I was studying the design of the serial port and the N2HET device on the TMS570, and emulating that in QEMU is not really an option. Since that's how the debug serial port is done and perhaps how some I2C devices are accessed, it doesn't make sense to do the QEMU emulator.
Just for details on this, the N2HET is a separate coprocessor, and would require writing an instruct set front end to work properly, or writing an emulator of some kind. That's a pretty big job in QEMU, but it could be done.
However, even if you got one of these working, it still wouldn't work for our purposes. The way the N2HET is used, it's bit-banging (sending and receiving a bit at a time) in and out serial and I2C data. That's extremely timing dependent for serial (not so much for I2C), and an emulator is not going to be able to do that easily. Again, it could be done, but the code required to take the outputs of the N2HET and covert it back to bytes would be hard.
It would be more feasible to emulate what the N2HET does in our configuration, but that's not going to be accepted into QEMU, so maintenance for this would fall on us.
Sorry for the bad news. It would have been nice to have this. Looks like I'm going to need a board.
Note, as an aside, this kind of thing uses a lot of power. The SCI and I2C devices on the TMS570 are likely to use a lot less power. Not all TMS570 SOCs have an I2C, though.