Messages in this thread | | | From | Jesse Barnes <> | Subject | Re: Weirdness in pci_read_bases() | Date | Mon, 3 Mar 2008 13:02:14 -0800 |
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On Monday, March 03, 2008 12:57 pm Jesse Barnes wrote: > > Not only iommu's. On lots of platforms, we have the PCI MMIO space > > mapped 1:N, that is, an access at MMIO location N turns into a PCI cycle > > with address 0. So outbound PCI is effectively remapped, thus allowing > > access to things like 0 etc... without punching holes in RAM and without > > other dirty x86-like tricks. > > Right, bus address space is really a separate entity; I was just using > IOMMUs as an example of that...
Err, wasn't really clear here. CPU->PCI space and PCI->host space are really separate entities... IOMMUs will definitely affect the PCI->host mapping, and CPU->PCI mappings can be arbitrarily complex as well, though as you say on PCs it's typically just flatly mapped into CPU physical space somewhere.
Jesse
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