Re: [Qemu-devel] [PATCH V3] virtio: do not require IOMMU to be created in advance

[Peter Xu]

On Wed, Mar 08, 2017 at 10:17:09AM +0200, Marcel Apfelbaum wrote:

[...]

> 
> I am sorry I was not clear enough:
> If a device is added after the system is up (hotplug), we cannot depend on 
> the "machine_done"
> event to enable "bus master".
> This is why we have
>    if (qdev_hotplug)
>         pci_init_bus_master(pci_dev);
> 
> The code you proposed changes the order, so this call is done *after* realize.
> 
> My question was: What if any other device may require the bus_master_as
> at realize time (and can be hot-plugged) ?
> For example: hcd-ehci/hcd-ohci devices call pci_get_address_space()
> and caches the bus_master_as.

Oh, I didn't notice that there are other devices that used
bus_master_as during realization. If so... Would this really work even
without hot plug? Considering that bus_master_as won't be inited until
machine done phase?

-- peterx