Canonical recently disclosed plans to support Raspberry Pi 4 and said it would support all Raspberry Pi devices.
With the release of Ubuntu Server 19.10, Canonical announced the official support Raspberry Pi 4, Raspberry Pi 4 strong performance but lower cost, can be integrated computing workloads on the edge.
In a blog, Canonical said it would strive to provide comprehensive support for all the official Raspberry Pi board series, Canonical will provide existing and upcoming Raspberry Pi offers Ubuntu Server and Ubuntu Core support.
Raspberry Pi 4 B has 1GB, 2GB of RAM and 4GB several different options, but, at present the official Canonical supports only 1GB and 2GB versions. Since the kernel error , 4GB RAM version of the official arm64 image does not support USB out of the box. Canonical engineers have determined kernel fixes, patches are being widely tested. Canonical said that after the successful completion of the test, will push updates within weeks.
However, developers can use a temporary workaround to enable USB on 4GB RAM version. Simply edit the file /boot/firmware/usercfg.txt to limit the RAM 3GB, as follows:
total_mem=3072
For more details, check out the official blog:
https://ubuntu.com/blog/roadmap-for-official-support-for-the-raspberry-pi-4