* Marc Haber <mh+linux-kernel@xxxxxxxxxxxx> [230906 14:41]: > With my tools I have found out that it really seems to be related to the > CPU of the host. I have changed my VM definition to "copy host CPU > configuration to VM" in libvirt and have moved this very VM (image and > settings) to hosts with a "Ryzen 5 Pro 4650G" and to an "Intel Xeon > E3-1246" where they work flawlessly, while on both APUs I have available > ("AMD G-T40E" and "AMD GX-412TC SOC") the regression in 6.5 shows. And > if I boot other VMs on the APUs with 6.5 the issue comes up. It is a > clear regression since going back to 4.6's serial code solves the issue > on the APUs. Not sure why the CPU matters here.. One thing to check is if you have these in your .config: CONFIG_SERIAL_CORE=y CONFIG_SERIAL_CORE_CONSOLE=y Or do you maybe have CONFIG_SERIAL_CORE=m as loadable module? If you have CONFIG_SERIAL_CORE=m, maybe you need to modprobe serial_base if you have some minimal rootfs that does not automatically do it for you. Regards, Tony