On Thu, Sep 25, 2008 at 05:45:30PM +0300, Avi Kivity wrote: > Han, Weidong wrote: >> Is it possible DMA into an mmio page? > > I don't see why not.
Two reasons. First it makes no sense. MMIO pages don't have RAM backing them, they have another device's register window. So the effect of DMA'ing into an MMIO page would be for one device to DMA into the register window of another device, which sounds to me insane. Second, and more importantly, I've seen systems where doing the above caused a nice, immediate, reboot. So I think that unless someone comes with a valid scenario where we need to support it or something breaks, we'd better err on the side of caution and not map pages that should not be DMA targets. Cheers, Muli -- The First Workshop on I/O Virtualization (WIOV '08) Dec 2008, San Diego, CA, http://www.usenix.org/wiov08/ xxx SYSTOR 2009---The Israeli Experimental Systems Conference http://www.haifa.il.ibm.com/conferences/systor2009/ -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
