Opened 22 months ago

Last modified 21 months ago

#22289 new defect

OpenWRT fails on UBNT devices. UBNT updated u-boot in AirOS 5.6.X

Reported by: anonymous Owned by: developers
Priority: normal Milestone:
Component: base system Version: Trunk
Keywords: ubnt u-boot Cc:


In late 2015, UBNT released a new AirOS version, 5.6.XX which replaced the existing U-Boot (and mtd layout) from what was used in 5.5.XX. Because of this change, it is not possible to load OpenWRT onto the range of ath7xx UBNT products if they are running 5.6.XX, which is what all UBNT products are now shipping with.

There have been reports of OpenWrt bricking the device when loaded, or in our case, OpenWrt will run, but it is not possible to save any config changes as the memory layout is not correct for OpenWrt.

The workaround is to first install AirOS V5.5.XX on top of 5.6.XX which will replace the U-Boot with what OpenWrt expects (, and then it is possible to load OpenWrt onto the device.

However, I feel we should modify OpenWrt to work with both U-Boots (likely not possible), or update OpenWrt to work with the latest version of U-Boot ( from UBNT so OpenWrt can be loaded directly again.

There is more information here about the changes to the U-Boot and the mtd layout:

See "Special Firmware Note".

Related threads:

Attachments (0)

Change History (2)

comment:1 Changed 21 months ago by anonymous

I checked the changes in the wiki. The needed change in openwrt is a one liner. It would then work on older and newer u-boot. Probably every dev here knows what change is needed and could quickly add it upstream.

comment:2 Changed 21 months ago by anonymous

The flash layout has not changed contrary to what some think. If you see the dmesg output on stock 5.6.x firmware you can see the mtd layout has not changed. Barrier breaker bricks the ubnt devices running 5.6.x due to a bug in the final image generation process where an incorrect firmware length was specified, this seems fixed in CC and trunk. However no settings can be saved, and I believe it's because the newer uboot is only allowing read only access to the root file system data partition, hence every time openwrt boots it's the same as first boot after a flash or factory reset. If ubnt would give access to the source code of their newer uboot, these issues could possibly be resolved, but ubnt insist on keeping it closed source and hence violating the GPL.

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