On Sun, Mar 13, 2005 at 07:25:15PM -0500, Jon Smirl wrote: > On Mon, 14 Mar 2005 10:48:19 +1100, Benjamin Herrenschmidt > <[EMAIL PROTECTED]> wrote: > > > > > > That shouldn't matter the page brought in would be for a speculative > > > > read and never accessed. It should just fall out of the cache and not > > > > be written back. There is only one cachable mapping. In this model > > > > writes are always followed by a flush before telling the GPU to access > > > > the memory that has just been written. > > > > > > What about this scenario? > > > > > > Speculative read -> AGP master writes new data -> CPU has invalid data in > > > cache :( > > > > You need to reverse the cache flush process if you are going to read > data written by the GPU. > > 1) Make sure GPU is finished writing > 2) flush your cache > 3) read AGP memory like normal RAM.
Oh right. The CPU shouldn't write back the cached data since it hasn't changed. I think you'd also need the GPU to issue an AGP flush command between steps 1 and 2. -- Ville Syrjälä [EMAIL PROTECTED] http://www.sci.fi/~syrjala/ ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
