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Re: [Qemu-devel] PCI access virtualization
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] PCI access virtualization |
Date: |
Fri, 6 Jan 2006 13:27:47 +0000 |
User-agent: |
KMail/1.8.3 |
> > IIUC PCI cards don't really have "DMA engines" as such. The PCI bridge
> > just maps PCI address space onto physical memory. A Busmaster PCI device
> > can then make arbitrary acceses whenever it wants. I expect the default
> > mapping is a 1:1 mapping of the first 4G of physical ram.
>
> I was under the impression that the on-card bus-mastering engines were
> often one of a few standard designs - this was suggested to me by someone
> more knowledgeable than myself but must admit I don't have any hard
> evidence that it's the case ;-)
What about 64-bit systems that use an IOMMU? Don't they already have a 64-bit
physical -> 32-bit IO address space mapping? I don't know if this mapping is
per-bus or system global.
Paul
Re: [Qemu-devel] PCI access virtualization, Mark Williamson, 2006/01/05