I hope this is the right spot for a question like this, if not, please feel free to move it somewhere else.
I have the 4-port dual-display DP 1.2 KVM from Level1 (PAAG-E3124A).
First of all, I am very happy with it, great device. But, apparently, a Linux VM I run, isn’t.
I have three ports in use on the KVM:
- host, it uses a USB-port that is separate from the VMs port’s IOMMU groups
- Linux guest with passed thru GPU, USB-C passed thru from GPU
- Windows guest with passed thru GPU and USB from host (the only controller in it’s own IOMMU group)
Keyboard and mouse are connected via the HID ports, the rear USB 3 connects the monitors USB hub.
The host and guests all run fine, aside from one little problem with the Linux guest:
Its mouse and/or keyboard randomly, but frequent, stop working, like they freeze. If I use a model with some sort of LED lighting it will stay on, so power is there. Fun fact: I can communicate with the KVM → ctrl-ctrl-number works for switching to a different console. And mouse and keyboard will work just beautifully on the other ports.
However, switching back and forth will not unfreeze the Linux guests mouse or keyboard. This can only be achieved by unplugging it from the KVM and plugging it in again while KVM is set to the guests port.
I tried various things, like different kernels for the guest, disabling usb-autosuspend, even acpi. I tried connecting the mouse/keyboard to the USB 3 ports in the KVM(can’t switch there but still freezes). Makes no difference.
udevadm monitor does not see the “event”, as any other log doesn’t. As far as the guest is concerned, nothing happens. It seems as if KVM and the USB controller just don’t speak any more → but only for mouse and keyboard, a conference speaker or webcam connected via the KVM simultaneously work just fine and keep working even if keyboard/mouse don’t. So there is communication between the connected devices and the USB controller, and it does work.
Now, someone suggested it could be related to mouse-emulation(?) on the KVM, and here lies my question:
Is this the case? How can I switch it off or on? How can go about further debugging this issue?
And, does anybody have a PDF from the manual for the KVM? I can’t find the printed one that was included :-/
Sorry for the long winded text, but I tried to describe it as best as possible.