Re: [PATCH] trim memory not covered by WB MTRRs

From: Andi Kleen
Date: Wed Jun 20 2007 - 10:38:00 EST


> I assume this cannot be fixed by the simple approach
> of echoing some useful numbers into /proc/mtrr like
> we used to do for video memory? (Before X did this
> automatically?)
>
> An extra bootscript seems better than loosing memory.

In some cases it probably can, in other cases not because the memory
controller is misconfigured or not the right bits are set
in the PCI bridges to enable DAC IO or ... or ...

There are also definite limits on how much quirks can do
to fix this -- Linux is a generic kernel, not a BIOS replacement,
and can never be as intimate with the current setup
as the BIOS is.

It's definitely far safer to not use the memory. You're
running in a situation never tested or considered by the
motherboard vendor and everything is possible.

-Andi

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