Only a very restricted set of signals allowed?
I read knotd's treatment of signals, i.e.,
src/utils/knotd/main.c in functions
enable_signals() and the callers of those functions. It looks like knotd blocks almost all signals except for a very limited subset like
SIGTERM, which by default do not dump core.
I would recommend also allowing a few more signals that are typically used for debugging, e.g.
SIGQUIT. I recently needed to verify that coredumps would be collected from a running knotd process and the easiest thing to do was to patch knotd to allow a signal like
SIGQUIT that would by default dump core.