Hello,
I see that as part of libvirt's documentation [0] the q35 machine type will feature at most 1 hotplugged PCIe device - default - and users must prepare in advance according to their expectations of how many ifaces will be hotplugged:
"""
Slots on the pcie-root controller do not support hotplug, so the device will be hotplugged into the pcie-root-port controller. If you plan to hotplug more than a single PCI Express device, you should add a suitable number of pcie-root-port controllers when defining the guest: for example, add
```xml
<controller type='pci' model='pcie-root'/>
<controller type='pci' model='pcie-root-port'/>
<controller type='pci' model='pcie-root-port'/>
<controller type='pci' model='pcie-root-port'/>
```
if you expect to hotplug up to three PCI Express devices, either emulated or assigned from the host.
"""
Is there any alternative to this ?
For our use case, I'm considering mimicking Openstack's implementation - [1] - and expose a knob that indicates what is the number of PCIe root ports to be used upon the domain definition.
I wonder how open would the community be to having a machine type alias that would provide a "better" default - in the sense that it would have more root port controllers.