On Fri, Nov 13, 2015 at 04:02:48PM -0500, Alan Stern wrote: >> So what is the road from here? I guess the original questions about cache >> coherency still apply, and that this is what I'm seeing in dmesg. > What questions? It should be obvious that the user program should not > touch the buffer contents while the transfer is taking place. The subthread I'm thinking of starts at http://marc.info/?l=linux-usb&m=138091207413756&w=2 I can't claim to have gone deeply into the details, though. > What are you seeing in dmesg? Several copies of [ 1175.838536] x86/PAT: app:2838 map pfn RAM range req uncached-minus for [mem 0x9fa4c000-0x9fa4ffff], got write-back > The next step would be to massage the patch and get it into a form > suitable for applying. This may well include changing the way the API > works; for example, I'm not sure that allocating memory should be a > separate step from mmap. Yes, it sounds a bit odd to me, too. I suppose there's no way to let userspace allocate this memory? Again, for me personally it would be ideal to be able to give it in from a PBO (ie., GPU memory). /* Steinar */ -- Homepage: https://www.sesse.net/ -- 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
