Re: MTRR patch v1.5

Richard Gooch (rgooch@atnf.CSIRO.AU)
Fri, 23 Jan 1998 14:06:17 +1100

Chris Evans writes:
> On Mon, 19 Jan 1998, Richard Gooch wrote:
> > Hi, Linus. Below is v1.5 of my MTRR patch (set Memory Type Range
> >
> > Registers to speed frame-buffer access by 2.5x). It includes a patch
> > by David Wragg <> to properly set the passive-release
> > enable bit (some BIOSes don't do this).
> Does this help at all for normal Pentiums? Isn't there some trick Windows
> pulls off to speed up access to PCI cards with mapped memory on normal
> Pentiums? etc.?

Pentiums don't have MTRRs. The Windows trick is probably the same
linear FB access that XFree86 has been doing for years. The only
difference is that M$ spends $10M on advertising this "new feature"
(sure, it's new for windoze).