Re: any way to apply tag across all branches in repository?

Brandon Casey wrote:

If I understand you correctly, you are doing your primary development on
the "main" branch and then merging this into the architecture specific
branches which contain additional architecture specific changes.

Correct.

All you need to do is tag the "main" branch.  Actually, you are tagging
the commit that the branch currently points at.  When this branch is
merged into the other branches, they will also contain this commit, and
'git describe' will use the tag you created when generating the version
string.

I think this would work if the most recent commit is on the main branch.

However, if I make a change on the arch-specific branch, then tag the
main branch and merge it into the arch-specific branch, git tells me
the arch-specific branch is already up-to-date and the tag doesn't
get propagated.

Chris