Re: [Qemu-devel] [PATCH v7 08/25] x86-iommu: introduce parent class

[Marcel Apfelbaum <marcel.apfelbaum@gmail.com>]

On 05/23/2016 08:06 PM, David Kiarie wrote:
> On Tue, May 17, 2016 at 10:15 AM, Peter Xu <peterx@redhat.com> wrote:
>> Introducing parent class for intel-iommu devices named "x86-iommu". This
>> is preparation work to abstract shared functionalities out from Intel
>> and AMD IOMMUs. Currently, only the parent class is introduced. It does
>> nothing yet.
>>
>> Signed-off-by: Peter Xu <peterx@redhat.com>
>> ---
>>   hw/i386/Makefile.objs         |  2 +-

[...]

>> +
>> +static const TypeInfo x86_iommu_info = {
>> +    .name          = TYPE_X86_IOMMU_DEVICE,
>> +    .parent        = TYPE_SYS_BUS_DEVICE,
>> +    .instance_size = sizeof(X86IOMMUState),
>> +    .class_init    = x86_iommu_class_init,
>> +    .class_size    = sizeof(X86IOMMUClass),
>> +    .abstract      = true,
>> +};
>
> As I suspected am having some trouble parenting a PCI device from a
> Bus device but I will investigate further to see if I can manage
> something.
>

You cannot derive from both SYS_BUS_DEVICE and PCI_DEVICE.
You would need a composition; your device would be a SYS_BUS_DEVICE
and its state would include a PCI_DEVICE (or the other way around).
Then you can divide the responsibilities between them.

Thanks,
Marcel

>> +

[...]