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Comment by ccakes | Hacker News Reader

> KVM users are underserved for sure.

100%

I want to share keyboard, mouse and monitor between a PC and a MacBook. A KVM with DP+USB on one side and Thunderbolt on the other doesn’t seem to exist.. I feel like this has to be a common use case :(

I know I could break out on a dock first, but I have a particularly high-res monitor which most of the docks baulk at, or only support at 30Hz

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If you want a proper kvm, see the offering from level1techs/wendell (not affiliated, just a satisfied customer) at https://www.store.level1techs.com/products/hardware

I used one with 4x dual dp switching at home to run desktop with linux, pcie passthrough gaming vm on same machine and my work laptop via a dell thunderbolt dock connected to it.

Works extremely well, with modern features tested for (gsync, high refresh etc etc).

edit: one thing to note is that you need really good quality cables, so don't cheap out

I get how the Linux desktop and the Work Laptop would work in this setup.

But how does the KVM come into play for the Gaming VM when it is on the same host?

It was pci passthrough so the vm had a dedicated gpu, usb controller and nvme drive which I wired to the hardware KVM as extra inputs.

There are other options like https://looking-glass.io/ , but I preferred having this option, which is like having 2 computers if there's enough resources to share to the gaming guest (cpu pinning + huge pages).

I'm in the same boat as you. After trying and returning a few KVMs, I found a decent USB-only KVM switch [0] that works with 4K HDR + PD devices (I think it just electronically connects and disconnects cables), it works amazingly with switching between Macs, but my PC GPU doesn't have USB output, just DP. I have bought a Thunderbolt PCI-E card (ASUS ThunderboltEX 4), it worked, but only turned on once Windows has fully booted, so I returned it too. I'm considering buying an USB-C signal muxer [1] but they are a bit too expensive for my liking. I guess there isn't enough market to produce them and sell them at reasonable price - most people, including myself, just accept having to switch video input separately from USB KVM.

[0] https://www.amazon.co.uk/dp/B0BN5D2NXX

[1] https://www.amazon.co.uk/dp/B0732W9DG8

Check out https://www.store.level1techs.com/products/p/kvm-switch-usbc... paired with https://www.store.level1techs.com/products/p/dp-repeater-hdm... for one of your computers - it may do the trick for you. There are other models if you want more monitors or computers (or different set of inputs).

No affiliation with them except that I've got one their KVMs (not an USB-C version, though) myself and it's been quite reliable (only infrequent accidental hiccups, nothing unplugging the power for a second can't solve), much better than my previous pile of hacks juggling monitor inputs via DCI and using USB switches for the peripherals.

I share two monitors and audio equipment between a desktop and a windows laptop (dell XPS) using a "dumb kvm" that wrangles a few USB outputs and two DisplayPort inputs. the laptop only has USB-C output so it connects to a fancy thunderbolt dock borrowed from a friend which then goes to the KVM. I have a third monitor only connected to the desktop with a laptop stand in front of it for a third screen

It takes a couple seconds to switch but otherwise works flawlessly unlike my previous solution of shitty dongles, switching dual input monitors, and moving a usb hub input cable between machines. I also considered rebuilding the desktop to have a thunderbolt output and buying a thunderbolt switching KVM but I couldnt make it work

desktop - kvm - fancy dock - laptop Full diagram: https://imgur.com/a/ah54fjd

Closest I’ve found is manually switching the machine plugged into a TB 4/USB 4 dock (CalDigit TS4), with the cables for each computer being managed when unplugged by a magnetic cable pad[0].

It’s a bit clunky but not too bad once you have a feel for swapping cables and is less flaky than the more affordable KVMs I’ve tried. Gets me a nicer port loadout to share between machines too, and can be expanded to support as many computers as you’ve got space and patience for.

This does however assume all machines involved can handle outputting a display signal via Thunderbolt or USB C. Not too much of an issue with laptops but it’s still unusual for desktop PCs to have their GPUs hooked up to support TB/USB alt modes.

[0]: https://www.amazon.com/dp/B08XYZFM7D

I even got TB4 signal through one of those USB-C "magnetic" adapters [0], I figured that this would shift wear from repeated plugging from the expensive device to a cheap adapter.

Super annoying when you accidentally disconnect and then the entire device tree has to reboot, but on the hub side, accidental disconnect might be much less of a problem (I use it at the laptop side, to dock with different screen setups)

[0] like this, https://www.amazon.com/dp/B0BV7BPVCL/ but ordered from the Chinese site

I have a compromise setup but it seems to work ok. Two MacBooks, one pro, both M1.

One is plugged into a TS3+. The other is plugged into a USB-C dock to get Ethernet and a USB-A input, but I don't use the video out. Instead, I run a Thunderbolt to DP cable from a second TB port to the KVM switch.

I use this KVM ordered on Amazon: Cable Matters USB 3.0 KVM Switch DisplayPort 1.4 for 2 Computers with 8K@60Hz

Pros: preserves 5K@60Hz for both machines, switches keyboard, mouse, and a webcam just fine.

Cons: no hot key switching, another remote to lose, no EDID emulation so the computers fall asleep when they're not active, switching takes a bit. Sometimes a machine doesn't wake up when I switch back to it so I have to fiddle with cables, but that's been pretty rare.

how about these?

Anker 553 USB-C Docking Station (KVM Switch): - https://www.anker.com/products/83k2?variant=42726922125462 - https://www.amazon.com/Anker-Docking-Station-Desktop-Display...

iDock C10 KVM Switch Docking Station - https://www.avaccess.com/products/idock-c10/

> I want to share keyboard, mouse and monitor between a PC and a MacBook. A KVM with DP+USB on one side and Thunderbolt on the other doesn’t seem to exist.

It does if you use the built-in KVM in a recent Dell Ultrasharp display, and change Thunderbolt to USB-C.

My setup is a MacBook Air plugged into the USB-C port, a Windows PC plugged into the Displayport/USB port. Mouse and keyboard are plugged into the display.

I switch inputs via a StreamDeck. The StreamDeck just sends a key command; on macOS, BetterDisplay handles input switching, and on Windows, the Dell Display Manager app does the job.

Switching is a touch slower than I'd like, but beyond that, it's flawless.

Most monitors have 2-3 inputs. Mine has a desktop, a laptop, and occasionally my phone attached to it, using HDMI, DP, and another DP / USB-C respectively.

Unless you switch really often and want subsecond switching time, three's no need to even use a KVM to switch the monitor.

Even at twice per day switching using monitor controls would drive me nuts. The buttons, the menu, the delays, blanking and disconnects. By then I already forgot why I was even switching

Most of the time the reason for a KVM is wanting to switch the monitor, mouse and keyboard, and possibly other devices (e.g. I want to use the same webcam that remains in the same position) at the same time.

Switching just the monitor isn't really the use case they address.

I share a mouse and keyboard between pc and mac with a usb switcher.

Two monitors. Both the mac and pc are connected to each monitor. I just switch inputs as needed.

It’s not as good as one button press but heck i can monitor something in both systems if I want

I know it's suboptimal, but can't you do the split on the macbook? The TB port should output pure DP, so you plug that on the DP-in on the KVM. You plug a second USB-only cable that goes to the KVM USB in.

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