[Jack-Devel] What functions are missing if ALSA cannot memmap?

I am helping check out a new ALSA driver, and it seems that jackd is not happy with the capabilities this driver provides: configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods ALSA: mmap-based access is not possible for the capture stream of this audio interface ALSA: cannot configure capture channel Not just capture: configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods ALSA: mmap-based access is not possible for the playback stream of this audio interface ALSA: cannot configure playback channel I am not very familiar yet with low level ALSA drivers, any tips where I should look to see what the driver messed up? Is mmap access usually a requirement for ALSA drivers? Is it technically optional but highly recommended, or it is required and this driver is just incomplete? -- Chris Caudle