Google protocol buffers cross compiling

Question

My problems of using Google protocol buffers has two parts, one is about compiler options, another is cross compiling. The build machine is a Power6, 64bit; host machine is a PowerPC450, 32bit. Gcc 4.1.2.

First problem is about compiler options:

I'm trying to install Google protocol buffers on a PowerPC machine which requires cross compiling. The build machine is a Power6, 64bit; host machine is a PowerPC450, 32bit. Firstly I tried to install on the build machine directly, with options to tell compiler which to use:

./configure --prefix=/home/where_to_install --host=powerpc-bgp-linux

Then make, make check, make install, everything's fine. I think that I've specified the host machine, that should include enough information that compile need to know. When I try to compile my code with

/bgsys/drivers/ppcfloor/gnu-linux/powerpc-bgp-linux/bin/g++ -g -zmuldefs -Xlinker -I/home/somewhere_installed/include $sourceFile -o $fileName -L/home/somewhere_installed/lib -lz -lstdc++ -lrt -lpthread -lm -lc -lprotobuf -lprotoc msg.pb.cc

I was given error:

g++: unrecognized option '-zmuldefs'
In file included from zht_util.h:20,
                 from hash-phm.cpp:9:
meta.pb.h:9:42: error: google/protobuf/stubs/common.h: No such file or directory

and a lot of error about variables in common.h were not found.

I know it's because the compiler doesn't recognize the option -zmuldefs so can't find the file common.h which does exist. I Googled it and didn't get any clear idea. How can I make the complier can use the option or can find the file? Or is any problem in my compiling command?

---

The second problem is about cross compiling. The readme file of Google protocol buffers is not clear about how exactly cross compile. It said I must use --with-protoc=protoc to tell configure which to use, OK, but before that I have to install a copy for host machine. I use the command first to install a copy for host

./configure --prefix=/home/where_to_install/built --host=powerpc-bgp-linux

then make, make install.

Then cross compile with below which uses same compiler as host machine uses:

./configure --prefix=/home/tonglin/Installed/built_3 CC=/bgsys/drivers/ppcfloor/gnu-linux/bin/powerpc-bgp-linux-gcc CXX=/bgsys/drivers/ppcfloor/gnu-linux/bin/powerpc-bgp-linux-g++ --host=powerpc-bgp-linux --with-protoc=/home/where_already_Installed/built/bin/protoc

Then make and got error:

a lot of compiling info ...blabla.....

collect2: ld returned 1 exit status
make[3]: *** [protoc] Error 1
make[3]: Leaving directory `/gpfs/home/somewere/src/protobuf-2.4.1/src'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/gpfs/home/somewere/src/protobuf-2.4.1/src'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/gpfs/home/tonglin/Installed/src/protobuf-2.4.1'
make: *** [all] Error 2

Where did I do wrong? I also tried with the specified compiler in the first installing(for host), it got same error as second install did above. Once I succeed to finish installations, here I will have two installs, which should I use? Is there any one can give me an example of how exactly can I cross compile Google protocol buffers? I didn't find any detailed example about this.

Thanks a lot,

-Tony

Answer 1

I'm going to try to answer your second question:

When I cross-compiled the protobuf library I first installed it on my host machine. This is relatively straightforward:

./configure --prefix=/usr
make
make check
make install

Then you should have it running on your build machine. Don't forget to do a

make distclean

afterwards or artifacts from this compilation will interfere with the next build.

Now I build it for my other machine (on the build machine) by configuring with

./configure --host=ppc CC=powerpc-none-linux-gnuspe-gcc CXX=powerpc-none-linux-gnuspe-g++ --with-protoc=protoc --prefix=/path/to/built/files

Then do the usual make, make check and make install and the files you need to copy to your other machine are in /patch/to/built/files.

Answer 2

For the first question, after you compiled and installed protobuf library with

./configure --prefix=/your_dir
make
make check
make install

You need add the include path under /your_dir/include to your makefile with -I flag, for example

-I/your_dir/include

.