Messages in this thread |  | | Date | Fri, 13 Sep 2002 16:52:41 -0400 | From | Adam Kropelin <> | Subject | Re: Streaming DMA mapping question |
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On Fri, Sep 13, 2002 at 01:28:42PM -0700, David S. Miller wrote: > From: Adam Kropelin <akropel1@rochester.rr.com> > Date: Fri, 13 Sep 2002 16:21:50 -0400 > > On Fri, Sep 13, 2002 at 12:36:41PM -0700, David S. Miller wrote: > > Actually, rather it appears that the i386 pci_unmap_*() routines need > > the write buffer flush as well. > > Ah, a bug then. > > On further discussion with Alan Cox, the bug is actually that > pci_map_*() needs the write buffer flush added. pci_map_*() > and pci_dma_sync_*() transfer ownership from CPU to PCI controller > as abstracted in DMA-mapping.txt Therefore these are the cases > where the CPU write buffers need to be flushed.
Makes sense to me.
> Really, the cases handled by the x86 write buffer fluses are very > marginal and unlikely to happen. In fact the write buffer flush on > x86 is done on winchip and ppro chips only. > > I think you're problems are elsewhere :-)
Probably true, but the test machine I'm running on *is* SMP ppro ;)
--Adam
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