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Comment by somanyphotons | Hacker News Reader

I wish there was a KVM out there that didn't need HDMI, where it sat on PCIe bus and presented a really dumb framebuffer/kb/mouse to the BIOS/OS, but sent it out over the network

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Yeah there are sort of some BMC/IPMI options like [0] but all of the ones I've seen still require some kind of special (generally proprietary) internal connector on the motherboard, which might not be "HDMI" exactly, but still violates the spirit of your requirements.

0: https://www.lenovo.com/us/en/p/accessories-and-software/thin...

I'm thinking similarly, but not via PCIe, but via USB: There are plenty of USB->VGA and USB->HDMI adapters that contain a dumb graphics card. So, embedd one of these and grab the video signal internally.

Thereby, plugging in just a single USB cable would deliver the power needed, keyboard, video and mouse. And bonus for an emulated USB-Stick/DVD drive.

What I don't know if these USB video cards are initialized during early boot and usable during the UEFI/BIOS phase. Is that why they grab the HDMI?

I've had this project idea in my list for a while, I even implemented thr software side (an option rom for the pci card) but the hardware side is quite difficult to get started. My plan was to get an FPGA with a hard pci core to do this, but I don't even know what to buy.

I got a cheap Tang Mega 238k but I never managed to even get the PCI examples working (and couldn't even adjust BAR settings)

Something like Intel AMT? Some prosumer motherboards like ASRock Rack have out of band management controllers in them.

annoyingly, AMT still requires me to have a dummy HDMI dongle plugged in to work

Yes - but a bolt-on solution for nearly any motherboard with an extra PCIe or NVMe slot.

I’ve seen raspberry pi based kvms that do just this - draw power from PCI to operate. Except they still usually require a cable to HDMI/USB ports on the computer. I suspect you’d like to have the whole thing to be on card without cables.

Example: https://geekworm.com/collections/pikvm (but I think this still requires separate power)

To do this, wouldn’t you effectively need to make a graphics card (VGA would work) where a separate chip could read the screen buffer? And somehow get this card to display preferentially over the on-board video card?

I’m sure the all in one card version exists, but honestly a cabled version seems more robust (w/o vendor support that is).

> To do this, wouldn’t you effectively need to make a graphics card (VGA would work) where a separate chip could read the screen buffer? And somehow get this card to display preferentially over the on-board video card?

If you do basic VGA (and UEFI), that'd be plenty for most. If it had a local output it'd be great for systems without video on the cpu (am4 non-apus, but also others)

I have a desktop that I'm using as a server box, I'd like to avoid plugging in a GPU just to change BIOS options or debug a boot failure

or that just connected over usb and acted as a usb display adapter

afaik usb isn't an option for bios/preboot display. so only useful if the thing is booting up OK enough to run a usb display driver

USB-C in DisplayPort Alt mode plus USB 2.0 signalling for the keyboard and mouse inputs is starting to be a pretty common option on consumer systems. Capturing that would allow remote control of a PC including the BIOS using a single cable (though a second cable would still be needed for connecting to a desktop motherboard's header for power and reset buttons).

I think there just aren't as many options for DisplayPort capture chips as for HDMI/DVI capture.

That seems to be one of their products

https://jetkvm.com/products/atx-extension-board

That’s not what that is

Looks like standalone AST2400 PCIe x1 cards exist and are sold on AliExpress, but none of them has the Ethernet port for some reason, strange.

Teradici is that, but too expensive for home users.

It looks like I can find Teradici card for $50-200 (used to new), which is in a similar range as the JetKVM. However, according to the installation manual that I found [0], you still need to plug in the DisplayPort connector on the Teradici host card to the GPU output port(s).

0: https://anyware.hp.com/web-help/pcoip_remote_workstation_car...

Lights out kvm

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