Just forget about the Raspberry thing. I presume when you want to teach about programming it does not matter if the platform is Raspberry or PC. What ESXi gives you is a large number of virtual Intel (PC) machines on a single box, and the way to monitor it all via the network. You can see the console and input keyboard/mouse input over the network. And the virtual machines of course also have network so you can do SSH or VNC just as well.
This suggestion was just meant as a solution to the original problem of setting up some system where multiple users in a classroom should be able to work on a computer with someone monitoring their activity, not a solution to the problem that was described in the first post where already the assumption was made that it would be done on RPi and some hardware was required to switch their HDMI/USB connections onto a monitoring station.
Yes. How do you think the software in ARM based phones gets designed and written? How do you think the software for ECUs gets written? How do you think car dashboard display software gets written?
All of this stuff starts on accurate simulations of not just the CPU but large amounts of the silicon is simulated (in software) either as cycle accurate models for accurate bus simulation, or a loosely timed models which approximate bus performance or untimed models which allow software to be developed and tested.
Software simulations can be produced 18-24months before silicon is available and gives designers a huge startup boost. As soon as silicon is produced, code can be moved from simulation to hardware for real world testing.
Why? The whole point of some of what I am looking at is to run on the specific Raspberry Pi hardware. I think you are mixing my requirements up with someone else's.
I don't want to teach about programming... Perhaps you are thinking of the post by "DisneyWizard"?
I don't know about "DisneyWizard" but I currently use Oracle VirtualBox and DosBox for such testing on a PC. ESXi sounds like another option, though.
"Yes"? The question was "how?". The word "Yes" doesn't answer it!
Sure. I don't disagree but you are talking about something else. In the paragraph above I was asking Rob how he proposed to get a good Raspberry Pi emulation on a PC. That would be useful. It turns out he was really thinking about someone else's problem, though, and AFIACT doesn't know of a good Raspberry Pi emulation that will run on standard PC hardware. If you do, of course,.....
I think this is what we are describing. A main rPi (or some other device such as a PC) with a real keyboard, mouse and display connects via Ethernet to a series of "things" which provide the emulated mouse, kayboard and HDMI signals to a collection of rPi (or even other devices). The main computer requires special software to drive the "things" via the Ethernet and the "things" will be some special hardware which responds to the commands and emulate the three I/Os.
I didn't draw the power because that is not clear to me if it is intended for the "thing" to channel power to the rPi or if the rPi will power the thing. Since the keyboard/mouse will be plugged into at least one USB port, the rPi would power the "thing".
I don't see a need for a special "thing" on the head computer which has the physical keyboard/mouse/monitor attached. This unit is just a computer with special software. The "things" will need a slave USB port and an HDMI port to emulate a monitor, so I think that will require some special hardware. I am not familiar with the HDMI spec, so I don't know exactly what will be required for that. But otherwise, this will be not too much different from an rPi needing enough of a CPU to handle two Ethernet ports and being able to shuttle the HDMI graphics around.
I drew the Ethernet as a daisy chain. Perhaps that should use a conventional star configuration with a hub/switch instead.
Another I/O that might be useful is something to force a reset, possibly even a power switch. I run into a need for that more often than I like.
It sounds like what you need is a serial console in order to see the Pi boot, and to control it via a shell. You could get UART to Ethernet converters to be able to access them remotely.
How remote does it need to be? Why not an old serial mouse kvm* using only the serial switch part. Connect the ``master pi'' serial pins to the switch and the other pi's to the other side. If they're all pis you won't need voltage convertion. If the master's a PC you'll need something.
You can get a cheap SFF PC, install Linux or *BSD on it, and stick a bunch of USB serial adapters in it. I actually use my RPi B+ as a baby console server for an old Sun pizzabox and an ASIC miner. My preferred serial terminal client for console work is C-Kermit (available as "ckermit" in the Debian repositories) since it's highly scriptable - you can write a Kermit script for each individual port and set it executable, and it supports Kermit protocol file transfers. Very handy.
If you're not comfortable with a Unix shell you really aren't getting the most use out of your RPi. This makes as good an excuse to learn as any.
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