I have a C project that won't link correctly, and I suspect it's because of the --as-needed flag passed to the ld program by gcc. Because of that flag, gcc sees any linked library listed as an option before the *.c files as unnecessary, and won't link them.
PREFIX?=/usr/local
CFLAGS=-D_LARGEFILE64_SOURCE=1 -g -Wall -I${PREFIX}/apr/include/apr-1 -I${PREFIX}/apr/include/apr-util-1
LDFLAGS=-lapr-1 -pthread -laprutil-1
all: devpkg
devpkg: bstrlib.o db.o shell.o commands.o
install: all
install -d $(DESTDIR)/$(PREFIX)/bin/
install devpkg $(DESTDIR)/$(PREFIX)/bin/
clean:
rm -f *.o
rm -f devpkg
rm -rf *.dSYM
When I run this makefile I get the following.
cc -D_LARGEFILE64_SOURCE=1 -g -Wall -I/usr/local/apr/include/apr-1 -I/usr/local/apr/include/apr-util-1 -c -o bstrlib.o bstrlib.c
cc -D_LARGEFILE64_SOURCE=1 -g -Wall -I/usr/local/apr/include/apr-1 -I/usr/local/apr/include/apr-util-1 -c -o db.o db.c
cc -D_LARGEFILE64_SOURCE=1 -g -Wall -I/usr/local/apr/include/apr-1 -I/usr/local/apr/include/apr-util-1 -c -o shell.o shell.c
cc -D_LARGEFILE64_SOURCE=1 -g -Wall -I/usr/local/apr/include/apr-1 -I/usr/local/apr/include/apr-util-1 -c -o commands.o commands.c
cc -D_LARGEFILE64_SOURCE=1 -g -Wall -I/usr/local/apr/include/apr-1 -I/usr/local/apr/include/apr-util-1 -lapr-1 -pthread -laprutil-1 devpkg.c bstrlib.o db.o shell.o commands.o -o devpkg
/tmp/ccZcAm9b.o: In function `main':
/home/zach/Desktop/devpkgzed/devpkg.c:14: undefined reference to `apr_pool_initialize'
/home/zach/Desktop/devpkgzed/devpkg.c:15: undefined reference to `apr_pool_create_ex'
/home/zach/Desktop/devpkgzed/devpkg.c:29: undefined reference to `apr_getopt_init'
/home/zach/Desktop/devpkgzed/devpkg.c:31: undefined reference to `apr_getopt'
My issue is that I don't really understand how make is coming up with these commands via the CFLAGS that are set. How can I get the linker options to follow the compilation part instead of the other way around, which is triggering this issue?
Make has built-in rules to compile source files and link executables and libraries. The commands you list are produced by these rules.
The reason this fails for you is that, when linking, libraries should be listed after object files, because the linker does a single pass through its arguments and will discard any symbols that are not unresolved at the time they are seen. To correct it, put your libraries in the LDLIBS variable, not the LDFLAGS variable (i.e. just replace LDFLAGS by LDLIBS). The LDFLAGS variable is meant for non-library options for the linker, such as -L or -shared etc
Related
I'm trying to link a static library archive file (libx/libx.a) with a C code. The library requires 2 flags (-lx -lpthread). After linking the static library my ultimate goal is to create a shared library. I have the following Make file,
rsa-engine: rsa/rsa.c rsa/bignum.c rsa/aes.c rsa/x509parse.c rsa/pem.c
gcc -fPIC -o rsa/rsa.o -c rsa/rsa.c
gcc -fPIC -o rsa/bignum.o -c rsa/bignum.c
gcc -fPIC -o rsa/aes.o -c rsa/aes.c
gcc -fPIC -o rsa/x509parse.o -c rsa/x509parse.c
gcc -fPIC -o rsa/pem.o -c rsa/pem.c
gcc -fPIC rsa-engine.c libx/libx.a -L.libx/ -lx -lpthread -o rsa-engine.o
gcc -shared -o librsa_engine.so -lcrypto rsa-engine.o rsa/rsa.o rsa/bignum.o rsa/aes.o rsa/x509parse.o rsa/pem.o
clean:
rm -f *.o rsa/*.o *.so rsa-engine
After using the make command it produces the following output,
/usr/bin/ld: cannot find -lx
collect2: error: ld returned 1 exit status
Makefile:2: recipe for target 'rsa-engine' failed
make: *** [rsa-engine] Error 1
I found similar questions here. But that did not help. Seems like I can't make the link work. Any help with what I'm doing wrong?
I would like to achieve the same result generated by the following command,
CC := gcc
CFLAGS := -Wall -g -MD -O2 -I ../
LDFLAGS := -lx -lpthread
tests_files := hello
all: $(tests_files)
hello: hello.o ../libx/libx.a
$(CC) $(CFLAGS) -static $(<) -L../libx/ $(LDFLAGS) -o $(#)
It seems that your libx.a is located in libx, yet -L references .libx directory. Anyway, since you reference libx/libx.a directly, you may skip both -L.libx/ -lx and it should link just fine.
When I link the .ld file using gcc I got the following error
/usr/bin/ld: cannot find -lreadline
collect2: error: ld returned 1 exit status
my run.sh scripts contains the following command
rm *.o *.bin *.iso
rm -rf isodir
assemble boot.s file
as --32 boot.s -o boot.o
linking the kernel with kernel.o and boot.o files
gcc -m32 -lunistd -Wno-unused-result -c kernelCheck.c -o kernel.o -std=gnu99 -ffreestanding -flto -O2 -Wall -Wextra -L/usr/lib -fno-exceptions
gcc -m32 -T linker.ld -o MoraWing.bin -ffreestanding -Wl,--build-id=none -O2 -nostdlib boot.o kernel.o -lgcc
grub-file --is-x86-multiboot MoraWing.bin
building the iso file
mkdir -p isodir/boot/grub
cp MoraWing.bin isodir/boot/MoraWing.bin
cp grub.cfg isodir/boot/grub/grub.cfg
grub-mkrescue -o MoraWing.iso ./isodir
run it in qemu
qemu-system-x86_64 -cdrom MoraWing.iso
You need to install libreadline-dev, or a similar package suitable for your system (you should also specify what your system is).
During installation of pintos, I had to run make.
Following is the Makefile.
all: setitimer-helper squish-pty squish-unix
CC = gcc
CFLAGS = -Wall -W
LDFLAGS = -lm
setitimer-helper: setitimer-helper.o
squish-pty: squish-pty.o
squish-unix: squish-unix.o
clean:
rm -f *.o setitimer-helper squish-pty squish-unix
In one computer it executed correctly. (output for the command is given below)
gcc -Wall -W -c -o setitimer-helper.o setitimer-helper.c
gcc -lm setitimer-helper.o -o setitimer-helper
gcc -Wall -W -c -o squish-pty.o squish-pty.c
gcc -lm squish-pty.o -o squish-pty
gcc -Wall -W -c -o squish-unix.o squish-unix.c
gcc -lm squish-unix.o -o squish-unix
but in other computer I got the following error
gcc -lm setitimer-helper.o -o setitimer-helper
setitimer-helper.o: In function `main':
setitimer-helper.c:(.text+0xc9): undefined reference to `floor'
collect2: error: ld returned 1 exit status
<builtin>: recipe for target 'setitimer-helper' failed
make: *** [setitimer-helper] Error 1
If looked at first line of outputs of both make commands
gcc -Wall -W -c -o setitimer-helper.o setitimer-helper.c
and
gcc -lm setitimer-helper.o -o setitimer-helper
They are different.
Why make is executing different commands for the same Makefile? and What should I do to remove error?
In the first computer, the setitimer-helper.o file either doesn't exist or the setitimer-helper.c file is newer, so make needs to rebuild it. Thus it runs the compiler, then afterwards it performs the link operation:
gcc -Wall -W -c -o setitimer-helper.o setitimer-helper.c
gcc -lm setitimer-helper.o -o setitimer-helper
On the second computer, the setitimer-helper.o file already exists and is newer than the setitimer-helper.c file, so the compile command was not needed and the second computer proceeded directly to the link line:
gcc -lm setitimer-helper.o -o setitimer-helper
The real question is why you got the linker error on the second computer.
The answer to that is that the -lm flag needs to come on the linker line after the object files. This happens because you added -lm to the LDFLAGS variable which is not the right one: that should contain options that tell the linker where to look for files, etc. (for example, the -L option).
Libraries should be added to the LDLIBS variable, not LDFLAGS. Change your makefile to this:
all: setitimer-helper squish-pty squish-unix
CC = gcc
CFLAGS = -Wall -W
LDLIBS = -lm
setitimer-helper: setitimer-helper.o
squish-pty: squish-pty.o
squish-unix: squish-unix.o
clean:
rm -f *.o setitimer-helper squish-pty squish-unix
Your link line will then look like:
gcc setitimer-helper.o -o setitimer-helper -lm
and should work properly.
Last time i asked sth about how to use CLAPACK.
Using CLAPACK undefined reference error
After that i tried to separate everything for a larger project.
Now I have "blitzLA.cpp" "InterfaceCLAPACK.cpp" "InterfaceCLAPACK.hpp"
I could successfully make it work just by calling
g++ -Wall -g InterfaceCLAPACK.cpp blitzLA.cpp -llapack -lblas -lf2c -o blitzLA
But if I do the Makefile, it gives me some errors.. My makefile is shown below.
CC = g++
CFLAGS = -Wall -g
linker = -llapack -lblas -lf2c
blitzLA: blitzLA.o InterfaceCLAPACK.o
${CC} ${CFLAGS} InterfaceCLAPACK.o blitzLA.o -o blitzLA
blitzLA.o: blitzLA.cpp InterfaceCLAPACK.hpp
${CC} ${CFLAGS} ${linker} -c blitzLA.cpp
InterfaceCLAPACK.o: InterfaceCLAPACK.cpp InterfaceCLAPACK.hpp
${CC} ${CFLAGS} ${linker} -c InterfaceCLAPACK.cpp
clean:
rm -rf *.o blitzLA
I guess the problem is where do i leave "-llapack -lblas -lf2c"..Now i get the errors shown below.
g++ -Wall -g -llapack -lblas -lf2c -c blitzLA.cpp
g++ -Wall -g -llapack -lblas -lf2c -c InterfaceCLAPACK.cpp
g++ -Wall -g InterfaceCLAPACK.o blitzLA.o -o blitzLA
InterfaceCLAPACK.o: In function `quantfin::interfaceCLAPACK::SolveLinear(blitz::Array<double, 2>
bunch of things here..
/home/baozi/Dropbox/Linux/LinearAlgebra/InterfaceCLAPACK.cpp:64: undefined reference to `dgttrf_'
/home/baozi/Dropbox/Linux/LinearAlgebra/InterfaceCLAPACK.cpp:67: undefined reference to `dgttrs_'
collect2: error: ld returned 1 exit status
make: *** [blitzLA] Error 1
Where do i go wrong.. Help plz
I am using the Boost library in Unix, GCC. I read the following topic: Boost static linking and added -static to my Makefile. However, this does not work.
Here is my Makefile:
all: nbbo
nbbo: nbbo.o reader.o
g++ -static -O3 -ffast-math -funroll-loops -ansi -pedantic-errors -L/usr/lib -lboost_filesystem -lboost_serialization -lboost_iostreams -lz -I /usr/include/boost -o nbbo nbbo.o reader.o
nbbo.o: nbbo.cpp
g++ -static -O3 -ffast-math -funroll-loops -ansi -pedantic-errors -I /usr/include/boost -c -o nbbo.o nbbo.cpp
reader.o: reader.cc reader.h
g++ -static -O3 -ffast-math -funroll-loops -ansi -pedantic-errors -I /usr/include/boost -c -o reader.o reader.cc
clean:
rm *.o
And here is the error message:
nbbo.o: In function `__tcf_10':
nbbo.cpp:(.text+0x3d9): undefined reference to `boost::serialization::extended_type_info::key_unregister() const'
nbbo.cpp:(.text+0x3e3): undefined reference to `boost::serialization::typeid_system::extended_type_info_typeid_0::type_unregister()'
nbbo.cpp:(.text+0x3fb): undefined reference to `boost::serialization::typeid_system::extended_type_info_typeid_0::~extended_type_info_typeid_0()'
etc
Which "UNIX" are you using? Using the -static flag should work fine on linux. But not on OSX. On OSX you have to remove the static flag and give the complete path to the library in order to link statically. I dont know how this would work on other "UNIXes"
eg.
g++ ..... /path/to/your/lib.a ... -o ..