[Fwd: Re: use of bus_dmamap_sync]

[John Baldwin]

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 at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org