Re: [Fwd: Re: use of bus_dmamap_sync]

From: John Baldwin (jhb_at_freebsd.org)
Date: 10/26/05

  • Next message: John Baldwin: "Re: correct use of bus_dmamap_sync" 
    To: Scott Long <scottl@samsco.org>
Date: Wed, 26 Oct 2005 13:24:02 -0400

    On Wednesday 26 October 2005 11:54 am, Scott Long wrote:
    > > Perhaps on i386. Each arch implements sync(). Argh, it does look like
    > > the memory barriers needed on e.g., Alpha aren't used with static buffers
    > > because of the map != NULL check in sys/busdma.h. *sigh* I guess archs
    > > that need membars even without bounce buffers need to always allocate and
    > > setup a bus_dmamap. None of that matters for i386 though.
    >
    > Feel free to fix alpha. Again, long ago, I thought that alpha pretended
    > to be coherent in the 2GB DMA window that we use so that it could be
    > more like i386. If that's not true then that's fine. If you need to
    > make structural changes to the MI code on order to fix alpha, please let
    > me know.

    No, I'm just a moron. Alpha uses the nobounce_map for static buffers, so
    bus_dmamap_sync will use the appropriate membars. 

    -- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org
_______________________________________________
freebsd-hackers@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
  • Next message: John Baldwin: "Re: correct use of bus_dmamap_sync"