On 8/25/06, Jon Smirl <[EMAIL PROTECTED]> wrote:
What does the OGH address space look like?
The way we've spec'd it is this: The drawing engine doesn't have access to host memory, but our DMA engine does. We'll decide on something for the size of the host-accessible memory aperture (PCI BAR). It will be smaller than the size of the graphics memory space. We discourage direct framebuffer access, but there will be cases where we MUST do software rendering. We will provide an offset register that software can use to set an appropriate window into the graphics memory. If you want to move data between host memory and graphics memory, we strongly encourage you to use the DMA engine. The DMA engine has access to the full host address space (to the extent that the IOMMU gives it) and to the full graphics memory space. In that case, we're dealing with two pointers (host and graphics) and a number of words to move. (In addition to simple memory moves, there will be other DMA commands to move data with more complex operations.) Software is responsible for memory management, i.e. where off-screen surfaces are located in graphics memory. If you want to use a drawing surface as a texture or bitblt source or a drawing target, it must be located in graphics memory. In this generation, we will not be providing a way for the GPU to use textures directly out of host memory. Every objection will be met with "we can add more graphics memory." _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
