RT-Thread guest: serial console stuck (no output) after shutdown + switching assigned CPU core (RK3588)

[Jaxtonmax]

Description

When running an RT-Thread guest on RK3588 via hvisor, the guest boots and prints UART logs normally on the first run. However, if we shutdown the RT-Thread guest, change the zone config CPU assignment (e.g. cpus: [7] → cpus: [6]), and start the same guest again, the serial console becomes completely silent (no output). This issue is reproducible and looks correlated with switching the assigned physical CPU core after a prior shutdown.

How to reproduce:

1. Boot Root Linux on RK3588 with hvisor.ko loaded.
2. Start an RT-Thread guest .Initial config uses cpus: [7] (works).
3. On Root Linux, shutdown the RT-Thread zone:

• hvisor zone shutdown -id <zone_id>
  

4. Modify the RT-Thread zone config to use a different CPU core, e.g.:cpus: [7] → cpus: [6]
5. Start the same RT-Thread zone again.
6. Observe the serial output.

Behaviour

• Expected:RT-Thread should boot normally and print logs to UART after restart, regardless of which allowed pCPU core it is bound to.

• Actual:After shutdown + switching cpus to another core, the UART console shows a black screen (no output).

Environment

• Architecture: aarch64
• platform: rk3588