Messages in this thread | | | Date | Wed, 14 Feb 2018 12:49:57 +0100 | From | Joerg Roedel <> | Subject | Re: [PATCH] iommu/amd - Use dev_err to send events to the system log |
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On Tue, Feb 13, 2018 at 02:24:56PM -0500, Hook, Gary wrote: > Without actually running a driver and getting some debug info, I'll just > say that my example compiled, the amd_iommu structure points to a pci_dev > which contains a device, and the two possibilities are likely equivalent. > > I'll vet that, of course, but working under the assumption that they are > equivalent, the question becomes, do you have a preference?
They are not equivalent, your version points to the pci_dev containing the IOMMU, my version points to the (virtual) iommu-device for that particular iommu in the kernel.
So the difference in the prefix is:
your version: '0000:00:00.2:'
vs. my version: 'ivhd0:'
The latter is the better prefix, because it points to the iommu. A pci_dev can contain more than one iommu, so that prefix is not specific enough. I know that there is currently no hardware implementing multiple iommus on one pci_dev, but it is allowed according to the spec.
Regards,
Joerg
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