Subject: Re: 386/486 bus timing
To: None <email@example.com>
From: Charles M. Hannum <firstname.lastname@example.org>
Date: 04/22/1995 01:50:03
I realized this may not have been completely clear...
If you put some serious intelligence on the board, you can even have the
board do scatter/gather DMA directly into mbufs. I'm a little leery of that,
since you need to have a piece of "hardware" understand the layout of a
software structure, which might change -- [...]
Mbuf `clusters' use an optional function pointer to a `free' routine,
so you can DMA to and from the `cluster' area, and not have to teach
the board about the structure layouts. This is also advantageous
because you can make your `cluster' whatever size is convenient.
The idea here is that you can fake creating the `cluster' yourself, by
setting the pointers in the mbuf, and setting the M_EXT bit in the