Announced over the summer by Canonical was Stubble as a way to improve the ARM64 experience by providing a minimal UEFI kernel boot stub for loading machine-specific Device Trees embedded within a kernel image. The initial focus with Stubble is on improving the Qualcomm Snapdragon X Elite laptop experience on Ubuntu Linux. Thanks to some granted feature freeze exceptions, the support is ready for Ubuntu 25.10.
Canonical engineers have been working through Stubble over the summer with the Ubuntu X1E Concept images and then getting the integration ready for Ubuntu 25.10 proper. Thanks to feature freeze exceptions, the late changes were permitted into Ubuntu 25.10 and landed over the past week. This is in advance of the official Ubuntu 25.10 release next week.
This Launchpad ticket tracked the feature freeze exception for the Stubble-enabled kernel support. It looks like everything is ready to go and will be interesting to see how the Qualcomm Snapdragon X1 Elite laptop support is on the stock Ubuntu 25.10 ARM64 Desktop ISOs once released next week. My 25.10 development testing from last month can be found in Qualcomm Snapdragon X Elite Linux Performance Improving But Short Of AMD Ryzen & Intel Core Ultra.