Subject: Question about bus_dma and mbufs
To: None <>
From: Dave Huang <>
List: tech-net
Date: 07/04/2005 17:55:15
I was looking into changing the mac68k mc ethernet driver to use the
bus_dma interface, and was wondering what the best way was to get the
packet in an mbuf chain into DMA-able form. There's very little
documentation on the DMA engine used in the Mac AV series, but as far
as I can tell, the packet to be sent needs to be in one contiguous
buffer and aligned on a 2K boundary (not positive about that alignment
restriction; it may not be that strict).

Is there a way for me to do this with the various bus_dma(9) and/or
mbuf(9) routines, or will I have to copy the mbuf chain into my own
buffer that has the necessary requirements?
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