Add safe Windows firmware extraction for Snapdragon laptops

[birkskyum]

Summary

• Reads firmware names from the running device tree and stages signed vendor files from Windows before installation can overwrite it.
• Installs staged firmware under /usr/lib/firmware/updates.
• Resolves differing variants only through a unique companion-hash match within the exact device-tree node. Byte-identical duplicates are safe; unresolved variants are skipped.
• Continues processing other files when one is missing.
• Includes the board's device-tree-selected GPU zap firmware in the initramfs and rebuilds when that configuration changes, even if no firmware was copied.
• Uses one firmware resolver matching the kernel's plain, zstd and xz search order. Gzip files do not hide missing loadable firmware.

Why matching matters

The Yoga DriverStore contained multiple cdsp_dtbs.elf variants. The working variant's sibling qccdsp8380.mbn matched the installed companion. Newest-file selection was not reliable, and a different remote processor must not supply that match.

Dependencies and landing

• Prerequisites: no other open Snapdragon PR is needed to build this package.
• Enables: firmware installation in Add generic Snapdragon X support on aarch64 omarchy#8672, board-selected GPU firmware inclusion used by Add Lenovo Yoga Slim 7x board support omarchy#8673, and pre-installation staging in Boot and install Omarchy on Snapdragon X ARM64 systems omarchy-iso#129.
• Landing: this can merge and be published before those consumers, independently of the kernel shim in Add linux-aarch64 kernel compatibility shim #222 and reusable workflow in Publish a reusable aarch64 repository artifact #223.

Provenance

Jimmy Van Veen authored the original extractor in JimmayVV/omarchy-pkgs@snapdragon. Birk Skyum added matching and partial-install fixes. Original authorship is preserved.

Validation

• ARM64 regression tests pass for companion matching, node isolation, missing files, identical/conflicting variants, independent zstd/xz selection, gzip rejection, search precedence and configuration-only rebuilds. These tests now run in the existing CI job.
• Native ARM64 makepkg --nodeps build of version 1-4 and archive inspection pass. The September 6 pinned integration build also built and published this package with the kernel shim.
• ShellCheck and whitespace checks pass.
• Firmware extracted from the Yoga's Windows DriverStore started ADSP and CDSP on the physical machine. This revision's extractor changes have not been redeployed there.

[JimmayVV]

Confirming provenance. qcom-firmware-extract is mine. The companion-hash matching is a real improvement. The "newest wins" rule was only ever tested against one driver store. Thanks for catching it.