> > It is _probably_ an undocumented performance thing, and clearing that
> > bit may slow something down. But it might also change some behaviour,
> > and knowing _what_ the behaviour is might be very useful for figuring
> > out what it is that triggers the problem.
>
> AFAIK noone has even tested it yet to see what it does to performance! Eg
> it might slow down memory access so that athlon-optimized memcopy is now
> slower than non-athlon-optimized memcopy. And if it turns out to be the
> case, we might as well just use the non-athlon-optimized memcopy instead
> of twiddling undocumented northbridge bits...
And if someone does optimized copy in userspace, whole machine is dead?
Do you really wnt me to post bugtraq?
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