I ran `sudo rpi-update` on my 3B+ 16.04.5 ubuntu Mate installation

Support & Help Requests Raspberry Pi
#1

I ran sudo rpi-update on my 3B+ 16.04.5 ubuntu Mate installation before reading that it might be unwise to do so and could possibly cause instability. It upgraded my kernel from 4.14.79-v7+ to 4.14.90-v7+. I am booting this Pi from sd card and running ubuntu Mate on an usb external ssd.

Everything seems to be running ok so far with the 4.14.90-v7+ kernel. Since I am booting from sd card it would be easy for me to revert back to the original 4.14.79-v7+ kernel.

I have 2 questions about this situation:

  1. If there are no obvious issues with the new kernel, is there any reason to go back to the original one?
  2. Since I am booting from sd card, is it safe to believe that all of the new updated kernel files are located in the PI_BOOT folder on the sd card and not in the PI_ROOT folder on the SSD drive?
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#2

If the kernel runs without any issue, there’s no need to downgrade. Still, I would advise against running rpi-update in the future because it can download an unstable kernel that may cause functionality issues.

rpi-update installs the new kernel on the FAT partition, which in this case, is indeed PI_BOOT.

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#3

rpi-update also updates the kernel modules under /lib/modules, /opt/vc, and potentially /lib/firmware/brcm all on the PI_ROOT partition.

However, if you’re asking this question specifically to see if you can toggle kernel versions by only restoring files under PI_BOOT, that approach is usually okay. Multiple versions of the kernel modules accumulate side-by-side under /lib/modules without conflicts so you need not restore files there.

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#4

Thank you code_exec and jdonald for your replies. I decided to revert back to the 4.14.79-v7+ kernel. I had a backup of the PI_BOOT folder from the sd card and a recent image of the ssd. Gotta love win32diskimager and etcher.