On the Getting Started document (https://review.trustedfirmware.org/plugins/gitiles/hafnium/hafnium/+/HEAD/do...) there's a command listed to get the source code:

git clone --recurse-submodules https://git.trustedfirmware.org/hafnium/hafnium.git && (cd hafnium && f=`git rev-parse --git-dir`/hooks/commit-msg ; curl -Lo $f https://review.trustedfirmware.org/tools/hooks/commit-msg ; chmod +x $f ; for m in `git rev-parse --git-dir`/modules/*; do cp $f $m/hooks/commit-msg; done)

However, on my system it's erroring out because the 'hooks' directory it tries to write to doesn't exist:

% Total    % Received % Xferd  Average Speed   Time    Time     Time  Current                                  Dload  Upload   Total Spent    Left  Speed 100  2174  100  2174    0     0   4221      0 --:--:-- --:--:-- --:--:--  4221 cp: cannot create regular file '.git/modules/driver/hooks/commit-msg': No such file or directory cp: cannot create regular file '.git/modules/project/hooks/commit-msg': No such file or directory cp: cannot create regular file '.git/modules/third_party/hooks/commit-msg': No such file or directory