2023-07-10 15:43:08 +00:00
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---
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title: U-Boot payload
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x-toc-enable: true
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...
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extreme cleanup / grandiose gesture
make canoeboot a truly GNU FSDG compliant coreboot distro,
by removing all overly positive reference to Libreboot;
what remains is technical in nature, so as to provide
historical context since Canoeboot is a fork of Libreboot.
I've stated before that I wish to take a more neutral tone
toward the FSF, in contrast to the *coldboot war* of 2023
when GNU Boot started.
Canoeboot was heavily linking to Libreboot, even going so far
as to call itself "inferior" and tell the reader to use
Libreboot.
From now on, Canoeboot will be maintained as though I actually
believed in FSF propoganda. I don't, but its users do. Treat
them with respect. My reason for providing Canoeboot is
precisely that I wish for such people to have a high quality
coreboot distro, much unlike the inferior *GNU Boot* project;
inferior because to this day, it's still based on very old
Libreboot, with not much changed (of any real substance)
relative to the Libreboot 20220710 release on which it forked.
In general, I've also found a lot of stragglers from when
Canoeboot started, where paragraphs referred to Libreboot that
should have actually referred to Canoeboot, or paragraphs
with Libreboot-specific information that does not make sense
in the Canoeboot project e.g. references to vendor scripts.
The resulting canoeboot.org will now look no different to any
typical reader than a typical FSF-aligned project.
There is a next stage to this, which will become apparent to
everyone if I have my way.
Signed-off-by: Leah Rowe <info@minifree.org>
2024-05-10 02:12:44 +00:00
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Canoeboot has experimental support for using U-Boot as a coreboot payload.
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Refer to [docs/hardware/](../hardware/) for a complete list of U-Boot
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targets in Libreboot. Canoeboot inherited U-Boot support from Libreboot.
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U-Boot integration in Canoeboot is currently at a proof-of-concept
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stage, with most boards completely untested and most likely not working.
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ROM images for them are mostly intended for further testing and
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development. If you have one of these machines and want to help fix
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things, you can ping `alpernebbi` on Libera IRC, who ported these boards
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2023-10-26 00:10:41 +00:00
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to Canoeboot.
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2023-10-26 00:10:41 +00:00
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Make sure you have the latest `cbmk` from the Git repository,
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and the build dependencies are installed like so, from `cbmk/` as root:
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./build dependencies debian
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This installs everything needed for `./build boot roms`, and part of the
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build process makes use of coreboot's own cross-compile toolchain.
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[QEMU x86/ARM64 virtual machines](../misc/emulation.md) are also
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supported, which should be easy targets to start tinkering on if you
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want to contribute.
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Usage
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=====
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When your board is powered on, U-Boot will ideally turn on the display
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and start printing console messages there. After a countdown of a few
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seconds it will proceed to automatically boot whatever it can find.
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U-Boot will fall back to an interactive prompt if its boot sequence
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fails or if you interrupt the countdown.
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U-Boot supports UEFI to some extent, enough to run a GRUB package that
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would be installed by whatever OS you want to have on your device. The
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boot sequence checks for the standard UEFI removable media paths like
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`/efi/boot/bootaa64.efi`, so you should be able to use your desired OS'
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generic installer images. For details, see upstream documentation for
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[UEFI on U-Boot](https://u-boot.readthedocs.io/en/latest/develop/uefi/uefi.html).
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Otherwise, the boot sequence also checks an `extlinux.conf` file that
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can configure which kernel, initramfs, device-tree file and kernel
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command line arguments should be used. See upstream documentation for
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[Generic Distro Configuration Concept](https://u-boot.readthedocs.io/en/latest/develop/distro.html).
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If you want to work inside the U-Boot shell, see an incomplete list of
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[shell commands](https://u-boot.readthedocs.io/en/latest/usage/index.html#shell-commands),
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or use the `help` command inside the prompt. Configuration is done via
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[environment variables](https://u-boot.readthedocs.io/en/latest/usage/environment.html)
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inside the shell, which can be saved to and automatically loaded from
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persistent storage configured at build-time.
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WARNING: Environment variable storage has not been explicitly configured
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so far and is untested in the context of Canoeboot. It may cause data
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loss or even brick your device by overwriting your disk's partition
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table, unexpected parts of the SPI ROM image, or do something else
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entirely.
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Known issues
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============
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U-Boot integration in Canoeboot is incomplete. Here is a list of known
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issues that affect all boards:
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- Branding is U-Boot with their logo (Canoeboot only in version number)
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- Splash screen might be better instead of console messages
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- Cursor/drawing bugs with video improvements patches
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- Environment storage is likely dangerously broken
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- SMBIOS info is missing, `Unknown`, `Unknown Product`, etc.
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- Coreboot tables are ignored, unavailable to the OS
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- Re-inits display instead of using coreboot framebuffer
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- Chromebook FMAP layouts should match stock layout for GBB, VPD
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- Chromebook GBB, VPD are not handled, data may be unavailable to OS
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- U-Boot "coreboot\*" defconfigs needs more work and an ARM64 version
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- UEFI support is incomplete
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See also
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========
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- [U-Boot documentation](https://u-boot.readthedocs.io/en/latest/)
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- [U-Boot documentation (unmigrated files)](https://source.denx.de/u-boot/u-boot/-/tree/master/doc)
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- [U-Boot and generic distro boot](https://marcin.juszkiewicz.com.pl/2021/03/14/u-boot-and-generic-distro-boot/)
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