Question

I m cross-compiling an application, but linking blows up with an error that it

"cannot find /lib/libc.so.6".

The libc.so.6 that it should be using is the one that sits at /home/work/worldcom/filesys/lib/libc.so.6. What have I got wrong here?

linking libobj.so
arm-none-linux-gnueabi-g++ obj1.o obj2.o obj2.o  -o libobj.so -L/home/work/worldcom/filesys/usr -Wl,-O1 -Wl,-z,defs -Wl,--enable-new-dtags -Wl,--sort-common -Wl,--as-needed -Wl,--hash-style=both -L/home/work/worldcom/filesys -L/home/work/worldcom/filesys/lib -L/home/work/worldcom/filesys/usr/lib -lcurl -shared
/home/lishevita/armv5tel/arm-2009q3/bin/../lib/gcc/arm-none-linux-gnueabi/4.4.1/../../../../arm-none-linux-gnueabi/bin/ld: skipping incompatible /lib/libc.so.6 when searching for /lib/libc.so.6
/home/lishevita/armv5tel/arm-2009q3/bin/../lib/gcc/arm-none-linux-gnueabi/4.4.1/../../../../arm-none-linux-gnueabi/bin/ld: cannot find /lib/libc.so.6
collect2: ld returned 1 exit status<br />
make: *** [libobj.so] Error 1<br />

My makefile is handwritten (i.e. not generated by Autotools). In order to avoid a blanket "your Makefile is broken" here are some details from the makefile that might help clarify.

CROSS_COMPILE = arm-none-linux-gnueabi-  
SYSROOT = /home/work/worldcom/filesys/  
DESTDIR = /home/work/worldcom/filesys/  

RELEASE_CXXFLAGS = -Os  
DEBUG_CXXFLAGS = -O0 -gstabs  
PKGCONFIG=`env ROOT=/home/work/worldcom/filesys cross-pkg-config glib-2.0 libcurl --cflags`  

CC = $(CROSS_COMPILE)gcc  
CXX = $(CROSS_COMPILE)g++  
LD = $(CROSS_COMPILE)ld  
AR = $(CROSS_COMPILE)ar  

LDFLAGS = -Wl,-O1 -Wl,-z,defs -Wl,--enable-new-dtags -Wl,--sort-common -Wl,--as-needed -Wl,--hash-style=both -L$(SYSROOT) -L$(SYSROOT)lib -L$(SYSROOT)usr -L$(SYSROOT)usr/lib -lcurl  

libobj.so: $(LIBOBJ_OBJS)  
        @echo linking $@  
        $(CXX) $^ -o $@ $(LDFLAGS) -shared $(PKG_LIBS)

Of course there is also a definition and target for the LIBOBJ_OBJS but those are irrelevant to the problem.

Answer 1

You didn t indicate what gcc version you are using, but if it is a recent enough one (4.0.0 and above me thinks) you should try adding the --sysroot flag to g++/ld. Point it to $SYSROOT as defined in your Makefile. For example:

--sysroot=$(SYSROOT)

Assuming recent enough gcc version, it will work.

Answer 2

I just went through the same issue; adding --sysroot=/rootfs/prefix helped me get closer to the real issue. I got it fixed by installing package libstdc++-dev in target.

Answer 3

Have you not considered that possibly the LIBPATH is set and hard-coded to look for the /lib/libc.so.6 and therefore the /lib path?

Have you tried to set the environment variable like this on the command line, prior to issuing make when cross-compiling:

LIBPATH=/home/work/worldcom/filesys/lib

In your specific case, as you have mentioned in the tag cross-compiling , it might be worth it to remove any references to /lib to wholly force the linker to look in your own home directory instead as not to interfere with the cross-compile process.

The other possibility is that the gcc compiler when it was built for your environment, the configuration during the building of the compiler from source, was specified to point to the /lib path.

Hope this helps, Best regards, Tom.

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