[email protected] (Michael van Elst) writes: > [email protected] (Greg Troxel) writes: > >>My impression is that something, perhaps more umass than *hci, needs a >>very large chunk of memory. > > umass allocates two 64k (MAXPHYS sized) DMA buffers and a few smaller ones. > For all drivers but ehci each buffer must use contigous physical pages. > > ehci learned to use multiple DMA segments some time ago, so the > error is now rare. xhci still has to learn it, other drivers may > not be able to support it due to hardware limitations. > >>My fuzzy impression is that the standard wisdom is that drivers should >>not demand really large continuous chunks. > > 64kbyte is not really large.
Thanks for the clarity, and agreed that 64 kB is nowhere near large.
