$ make bootstrap
make: 'bootstrap' is up to date.
$ touch bootstrap.bpf.c
$ make bootstrap
BPF .output/bootstrap.bpf.o
GEN-SKEL .output/bootstrap.skel.h
CC .output/bootstrap.o
BINARY bootstrap
$ touch bootstrap.c
$ make bootstrap
CC .output/bootstrap.o
BINARY bootstrap
# working as expected till now
$ touch bootstrap.h
$ make bootstrap
make: 'bootstrap' is up to date.
# change in bootstrap.h doesn't trigger a rebuild