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): arm_64bit=1 enable_uart=1 dtoverlay=disable-bt kernel=u-boot.bin 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 https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/README.md If you try miniroot67.img from a snapshot you'll get a more recent version of u-boot. May be worth trying.