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
Put the $(LIBFLAGS) after lgainscalecalc.
The linker command line is position dependent. Placing the -lm after your library will cause the linker to use libm.a to resolve references your library uses.
Related
I'm writing a small study project in C. I need to create a dynamic library and configure its use with macros. First, I create object files with the command:
$gcc -fPIC -c ../data_module/data_process.c
$gcc -fPIC -c ../data_libs/data_stat.c
Then I create a dynamic library like this:
$gcc -shared -o data_process.so data_process.o data_stat.o
And finally I build an executable file using this library:
$gcc main_executable_module.o ../data_libs/data_io.o ../yet_another_decision_module/decision.o -L. data_process.so -o test_main
It works and the executable works correctly. But there is a task to configure the library using macros:
Make the necessary changes to the code of the main_executable_module, configuring the use of the dynamic library using macros.
That is, if I understand correctly, you need to add macros to the main_executable_module.o so that you do not use the -L flags during assembly. But I can't find information anywhere on how to do it. Can you please tell me how to implement this or where can I read about it?
UPD: John Bollinger says
It is possible that the word "macros" is intended to be interpreted as makefile macros, which many people instead call (makefile) "variables". That would make this a question about make / makefiles, not about C.
My Makefile:
CC=gcc
LDFLAGS=
CFLAGS=-c -Wall -Wextra -Werror
SOURCES=main_executable_module.c ../data_libs/data_stat.c ../data_libs/data_io.c ../yet_another_decision_module/decision.c ../data_module/data_process.c
DYNLIB=../data_module/data_process.c
STAT=../data_libs/data_stat.c
BUILDDYN=main_executable_module.c ../data_libs/data_io.c ../yet_another_decision_module/decision.c
OBJECTS=$(SOURCES:.c=.o)
OBJBUILDDYN=$(BUILDDYN:.c=.o)
OBJDYNLIB=data_process.o
OBJDATASTAT=data_stat.o
EXECUTABLE=../../build/main
DEXECUTABLE=../../build/Quest_6
DLIBS=data_process.so
all: $(SOURCES) $(EXECUTABLE)
data_stat.a: $(OBJLIB) $(LIBS)
ar -rcs $(LIBS) $(OBJLIB)
data_process.so: $(OBJDYNLIB) $(OBJDATASTAT)
$(CC) -shared -o $(DLIBS) $(OBJDYNLIB) $(OBJDATASTAT)
$(OBJDYNLIB): $(DYNLIB)
$(CC) -fPIC -c $(DYNLIB)
$(OBJDATASTAT): $(STAT)
$(CC) -fPIC -c $(STAT)
build_with_dynamic:$(OBJECTS) $(EXECUTABLE)
$(CC) $(OBJBUILDDYN) -L. $(DLIBS) -o $(DEXECUTABLE)
$(EXECUTABLE): $(OBJECTS)
$(CC) $(LDFLAGS) $(OBJECTS) -o $#
.c.o:
$(CC) $(CFLAGS) $< -o $#
clean:
rm -rf $(EXECUTABLE) $(OBJECTS)
lclean:
rm -rf $(LEXECUTABLE) $(OBJECTS) $(LIBS) $(DEXECUTABLE)
rebuild: clean $(SOURCES) $(EXECUTABLE)
The results of the checks revealed nothing. There are two opinions about this task.
Leave everything as above. And in the file itself, add a header process.h. Then everything is assembled and working. And at the same time, if you change the code in the library, rebuild it, and do not rebuild the executable file, then the changes will be taken into account. That is, the idea of a dynamic library is respected.
Implement in such a way that there is no need to include headers in the main_executable_module.c. Then a special library is used for working with dynamic libraries, which allows you to write the path to the library and take individual functions from it. More about it here.
What was meant when it was said about macros, I still did not understand ...
I have program (in fortran) where I'm using three custom modules, which make use of LAPACK. Until now I've compiled my program using the following shell script:
filestring="main"
gfortran -c mod_exp.f90 mod_genmat.f90 mod_print.f90 $filestring.f90
gfortran mod_exp.o mod_genmat.o mod_print.o $filestring.o -llapack -lblas
rm mod_exp.o mod_genmat.o mod_print.o $filestring.o exponentiate.mod genmat.mod printing.mod printing_subrtns.mod
mv a.out $filestring
Since I've been using more and more modules and different programs using them, I've decided to start using makefiles. Following a tutorial, I managed to write the following:
FC = gfortran
FFLAGS = -Wall -Wextra -llapack -lblas #-fopenmp
SOURCES = mod_print.f90 mod_genmat.f90 mod_exp.f90 main.f90
OBJ = ${SOURCES:.f90=.o} #substitute .f90 with .o
%.o : %.f90 #creation of all *.o files DEPENDS on *.f90
$(FC) $(FFLAGS) -c -O $< -o $#
main: $(OBJ)
$(FC) $(FFLAGS) -o $# $(OBJ)
clean:
#rm -f *.o *.mod main
However, when executing make, it says that the LAPACK functions are not recognized. One such mistake is the following:
/usr/bin/ld: mod_exp.o: in function `__exponentiate_MOD_diagun':
mod_exp.f90:(.text+0x37f): undefined reference to `zgees_'
...
collect2: error: ld returned 1 exit status
One possible mistake I've seen is that I need to specify the location of the libraries. However, it would seem strange since I didn't need to do it before; also, I don't know how to find it.
Please show the link command that make invoked, that caused the error to be generated.
I'm confident that if you cut and paste that exact command line to your shell prompt, you will get the same error you see when make runs it. So the problem is not make, but your link command.
The problem is that you have put the libraries before the objects in the link line. Libraries should come at the end, after the objects, else when the linker examines the libraries it doesn't know what symbols will need to be included (because no objects have been parsed yet to see what symbols are missing).
This is why LDLIBS is traditionally a separate variable:
FC = gfortran
FFLAGS = -Wall -Wextra #-fopenmp
LDLIBS = -llapack -lblas
SOURCES = mod_print.f90 mod_genmat.f90 mod_exp.f90 main.f90
OBJ = ${SOURCES:.f90=.o} #substitute .f90 with .o
%.o : %.f90 #creation of all *.o files DEPENDS on *.f90
$(FC) $(FFLAGS) -c -O $< -o $#
main: $(OBJ)
$(FC) $(FFLAGS) -o $# $(OBJ) $(LDLIBS)
I was trying to compile statically cpp-netlib and rpclib for ARM device.(Same as ZEDboard)
Everything i did is changed the compiler and system settings in CMakeLists.txt file.
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)
set(CMAKE_SYSROOT /home/a/buildroot-2018.05/output/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/)
set(tools /home/a/buildroot-2018.05/output/host/bin/)
set(CMAKE_C_COMPILER ${tools}arm-buildroot-linux-uclibcgnueabihf-gcc)
set(CMAKE_CXX_COMPILER ${tools}arm-buildroot-linux-uclibcgnueabihf-g++)
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
After Makefile is created by cmake i ran make and no output has been produced. As i understand build directories should appear.
For the rpclib things went better. It has compiled the librpc.a file but unftunately its not linking to my program.
arm-buildroot-linux-uclibcgnueabihf-g++ -I/home/a/rpclib/include/ -Xlinker -static /home/a/rpclib/librpc.a main.cpp
produces this output:
/home/a/buildroot-2018.05/output/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/bin/ld: cannot find -lgcc_s
/home/a/buildroot-2018.05/output/host/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/6.4.0/../../../../arm-buildroot-linux-uclibcgnueabihf/bin/ld: cannot find -lgcc_s
collect2: error: ld returned 1 exit status
but there is gcc_s in the sysroot directory.
~/buildroot-2018.05/output/host/arm-buildroot-linux-uclibcgnueabihf$ find ./ -name *gcc_s*
./sysroot/lib/libgcc_s.so
./sysroot/lib/libgcc_s.so.1
./sysroot/usr/include/boost/asio/detail/gcc_sync_fenced_block.hpp
./sysroot/usr/include/boost/atomic/detail/caps_gcc_sync.hpp
./sysroot/usr/include/boost/atomic/detail/ops_gcc_sync.hpp
./sysroot/usr/include/boost/atomic/detail/ops_gcc_sparc.hpp
./sysroot/usr/include/boost/atomic/detail/caps_gcc_sparc.hpp
./sysroot/usr/include/boost/smart_ptr/detail/sp_counted_base_gcc_sparc.hpp
./lib/libgcc_s.so
./lib/libgcc_s.so.1
I guess i am missing something important about cross-compilation.
So basically i have 3 questions:
Can you suggest some resources about cross-compilation for embdedd devices?
How to compile cpp-netlib?
How to link already compiled librpc?
Actually buildroot supports building static libraries.
Steps to build a custom library using buildroot:
Create a folder inside buildroot/package folder with the name of target library.
e.g. my path looks like this /home/a/buildroot-2018.05/package/rpclib
Create Config.in file in target library dir with the needed parameters which can be checked in buildroot manual or better
Create [package-name].mk
Then add entry in /buildroot/package/Config.in
Then package can be marked for installation in menuconfig/target pacckages
My Config.in file for rpclib
config BR2_PACKAGE_RPCLIB
bool "rpclib"
depends on BR2_INSTALL_LIBSTDCPP
depends on BR2_USE_WCHAR
help
rpclib is a modern C++ msgpack-RPC server and client library
http://rpclib.net
My rpclib.mk file
RPCLIB_VERSION = v2.2.1
RPCLIB_SITE = $(call github,rpclib,rpclib,$(RPCLIB_VERSION))
RPCLIB_INSTALL_STAGING = YES
RPCLIB_INSTALL_TARGET = NO
RPCLIB_CONF_OPTS = -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF
$(eval $(cmake-package))
And entry in Config.in in the buildroot/packages dir
source "package/rpclib/Config.in"
After executing make i received
./output/host/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/lib/librpc.a
Working in my little beatle (https://gitlab.com/melviso1/beatle) I have a custom makefile for building rpclib without using cmake stuff (I apologize but I really hate cmake and similar tools). Maybe that can help.
Put it in the root of rpclib for building, clean or install. Please review tabs in the following script, because my pasting here can make some loses.
I used this to compile rpclib inside arm. For cross-compiling you could edit and change build tools.
CXXFLAGS=-std=c++0x -O3 -pthread -DASIO_STANDALONE -DRPCLIB_ASIO=clmdep_asio -DRPCLIB_FMT=clmdep_fmt -DRPCLIB_MSGPACK=clmdep_msgpack -Wall
INCLUDE=-Iinclude -I./dependencies/include
OBJS=obj/format.o obj/posix.o obj/client.o obj/client_error.o obj/response.o obj/server_session.o obj/dispatcher.o obj/optional.o obj/rpc_error.o obj/server.o obj/this_handler.o obj/this_server.o obj/this_session.o
all: obj librpc.a
obj:
mkdir -p obj
librpc.a: $(OBJS)
ar -r -s librpc.a $(OBJS)
obj/format.o: dependencies/src/format.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./dependencies/src/format.cc -o obj/format.o
obj/posix.o: dependencies/src/posix.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./dependencies/src/posix.cc -o obj/posix.o
obj/client.o: lib/rpc/client.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/client.cc -o obj/client.o
obj/client_error.o: lib/rpc/detail/client_error.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/detail/client_error.cc -o obj/client_error.o
obj/response.o: lib/rpc/detail/response.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/detail/response.cc -o obj/response.o
obj/server_session.o: lib/rpc/detail/server_session.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/detail/server_session.cc -o obj/server_session.o
obj/dispatcher.o: lib/rpc/dispatcher.cc
g++ $(CXXFLAGS) $(INCLUDE) -c ./lib/rpc/dispatcher.cc -o obj/dispatcher.o
obj/optional.o: lib/rpc/nonstd/optional.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/rpc_error.o: lib/rpc/rpc_error.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/server.o: lib/rpc/server.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/this_handler.o: ./lib/rpc/this_handler.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/this_server.o: lib/rpc/this_server.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
obj/this_session.o: ./lib/rpc/this_session.cc
g++ $(CXXFLAGS) $(INCLUDE) -c $< -o $#
install:
cp -rf include/rpc /usr/local/include/
cp librpc.a /usr/local/lib/
uninstall:
rm -rf /usr/local/include/rpc
rm /usr/local/lib/librpc.a
clean:
rm -f librpc.a
rm -f obj/*
.PHONY: obj clean install uninstall`
So I have been searching and looking for something that could help me with the Makefile, but I did not find anything, so thats why I am here.
My makefile right now is like this:
CC = gcc
CFLAGS = -Wall
LDFLAGS += -L$(LIBB)
LDFLAGS += -static lib1.h
LDLIBS = -lm -lpthread -lrt -l
SOURCES=lib1.c prac3.c prac3_reader.c
LIBRARIES=lib1.o
INCLUDES=lib1.h
PROGRAMS=prac3 prac3_reader
all: $(OBJS) $(PROGRAMS)
$(PROGRAMS): $(LIBRARIES) $(INCLUDES)
$(CC) $(LDFLAGS) $(LIBRARIES) $(LDLIBS) $#.o -o $#
%.o: %.c $(INCLUDES)
$(CC) $(CFLAGS) -o $# -c $<
clean:
rm -rf *.o *~ $(PROGRAMS)
I know there are probably a lot of things that can be removed, but I do not really know which ones are. I have two programs called
prac3.c
and
prac3_reader.c
Also, I have my own library called
lib1.c
and also compiled like
lib1.h
When I go to my directory with the terminal and use the command make I recive this error:
gcc -L -static lib1.h lib1.o -lm -lpthread -lrt -l prac3.o -o prac3
/usr/bin/ld: no se puede encontrar -lprac3.o
collect2: error: ld returned 1 exit status
Makefile:15: recipe for target 'prac3' failed
make: *** [prac3] Error 1
I am running on Ubuntu.
The -l flag expects an argument. When it is combined in the gcc statement it causes the prac3.o argument to be considered as the name of a library. There is no such library prac3.o, so you get the error.
In general .o files aren't "libraries". They are object files. Remove the -l flag and you will be fine.
"libraries" are generally .a or .so files from a library path - but even then, you wouldn't specify the suffix (.e.g "-lpthreads").
I want to compile a very basic hello world level Cuda program under Linux. I have three files:
the kernel: helloWorld.cu
main method: helloWorld.cpp
common header: helloWorld.h
Could you write me a simple Makefile to compile this with nvcc and g++?
Thanks,
Gabor
I've never heard of Cuda before, but from the online documentation it looks as if X.cu is supposed to be compiled into X.o, so having helloWorld.cu and helloWorld.cpp is not a good idea. With your permission I'll rename the "kernel" helloKernel.cu, then this should work:
NVCC = nvcc
helloWorld.o: helloWorld.cpp helloWorld.h
$(NVCC) -c %< -o $#
helloKernel.o: helloKernel.cu
$(NVCC) -c %< -o $#
helloWorld: helloWorld.o helloKernel.o
$(NVCC) %^ -o $#
(Note that those leading spaces are tabs.)
If that works, try a slicker version:
NVCC = nvcc
helloWorld.o: %.o : %.cpp %.h
helloKernel.o: %.o : %.cu
%.o:
$(NVCC) -c %< -o $#
helloWorld: helloWorld.o helloKernel.o
$(NVCC) %^ -o $#
Just in case, here's my variant. I use it to compile CUDA projects on Mac, but I think it will suit Linux too. It requires CUDA SDK.
BINDIR = ./ # places compiled binary in current directory
EXECUTABLE := helloWorld
CCFILES := helloWorld.cpp
CUFILES := helloWorld.cu
# an ugly part - setting rootdir for CUDA SDK makefile
# look for common.mk - I don't know where SDK installs it on Linux -
# and change ROOTDIR accordingly
ROOTDIR := /Developer/GPU\ Computing/C/common
include $(ROOTDIR)/../common/common.mk
My version, verbose but transparent:
myapp: myapp.o
g++ -fPIC -o $# $< -L /usr/local/cuda/lib -lcudart
myapp.o: myapp.cu
/usr/local/cuda/bin/nvcc --compiler-options -fno-strict-aliasing \
-I/usr/local/cuda/include \
-DUNIX -O2 -o $# -c $<
matrixMul: matrixMul.o
g++ -fPIC -o $# $< -L /usr/local/cuda/lib -lcudart
# It MUST be named .cu or nvcc compiles as regular C !!! (no __global__)
matrixMul.o: matrixMul.cu
/usr/local/cuda/bin/nvcc --compiler-options -fno-strict-aliasing \
-I/usr/local/cuda/include \
-DUNIX -O2 -o $# -c $<
Here is an example what my current project looks like. As you can see there is a few OpenGL libraries
ce : cudaExample.c cudaExample.h
cp cudaExample.c cudaExample.cu
/usr/local/cuda/bin/nvcc -arch=sm_20 -o ce -lglut -lGL -lGLU -lXext -lXmu -lX11 -lm cudaExample.cu
then run make ce
and ./ce