Hi Ashok. On Mon, 2007-09-24 at 09:55 +0530, ashok.shanmugam@xxxxxxxxx wrote: > Is it possible to setup a DMA operation between harddisk and video > memory. Please let me know, is DMA can happen only b/w mainMemry-I/O > and not b/w the I/O devices. In the canonical sense, a DMA operation is arbitrated by a DMA controller so that data transfers between a peripheral and Core memory can be made without the CPU's direct intervention (which is expensive, there are a slew of entities memory controllers, caches, etc involved). That said, DMA Controllers are intrinsically simple beasts, you setup descriptors somewhere that describe the data transfer characteristics, including the source and destination addresses, and instruct the controller to proceed. Someone takes care of cache coherency issues along the way. Therefore, the source and destination can be I/O devices in principle. However, this is largely a platform specific issue and will need studying the manuals relevant to your platform, system controller etc. Cheers, Robin -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
