On Sun, Jul 05, 2020 at 09:18:55PM +0100, testing999...@zohomail.eu wrote:
> i can't get any u-boot serial output from miniroot67.fs on a raspberry
> pi 3.  i'm using a 'FTDI232' which cost ~$4 - USB to 3.3V jumper
> cables, connecting TX to RX and vice versa on GPIO header.
> my serial console setup works without issue with a pi 1 and a pi 3,
> running raspbian, with:
> $ screen /dev/ttyUSB0 115200
> i had to add 'enable_uart=1' to /boot/config.txt before with console
> became accessible, on the pi 3.
> i tried mounting the partitions after dd'ing miniroot67.fs and
> looking for some text files to edit, but there were only binaries
> any ideas? i can only think of trying older miniroots or snapshots
> next. thanks

The arm64 miniroot contains a fat filesystem with raspberry pi firmware,
config.txt and rpi_3 u-boot. The config.txt already has serial enabled
(with pl011 uart):


You can force the firmware stage which runs before u-boot to output on
serial by modifying bootcode.bin as described at the end of

If you try miniroot67.img from a snapshot you'll get a more recent
version of u-boot.  May be worth trying.

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