On 10/18/2016 5:49 AM, Ard Biesheuvel wrote: > On 18 October 2016 at 13:46, Mike Travis <travis@xxxxxxx> wrote: >> >> Have you tested this change on a system which has physical >> addressing > 40 bits to insure that addresses > 40 bits are >> not simply truncated to an incorrect (mod 40) address? > > The device should never see addresses > 40 bits, given that the DMA > mask is set to 40 bits not 64. I agree that the device should never see that. But how is that restriction imposed? If a user presents an buffer address > 40 bits how would that be converted to useful buffer at <= 40 bits? I believe I tried this (at the time the kernel was at version 2.6) and it did not work. Since audio I/O was such a low (relative) bandwidth, it was not worth the effort to rework the audio code to allow buffers > 32 bits but <= 40 bits. It may have changed since then? > >> By not restricting the addresses to 32 bits you are not >> restricting the device to the DMA32 zone. >> >> This is what caused the original panic on UV systems. >> >> Btw, the newest nVidia GPUs have > 40 bits of DMA address bits. >> > > Thanks, > Ard. > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
