On Tue, Sep 16, 2008 at 04:18:42PM -0600, Grant Grundler wrote: ... > > I think every gfx card has a prefetchable BAR. > > Indeed...but does the CPU ever read from that memory space or only write > to it? So this question got answered on Friday by Carl D. Worth (intel) in his presentation at Linux Plumbers Conf. They only read from the cards graphics buffers unwillingly. In general, the X server will avoid reads because reads are not burst either. ie very expensive to retrieve any data that is parked on the card but SW implementation needs to handle a gfx op. It's about 6x slower than if the SW would just do all the glyph rendering work in the first place. thanks, grant -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
