7. Installing the GNU C and C++ compilers

You need to restart your system back into the normal Linux system to compile the gcc compiler. Before you reboot, unmount the partitions you mounted (that contained the glibc sources) and mount the LFS root partition read only by running mount -o remount,ro / /

If you have used a previous version of this HOWTO to install an LFS system and you wish to update your LFS system conforming the changes made in this version, you first need to remove the existing files regarding the previously installed compilers before continuing with this section.

• If you have used LFS-HOWTO versions 1.0, 1.1 or 1.2 please read section 19.2 now before continuing

This HOWTO used to install the C++ compiler from source, but that has been changed and is an exception. The C++ compiler is installed using pre-compiled binaries. The reason is that I have not been able to find the sources for the C++ compiler version that I prefer to use. So until then we'll use pre-compiled binaries.

We also will link the C compiler statically. Although Glibc is installed on our LFS system, we still are compiling the compiler on our normal Linux system. The normal Linux system may contain a different version of Glibc and the compiler will be linked against that version. Therefore we will link the compiler statically and later on when all statically linked software is being re-installed we also will re-install the compiler. This procedure is not necessary if both your normal Linux system and the LFS system use the same Library version, but since I don't know that we will do it this way. This ensures this document is usable on every Linux system, no matter what version of libraries they use.

7.1 Making two small test programs

We'll create a little C and a little C++ program which we will use after the installations to determine if the compilers can find the necessary files in order to successfully compile a program.

• Create a new file $LFS/root/test1.c containing the following:

// Begin test.c
#include <stdio.h>
int main() {
printf("Hello World!\n");
return 0;
}
// End test.c

• Create a new file $LFS/root/test2.cpp containing the following:

// Begin test2.cpp
#include <iostream.h>
int main() {
cout << "Hello World!" << endl;
return 0;
}
// End test2.cpp

7.2 Installing GCC 2.7.2.3

• Unpack the gcc-2.7.2.3 archive
• Configure the package by running configure
• Build the compiler by executing these commands in sequence:

make LANGUAGES=c
make stage1 
make CC="stage1/xgcc -Bstage1/" CFLAGS="-g -O2 -static" LANGUAGES=c
make stage2
make CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O2 --static" LANGUAGES=c
make compare

• If make compare doesn't report any differences, the compiler is build successfully.
• Reboot your computer in the LFS system.
• Mount the partition that contains the gcc-2.7.2.3 source files.
• Install the package by running make CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O2" LANGUAGES=c install

7.3 Installing the g++_2.91.66-0slink2.deb package

• Extract the archive files by running ar x g++_2.91.66-0slink2.deb
• Extract the package itself by running tar xvfz data.tar.gz
• Copy the files by running cp -av usr /
• Remove the following files and directory: usr data.tar.gz control.tar.gz debian-binary

Note that this g++ compiler is already pre-compiled and linked against glibc 2.0.7. Therefore there is no need to re-install this package in a later stage.

7.4 Creating necessary symlinks

• Create the /lib/cpp symlink by running ln -s /usr/lib/gcc-lib/<host>/2.7.2.3/cpp /lib/cpp
• Create the /usr/bin/cpp symlink by running ln -s /usr/lib/gcc-lib/<host>/2.7.2.3/cpp /usr/bin/cpp
• Create the /usr/bin/cc symlink by running ln -s /usr/bin/gcc /usr/bin/cc

Replace <host> with the directory where the gcc-2.7.2.3 files were installed (i686-unknown-linux in my case).

7.5 Testing the compilers

We will compile two small programs which we will use to test if the compilers compile. Note that this is by no means an exhaustive test. It's just a little test to see if the compiler can find the necessary files in order to compile a basic program.

• Go to the /root directory
• Compile test1.c by running gcc test1.c -o test1
• Compile test2.cpp by running g++ test2.cpp -o test2
• Execute the test1 and test2 programs to make sure the programs run ok without dumping the core or perform other out-of-the-ordinary actions.