Hello,
I am trying to build an UBI image for the IPQ807x, but I am failing. What exactly do I need to set up in configuration to get the UBI image?
As of now, not a single ipq807x device is actually supported by OpenWrt yet - so you'd be the first to start developing/ implementing it.
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The incomplete efforts to tackle the Xiaomi AX3600 might provide some guidance.
Check the AX3600 thread, we have things booting on that device (IPQ8071) but wifi and eth are still mostly missing.