TL;DR: maybe allow org.zfsbootmenu:kernel to be a glob or regex pattern.

My situation; I have a number of systems which perform tasks like building modules for other systems. In order to achieve this, the kernel sources for the target systems need to be installed and, on some distributions (eg: recent Debian), this also brings in the kernel images for the target systems. However, obviously these might not be bootable on the current system.

I can set the desired kernel in org.zfsbootmenu:kernel of course, but there's a bit of a potential race condition here; if the system reboots before I have the opportunity to correctly set the kernel, there's a chance that an unbootable kernel will be chosen by ZBM's algorithm, necessitating tedious recovery.

If org.zfsbootmenu:kernel were interpreted as a glob or regular expression which filtered the available kernels in the relevant dataset and then chose the last one (ordered by version string), I think that would still be compatible with current usage, but also allow for richer automatic kernel selection.

Suppose for example we had the following kernels installed in /boot:

If I never wanted the current machine to boot any experimental kernels, and also exclude the -cloud- variants, I could set org.zfsbootmenu:kernel to something like *+[bd]*[o0-9]-amd64 and from the list above it would only match the first and thirs, and would pick vmlinuz-6.12.33+deb12-cloud-amd64 as the last in that list.

This might end up a bit inelegant with globs, so regular expressions might be better - maybe if org.zfsbootmenu:kernel begins and ends with / it would be interpreted as a regular expression, so we could set it to /(bpo|deb[0-9]+)-amd64$/ which would be clearer? This would not break any existing usage, as we would never expect to see / in an existing version string.