On Tue, Jan 27, 2009 at 9:30 PM, Eric W. Biederman ebiederm@xmission.comwrote:
Carl-Daniel Hailfinger c-d.hailfinger.devel.2006@gmx.net writes:
Assuming you don't have anything you want to cache near 4 GB (like
flash):
Both strategies are equally efficient if the contiguous cacheable area has a size of 2^n+2^(n-1). The additive strategy is more efficient if the size is 2^n+2^(n-k) and
k>1.
The subtractive strategy is more efficient if the size is 2^n-2^(n-k) and k>1.
I hope that you accept this without a detailed mathematical proof. ;-)
I wonder... the subtractive strategy you subscribe is mentioned in mtrr.c too and the comment claims it is implemented. But it very much seems it is not.
Ouch.
When did it break?
I remember the subtractive mtrr setup working correctly. At least most of the time.
??? I'm not seeing any code in v2 capable of calculating subtractive mtrrs, is it possibly in v1? Am I missing something? I'm only looking in mtrr.c.
Thanks, Corey