Hi Jianan,
The 4.18 kernel is no longer a supported kernel in Ubuntu, since Ubuntu Cosmic/18.10 is 'End of Life' a long time ago.
You have to upgrade to the current HWE kernel (4.18 was the HWE/hardware enablement kernel in the Cosmic timeframe) now it's 5.4, with something like:
$ sudo apt install linux-generic-hwe-18.04
Hope this helps, Mauricio
Hi Jianan,
The 4.18 kernel is no longer a supported kernel in Ubuntu,
since Ubuntu Cosmic/18.10 is 'End of Life' a long time ago.
You have to upgrade to the current HWE kernel (4.18 was the
HWE/hardware enablement kernel in the Cosmic timeframe)
now it's 5.4, with something like:
$ sudo apt install linux-generic- hwe-18. 04
Hope this helps,
Mauricio