[LFS] 6.10. Adjusting the Toolchain

1. Link any newly compiled program against these new libraries.

mv -v /tools/bin/{ld,ld-old}
mv -v /tools/$(gcc -dumpmachine)/bin/{ld,ld-old}
mv -v /tools/bin/{ld-new,ld}
ln -sv /tools/bin/ld /tools/$(gcc -dumpmachine)/bin/ld

2. Adjust the specs file so that GCC knows where to find the correct headers and Glibc start files.
Verify the intended change was actually made, so create specs.

gcc -dumpspecs | sed -e 's@/tools@@g'                   \
    -e '/\*startfile_prefix_spec:/{n;s@.*@/usr/lib/ @}' \
    -e '/\*cpp:/{n;s@$@ -isystem /usr/include@}' >      \
    `dirname $(gcc --print-libgcc-file-name)`/specs

3. Checking adjusted toolchain are working as expected.

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

There should be no errors, and the output will like following

[Requesting program interpreter: /lib/ld-linux-armhf.so.3]

4. Make sure that we’re setup to use the correct startfiles

grep -o '/usr/lib.*/crt[1in].*succeeded' dummy.log

The output of the last command should be:

/usr/lib/crt1.o succeeded
/usr/lib/crti.o succeeded
/usr/lib/crtn.o succeeded

5. Verify that the compiler is searching for the correct header files.

grep -B1 '^ /usr/include' dummy.log

output of the last command should be:

#include <...> search starts here:
 /usr/include

6. Verify that the new linker is being used with the correct search paths

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

The output of the last command should be:

SEARCH_DIR("/usr/lib")
SEARCH_DIR("/lib");

7. Make sure that we’re using the correct libc:

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

output of the last command

attempt to open /lib/libc.so.6 succeeded

8. Make sure GCC is using the correct dynamic linker:

grep found dummy.log

utput of the last command should be

found ld-linux-armhf.so.3 at /lib/ld-linux-armhf.so.3

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

rm -v dummy.c a.out dummy.log

Reference:
1. 6.10. Adjusting the Toolchain