000/
0xFFFFFFFFFFFFFFFF to alternate longs shows up the problem more
reliably: Bits 27-31 (the top 5 bits of the low word) occasionally
read as 0 instead of 1 (but never the opposite).  Swapping the memory
modules around does not affect the problem - which pretty well clears
the RAM.  Based on re-reading and cache-flushing, the problem seems to
be the CPU reading the L2 (external) cache.  The problem does not seem
to occur using 0x5555555555555555/0xAAAAAAAAAAAAAAAA as a pattern.

I've already replaced the (notorious) 74F623 and heat does not seem
to be a problem.

Does anyone have any suggestions on how to further narrow down my
problem?

Peter


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