I have customized a headless raspberry pi OS (Dec 2020 version). I performed all customizations while running the OS from a microSD card.

As a last step , I dd the microSD to a USB drive. The system boots and works fine apart from one detail. While from the microSD card I often used the serial to see boot messages and get a login prompt. Now that I boot from USB I can still see the boot messages on serial, but I get no login prompt.

The serial device that shows up in raspberry pi's gpio pins is /dev/ttyS0.

Needless to say config.txt and cmdline.txt boot files are the same in microSD card and USB drive.


console=serial0,115200 console=ttyS0,115200 console=tty1 root=PARTUUID=d8b18b6e-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait splash plymouth.ignore-serial-consoles


$ cat /boot/config.txt | egrep -v '^(#|$)'

I can only see a getty@tty1.service in systemd - which takes care of a login prompt for when connecting a screen. But I would still get a login from the serial gpio pins. Do you have any idea what is missing to get login prompt in serial while booting from USB?

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