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Re: mtrr funnies

Wolfgang S. Rupprecht wrote:
Roger Heflin <rogerheflin gmail com> writes:

Wolfgang S. Rupprecht wrote:
On the AMD's I remember one of the AMD experts mentioning that the
4GB memory stuff is automagic so is not listed as a MTRR at all.   It
is just there.

Does "cat /proc/meminfo" and top both show around 8GB like expected?

Yes, it shows most of the 8gig.  About half a gig are missing, but
then the bios boot screen also mentions that only 7.6 gigs are being
made available.  I wonder why the rest isn't remapped. to the top of


I know a bios engineer once told me that some chipsets/bios can only remap entire dimms (not parts of a dimm) and doing an entire dimm would result in only 2GB below 4GB and that bothers some vendors since it would cause issues with memory availability with 32bit only OSes.

Check to see if any bios settings change things, on the higher end boards there use to be a memory hole setting that could be set to hardware or software, though if I remember correctly setting it such that you found all of the memory also resulting in the machine being a couple of percent slower.


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