Re: Another DMA question

From: David S. Miller (davem@redhat.com)
Date: Mon Jul 22 2002 - 21:54:26 EST


   From: Thunder from the hill <thunder@ngforever.de>
   Date: Mon, 22 Jul 2002 20:38:51 -0600 (MDT)

   How can I get the _real_ address of a pci_map_single area, if needed? The
   thing bus_to_virt() did, basically. My problem is that I have code which
   changed the first byte of a buffer of stuff read via DMA, and I can't
   because the previous user did bus_to_virt() to get a pointer into that. I
   don't know how to get another pointer.
   
   After all the confusion, is the question clear?
   
You need to keep track of the back translations yourself. See how the
various net drivers do this by keeping a RX and TX ring of the SKB
buffers mapped into the various rings.
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