extlinux and a bootloader system rewrite

[Lilah Tascheter <lilah@lunabee.space>]

heyall!

I've been working on a large bootloader subsystem rewrite to get
everything working together nicer and support future bootloaders
better. however, extlinux is being a bit of an issue.

extlinux installs its second stage (ldlinux.sys) by copying it into the
root (or boot) filesystem, and then copying the on-disk block offset
into the bootblock first-stage. this relies on the now-heavily
discouraged practice of assuming files just stay in the same physical
spot. it requires special treatment with btrfs, will break if anything
rearranges the file-system, and will most likely never work on disk
images.

it hasn't been updated since 2014 and kinda shows.

a possible solution would be re-implementing its installer and instead
installing ldlinux.sys to a separate partition, or maybe see if it
could re-use GRUB's method of installing in the partition gap or even
editing the disk image installer to work in an losetup'd container or
some shit. but, honestly, I don't know if that would actually help
anyone.

does anyone use extlinux on guix still? would anyone mind if I just nix
it (guix it?) entirely in the patch series? grub supports every case
extlinux would support anyway.

thanks!
leila