Raspberry Pi Ubuntu 18.04 – Disabling UART during boot, how to set up UART
First video of know-how series – read more at https://www.youtube.com/post/UgxdZLqdza3E2SMuX_J4AaABCQ
This video describes the process of disabling UART during boot sequence for Raspberry Pi Ubuntu 18.04. Useful when you have UART device connected to PI during boot time and it interrupts the autoboot sequence with messages.
More information on setting up UART in Ubuntu 18.04 R PI:
https://ubuntu-mate.community/t/using-ttyama0-port-in-rpi/5332/10
https://raspberrypi.stackexchange.com/questions/114366/rpi4-serial-port-not-working-on-either-raspberry-os-or-ubuntu
Page from Ubuntu Wiki:
https://wiki.ubuntu.com/ARM/RaspberryPi
Documentation for autoboot:
https://gitlab.denx.de/u-boot/u-boot/blob/HEAD/doc/README.autoboot
Other ways to solve the problem(booting straight to Kernel made my system unbootable!)
https://raspberrypi.stackexchange.com/questions/84175/disable-uart-such-that-it-will-not-be-on-during-the-boot-process-but-only-after
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