I am compiling a demo project.
The project is written for windows and linux. I have written a Makefile. However, I am not sure how to specify the platform the compiler will be compiling on.
I will be compiling on Linux.
In my source file I have this:
#if defined(WIN32)
#include ...
#include ...
#elif defined(LINUX)
#include ...
#include ..
#else
#error "OS not supported"
#endif
My simple Makefile is this. And when I compile I get the error "OS not supported".
How can I add the directive so that it will compile with the #elif defined(LINUX).
LIBS_PATH = -L/usr/norton/lib
INC_PATH = -I/usr/norton/include
LIBS = -lntr
app: *.cpp *.h Makefile
g++ $(LIBS_PATH) $(INC_PATH) *.cpp -o app
Many thanks for any suggestions,
Decide which is going to be your default platform - say LINUX.
LIBS_PATH = -L/usr/norton/lib
INC_PATH = -I/usr/norton/include
LIBS = -lntr
PLATFORM = -DLINUX
CXX = g++
app: *.cpp *.h Makefile
${CXX} ${CFLAGS} ${PLATFORM} ${INC_PATH} *.cpp -o $# ${LIBS_PATH} ${LIBS}
You can use round brackets in place of braces. This uses a macro for the C++ compiler, allows you to add other flags via CFLAGS (though that is also usually set by 'make'), and adds a platform, the include path, the library path and the actual library to the compile line.
Note that your rule enforces a complete recompilation of everything every time anything changes. This is 'safe' but not necessarily efficient. Note that wild-cards are dangerous too - more so for the source than the headers. You may include that backup copy of a file in the build (old-reader.cpp - you only wanted reader.cpp in there really). More conventionally, you list the object files needed for the program so that each object file can be individually rebuilt when needed, and the results linked together. If you get your dependencies correct (a moderately big 'if'), then there's no problem. If you get them wrong, you can end up with inconsistent programs.
However, if the difference is between a 5 second recompile and a 5 minute recompile, you should probably take the 5 minute recompilation (as shown) and answer another SO question while waiting.
To compile on Linux (64-bit):
make CFLAGS="-m64"
To compile on Linux (32-bit):
make CFLAGS="-m32"
To compile on Windows 64:
make PLATFORM=-DWIN64
To compile on Windows 32:
make PLATFORM=-DWIN32
Etc.
You can add -DLINUX=1 when compiling.
Also, if you run:
echo "" | cpp -dD
You can see the list of default #define when compiling. In linux, there will always be a:
#define __linux__ 1
in the output. So if you change your LINUX by the above #define, you don't need to do anything special. Ie:
...
#elif defined(__linux__)
...
As for the Makefile itself, I would do something like:
CXX=g++
CPPFLAGS = -I/usr/norton/include
LDFLAGS = -L/usr/norton/lib -lntr
OBJ_FILES = one.o two.o
app: $(OBJ_FILES) Makefile
one.o: one.cpp one.h
two.o: two.cpp two.h
So the implicit rules are used.
Related
I have a project directory structure of:
Root
Source
Common
MyFolder
++ My 3 source files and header
When I am building my project it generates 3 to 4 shared libraries. Lib1 compiled using c++98 and others using c++11. Flags are added in CmakeList.txt which is at root.
I need my 3 source files to be compiled for Lib1 and for other Libs as as well. but here what happens is compiler is first compiling my source file for lib using c++11 and then it is trying to use same .o file for Lib1 as well. So for .o file which is generated using c++11 is throwing exception when same is used for c++98 compiled library.
So how do write this in CmakeList.txt such that compiler rather than trying to use same .o file will compile source file again for Lib1(c++98 compiled library)
Is there any flag I can specify so that it won't take precompiled .o file and will compile it again ?
Here flags are not being overridden for different shared libraries but actually same object file by make file is being used for different flags
This is sort of counter to how makefiles and cmake usually work.
Most users consider it really important that make performs an incremental build.
The usual way with makefiles is to do make clean which is supposed to remove any binaries and object files that were created.
However, sometimes I write cmake scripts that use globbing over the source directory to assemble the project. (That means, it says "just grab all *.cpp files in the /src folder and make an executable from them".) A makefile cannot check what files in a directory, so the make build will be broken after I add a new file, and make clean won't fix it -- the whole makefile will need to be regenerated by cmake.
Usually what I do is, I write a simple bash script, named rebuild.sh or something,
#!/bin/bash
rm -rf build
mkdir build
cd build
cmake ..
make -j3
./tests
And I put that in the root of my repository, and add /build to my .gitignore. I call that when I want to do a full rebuild -- it nukes the build directory, so its foolproof. When I want an incremental rebuild, I just type make again in the /build directory.
The rebuild.sh script can also serve a double purpose if you use travis-ci for continuous integration.
Most build system assume the compiled objects remain the same within the same pass. To avoid shooting your foot I would suggest telling the build system they were actually different objects, while still compiled from same source files.
I'm not familiar with cmake but this is how you do with make:
For example you have a a.cpp which you want to compile 2 times for different compiler options:
#include <stdio.h>
int main(int argc, char* argv[]) {
printf ("Hello %d\n", TOKEN);
return 0;
}
And the Makefile would looks like:
SRC := $(wildcard *.cpp)
OBJ_1 := $(patsubst %.cpp,%_1.o,$(SRC))
OBJ_2 := $(patsubst %.cpp,%_2.o,$(SRC))
all: pass1 pass2
pass1: $(OBJ_1)
gcc -o $# $(OBJ_1) -lstdc++
pass2: $(OBJ_2)
gcc -o $# $(OBJ_2) -lstdc++
%_1.o: %.cpp
gcc -DTOKEN=1 -c $< -o $#
%_2.o: %.cpp
gcc -DTOKEN=2 -c $< -o $#
clean:
rm -f $(OBJ_1) $(OBJ_2)
What I do here is generate two different list of object from the same source files, which you can even do the same for dependency(-MMD -MP flags).
I have a project with multiple files.. I want to compile it using gcc from command line.
the directory looks like this
lib/
Comp/ contains .cpp files
Decomp/ contains .cpp files
Globals.cpp
include/
Comp/ contains .h files
Decomp/ contains .h files
Globals.h
some of these .h files are not paired with .cpp files
to compile this i use something like this :
g++ lib/Comp/* lib/Decomp/* lib/Globals.cpp -std=c++0x -o TEST
the problem is,I have to add some #defines for each .h file and i have to do it through command line. how to do this ??
also if i had to compile each file on its own and then link them. what would be the appropriate order for doing this ?
The dirtiest ugliest way is that you want to use something like:
g++ -Iinclude lib/Comp/*.cpp lib/Decomp/*.cpp lib/Globals.cpp -o test
Your .cpp files should #include <Comp/foo.h> or whatever
The correct way to manage this is to use a makefile to build each object file and then link them together:
Makefile
Create a a file called Makefile and put the following in it:
CXX=g++
CPPFLAGS=-Iinclude -DFOO -DBAR=1 -DSOME_STRING=\"My Name\"
CXXFLAGS=-O2 -g
SOURCES=lib/Comp/file1.cpp \
lib/Comp/file2.cpp \
lib/Comp/file3.cpp \
lib/Decomp/file1.cpp \
lib/Decomp/file2.cpp \
...
OBJ=$(SOURCES:%.cpp=%.o)
default: test
test: $(OBJ)
<tab> $(CXX) -o $# $(OBJ)
%.o: %.cpp
<tab> $(CXX) $(CPPFLAGS) $(CXXFLAGS) -o $# -c $<
NOTES
Replace file1.cpp etc. with the actual filenames in your project. DO NOT include headers in SOURCES only your .cpp or .cc files
If you are using sub-paths like #include <Comp/foo.h> or #include "Comp/foo.h" in your source files then you only need to use -Iinclude in CPPFLAGS but if you are doing something like "foo.h" and foo.h is actually in include/Comp/ then add -Iinclude/Comp and -Iinclude/Decomp to the CPPFLAGS
Where it says <tab> make sure you use the TAB key to insert a tab (don't type the word '')
Before using this Makefile blindly . Know that it will NOT work as is you have to correct the entries. It is offered as a starting point... Read up on writing Makefiles ... http://frank.mtsu.edu/~csdept/FacilitiesAndResources/make.htm has a good introduction
Defines can be provided on the compiler command line using -DVAR=VALUE (on Windows, presumably /DVAR=VALUE). Note that you can not provide different defines for different headers as in:
compiler -DX=one first.h -DX=two second.h third.cc -o third.o
In such a case, my compiler spews warning and uses the last value of X for all source code.
Anyway, in general you should not list header files on the compilation line; prefer to include them from the implementation files (.cc/.cpp or whatever) that need them.
Be careful too - if you're changing defines to modify class definitions, inline function implementation etc. you can end up with technically and/or practically undefined behaviour.
In terms of how best to decide which objects to create and link - you probably want one object per .cc/.cpp file. You can link those objects then specify them on the command line when compiling the file containing main().
I've been attempting to make a folder for each architecture my code can support. In this folder are platform specific files to include. I include them as follows:
#define STR(x) #x
#define ASSTR(x) STR(x)
#include ASSTR(ARCHITECTURE/sizes.h)
My compilation line in make looks like this:
gcc -o $# -c $< -DARCHITECTURE=i386
Which works, until I define ARCHITECTURE to be i386. When this happens, it looks for 1/sizes.h, so I assume it's already defined somewhere.
I believe the C preprocessor (cpp), which is called by gcc, defines i386 (for i386 systems). You can find out what it defines like so:
touch foo.h; cpp -dM foo.h; rm foo.h
This method is described by the cpp man page, under -d, with the character M (so, -dM):
Instead of the normal output, generate a list of #define directives for all the macros defined during the execution of the preprocessor, including predefined macros. This gives you a way of finding out what is predefined in your version of the preprocessor. Assuming you have no file foo.h, the command
touch foo.h; cpp -dM foo.h
will show all the predefined macros.
$insmod helloworld module generates the error message "Invalid module format".
$dmesg outputs:
overflow in relocation type 10 val ffffffff88640070
'hello' likely not compiled with -mcmodel=kernel
The Makefile is a mix of tradition format (using (CC)) and module build system format "make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules".
The system is 1.6.18-194.el5 x86_64. The same Makefile works fine when it is used in i386 machine.
Any idea of what to look into? Thanks.
#Makefile, mix of (CC) and kernel module build system
CFLAGS+=-D"KBUILD_STR(s)=\#s" -D"KBUILD_BASENAME=KBUILD_STR(hello)"
CFLAGS+=-D__KERNEL__ -DMODULE -I$(KERNEL_BUILD_DIR)/include
KERNEL_BUILD_DIR=/lib/modules/2.6.18-194.el5/build
TARGETNAME=hello
BUILD_ALT_DIR=linux
# The main target (note that both library and driver are .ko files
#
all: $(BUILD_ALT_DIR)/$(TARGETNAME).ko
$(BUILD_ALT_DIR)/_$(TARGETNAME).o: hello.o
#echo Linking objects to loadable module
#mkdir -p $(BUILD_ALT_DIR)
#echo $(CURDIR)/$#
#$(LD) -Map=$#.map -r -o $# $^
#echo " LD_D [$#]"
$(BUILD_ALT_DIR)/$(TARGETNAME).ko: $(BUILD_ALT_DIR)/_$(TARGETNAME).o
#rm -f $(BUILD_ALT_DIR)/$(TARGETNAME).o
#echo create Makefile
#$(SHELL) -c 'echo "obj-m := $(TARGETNAME).o" > $(BUILD_ALT_DIR)/Makefile'
#$(SHELL) -c 'echo "$(TARGETNAME)-objs := _$(TARGETNAME).o" >> $(BUILD_ALT_DIR)/Makefile'
#$(SHELL) -c 'echo ".PHONY: `pwd`/$(BUILD_ALT_DIR)/_$(TARGETNAME).o" >> $(BUILD_ALT_DIR)/Makefile'
#$(SHELL) -c 'cd $(BUILD_ALT_DIR); $(MAKE) -C $(KERNEL_BUILD_DIR) M=`pwd`'
#echo " KO_D [$#]"
$(BUILD_ALT_DIR)/%.o: %.c
#echo Compiling C source to object file:
#mkdir -p $(BUILD_ALT_DIR)
# #echo $(CURDIR)/$#
#$(CC) -c -Wall $(CFLAGS) $(CFLAGS) $< -o $#
#echo " CC_D [$#]"
clean:
rm -f $(BUILD_ALT_DIR)/*.o $(BUILD_ALT_DIR)/*.d $(BUILD_ALT_DIR)/core $(BUILD_ALT_DIR)/*.map
hello.c
#include <linux/autoconf.h> // this is needed
#include <linux/init.h>
#include <linux/module.h>
static int hello_init(void)
{
printk(KERN_ALERT "Hello, world\n");
return 0;
}
static void hello_exit(void)
{
printk(KERN_ALERT "Goodbye, cruel world\n");
}
module_init(hello_init);
module_exit(hello_exit);
The dmesg output tells you what is wrong:
'hello' likely not compiled with -mcmodel=kernel
On the x86-64 architecture, all code running in the kernel (including modules) must be compiled with a special flag, which tells the compiler to generate code which will run in the top half of the virtual address space (user mode programs run on the bottom half of the address space).
If I am reading your Makefile correctly, you are compiling the C code outside the kernel build system, and calling into the kernel build system only for the final linking. Do not do this. It is not just the memory model, there are several other flags which must be added when compiling the C source code. These flags can change with the kernel version, or even with the kernel configuration — you do not know, and you are not supposed to have to know, since the kernel build system deals with it all for you.
It is not just -mcmodel=kernel. There are many others, and getting them wrong can and will cause problems.
The fact that you are missing the correct flags is quite visible in your code:
#include <linux/autoconf.h> // this is needed
No, this is not needed. If you need it, you are doing it wrong. Take a look at one of the flags the kernel build system passes to the C compiler:
-include include/linux/autoconf.h
This flags tells the C compiler to always implicitly include the linux/autoconf.h header. Since it is always implicitly included, you never have to include it manually. And since you never include it manually, its location is allowed to change — it moved to generated/autoconf.h and later to linux/kconfig.h, and who knows where else it will end up next.
The fact that it worked at all for you in 32-bit x86 is just luck. You should do it the correct way even on 32-bit.
Second iteration:
All right, you've confirmed that Make builds _helloworld.o and $(BUILD_ALT_DIR)/Makefile. Now could you post the makefile that's in $(KERNEL_BUILD_DIR) (on the x86_64)?
(I'll go out on a limb and suggest that maybe $(BUILD_ALT_DIR) and $(KERNEL_BUILD_DIR) are the same on the i386 but not on the x84_64.)
EDIT: (third iteration)
1400 lines? Most of that in one branch? Half a dozen include directives? Architecture-specific branches? Autoconf?
Are you allowed to modify this nightmare in place, or must you tinker with the higher-level tools like automake? (I ask only because in the latter case it won't do much good to figure out what the problem is, you'll probably have to start over from scratch.)
1) From $(KERNEL_BUILD_DIR), try make M=$(BUILD_ALT_DIR) (whatever $(BUILD_ALT_DIR) is). Verify that that gives you the same error message. If it doesn't then ignore what follows (in this iteration).
2) From $(BUILD_ALT_DIR), try make, and see if it gives the same error. If it does, try replacing the makefile (in $(BUILD_ALT_DIR)) with a trivial makefile like
all:
#echo trivial makefile working
and test it, then try step 1 again. If it just says "trivial makefile working" and doesn't give the error, then things look good.
EDIT: (fourth iteration)
All right, we can't change $(KERNEL_BUILD_DIR)/Makefile. That doesn't necessarily sink us.
"Your suggestion (1) would not work, since $(BUILD_ALT_DIR) is a output directory, no source is in it."
Make does not require the presence of source code, and whether or not this would work (whatever "work" means), it is what your makefile appears to be attempting:
#$(SHELL) -c 'cd $(BUILD_ALT_DIR); $(MAKE) -C $(KERNEL_BUILD_DIR) M=`pwd`'
Try it and see what happens.
"Is there a possibility that x86_64 doesn't support tradition format (CC) for the kernel module?"
I'm not entirely sure what you mean, but we can probably answer your question by experiment.
I'm trying to use the sprintf() function. Therefore I have to include the stdio.h in my C project. If I compile the project without including the stdio.h in my makefile, the compiler generates the error that sprintf() is a unknown function. Including the stdio.h to the makefile generates the error that there is "no rule to make target."
The makefile template gives the options as follows:
NAME = test
CC = arm-none-eabi-gcc
LD = arm-none-eabi-ld -v
AR = arm-none-eabi-ar
AS = arm-none-eabi-as
CP = arm-none-eabi-objcopy
OD = arm-none-eabi-objdump
CFLAGS = -I./ -c -fno-common -O0 -g -mcpu=cortex-m3 -mthumb
AFLAGS = -ahls -mapcs-32 -o crt.o
ASFLAGS = -Wa,-gstabs
LFLAGS = -Tlinkerscript_rom.cmd -nostartfiles
CPFLAGS = -Obinary
ODFLAGS = -S
I hope that you can help me out, because I have no desire to rewrite every standard function.
Sven
Makefiles don't read include files. The C preprocessor reads include files, before the resulting file is compiled by the compiler. You should include the header in your C file. Just add:
#include <stdio.h>
Somewhere close to the top, before any function definitions etc.
This will show a declaration of the function to the compiler, which will remove the warning.
Just include stdio.h at the top of your c file
#include <stdio.h>
The only reason to put a .h file in your makefile is so that the files dependent upon your header will be recompiled if anything in the header is changed. Needless to say, this is most commonly with header files you have written.
If there is an error after including stdio.h, you have a broken tool chain. If you update your question to indicate your platform, we may be able to help you fix it :)