Re: [PATCH v14 08/11] virtio-iommu-pci: Introduce the x-dt-binding option

[Auger Eric]

Hi Jean,

On 2/7/20 11:05 AM, Jean-Philippe Brucker wrote:
> Hi Eric,
> 
> On Fri, Feb 07, 2020 at 10:32:00AM +0100, Eric Auger wrote:
>> At the moment, the kernel only supports device tree
>> integration of the virtio-iommu. DT bindings between the
>> PCI root complex and the IOMMU must be created by the machine
>> in conformance to:
>>
>> Documentation/devicetree/bindings/virtio/iommu.txt.
>>
>> To make sure the end-user is aware of this, force him to use the
>> temporary device option "x-dt-binding" and also double check the
>> machine has a hotplug handler for the virtio-iommu-pci device.
>> This hotplug handler is in charge of creating those DT bindings.
>>
>> Signed-off-by: Eric Auger <address@hidden>
>> Suggested-by: Michael S. Tsirkin <address@hidden>
> [...]
>> @@ -39,6 +42,21 @@ static void virtio_iommu_pci_realize(VirtIOPCIProxy 
>> *vpci_dev, Error **errp)
>>      VirtIOIOMMUPCI *dev = VIRTIO_IOMMU_PCI(vpci_dev);
>>      DeviceState *vdev = DEVICE(&dev->vdev);
>>  
>> +    if (!dev->dt_binding) {
>> +        error_setg(errp,
>> +                   "Instantiation currently only is possible if the machine 
>> "
>> +                   "creates device tree iommu-map bindings, ie. ACPI is not 
>> "
>> +                   "yet supported");
>> +        error_append_hint(errp, "use -virtio-iommu-pci,x-dt-binding\n");
> 
> "use -device virtio-iommu-pci,x-dt-binding"?
> 
> Can the option be safely removed as soon as we implement a topology
> description for the remaining platforms?  Or will we need to carry it
> forever for backward-compatibility (ie. ensure that an old command-line
> invocation that contains this option still works)?

"x-" properties are experimental so yes it is bound to be removed as
soon as we get the topology description feature.

I now have to figure out how to fix the make-check issue it introduces :-(

Thanks

Eric
> 
> Thanks,
> Jean
>