Abort on data transfer when using KVM

I’ve just been putting my shiny, new and, above all, cheap KVM through its paces. It works well enough, but I get a repeatable error the first time I switch away from RISC OS and back to it again.

I am using the Raspberry Pi Imager RISC OS image, which tells me that it is 5.28, released 2020-12-20. This is an absolutely clean install with no configuration changes whatsoever. I’ve simply booted up into RISC OS, switched to Windows using the KVM, and then switched back again. The error only occurs the first time I switch, but repeats after every restart.

The hardware is an 8GB Raspberry Pi 4, and an “ABLEWE” 2-port HDMI KVM (it appears to be completely unintelligent; just some input and output ports, and a button).

The error message is as follows:
Internal error: abort on data transfer at &FC223FB0

Once I’ve clicked on “Describe”, it goes away and doesn’t appear to have broken anything obvious. However, I do worry that it is doing unspeakable things in the background…

The wisdom of the forum is humbly sought.

Once I’ve clicked on “Describe”, it goes away

If it ain’t actually broke, …

*where fc223fb0

Address &FC223FB0 is at offset &0000416C in module ‘XHCIDriver’

If it ain’t actually broke, …

Aye, it isn’t stopping my from doing anything, but someone might be interested to know that something went ‘boom’.

*where fc223fb0

Thanks. I knew there was a *command which did that, but my brain hurts. Which is worrying as it’s only Wednesday.

I’m actually posting this from !NetSurf. Woot.

Some KVMs have the option of being “intelligent” (and then do strange USB things to e.g. capture hotkeys to keyboard-switch consoles) or “dumb” (where the USB ports are just connected to a USB hub). Try the “dumb” one.

I had one specific KVM switch that just needed to be connected to the Titanium to prohibit startup (i.e. before RISC OS even inited the screen!). But I think this was fixed some time ago – I did the easy cop-out and switched the KVM switch…

Try the “dumb” one.

Oh yes. “Smart” things scare me, and the “improvements” are rarely things I find I use or need, and almost never anything I actually want. No clever keypress-capturing with this hub. Just a nice clicky button on the top of the device to switch between inputs.

Druck pointed out that the abort is inside XHCIDriver, so it’s possible that one of the USB-savvy developers will see this and identify a fix that can slip into the module. :-)

The XHCI Driver is not able to adjust itself to deal with dodgy USB devices. Previously this could be done in software. XHCI requires compliant hardware. So just chuck away some of the cheapo items that don’t work.

That’s vexing. It cost me £30, so I’m not overwhelmingly happy with the prospect of throwing it away quite so soon. However, if I must, I must.

Can anyone recommend a reliable KVM with HDMI before I throw more money away?

I have been using the CPC Farnell Pro Signal PSG 91076 4-port KVM, under a different brand, for a good while. I think there are others here that also use it. The 2-port version is PSG90982. They are neither of them cheap, but I have had no problems with a mini.m, a RISC OS Pi, a Raspian Pi and a Windows XP connected.

Slightly OT: My setup here has one one HDMI source (ARMX6), one DVI source (Windows laptop with dock), and two VGA sources. I am at present using a 4-port VGA KVM. The HDMI and DVI sources go through HDMI-VGA adapters, giving remarkable good results. The ARMX6 is running at 2560×1440 with no discernable fuzziness.

There is a long delay switching between sources, because the monitor takes 10 seconds to resync. I don’t know whether using an HDMI KVM would shorten this delay. Any thoughts?

Is there a way to use an HDMI KVM with VGA sources? I’ve seen converters, but two of them would be ridiculously expensive.

Thanks, Steve. That’s not too expensive, and if, as seems likely, I get another Pi, I’ll go shopping with Farnell. Meantime I’ll just manage with the occasional error. It’s not a showstopper, just an annoyance.

I stuck with my trusty twenty-year-old 4-port VGA KVM with PS/2 to avoid most issues of things trying to be too clever. Just have a PS/2 to USB adaptor to feed my ARMX6.

My ARMX6 feeds HDMI to monitor separately – $deity knows why it takes so long to re-sync to HMDI input using monitor front panel button, you’d think that it would be too fast to notice.

Can anyone recommend a reliable KVM with HDMI before I throw more money away?

I use a TESmart (ex Tesla – probably renamed to avoid confusion with the now well-known car maker…) 16 port switch which is nice, and cheap for a 16 port one, but expensive if you need only 4 or less ports.

Also has a LAN port where you can software-switch the ports via IP which I keep meaning to write some RISC OS software for.

Be aware that HDMI switching becomes more of a minefield with higher resolutions – 4K@60Hz ist still the exception rather than the rule. It is often a good idea to dial back to 4K@30Hz for reliable operation.

nice, and cheap for a 16 port one, but expensive if you need only 4 or less ports.

Hmm. If I have too many ports, I might be unable to stop myself buying more RPi modules to fill them. I’m not sure what I would do with all those compute modules, but it would be fast.

4k is still a fantasy for me. I haven’t worn this 1080p monitor out yet!

That’s not too expensive, and if, as seems likely, I get another Pi, I’ll go shopping with Farnell.

Maybe wait until someone else with a Pi 4 confirms that it’s OK (unless Steve’s Pi is a Pi 4). I’ve just bought one to use with a Titanium, on which the StarTech KVM that I’ve used for years completely repeatably takes out the XHCIDriver when the keyboard and mouse are switched back to it…

…and the ProSignal has exactly the same effect. At least I’ve now got a solidly-built doorstop — the StarTech has separate buttons for each of the inputs (and no need for a mains socket), so I’ve switched back.

This is not a dig at Steve’s suggestion, by the way; I bought it as a gamble on the off-chance that it might work and fully in the expectation that it probably wouldn’t. I would really like the desk space taken up by the Titanium’s keyboard and mouse back.

Meantime I’ll just manage with the occasional error. It’s not a showstopper, just an annoyance.

Unfortunately it’s completely unusable here. Once XHCIDriver has crashed, the KVM switched devices are useless and I need to plug in the separate ones.

So, does anyone have a recommendation for a four-port USB (plus HDMI, probably, but that’s not used at present) KVM which is usable with the RISC OS XHCIDriver?

Maybe wait until someone else with a Pi 4 confirms that it’s OK (unless Steve’s Pi is a Pi 4). I’ve just bought one to use with a Titanium, on which the StarTech KVM that I’ve used for years completely repeatably takes out the XHCIDriver when the keyboard and mouse are switched back to it…

Fair point. Although to be fair it is unlikely that I will be in the market for more toys for several months at least, as I have now been Officially Told Off about having too many projects on the go, and that’s without including the redecorating and the garden…

This is not a dig at Steve’s suggestion

Has it been mentioned before that there are too many Steves around here? I feel sure it might have been…

Unfortunately it’s completely unusable here. Once XHCIDriver has crashed, the KVM switched devices are useless and I need to plug in the separate ones.

That seems… odd. I wonder what your KVM is doing that mine isn’t, or vice-versa.

I’ve just bought one to use with a Titanium, on which the StarTech KVM that I’ve used for years completely repeatably takes out the XHCIDriver when the keyboard and mouse are switched back to it…

…and the ProSignal has exactly the same effect.

I have exactly the same problem with a Titanium. I have tried two different KVMs (which function perfectly with every other hardware I have tried) but both kill the XHCIDriver on the Titanium when KVM is switched away and back. Like Steve, I am stuck with using a second mouse and keyboard for the Titanium.

I’ve been using a Avocent/Emerson HDMI/USB/Audio KVM for several years now. I use it with An ArmX6, HP laptop (Win10), MSI laptop (ZorinOS) and a Windows server without any issues. It has the ability to lock the audio, so you can listen to one source regardless of the KVM selection, or to switch it with the source. It also has a USB3 hub built-in. Not cheap, but very useful.

It is a pity my suggestion is not serviceable with all machines.

My Pi4 is Raspian, my RISC OS Pi is a 2, but I have to make a special arrangement for my my mini.m.

If its USB is connected directly to the KVM the keyboard and mouse are lost when it is dis- and re-connected. My solution is to connect a cheap hub to the mini.m and from there to the KVM. Could this solve the problems with Pi4 and Titanium?

My solution is to connect a cheap hub to the mini.m and from there to the KVM. Could this solve the problems with Pi4 and Titanium?

Just given this a try on the Titanium, using a powered hub. Unfortunately, this does not work on the Titanium. The mouse and keyboard are still inoperative after switching away and back.

Just in case, how about unpowered? Maybe the cheapness helps.

how about unpowered?

Managed to find one in the junk box, but to no avail. Behaviour still the same.

Interestingly I have a long-standing issue with a VGA KVM. Sometimes when I switch to the ARMX6 (from RO5.23 to 5.29, all versions), the keyboard and most mouse functions don’t work. (The pointer moves, that’s all). Plugging in other USB devices does nothing. I can fairly reliably make this behaviour occur if I move the mouse significantly while it’s switching over (i.e. during the ten seconds it takes the monitor to sync).

Once this has happened, waiting 30 seconds will sometimes get control back, indicated by the num lock light appearing on the keyboard. Other times switching away and back might fix it. Usually I have to power off and on.

I’ve very occasionally seen a similar problem when switching to the RPC running RO4.02.

Looking at the above, it seems to me it might be part of the same issue.

Would using a seperate HDMI switch and then a USB keyboard and mouse switch?

Would using a seperate HDMI switch and then a USB keyboard and mouse switch?

That was my previous set up, which worked with every machine except the Titanium.

I am currently using my latest HDMI KM switch to switch the Ti video, but separate USB K and M.