On Tue, 27 Jul 2010 14:45:58 +0200 Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: > > How does one obtain the CPU address of this memory in order for the CPU > > to access it? > > Right, we did not cover such case. In CMA approach we tried to separate > memory allocation from the memory mapping into user/kernel space. Mapping > a buffer is much more complicated process that cannot be handled in a > generic way, so we decided to leave this for the device drivers. Usually > video processing devices also don't need in-kernel mapping for such > buffers at all. Still...that *is* why I suggested an interface which would return both the DMA address and a kernel-space virtual address, just like the DMA API does... Either that, or just return the void * kernel address and let drivers do the DMA mapping themselves. Returning only the dma_addr_t address will make the interface difficult to use in many situations. jon -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>