Ubuntu 24.10, Kernel 6.12, and ZFS

Not as straightforward in practice.

So I stumbled across this article on itsfoss detailing how to install the latest mainline kernel on Ubuntu. It seemed simple enough thanks to the 'mainline' application, and I was curious about what the experience of installing a new kernel version was like.

The process of installing the kernel was as simple as clicking 'Install' on the latest entry in the list, but something I hadn't considered was that my root partition uses ZFS.

So after rebooting into my shiny new kernel I was greeted by a BusyBox shell informing me that the ZFS module couldn't be loaded. Running 'modprobe zfs' doesn't return anything, and I'm unable to poll any zpools.

Reverting to my usual 6.11 kernel boots fine, so I start digging a little, and apparently I need the zfs-dkms package because it should support any kernel version.

However, installing the version in the Ubuntu 24.10 repos results in an error when compiling the module for the 6.12 kernel.

So on top of that I needed a newer version of zfs-dkms that supports the 6.12 kernel, and as usual there's a PPA for that.

Installing this PPA allows me to install zfs-dkms without issue, and I'm then able to reboot into the 6.12 kernel.

I've seen this post suggesting that zfs-dkms is no longer needed in Ubuntu and not recommended for use at all, but in my testing just updating to the newer OpenZFS version was not enough for 6.12 to boot, I needed the zfs-dkms package too.

Turns out manually booting to newer kernels can cause issues, who knew.