Unable to find reference to std library math function inside library

Posted by Alex Marshall on Stack Overflow See other posts from Stack Overflow or by Alex Marshall
Published on 2010-03-18T17:12:59Z Indexed on 2010/03/18 17:41 UTC
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Hello,

I've got several programs that use shared libraries. Those shared libraries in turn use various standard C libraries. ie

Program A and Program B both use Shared Library S. Shared Library S uses std C math. I want to be able to statically link Shared Library S against the standard library, and then statically link Programs A and B against S so that I don't have to be dragging around the library files, because these programs are going to be running on an embedded system running BusyBox 0.61. However, when I try to statically link the programs against Shared Library S, I get an error message from GCC stating :

../lib/libgainscalecalc.a(gainscalecalc.): In function 'float2gs':
[path to my C file].c:73: undefined reference to 'log'

Can somebody please help me out ? The make commands I'm using are below :

CFLAGS += -Wall -g -W
INCFLAGS = -I$(CROSS_INCLUDE)/usr/include  
LIBFLAGS += -L$(CROSS_LIB)/usr/lib -lm

gainscalecalc_static.o: gainscalecalc.c
$(CC) $(CFLAGS) -c $< -I. $(INCFLAGS) -o $@

gainscalecalc_dynamic.o: gainscalecalc.c
$(CC) $(CFLAGS) -fPIC -c $< -o $@

all: staticlib dynamiclib static_driver dynamic_driver

clean:
$(RM) *.o *.a *.so *~ driver core $(OBJDIR)

static_driver: driver.c staticlib
$(CC) $(CFLAGS) -static driver.c $(INCFLAGS) $(LIBFLAGS) -I. -L. -lgainscalecalc -o $@

dynamic_driver: driver.c dynamiclib
$(CC) $(CFLAGS) driver.c -o $@ -L. -lgainscalecalc

staticlib: gainscalecalc_static.o
$(AR) $(ARFLAGS) libgainscalecalc.a gainscalecalc_static.o
$(RANLIB) libgainscalecalc.a
chmod 777 libgainscalecalc.a

dynamiclib: gainscalecalc_dynamic.o
$(CC) -shared -o libgainscalecalc.so gainscalecalc_dynamic.o
chmod 777 libgainscalecalc.so

Edit: Linking against the shared libraries compiles fine, I just haven't tested them out yet

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