Re: DMA API issues
From: Oliver Neukum
Date: Sun Jun 20 2004 - 14:36:15 EST
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Am Sonntag, 20. Juni 2004 21:27 schrieb James Bottomley:
> On Sun, 2004-06-20 at 13:02, Oliver Neukum wrote:
> > > The DMA API is about allowing devices to transact directly with memory
> > > behind the memory controller, it's an API that essentially allows the
> > > I/O controller and memory controller to communicate without CPU
> > > intervention. This is still possible through the hypervisor, so the
> > > iSeries currently fully implements the DMA API.
> > Then what's the problem?
> If you look at the diagram, you'll see that the OHCI memory isn't behind
> the memory controller...
And that means what? We don't care about how memory is implemented
in the machines we run on. All we care about is the consequences of the
We have an area of memory here that the CPU and a subset of devices
can directly access. What to do about it?
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