Standardising booting on armv7 – Dennis Gilmore

Dennis is the lead Fedora release engineer and has a strong interest in ARM.

The goal is to simplify the on-ramp for new users to U-Boot and to simplify distribution support of systems. When you come from a grub background, you become lost very quickly because you need to know a bunch of weird details to be able to use U-Boot. For distros, it’s a pain that you have to make a board-specific image.

You also need to wrap the images with mkimage.

But U-Boot also supports syslinux config files (because that’s what used for PXE boot).

For device trees, they have added an option fdtdir to specify a device tree directory, and uboot will look for the right dtb there. Currently this is based on a filename stored in the environment, but ideally it should be based on the ID string in the dtb [this was a comment from the audience].

Fedora currently builds about 40 different U-Boot images, but actually the board vendors should do this so that it becomes like a BIOS. The configs are updated to have a lot more boot options (like ext2, ext3, fat, … while specific boards typically select only 1).

The extlinux.conf files are still board specific (e.g. it has a console= entry, rootfs reference) but it’s generated by anaconda – which already does the same thing for x86 anyway.

There is no secure boot support at the moment.

Still to do: integrate with the menu system; output on video in parallel with serial; interactive editing of boot commands (cfr. grub). Currently this is Fedora-specific, it would be good to have a cross-distro project that can also install and update U-Boot. Ideally cross-bootloader so it can be used for barebox as well.

Debian is on board with these ideas, but SUSE wants to use grub2/UEFI because several packages already rely on that.


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