Kvm keyboard passthrough

Hello, I previously created a thread about not being able to use my USB keyboard with this KVM. I recently noticed that, although my keyboard functions properly when I get into windows, my bios doesn’t detect the keyboard on boot. Is this expected when using USB passthrough with the L1 KVM switch?

that confirms that your keyboard, once it is in windows, loads a driver to make it not a real hid keyboard anymore.

the bios cant recognize keyboards without a drive either. corsair has a “bios mode” you can toggle on and off explicitly which works great.

if this is steel series you can “never” load the driver and it will “always” stay in bios mode, then it will work.

The kvm does not reset the keyboard (the usb 3 ports do a half second reset whereas the hid ports do not).

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Without the KVM the bios detects the keyboard. Is there a difference or do you think there’s a problem with my bios configuration? Again, if I need to get into bios I can always connect another keyboard - this is more for my information.

so the kvm doesnt pass through the host power reset because it can’t. in tests it caused all sorts of problems if one input is reset but the other one is totally unaware of it. Again you do get a similar reset on the usb3 ports but steelseries may be relying on a hard power reset or something weird.
if you reboot the kvm it’ll do the same, but their keyboard design seems to rely on restarting the entire usb controller to reset it back from “driver” mode to hid mode.

there isn’t really a mechanism for one input to notify another input that the protocol the device is using is switching from “hid” to “not hid” so this is the consequence. almost all vendors handle this kind of thing properly – even qmk custom firmware handles it. Sometimes there is a bad usb implementation thats sketch – early atmel avr devices violate usb spec buuuuut it mostly works anyway. So qmk running on some atmel avrs dont work. modern ones are fine, ofc, but old ones are weird. Some folks managed to figure out how to bitbang and work it out. I ramble here because I put a lot of work into testing all the edge cases but some things just aren’t implemented well outside the kvm and its a bridge too far to try to fix it on my end

Hah, of course. I watched the youtube video on this and I understand KVMs are extremely complicated. TBH, I didn’t know how complicated they were until I started looking into them. As said, under normal workloads it works flawlessly. It’s just this steelseries keyboard that’s being a pain. I probably should have gone for something else, maybe something more reasonable, but I’m a sucker for magnets. When they advertised that each key had a magnet I was sold! lol, but after using it, I can’t really tell the difference and I feel like I’ve fallen victim to marketing.

Either way, These questions were more for my information to see if there was to get my setup to work better, but it is working as expected now. The only thing that sucks is the windows shifting as I swap between monitors. That’s diving me crazy, however, I purchased two of the DP Repeaters. Hopefully this will solve my issue by creating that repeater signal and prevent my windows from flying all over the place.

Again, this is not me trying to criticize your hard work and testing, nothing ever works as expected in production. I’m just trying to get my equipment working as best as possible by trying everything I can think of. If this is as good as it gets, I’m happy. Maybe one of these days I will upgrade my peripherals to Logitech, but that’s a different conversation altogether.

Buying a USB controller and passing through the entire controller is the best method in terms of latency and performance. This way you are by passing more of guest to kernel functions.

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no worries. and yes, seelseries seems especially problematic. Custom keyboards on qmk are fine, and corsair can work in “always hid” bios mode (or not in usb3 pords). Logitech is fine also, with a bit of cajoling.

Hey @wendell, I borrowed a friends keyboard, it was a corsair k100. This keyboard is not able to get working as either. After a while of using the KVM, because the usb unplugs and plugs back in that sound drives me crazy because it keeps beeping between the two computers. Is bios mode the only way to get a corsair working with the KVM on HID ports? Will all the higher end keyboards yield the same results?

Yes. Use the usb3 ports with the Corsair.

Once it’s out of bios mode it’s a strange not hid protocol.

If you disable nkey rollover it’ll work fine with high end custom keyboards like qmk because qmk doesnt try to do weird stuff.

Yes. Use the usb3 ports with the Corsair. It’ll work 100% but no keyboard shortcuts for the KVm.

Once it’s out of bios mode it’s a strange not hid protocol. Bios mode is normal hid.

If you disable nkey rollover it’ll work fine with high end custom keyboards like qmk because qmk doesnt try to do anything weird. So qmk can work in a hid port just fine giving both high end features and KVm keyboard shortcuts.

I couldn’t get it working with the corsair working with bios mode. Also, the fact that bios mode disables a couple of this, I didn’t want to go down that path. I did get it working with a keychron, so that’s interesting. After reading this poston super user about KVMs detecing keyboards as usb hubs, and seeing that the keychron worked, I thought maybe keyboards with integrated usb hubs are what’s giving me problems. Right now I’m using a ducky one 3. The RGB comes on, however, it’s unresponsive. I tried using hot keys, but they didn’t work. I also tried resetting the switch, but that also didn’t help.

I guess at this point I’m curious, what would the most low latency premium mechanical keyboard be for this KVM? I’m liking the cherry red switches if that matters. I was going to get another keychron, full size, but latency is a little high. Will I notice the latency when gaming? Probably not. However, if there’s a better keyboard that I can get, I’d be willing to pick one up just to get this thing working.

Also, for the ducky one, I’ve used the dip switches to disable nkey rollover. I unplugged, set the nkey rollover, pluged it back in, reset the kvm, but nothing worked.