On 23/11/2018 21:48, Michael S. Tsirkin wrote: >> +struct virtio_iommu_config { >> + /* Supported page sizes */ >> + __u64 page_size_mask; >> + /* Supported IOVA range */ >> + struct virtio_iommu_range input_range; >> + /* Max domain ID size */ >> + __u8 domain_bits; >> + __u8 padding[3]; > > Not enough padding here it seems. Structure is 8 byte > aligned on 64 bit systems. The next field (probe_size) is 4 bytes, so the alignment ends up fine. That field is introduced in patch 6, maybe I should move it here? Thanks, Jean