bus dma: a flag/quirk for page zero

Matthew Jacob mj at feral.com
Tue Jan 10 22:23:44 UTC 2012

>> At the very least, require bounce buffers.
> Not sure if I got this suggestion in this terse form.
> Could you please explain?

Physical address zero can be DMA'd, but via bounce buffers.
bcopy from address zero up through a pagesize to a bounce buffer, do the 
dma from there (read case), write case the opposite order

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