No console output when the linux kernel panics

Using recent distros and systems, for the default setup and also when setting the kernel command line to have

=tty0

there is no output on the console when the kernel panics. With a CentOS 7 system, I get panic output on the console. On my VM instance with this default kernel command line: BOOT_IMAGE=/vmlinuz-3.10.0-1062.1.2.el7.x86_64 root=/dev/mapper/centos-root ro crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet LANG=en_US.UTF-8 This is seen on VMs and on two different bare metal systems. On the one system, I was able to see the panic output using its Serial Over Lan (SOL, via BMC on a Supermicro system). I'd guess an actual serial line would work too but that system doesn't have one. I'm able to get console output via

p > /proc/sysrq-trigger

and

9 > /proc/sysrq-trigger

or by echoing directly to the /dev/tty devices. But then a crash / panic induced via

c > /proc/sysrq-trigger

has no output, and I have one system that is likely panicing but I'm just not seeing it on the console. (The system that is panicing / hung takes 6 - 40 hours before it panics, it's been frustrating to finally figure out it's probably panic, and at this time I no longer have access to the system for further testing - when I do I'll set it up to use the SOL). Is there some kernel command line setting change I need to use? Did the kernel console code change so that it can no longer output to the console during a panic? The only old kernel I tried on CentOS 7 was 3.10.0-1160.114.2.el on both bare metal and in a virtualbox VM, and they get panic output on the console. These failed to output on the console on panic: Ubuntu 20.04 bare metal Supermicro and Intel systems, kernel 5.8.0-55-generic Ubuntu 22.04, kernels 5.15.0-119-generic, 6.8.0-38-generic, 6.8.0-40-generic on bare metal and virtualbox VM Using the default kernel command line for the Ubuntu 22.04 on VM: BOOT_IMAGE=/vmlinuz-5.15.0-30-generic root=/dev/mapper/ubuntu--vg-ubuntu--lv ro Rockylinux 8 / 9 on virtualbox VM, not sure of kernel versions