search for: of_iommu_driver_present

Hi Jean-Philippe, I love your patch! Yet something to improve: [auto build test ERROR on linus/master] [also build test ERROR on v4.16-rc2 next-20180221] [cannot apply to iommu/next] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Jean-Philippe-Brucker/Add-virtio-iommu-driver/20180217-075417

Hi Jean-Philippe, I love your patch! Yet something to improve: [auto build test ERROR on linus/master] [also build test ERROR on v4.16-rc2 next-20180221] [cannot apply to iommu/next] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Jean-Philippe-Brucker/Add-virtio-iommu-driver/20180217-075417

...tate, because the IOMMU subsystem isn't entirely ready to have IOMMU drivers built as modules. In addition to exporting symbols it would also needs to hold off probing endpoints behind the IOMMU until the IOMMU driver is loaded. At the moment (I think) it gives up once userspace is reached (see of_iommu_driver_present). The above report is due to VIRTIO=m and VIRTIO_IOMMU=y. To solve it we could: a) Allow VIRTIO_IOMMU to be built as module by exporting a dozen IOMMU symbols. It would be a lie. The driver wouldn't be usable because of the probe issue discussed above, but it would build. b) Actually make an...