What kind of mapping does URBs require? A virtual mapping?
> > (1) Do the USB HCDs support highmem? I seem to recall they do, but
> > I'm not certain.
>
> If URBs can't describe highmem, the HCD's won't support them per se;
> you'd have to turn highmem to "lowmem" or whatever it's called, and
> then let the HCDs manage the lowmem-to-dma_addr_t mappings.
>
> Alternatively, in 2.5 we might add "highmem" support to USB. Now that
> I've looked at it a few minutes, I suspect we must -- just to support
> block devices (usb-storage) fully. Is there more to it than adding
No, you can always ask to get pages low mem bounced. Highmem is no
requirement, and if your device really can't support it there's no point
in attempting to support it.
> page+offset as an alternative way to describe the transfer_buffer?
no
> (And making all the "single" mapping calls in the HCDs use page
> mappings.)
exactly
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