[Qemu-arm] [BUG] qemu-system-arm/aarch64 QMP hangs after kernel boots

[Cleber Rosa]

Hi,

This is just a FIY about the following bug report:

 - https://bugs.launchpad.net/qemu/+bug/1829779

And add some extra clarifications that I've tested extensively the
behavior of other targets (all that have a similar test under
tests/acceptance/boot_linux_console.py) and none exhibited the same
behavior.

Also, because qemu-system-arm and aarch64 sometimes fails on the very
first QMP command, the regular boot test sometimes will hang on a
"quit" command that happens when the test run its "tear down" and
attempts to cleanly shut down the "vm".

Let me know if I can be of any further help.

Thanks,
- Cleber.