mtracy:

NOTE: FS#3531 appears to be related and having the same issue, but for ipq806x

Hi all, building from master is resulting in unbootable firmware for ath79. The compile completes ok and no errors, but the resulting firmware will not boot on the device. I build from fresh clones of master on a regular basis for well over a year and this is my first time seeing this.

Steps to reproduce:

git clone https://git.openwrt.org/openwrt/openwrt.git
cd openwrt
./scripts/feeds update -a && ./scripts/feeds install -a
make clean (select target Ubiquiti UniFi AC Pro)
make defconfig
make download
make

Same thing happens when compiling for target Ubiquiti UniFi AC LR. Compile completes ok but the firmware won't boot on the unit. Tried both via sysupgrade from an older working OpenWrt build and from a factory restore via mtd write. U-boot on both models is where it should according to the device wiki and both units have been running builds from master for months.

Thinking it may have been some issue with the server I use for the builds (Debian 10), I reinstalled it with Fedora 33 and have the exact same problem with it producing unbootable ath79 builds.

Strangely, building from the same clone of master for ramips (mt7621) and x86_64 produces working bootable firmware.