New review comment by jjsullivan5196 on void-packages repository

https://github.com/void-linux/void-packages/pull/24072#discussion_r471060505

Comment:
I was thinking of having something like a `/etc/default/cmdline` for specifying boot args, but I didn't want to stray too far from the pinebookpro template. I agree that it would be better to make this more end-user friendly, so I'm willing to try something else.

As for the complicated part, I 100% agree. I tried something a little less hacky by using blkid's `eval` output mode, which just spits out conf style variable assignments eg `PARTUUID=deadbeef` that can be sourced by sh.

I personally think the best approach for flexibility reasons would be to source cmdline arguments from `/etc/default/cmdline` and have this configure hook fill it into the boot script. It sits inline with what `grub-mkconfig` does with `/etc/default/grub`, and `void-mklive` could just append `root=...` when creating base images.