Defining rule for makefile for making a shared library

Question

I am currently working on a JNI Project where the C part uses local libraries on my NanoPi. Construction of Headers, Implementing it in C and Testing the Wrapper worked fine. Now I tried to add shared library support to my make file and I can't get it to run. Unfortunately I am new to Makefiles and couldn't find a tutorial so far which explains all my needs in detail so I can fix it by myself.

Below you can find the Makefile I constructed so far and which was used for testing the implementation.

DYN_VERS_MAJ=2
DYN_VERS_MIN=0
VERSION=$(DYN_VERS_MAJ).$(DYN_VERS_MIN)

DEBUG   = -O3
CC  = gcc
INCLUDE = -I/usr/local/include -I/usr/lib/jvm/java-1.8.0-openjdk-
armhf/include -I/usr/lib/jvm/java-1.8.0-openjdk-armhf/include/linux
CFLAGS  = $(DEBUG) -Wall $(INCLUDE) -Winline -pipe -fPIC -Wformat=2 

LDFLAGS = -L/usr/local/lib 
LDLIBS  = -lwiringPi -lwiringPiDev -lpthread -lm -lwiringPiPca9685

SRC = pwm_native_PCA9685Native.c
DYNAMIC=libPca9685Native.so.$(VERSION)
OBJ = $(SRC:.c=.o)

BINS =$(SRC:.c=)

all:    $(DYNAMIC)
$(Dynamic): $(OBJ)
        @echo "[Link (Dynamic)]" 
        @$(CC) -shared -Wl,-soname,libPca9685Native.so -o libPca9685Native.so.$(VERSION) -lpthread $(OBJ)

driver: pwm_native_PCA9685Native.o
        @echo [link]
        @$(CC) -o $@ pwm_native_PCA9685Native.o $(LDFLAGS) $(LDLIBS)
.c.o:
        @echo [Compile] $<
        @$(CC) -c $(CFLAGS) $< -o $@
clean:
        @echo "[Clean]"
        @rm -f $(OBJ) *~ core tags $(BINS)
tags:   $(SRC)
        @echo[ctags]
        @ctags $(SRC)
depend: 
        makedepend -Y $(SRC)

The (Dynamic) part is the new added part. All the time I try to run I get the message make: No rule to make target 'libPca9685Native.so.2.0', needed by all. The output is clear to me. A rule is missing to create the so file but I don't know how to add that rule... Help would be really appreciated. Regards Peter

Answer 1

Here:

all:    $(DYNAMIC)
$(Dynamic): $(OBJ)

Makefile variables are case sensitive (even with MinGW gnu make on Windows). So you have to respect casing else $(Dynamic) isn't evaluated properly. Fix:

all:    $(DYNAMIC)
$(DYNAMIC): $(OBJ)

(there may be other issues in your makefile, mind)