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That legacy requirement now depends on > > > > PCI_P2PDMA, which depends on 64BIT and ZONE_DEVICE. > > > > > > That should be split up now, Leon missed it when he added the new > > > APIs that didn't require ZONE_DEVICE.. > > > > Sorry, what did I miss here? > > VFIO_DMABUF is an optional feature and is enabled only when P2P support is > > available. It does not affect legacy systems where P2P cannot be enabled. > > If we look at the long term view of moving exclusively to cdev/iommufd, > where VFIO_DMABUF becomes the mechanism for implementing P2P DMA > mappings, VFIO_DMABUF may be optional, but it's highly desirable for > legacy compatibility. There's an argument though that providing P2P > compatibility on platforms that support PCI_P2PDMA is probably > sufficient. The whole reason we developed the P2PDMA stuff the way we did was so that all VFIO platforms could use it and get P2P. Thec code is fine, there is a kconfig/kbuild issue that we can't enable P2PDMA without also ZONE_DEVICE and those need to be split up. Once P2PDMA is available on all arches it is no longer a concern.. Jason