Hi Johannes, On Tue, 26 Aug 2025 at 11:13, Johannes Schauer Marin Rodrigues <[email protected]> wrote: > > Hi, > > Quoting Christopher Obbard (2025-08-25 21:13:23) > > Package: wnpp > > Severity: wishlist > > Owner: Christopher Obbard <[email protected]> > > X-Debbugs-Cc: [email protected], Christopher Obbard > > <[email protected]>, Tobias Heider <[email protected]> > > > > Package name : stubble > > Version : v3 > > Upstream Contact: Tobias Heider <[email protected]> > > URL : https://github.com/canonical/stubble > > License : LGPL2.1 > > Programming Lang: C > > Description : UEFI kernel stub with device-tree loading capability > > > > Small Linux kernel EFI boot stub bundling device trees, a CHID database > > and the kernel. The stub finds a matching device tree based on CHIDs > > generated from SMBIOS and loads it before executing the embedded > > kernel. > > > > Booting generic Distro images on ARM64 laptops is quite hard due to > > (currently) no way to tell what hardware the image is running on, or to > > load the correct device tree from the kernel. > > > > Stubble aims to mitigate against this by loading the correct device tree > > for the laptop at runtime. > > > > This package will be useful to build ARM64 Debian images which > > "just-work" on ARM laptops, specifically Qualcomm X-Elite laptops. > > I'm very interested in this as I maintain the Debian integration for the MNT > Reform and MNT Pocket Reform open hardware laptop. They usually boot via > u-boot > and then either /boot/boot.scr or /boot/extlinux/extlinux.conf which are > populated by flash-kernel and u-boot-menu with the correct device tree for the > platform, respectively. We can create images that work on all platforms > supported by MNT by using u-boots $fdtfile option which allows the > platform-specific u-boot binary to select the right device tree from an > otherwise device-agnostic system image. > > I already have a POC for EFI booting with EDK2 but one big downside is, that > using the facilities provided by systemd-ukify, systemd-boot and > systemd-boot-efi creates a binary which has a device-specific dtb baked into > the binary making it device specific. > > If stubble would allow us to create efi stubs which are identical independent > of the platform because they select the dtb "at runtime" then I am extremely > interested in using stubble for the MNT Reform. > > Can you confirm that stubble might be providing the functionality we are > looking for?
Yes, it looks like it will also work perfectly for this use case :-). The idea is to generate a UKI image in the standard systemd-boot way, but with the generic "stubble" stub instead of systemd-boot's stub, kernel, initrd, as well as a list of DTBs to choose from. This UKI image could then be signed with MOK (or signed upstream... but that's a little further down the road I guess). When stubble loads, it detects which DTB to load (currently by matching CHIDs in stubble to what is running on the hardware). Thanks! Chris
