On Sunday 02 July 2006 17:20, Ian Dowse wrote: > In message <[EMAIL PROTECTED]>, Ian Dowse writes: > >The trick is that if the 0x6000 bytes are contiguous in virtual > >memory then they never span more than 6 pages so one iTD is enough. > > Sorry, I meant of course 6 page boundaries, which means no more > than 7 pages. This is why the 7 physical address slots in the iTD > is always enough for 8 x 3k transaction records if the 24k buffer > is contiguous in virtual memory. >
Ok. So the solution to my problem is to use scatter and gather. I will see about updating my USB system to do it like that. But there is one thing I do not understand yet. When you load a page that physically resides above 4GB, because a computer has more than 4GB of memory, how does "bus_dmamap_load()" move that page down below 4GB, so that the 32-bit USB host controllers can reach it? --HPS _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
