On Tue, Oct 26, 2010 at 7:51 PM, Mitch Bradley <[email protected]> wrote:
>  It's probably unnecessary on modern machines, but old PCs were fairly
> restrictive about DMA addresses due to short counters.  The buses on which
> such restrictions applied are no longer at the root level, but they were
> once there...

It's still necessary.  The QE, which we ship on several of our current
parts, can only DMA to/from 32-bit addresses, even on SOCs that
support 36-bit addressing for everything else.

-- 
Timur Tabi
Linux kernel developer at Freescale
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