Ubuntu 22.04 LTS Planning To Stick With Linux 5.15 By Default
In the discussion over Ubuntu 22.04's GNOME plans, it was mentioned by Sebastien Bacher of Canonical that "the plan is to use 5.15 for the LTS but the oem and hwe variants will get 5.17 as some point."
Thus if that plan sticks, by default would be Linux 5.15 for Ubuntu 22.04 LTS while in 2023 with Ubuntu 22.04.2 LTS would be the new hardware enablement kernel from Ubuntu 22.10 that would provide a fresher kernel, etc. Ubuntu's OEM partners like Dell also have the ability to ship a newer kernel for their latest Linux pre-loaded systems.
Linux 5.15 does make sense for Ubuntu 22.04 in that both are Long-Term Support (LTS) releases. Linux 5.15 LTS debuted though at the end of October with Linux 5.16 having debuted last week and then Linux 5.17 should be out around the end of March. Linux 5.17 would cut too close anyhow to see by default in Ubuntu's 22.04 release, but there is a lot on the table now missing out from the default kernel.
Linux 5.16 brings Alder Lake S graphics enabled by default (we'll probably see Ubuntu's kernel configuration modified to force probe there given its significance), the FUTEX2 futex_waitv system call that will be important for Wine / Steam Play gaming moving forward, I/O optimizations, much more adequate AMD Ryzen 6000 mobile series support, Intel AMX support that will be important for Xeon Sapphire Rapids servers with the Ubuntu LTS release, and many other hardware support additions and improvements. (Similarly, a lot on the table for Linux 5.17.) Some of the fixes / PCI ID additions may get back-ported to Linux 5.15 or carried by Ubuntu's kernel build but likely not any of the big ticket items. It's a never-ending, vicious cycle with all of the drivers part of the kernel and the open-source software continually advancing.
So while Linux 5.15 LTS makes sense for Ubuntu 22.04 LTS from a logistical perspective, Linux enthusiasts in particular and those wanting to run Ubuntu on the very latest Intel/AMD hardware will be best off using a third-party/unofficial kernel build until the new HWE kernels in future Jammy Jellyfish point releases. Thankfully the Ubuntu Mainline Kernel PPA provides convenient mainline kernel builds of Linux 5.16 or Linux 5.17 by the time Ubuntu 22.04 officially ships, among other third-party kernel builds/PPAs. With Canonical wanting to make Ubuntu "the best Linux desktop for gaming" perhaps they will come up with a more endorsed/user-friendly way of running more recent mainline Linux stable releases on Ubuntu, considering the graphics driver benefits and other advantages enthusiasts/gamers will find from the more recent kernels.