Building (a minimal) Haiku

I’m trying to make progress on Checkfs output topic and get a binary for bfswhich, so I cloned the haiku repository and made a few attempts.
BUT I can’t just run ‘make’ or ‘jam’ into src/bin/bfs_tools/ as jam complains about missing ‘BuildConfig’ into …/…/…/generated/build
OTOH the usual haiku build using ‘jam @nightly-raw’ cannot complete due to disk full error, although should this end successful (in a 32 bit install inside a VM it’s ok), the needed BuildConfig file would appear into the proper dir (and let me build the BFS tools just calling ‘jam’).