Multiple UARTs using -chardev and -device instead of -serial

[Michael N. Moran]

I'm working on Linux with `qemu-system-arm -machine olimex-stm32-h405`, which 
uses an `stm32f405-soc` that implements 8 USARTs(UARTs).

I currently use two "-serial telnet" options which assigns the first two USART 
ports sequentially and I can connect to both using telnet. This works fine.

I would like to avoid the sequential assignment and instead specify a subset of 
the USARTs that is not sequential.

The === Character Devices === section in qdev-device-use.txt alludes to a "new 
way" to do this using "-chardev" and "-device" that I'm not able to make work. 
The problem seems to be choosing an appropriate "-device" incantation.

Ideally the incantation would involve specifying the host side (-chardev) as a 
telnet server as before and then selecting the guest side (-device) USART.

I have not stumbled on a way to specify telnet for the host side, but I can 
quite easily use pty without error (e.g., -chardev pty,id=usart3).

How do I use -device to connect to chardev=usart3?

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Michael N. Moran           (h) 770 704 9751
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