On Sat, Nov 28, 2015 at 10:19:14AM +0800, chenfeng wrote: > On 2015/11/27 20:02, Joerg Roedel wrote: > > You need to create an iommu-group per smmu in your system and put all > > devices translated by this smmu in that group. And then you must change > > your code to allow attaching/detaching this iommu-group to different > > domains. > > > I read the code,I am confused about these concepts. > In my opinion, > IOMMU-Domain: The masters in one domain share the same iova space. Is that right? Yes, an iommu-domain is an abstraction of a single page-table and describes one iova address space. The SMMU in your hardware supports only on page-table, so all devices behind it share a single iova address space, und must be in the same domain. But the way you implemented it there could be only one domain per SMMU. With the IOMMU-API we must support to change the domain of an SMMU. Think of one domain for DMA-API usage and another for VFIO, for example. > IOMMU-GROUP: As you mentioned up,all devices translated by this smmu > should be into one group. I can do this. But if there is only on > domain in the system, how can I attaching/detaching the group to > different domains. IOMMU-groups describe the isolation capabilities of the IOMMU between devices. If devices are in a different IOMMU-group, this means that the hardware can isolate them from each other. Attaching the devices in a group to a new domain means in your case, that you set a different page-table for them. Since you can only do that for all devices behind a SMMU, these devices must be in on IOMMU-group. Joerg -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
