Then, this is passing -1 as print_level argument to print_stack_frame.
-1 is not a valid print_level value (it's a regular boolean). But, it
used to be, before
<https://sourceware.org/ml/gdb-patches/2004-04/msg00585.html>.
What happened is that bsd-kvm.c did not exist at the time of that
patch, but went into the tree about a month after, without being
adjusted to the new interface.
Fixed now, exactly as e.g., ocd.c had been adjusted: