On Sat, 14 Nov 2015, Steinar H. Gunderson wrote: > On Sat, Nov 14, 2015 at 12:09:38PM -0500, Alan Stern wrote: > > And you probably couldn't use GPU memory for this purpose because (I > > assume) the USB host controller wouldn't be able to access it via DMA. > > I guess that depends a bit; on my particular system, I'm using an Intel GPU, > so memory is shared. But I assume you can't do this if the memory is > dedicated and just mapped up from a dedicated GPU. Hmmm. If the shared memory can be accessed by the CPU using ordinary load and store instructions and it can be kmalloc'ed, then it should be usable for zerocopy I/O. But again, only if it satisfies the restrictions imposed by the USB controller's DMA hardware. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
