Hi, Luigi,
Short Answer
After you’ve installed the new firmware image, delete /legato/mntLegatoVersion and reboot.
root@swi-mdm9x15:~# rm /legato/mntLegatoVersion
root@swi-mdm9x15:~# reboot
Or: After you’ve installed the new firmware image, stop Legato, delete everything under /mnt/flash/legato and reboot.
root@swi-mdm9x15:~# legato stop
Stopping Legato...
DONE.
root@swi-mdm9x15:~# rm -rf /mnt/flash/legato/*
root@swi-mdm9x15:~# reboot
Long Answer
Your module (and other Qualcomm 9x15-based modules by Sierra Wireless) have 2 places where Legato systems are installed:
- On the writeable flash file system mounted at
/mnt/flash, under the legato directory (which is also bind-mounted at /legato). This can hold up to two Legato systems at the same time (one “good” and one “trying”), and is where the files are kept that indicate the statuses of the installed systems, among other things.
- On a read-only flash file system mounted at
/mnt/legato.
When you install a firmware image “containing Legato”, it replaces your /mnt/legato system.
Every time you boot, the init scripts will run the start program in /mnt/legato. This program will check to make sure that /mnt/flash/legato (aka /legato) is set up properly before launching /legato/systems/current/bin/supervisor.
If you have nothing in /mnt/flash/legato yet, then the start program will create a new /mnt/flash/legato/ directory and create a bunch of symlinks pointing to the files it needs on /mnt/legato. When this is all set up, it will copy /mnt/legato/system/version to /mnt/flash/legato/mntLegatoVersion (you’ll see why in a minute) before starting /mnt/flash/legato/systems/current/bin/supervisor.
At this point, if you were to reboot, the start program can see that /mnt/legato/system/version is the same as /mnt/flash/legato/mntLegatoVersion, so it knows that it doesn’t have to install that system into /mnt/flash/legato this time.
Later, when you use the update tool to install a new system, it will be installed into /mnt/flash/legato and Legato will shut down. The start program sees that Legato shut down cleanly due to an update, selects this new system to be the “current” system, and runs it.
Again, if you were to reboot now, the start program can see that /mnt/legato/system/version is the same as /mnt/flash/legato/mntLegatoVersion, so it knows that it doesn’t have to install that version of Legato into /mnt/flash/legato. This ensures that your new updated version of Legato doesn’t get replaced with whatever is in /mnt/legato on reboot.
If you were to now replace /mnt/legato with a different Legato system and reboot, the start program would see that /mnt/legato/system/version is different than /mnt/flash/legato/mntLegatoVersion and know that it has to install that new Legato system from /mnt/legato (finishing that by copying /mnt/legato/system/version to /mnt/flash/legato/mntLegatoVersion).
The problem you’re running into is that you’ve replaced /mnt/legato with exactly the same image you had in there before. So, when the start program runs, it sees that /mnt/legato/system/version is the same as /mnt/flash/legato/mntLegatoVersion, and it ignores /mnt/legato, keeping your “current” system at your 17.06-based version.
If you delete /mnt/flash/legato/mntLegatoVersion (or change it in any way, really) and reboot, the start program will see a mismatch between /mnt/legato/system/version and /mnt/flash/legato/mntLegatoVersion and will install the system from /mnt/legato (copying over configuration settings and other writeable files for apps that have not been removed between versions).
Of course, if you delete everything under /mnt/flash/legato, then this will be an even cleaner reset back to the old “factory” state, because any persistent app-specific settings will also be removed. But, don’t delete everything under /mnt/flash, because you could wipe out some other factory settings unrelated to Legato.
I hope this demystifies this a bit for you.
Cheers,
–Jen