Re: solution Re: lost memory on a 4GB amd64

[Andreas Klein]

Hello,

On Wed, 27 Oct 2004, Sergei Haller wrote:

> On Wed, 27 Oct 2004, Andreas Klein (AK) wrote:
> 
> Are you sure this is the same problem, that I have? You discovered
> Problems with memtest86:
> 
> > Memtest sees 0-2GB mem usable and 4-6GB unusable (complains 
> > about each memory address).
> 
> I didn't:
> 
> > memtest86 is happy with the memory.

Memtest is happy with my memory too, if all 4 modules are installed in the 
slots belonging to CPU1. If I install 2 modules for each CPU, memtest86 is 
not happy anymore.

> 
> The next difference: 
> You have the S2885 (thunder K8W) and S2875S (tiger K8W single processor) 
> boards and I have a S2875 (tiger K8W double processor)

The boards are nearly identical (on-board lan is different, and your 
memory-slots are connected to one CPU).
If all memory modules are installed for one CPU, I have your problems. 
Additionaly there are some other problems that only occur, when the 
modules are installed one pair for each CPU.

Since I have a pre-producion board and bios which is running solid as a 
rock, regardless if a SMP/no-SMP kernel is installed, I hope that they
will fix all problems.

> I summarize (again) my problems:
> 
> Independantly of the memory settings in the BIOS:
>  - non-SMP Kernel is stable
>  - memtest86 does not report any errors
> 
> If the memory (4GB) is set up in one block (0-4GB) in the BIOS, then
>  - SMP Kernel is stable 
> 
> If the memory (4GB) is set up in two blocks (eg. 0-3GB, 4-5GB) in the
> BIOS, then
>  - SMP Kernel is stable _if_and_only_if_ NUMA is _disabled_.
> 
> 
> BTW.: I won't be able to flash a new BIOS to our machine, since it is in 
> production use and runs _rock_stable_ with _full_memory_ after we
> _disabled_ NUMA support in the kernel. (see the two small programs posted 
> by me and by Andi Kleen)
> 
> What I COULD do is running some tests if needed. (e.g. to check if the 
> Board/BIOS is lying about its capabilities)
> 
> 
>         Sergei
> -- 
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-- Andreas Klein
   asklein@xxxxxxxxxxxxxxxxxxxxxxxxxxx
   root / webmaster @cip.physik.uni-wuerzburg.de
   root / webmaster @www.physik.uni-wuerzburg.de
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