The QubesOS PS/2 Problem
Since the title says everything and nothing, let me explain. I am a QubesOS user and QubesOS discourages the use of USB keyboard and mouse because of the massive USB stack attack surface. Instead QubesOS uses PS/2 by default and optionally you can use sys-usb for your QubesOS system with USB devices. However, this means that if sys-usb crashes or you are just brain dead and shut down the VM, you will be locked out of the system. Then the only option is to get your drive, swap it to another system, mount and decrypt it, and change some parameters. But this is more disaster recovery than anything practical. So if you want to use QubesOS, you want to use PS/2.
My Multiple PC Problem
While QubesOS has been my daily driver for many years, I also have some other PCs that I like to use. So let’s say I have about 4 PCs in my office. The installation configuration changes sometimes, but usually I have 1-2 Qubes systems (the ones that need PS/2 for mouse and keyboard) and 2-3 Linux systems. Never more than 4 physical boxes, but as I said, the OS configuration changes sometimes. Because of the number of PCs, I would like to have a single mouse and keyboard to manage all my systems, as it is very unlikely that I will need to use all the systems at the same time, and switching is not a big problem. So I need a KVM switch for 4 PCs with 2 (more would be great) 4K displays.
Back to the Future
With this long introduction, I need a KVM switch that will connect a USB mouse and keyboard to PS/2 (or least a KM switch). I know I need an adaptive adapter, but I cannot find any good ones. Probably because nobody cares about PS/2 anymore, and if they do, it is always in the direction of having old peripherals that now connect to USB. I need the other way. But not always, because I want to be able to connect my other systems via USB, since not all of them have a PS/2 port.
Solution
A KVM switch that supports up to 4 PCs and 2 4K displays. At least one PS/2 port so I can have a single USB mouse and keyboard to connect to all my PCs and keep QubesOS happy. Alternatively, I can connect my PCs directly to my displays (since they are more expensive displays and have multiple video in connectors) and just go for a KM switch.
+-----------------------------+PS/2 Mouse/Keyboard
| KVM SWITCH -+------------------->
USB Mouse | |
-------------|> |USB for PC 2
| -+------------------->
USB Keyboard | |
-------------|> |USB for PC 3
| -+------------------->
| |
| |USB for PC 4
| -+------------------->
+----------------+----+-------+
| |
| |
| |Video 1 4K
| +-------------->
|
| Video 2 4K (144Hz optional)
+------------------->
Wendel, can you please solder me one?
Do you have any idea how I can get such a setup? Alternatively, I could just use a KVM switch for all my USB systems and a separate keyboard/mouse pair for QubesOS. My biggest problem here is that there are only ultra crappy PS/2 mouse options, while there are still some nice mechanical PS/2 keyboards for sale (like the ones from Cherry).