J.A. Magallon wrote:
quoted text
> Hi...
> 
> I have some Quad-Opteron boxes with 4Gb memory and two of them are
> running two different Linux distros.
> 
> Box one sees 4Gb of memory, but box two just sees 3.
> Their mtrr setups are different:
> 
> Why ? Is it a bios setup problem ? A kernel problem ?
> grep HIGHMEN in configs for both kernels does not give anything, so
> I still understand less this thing...
> 

It would depend on how the BIOS programmed the memory controllers.  For 
32-bit (and lots of device) compatibility, a memory hole is required 
below 4 GB.  Not all memory controllers can remap memory in the 3-4 GB 
range above the 4 GB memory; I'm not sure if that varies with the 
different Opteron processors.

Also, if you run a 32-bit distribution, you need to have HIGHMEM_64G 
enabled in the kernel.

	-hpa
-
unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/