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First the kernel will need a command line parameter to configure the serial port. Edit /etc/default/grub and set GRUB_CMDLINE_LINUX="console=ttyS0,115200n8". Note if there were already values set, the serial one can be appended. Then update grub and reboot:
$ sudo update-grub; rebootpoweroff
Next the emulated QEMU serial port is setup to redirect the kernel trace to another host:
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