A couple of days ago, Linus Torvalds announced that the Linux 5.5 stable version is coming soon. Now, there are reports that the stable version of Linux 5.5 is available. Torvalds pointed out in the release announcement that despite the increase in patches this week and concerns about the possible extension of the Linux 5.5 cycle due to downtime around Christmas and New Year holidays, it chose to release the 5.5 kernel on time.
Linux 5.5 brings many changes, including support for Raspberry Pi 4, overclocking AMD Navi GPUs, support for new and upcoming Intel platforms, level 5 paging enabled by default, better than current userspace utilities, NVMe driver temperature driver, support for Chromebook voice wake-up, KUnit for unit testing in the kernel, etc.
This also means that the Linux 5.6 merge window will open immediately. Linux 5.6 appears to be a compelling release, with changes including the addition of WireGuard, initial USB4 support, network improvements, many new hardware features. Linux 5.6 should be released in April, but this is too close for Ubuntu 20.04 LTS, so the upcoming release of Ubuntu Linux is almost certainly based on the 5.5 kernels.
The Linux 5.5 codename is “Kleptomaniac Octopus.” You can read more about the announcement HERE