5.5. Glibc-2.41

5.5.1. Installation of Glibc

First, create a symbolic link for LSB compliance. Additionally, for x86_64, create a compatibility symbolic link required for proper operation of the dynamic library loader:

case $(uname -m) in
    i?86)   ln -sfv ld-linux.so.2 $LFS/lib/ld-lsb.so.3
    ;;
    x86_64) ln -sfv ../lib/ld-linux-x86-64.so.2 $LFS/lib64
            ln -sfv ../lib/ld-linux-x86-64.so.2 $LFS/lib64/ld-lsb-x86-64.so.3
    ;;
esac

Some of the Glibc programs use the non-FHS-compliant /var/db directory to store their runtime data. Apply the following patch to make such programs store their runtime data in the FHS-compliant locations:

patch -Np1 -i ../glibc-2.41-fhs-1.patch

The Glibc documentation recommends building Glibc in a dedicated build directory:

mkdir -v build
cd       build

Ensure that the ldconfig and sln utilities are installed into /usr/sbin:

echo "rootsbindir=/usr/sbin" > configparms

Next, prepare Glibc for compilation:

../configure                             \
      --prefix=/usr                      \
      --host=$LFS_TGT                    \
      --build=$(../scripts/config.guess) \
      --enable-kernel=5.4                \
      --disable-nscd                     \
      libc_cv_slibdir=/usr/lib

During this stage the following warning might appear:

The missing or incompatible msgfmt program is generally harmless. This msgfmt program is part of the Gettext package, which the host distribution should provide.

Compile the package:

make

Install the package:

make DESTDIR=$LFS install

Fix a hard coded path to the executable loader in the ldd script:

sed '/RTLDLIST=/s@/usr@@g' -i $LFS/usr/bin/ldd

Now that our cross toolchain is in place, it is important to ensure that compiling and linking will work as expected. We do this by performing some sanity checks:

echo 'int main(){}' | $LFS_TGT-gcc -x c - -v -Wl,--verbose &> dummy.log
readelf -l a.out | grep ': /lib'

There should be no errors, and the output of the last command will be (allowing for platform-specific differences in the dynamic linker name):

[Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]

Note that this path should not contain /mnt/lfs (or the value of the LFS variable if you used a different one). The path is resolved when the compiled program is executed, and that should only happen after we enter the chroot environment where the kernel would consider $LFS as the root directory (/).

Now make sure that we're set up to use the correct start files:

grep -E -o "$LFS/lib.*/S?crt[1in].*succeeded" dummy.log

The output of the last command should be:

/mnt/lfs/lib/../lib/Scrt1.o succeeded
/mnt/lfs/lib/../lib/crti.o succeeded
/mnt/lfs/lib/../lib/crtn.o succeeded

Verify that the compiler is searching for the correct header files:

grep -B3 "^ $LFS/usr/include" dummy.log

This command should return the following output:

#include <...> search starts here:
 /mnt/lfs/tools/lib/gcc/x86_64-lfs-linux-gnu/14.2.0/include
 /mnt/lfs/tools/lib/gcc/x86_64-lfs-linux-gnu/14.2.0/include-fixed
 /mnt/lfs/usr/include

Again, the directory named after your target triplet may be different than the above, depending on your system architecture.

Next, verify that the new linker is being used with the correct search paths:

grep 'SEARCH.*/usr/lib' dummy.log |sed 's|; |\n|g'

References to paths that have components with '-linux-gnu' should be ignored, but otherwise the output of the last command should be:

SEARCH_DIR("=/mnt/lfs/tools/x86_64-lfs-linux-gnu/lib64")
SEARCH_DIR("=/usr/local/lib64")
SEARCH_DIR("=/lib64")
SEARCH_DIR("=/usr/lib64")
SEARCH_DIR("=/mnt/lfs/tools/x86_64-lfs-linux-gnu/lib")
SEARCH_DIR("=/usr/local/lib")
SEARCH_DIR("=/lib")
SEARCH_DIR("=/usr/lib");

A 32-bit system may use a few other directories, but anyway the important facet here is all the paths should begin with an equal sign (=), which would be replaced with the sysroot directory that we've configured for the linker.

Next make sure that we're using the correct libc:

grep "/lib.*/libc.so.6 " dummy.log

The output of the last command should be:

attempt to open /mnt/lfs/usr/lib/libc.so.6 succeeded

Make sure GCC is using the correct dynamic linker:

grep found dummy.log

The output of the last command should be (allowing for platform-specific differences in dynamic linker name):

found ld-linux-x86-64.so.2 at /mnt/lfs/usr/lib/ld-linux-x86-64.so.2

If the output does not appear as shown above or is not received at all, then something is seriously wrong. Investigate and retrace the steps to find out where the problem is and correct it. Any issues should be resolved before continuing with the process.

Once everything is working correctly, clean up the test files:

rm -v a.out dummy.log