[Qemu-discuss] Question on Q35 and nec-xhci emulated USB controller

[Jon Panozzo]

Hello QEMU team and users!  I have two questions for you today.

First question:  In the early days of attempting to use VFIO to pass through 
PCIe graphics devices to virtual machines, some users had reported success in 
using Q35 over i440fx.  Today, it seems like this isn’t the case anymore.  So 
aside from that particular scenario, I’m curious as to what benefits the QEMU 
team feels that Q35 offers over i440fx both now and plans for the future.

Second question:  lately I’ve been experimenting quite a bit with the nec-xhci 
emulated USB controller and have been quite pleased with the result, especially 
on Windows 8.1 / 10 VM guests.  That said, I’ve also seen some oddities using 
it, especially with a large number of devices assigned (seems like there may be 
a limit as to how many will work with a single guest at one time).  Is there 
support for using a companion controller with this nec-xhci controller and are 
there are any current efforts to further develop this controller in the future?

Lastly, I want to give a huge thanks to everyone on the QEMU team.  This 
project is constantly evolving and I’m continually impressed by what we can do 
with it.  Thanks for everything you guys do!

Best Regards,

Jonathan Panozzo
Lime Technology, Inc.