The CM5 DTB (bcm2712-rpi-cm5-cm5io.dtb) lacks the pciex1 alias that
the Pi 5 DTB provides, making dtparam=pciex1_gen=3 silently fail.
Add a custom device tree overlay (pcie-gen3.dtbo) that targets
/axi/pcie@1000110000 directly to set max-link-speed = <3>. The overlay
is embedded in the SBC installer and written to /boot/EFI/overlays/
during install/upgrade.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
