Hello,

I have looked online for this problem, and my results have turned up cold. My problem is using both Gnome Boxes and virt-manager under Fedora and Arch respectively, and occurs whenever a usb device is inserted. I have tested this with both usb 3.0 and 2.0. All ports available on the PCs are usb 3.0, and I have had a consistent error when plugging in the devices with an "Unknown Device" flag. The usb devices tested include three flash drives (two of which are 3.0 drives, and one 2.0) and a RS232 to usb. I am using SPICE, and I have already installed the guest utilities via the spice-space website. I am able to get a keyboard and mouse, of which are placed on a ps/2 and usb 2.0 respectively inside my Arch kvm. Both KVMs came from the same qcow2 image and have been copied over, just to include a background of its source. Any help or redirection would be greatly appreciated, thank you in advance.

EDIT: Following up, I have concluded that it is the USB 3.0 ports that cannot communicate with the windows vm. I also found this page under Red Hat, after further searching: https://access.redhat.com/documentat...alization.html in case anyone else has had this problem. Knowing this, is there a simple way to make this work? I have a laptop that only has 3.0 ports, and for back story - I need bus communication in the guest for an 8051 micro controller in a class.

Are you passing through the USB device, or passing through the controller? If you passthrough the controller and install the appropriate Windows driver, it's got a fair, though not 100% chance of working. If you passthrough the device by itself (which is usually what people do) then it's less likely to work. I've also found that some USB devices, like mice and keyboards, are much more likely to work than others, such as media devices (thumb drives, TV adapters)

Thank you for your assistance mostlyharmless. Apologies for the delay, I was doing a bit of testing to see where things failed, and I tried a couple of methods of passing through. Just correct me if I have made an error, or if I have not yet passed the controller correctly. I have tried two approaches, one is with Gnome-Boxes which unfortunately restricts to only passing the device through; second is with virt-manager, and with this I have tried the device - which like the previous approach with boxes, fails (and like you stated is probably not going to work), changing the usb hub device passthrough from 2.0 to 3.0, and finally the motherboard's usb hubs to the KVM (which is not permitted by the OS). I have another roundabout way of accomplishing what I need to do, but it involves using a standing FTP server to and from the VM and host, and using the RS232 to USB in Linux through PuTTy. This is a solution, but I want to know if a direct approach with the USB possible, since the driver actually installs and recognizes the COM port, just not the usb.

Don't know about your PUTTY route; that seems unlikely to work, though I'm unfamiliar with what you are planning. Doesn't seem low level enough though. I use qemu-KVM to passthrough the hub: which hubs can be passed successfully depend on your motherboard and IOMMU groups. There's a KVM vfio mailing list that might be helpful for you: vfio-users@redhat.com

You might also find this useful: https://rokups.github.io/blog/#!pages/kvm-hid.md

Thank you for your help, I really appreciate it. I'll take a look at that GitHub, and I will subscribe to that list as well; now I see what you mean with the usb hub, and that sounds perfect. As for the PuTTy approach, that is just what is required for the course to program our 8051 boards using the serial cable. As a worst case, this was the approach I had: compile the hex files on the windows vm, and use my SFTP server to upload the hex file. Since either PuTTy or hyperterminal need to be used for the programming in the course, I can download the hex file to Linux from the server and use PuTTy in Linux to upload the hex to the 8051 with the usb to rs232. I'll definitely try your suggestion using a usb hub, and I'll do some research on success stories. Thanks for all your help, I'll mark this as solved.