If we receive an option 67 (bootfile) matching http://IP/rootfs.itb,
use U-Boot's wget implementation to download the file. The web server
must listen on port 80. tftp:// is also supported.
Without a protocol prefix, assume that the bootfile should be fetched
using TFTP from ${serverip}.
Generate a boot menu, accessible with C-c during a short window, where
a user can interactively select a custom boot source and/or trigger a
factory reset of the device.
With this in place, we should always be able to unbrick a device, as
the image can be fed over the network, and local data can be ignored
by opting in to a factory reset.
This ensures that U-Boot images that we build can always:
- Rely on the environment extensions in env.dtsi being available
- Access the configured signing keys
- Use SD/eMMC cards
- Extract files from SquashFS filesystems
All of which are foundations that we intend to design our image
loading around.
Tobias Waldekranz