Do we normally put examples in etc (that aren't comments in the actual file)? I would expect them to be in usr/share.

Fix

METALOG must be kept in sync so -DNO_ROOT builds keep working fully

Don't add trailing whitespace

Don't add trailing whitespace

Does -B little make sense for FAT? I thought it had a fixed endianness?

Why force it to FAT16?

-D isn't needed when you have no METALOG

Space before \

Use a loop, don't copy paste big chunks of code unnecessarily

Do we need FAT32? I think it just a simple configuration file.

Why does this exist? What purpose does it serve? People are not routinely opening up their ISO to go and read a file on it. And if this is really an important example to have it should be installed by installworld like any other file, and into /usr/share/examples, not /usr/share.

I don't love chucking a directory named like this into the root, but I don't have a good suggestion at the moment for the right path to use

This is currently amd64-only, and only for memstick. The directory should only be created when the corresponding partition is also added, and probably the corresponding partition should be created in more cases too.

FAT12 vs FAT16 vs FAT32 is supposed to be a function of the size of the filesystem. There is a formula in the specification for how to pick which to use. You should therefore leave it up to makefs to automatically pick the right one, rather than force it to use a format that's potentially invalid (even if it can technically otherwise work).

Why the duplication? Just use an expansion for the -D argument that is either -D or empty.

??

Gone from missing the trailing newline to having an extra blank line from what I can tell?

share/bsdinstall/Makefile doesn't exist, you've just dropped a file into the directory that release/ is using, so I don't think this is right.

for ...; do

This indentation is broken. If you're trying to avoid indenting the whole block then invert the condition and continue. Or split out the loop to find the file from the code that actually runs it if present.

config_dir yet -f?

$?

Don't we need this so that bsdinstall.example will be exist in BASEBITSDIR?

Is it fine to add file to artifact in make-memstick.sh? I thought it is a little bit strange. Or should I place the mkdir in other place?