In line 13 .include "$(TOP)/mk/os161.config.mk" I've installed OS161 tools and is trying to run OS161 over eclipse and was compiling the dependencies.
# Automatically generated by config; do not edit.
#
# Top of the kernel tree
KTOP=../..
# Top of the whole tree
TOP=$(KTOP)/..
# Debug vs. optimize
KDEBUG=-g
# Name of the kernel config file
CONFNAME=ASST0
.include "$(TOP)/mk/os161.config.mk"
.include "files.mk"
.include "$(TOP)/mk/os161.kernel.mk"