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Tow-Boot
An opinionated distribution of U-Boot.

What is this?

The goal is to produce a user-friendly distribution of U-Boot, where there is as few differences in features possible between boards, and a "familiar" user interface for an early boot process tool.

Goals

Simple and boring

Install firmware, boot distro. No other steps.

"Normal" BIOS-like experience

On boards with dedicated storage for the firmware, the Tow-Boot build should be independent from, and not care about the installed system media.

Update should be handled out-of-band (through a firmware update option in the firmware, or from distro-independent systems like fwupd). The firmware is not "owned" by the currently running distro. The firmware is not updated or changed through package upgrades.

Having no bootable storage, or all blanked bootable storage should still show a "useful" boot interface. (E.g. explaining what to do and giving some basic information about the board)

Configuration should be handled through menu-based interfaces. Options changed in the menu interface are saved to the firmware storage.

Boot modes

Support for generic mainline-based ARM distros as a first class citizen. Whether they boot using UEFI (preferred), or extlinux-compatible boot.

See README.distro from U-Boot for all the boot modes that aim to be supported.

Pretty and boring

A logo, instructions on how to to get to the firmware interface. That's it.

Serial output should stay as verbose as mainline U-Boot is.

The firmware interface is menu-driven. Though breaking out into hush is supported for more involved needs.

Unsurprising and boring

No needless board-specific or SoC-specific differences in builds.

Boot order is unsurprising: on shared storage, the storage from which the currently running Tow-Boot is running is prioritized by default.

Bootable targets are listed in the menu driven interface.

Documentation

Until a website is produced with the documentation, please read the documentation found under the doc/ directory.

There may be additional .md files elsewhere in the tree, relevant to the files close-by.

Questions

Why this instead of my distro's U-Boot build?

In this project's opinion, the distribution shouldn't be managing the firmware used to boot the system.

Confusingly enough, U-Boot is both a firmware (think "BIOS") and a bootloader (think "grub").

The firmware should be a basic constant on the system, with well-defined semantics allowing either a bootloader or an operating system to start.

Should all the distributions have to build and manage all the BIOS for all your boring x86_64 machines too?

Why the Tow-Boot name?

Because of the pun on towboats.


License

Unless stated otherwise with a SPDX header, the Nix expressions are under the license declared in COPYING, the MIT License. This applies only to the packaging infrastructure.

U-Boot derived code is licensed the same as U-Boot, which is GPL-2.0+. All patches are owned by their authors under the same license.

At the risk of repetition the produced binaries are GPL-2.0+, since U-Boot itself is.