AMDIOMMU_CMD_SZ
AMDIOMMU_CMD_SZ;
unit->x86c.inv_queue_tail += AMDIOMMU_CMD_SZ;
unit->x86c.qi_cmd_sz = AMDIOMMU_CMD_SZ;
ci += AMDIOMMU_CMD_SZ;
_Static_assert((1 << AMDIOMMU_CMD_SZ_SHIFT) == AMDIOMMU_CMD_SZ,