There was an issue with installing OpenWRT 19.07.2 on the Ubiquiti EdgeRouter X : The new distribution build did not come automaticaly with the usual openwrt-19.07.2-ramips-mt7621-ubnt-erx-initramfs-factory.tar file that allow installing OpenWRT on top of EdgeOS to replace it by OpenWRT within the router.
Using older versions like openwrt-18.06-ramips-mt7621-ubnt-erx-initramfs-factory.tar to reflash the router, and then apply a sysupgrade command with the openwrt-19.07.2-ramips-mt7621-ubnt-erx-squashfs-sysupgrade.bin file was not working either, no matter what version of EdgeOS you had factory installed on the router.
The reason why the new built doesn't come with the usual factory tar file, but with an unusable bin file instead is that the kernel image of this new distribution is too big of a few 200 Kb to fit into the kernel image partition. The make file to make the built has an embedded simple security mecanism to prevent generating incorrect tar file if the kernel is too big, it generates an unusable bin file instead.
I have changed a few compilation option so that the make file can finaly generate a custom 19.07 built that fits the correct kernel partition size and therefore generate a usable tar file.
Once the router under the original EdgeOS is updated with this temporary custom OpenWRT built, you can sysupgrade it with the "Official OpenWRT stock" openwrt-19.07.2-ramips-mt7621-ubnt-erx-squashfs-sysupgrade.bin so that your router goes with OpenWRT "stock official images" ensuring all the repositories and further sysupgrade of this distribution will work as desired.
The following instructions should allow you to apply these custom compilation settings if you intend to compile your own tar image.
I also provide a copy of my own operational custom 19.07 factory image tar file for those who are lazy at recompiling it themselves. You will also find my menuconfig .config configuration file (Named dot.config on my repository, you will have to rename it manualy .config), so that you can copy/past it into your /openwrt directory so that make menuconfig becomes unnecessary, and directly compile the target with make -jXXX (XXX being the number of core/thread of your processor, to speed up compilation) exactly what options were disabled to reproduce this "short receipt".
Here is the detailed procedure to compile an equivalent operational "short receipt" Tar factory image as I have been doing in my previous post.
These things where done under Xubuntu 18.04.2 :
Open a terminal.
Then type the following commands (One of them related to feeds install is doubled because some errors happen on the first launch):
sudo apt-get update
sudo apt-get install subversion g++ zlib1g-dev build-essential git python python3 python3-distutils libncurses5-dev gawk gettext unzip file libssl-dev wget libelf-dev ecj fastjar java-propose-classpath libldap2-dev libcap-dev libidn2-dev liblzma-dev libjansson-dev libpam-dev
git clone https://www.github.com/openwrt/openwrt -b openwrt-19.07
cd openwrt
./scripts/feeds update -a
./scripts/feeds install -a
./scripts/feeds install -a
make menuconfig
Now, from the menuconfig main screen,
- Set Target System to : MediaTek Ralink MIPS
- Set Subtarget to : MT7621 based board
- Set Target Profile to : Ubiquiti EdgeRouter X
Then select Save and accept to save the configuration under the proposed default filename .config and then select Exit until you quit the menuconfig utility and are back to the terminal bash prompt.
From here, enter the following bash commands :
make defconfig
make menuconfig
Go into Global Build Options submenu, and then :
- Set Strip unnecessary export from the kernel image to *
- Set Strip unnecessary functions from libraries to *
From this screen, enter the submenu Kernel build options and then :
- Unset Compile the kernel with debug filesystem enabled
- Unset Compile the kernel with symbol table information
- Unset Compile the kernel with debug information
Then select Exit until you back reach the menuconfig main screen, then select Save , it will propose you to save the configuration under the default filename .config , accept it, and then select Exit until you are back to the terminal bash prompt.
Back to the terminal bash prompt, enter the following commands :
make download
make -jXXX
For the last command above please replace XXX by the number of processor cores your computer has. In my case, I used the command make -j8 because I have an 8 cores computer. If you ignore how many cores your microprocessor has, please just type make alone.
The compilation should take about 10 minutes with 8 cores. Once it is finished, enter the following bash commands :
cd ./bin/targets/ramips/mt7621
ls -al
And you should see the following files :
user@PC:~/openwrt/bin/targets/ramips/mt7621$ ls -al
total 8684
drwxr-xr-x 3 user user 4096 mai 18 14:01 .
drwxr-xr-x 3 user user 4096 mai 18 13:55 ..
-rw-r--r-- 1 user user 335 mai 18 13:55 config.buildinfo
-rw-r--r-- 1 user user 263 mai 18 13:55 feeds.buildinfo
-rw-r--r-- 1 user user 1880 mai 18 14:01 openwrt-ramips-mt7621-device-ubnt-erx.manifest
-rw-r--r-- 1 user user 2938880 mai 18 14:01 openwrt-ramips-mt7621-ubnt-erx-initramfs-factory.tar
-rw-r--r-- 1 user user 2923299 mai 18 14:01 openwrt-ramips-mt7621-ubnt-erx-initramfs-kernel.bin
-rw-r--r-- 1 user user 2990868 mai 18 14:01 openwrt-ramips-mt7621-ubnt-erx-squashfs-sysupgrade.bin
drwxr-xr-x 2 user user 4096 mai 18 14:01 packages
-rw-r--r-- 1 user user 720 mai 18 14:01 sha256sums
-rw-r--r-- 1 user user 18 mai 18 13:55 version.buildinfo
As you can see, there is an openwrt-ramips-mt7621-ubnt-erx-initramfs-factory.tar that was generated. Use this file to update your router from EdgeOS with usual procedures.
Then, update again the router under this temporary OpenWRT 19.07 built with the official stock sysupgrade 19.07.2 bin file from the OpenWRT website, and you're done.