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List:       linux-smp
Subject:    Re: lost memory on a 4GB amd64
From:       Sergei Haller <Sergei.Haller () math ! uni-giessen ! de>
Date:       2004-09-24 4:38:27
Message-ID: Pine.LNX.4.58.0409241422050.15313 () fb07-calculator ! math ! uni-giessen ! de
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I just discovered the linux-smp list and decided to summarize the topic 
and take the opportunity to cross-post to there.

an archive of the discussion can be found e.g. here:
http://marc.theaimsgroup.com/?t=109525952600004&r=1&w=4


The machine at hand is the Tyan Tiger K8W with two Opterons 246
(http://www.tyan.com/products/html/tigerk8w.html) and 4GB of memory

we are using vanilla 2.6.8.1 kernel.

 * if the memory is set up in the ordinary way in the BIOS, then
   approximately 512MB are lost (PCI/AGM adressing and stuff), but
   everything is stable
 * if the memory is set up in the BIOS to be in two chunks (e.g. 3GB at 
   the address range 0-3GB and 1GB at 4-5GB address range), then
    - memtest86 tells everything is fine.
    - if we run a non-SMP kernel, everything is stable
    - if we run an SMP kernel, it crashes as soon as approx. 1GB of memory
      is allocated and set to 0 (see the test case C-program in my
      previous mail)

Is there anything we can do? Any logs I can provide? Something to try out?

Thanks,
        Sergei
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