Thread (62 messages) 62 messages, 20 authors, 2000-09-12

Re: Discrepancy in BAT mapping?

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From: Benjamin Herrenschmidt <hidden>
Date: 2000-09-12 09:01:20

Hmmm, setting the G bit for instruction pages should never be necessary.
I may be totally wrong, but as I see the logic, your instructions are
not supposed to modify themselves when read. So there is no reason to
protect them from speculative access. Hence, clear the G bit on all
instruction-only mappings, so speculative access may be used to a
performance advantage.
Well, who will ever execute code out of the framebuffer anyway ? Also, I
beleive we can remove the G bit completely, there's no need to prevent
speculative access to the fb. I'll look into this.

Ben.


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