OK my experimentation has continued and I've discovered an interesting problem. USB doesn't work. I've flashed a vanilla Hardkernel image (ubuntu-20.04-3.10-minimal-odroid-c1-20200519.img.xz) and all is well, ruling out any hardware issue.
lsusb shows the root controller hub on the custom Bookworm armbian build: Armbian-unofficial_25.02.0-trunk_Odroidc1_bookworm_current_6.6.43_minimal.img.
I've plugged in a webcam and a flash drive, non of which appear in lsusb nor generate any stimulus within dmesg.
I've since done git pulls on the repo so I can't tell exactly which git rev this was built on or from; I'd suggest it dates from my last post, Dec 17 2024.
lsusb under the Hardkernel image shows the controller hubs as well as the listing in lsusb, plus dmesg. All seems well.
Any one else experience this?