@@ -398,7 +398,11 @@ urbit -F zod
398398
399399### `-g, --gc`
400400
401−Set GC flag, dumping garbage collector logs to stdout.
401+Set GC flag, dumping garbage collector logs to stdout. This runs a GC pass at
402+the end of every virtualized computation. This is intended as a runtime
403+developer/QA tool for verifying refcounts. This currently only works if the
404+binary was built with `MEMORY_DEBUG` (which changes allocation structures and
405+produces incompatible snapshots).
402406
403407- Undocked: `urbit -g [pier]`
404408- Docked: `[pier]/.run -g`