You do not need that.
The commit message explains two ways to flash WITHOUT knowing the root password:
- First method is using serial cable connection to access the u-boot bootloader, and
- the second method uses failsafe mode to access the router in early boot stage, before root password is needed, and the root password is changed there, so that you can then use root login after a normal boot.
Flash instruction under U-Boot, using UART:
1. tftp 0x80060000 lede-ar71xx-generic-ap90q-squashfs-sysupgrade
2. erase 0x9f050000 +$filesize
3. cp.b $fileaddr 0x9f050000 $filesize
4. setenv bootcmd "bootm 0x9f050000"
5. saveenv && reset
Flash instruction under vendor fimrware, using telnet/SSH:
1. Connect PC with 192.168.1.x address to WAN port
2. Power up device, enter failsafe mode with button (no LED indicator!)
3. Change root password and reboot (mount_root, passwd ..., reboot -f)
4. Upload lede-ar71xx-generic-ap90q-squashfs-sysupgrade.bin to /tmp using SCP
5. Connect PC with 192.168.188.x address to LAN port, SSH to 192.168.188.253
6. Invoke:
- cd /tmp
- fw_setenv bootcmd "bootm 0x9f050000"
- mtd erase firmware
- mtd -r write lede-ar71xx-generic-ap90q-squashfs-sysupgrade.bin firmware
As the advice says, you need to flash using the sysupgarde image. Apparently the recipe for a proper factory firmware has not been found out.
Please read that commit message again, and try to believe it.