6.21.1. Installation of GCC
If building on x86_64, change the default directory name for 64-bit
libraries to “lib”:
case $(uname -m) in
x86_64)
sed -e '/m64=/s/lib64/lib/' \
-i.orig gcc/config/i386/t-linux64
;;
esac
The GCC documentation recommends building GCC in a dedicated build
directory:
mkdir -v build
cd build
Prepare GCC for compilation:
SED=sed \
../configure --prefix=/usr \
--enable-languages=c,c++ \
--disable-multilib \
--disable-bootstrap \
--with-system-zlib
Note that for other languages, there are some prerequisites that
are not yet available. See the BLFS
Book for instructions on how to build all of GCC's supported
languages.
The meaning of the new configure parameters:
-
SED=sed
-
Setting this environment variable prevents a hard-coded path
to /tools/bin/sed.
-
--with-system-zlib
-
This switch tells GCC to link to the system installed copy of
the Zlib library, rather than its own internal copy.
Compile the package:
make
Important
In this section, the test suite for GCC is considered critical.
Do not skip it under any circumstance.
One set of tests in the GCC test suite is known to exhaust the
stack, so increase the stack size prior to running the tests:
ulimit -s 32768
Test the results as a non-privileged user, but do not stop at
errors:
chown -Rv nobody .
su nobody -s /bin/bash -c "PATH=$PATH make -k check"
To receive a summary of the test suite results, run:
../contrib/test_summary
For only the summaries, pipe the output through grep -A7 Summ
.
Results can be compared with those located at http://www.linuxfromscratch.org/lfs/build-logs/9.0/
and https://gcc.gnu.org/ml/gcc-testresults/.
Six tests related to get_time are known to fail. These are
apparently related to the en_HK locale.
Two tests named lookup.cc and reverse.cc in experimental/net are
known to fail in LFS chroot environment because they require
/etc/hosts and iana-etc.
Two tests named pr57193.c and pr90178.c are known to fail.
A few unexpected failures cannot always be avoided. The GCC
developers are usually aware of these issues, but have not resolved
them yet. Unless the test results are vastly different from those
at the above URL, it is safe to continue.
Install the package and remove an unneeded directory:
make install
rm -rf /usr/lib/gcc/$(gcc -dumpmachine)/9.2.0/include-fixed/bits/
The GCC build directory is owned by nobody
now and the ownership of the installed
header directory (and its content) will be incorrect. Change the
ownership to root
user and group:
chown -v -R root:root \
/usr/lib/gcc/*linux-gnu/9.2.0/include{,-fixed}
Create a symlink required by the FHS
for "historical" reasons.
ln -sv ../usr/bin/cpp /lib
Many packages use the name cc to call the C compiler. To
satisfy those packages, create a symlink:
ln -sv gcc /usr/bin/cc
Add a compatibility symlink to enable building programs with Link
Time Optimization (LTO):
install -v -dm755 /usr/lib/bfd-plugins
ln -sfv ../../libexec/gcc/$(gcc -dumpmachine)/9.2.0/liblto_plugin.so \
/usr/lib/bfd-plugins/
Now that our final toolchain is in place, it is important to again
ensure that compiling and linking will work as expected. We do this
by performing the same sanity checks as we did earlier in the
chapter:
echo 'int 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 of the last command will
be (allowing for platform-specific differences in dynamic linker
name):
[Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]
Now make sure that we're setup to use the correct start files:
grep -o '/usr/lib.*/crt[1in].*succeeded' dummy.log
The output of the last command should be:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../lib/crt1.o succeeded
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../lib/crti.o succeeded
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/../../../../lib/crtn.o succeeded
Depending on your machine architecture, the above may differ
slightly, the difference usually being the name of the directory
after /usr/lib/gcc
. The important
thing to look for here is that gcc has found all three
crt*.o
files under the /usr/lib
directory.
Verify that the compiler is searching for the correct header files:
grep -B4 '^ /usr/include' dummy.log
This command should return the following output:
#include <...> search starts here:
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/include
/usr/local/include
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/include-fixed
/usr/include
Again, note that the directory named after your target triplet may
be different than the above, depending on your 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("/usr/x86_64-pc-linux-gnu/lib64")
SEARCH_DIR("/usr/local/lib64")
SEARCH_DIR("/lib64")
SEARCH_DIR("/usr/lib64")
SEARCH_DIR("/usr/x86_64-pc-linux-gnu/lib")
SEARCH_DIR("/usr/local/lib")
SEARCH_DIR("/lib")
SEARCH_DIR("/usr/lib");
A 32-bit system may see a few different directories. For example,
here is the output from an i686 machine:
SEARCH_DIR("/usr/i686-pc-linux-gnu/lib32")
SEARCH_DIR("/usr/local/lib32")
SEARCH_DIR("/lib32")
SEARCH_DIR("/usr/lib32")
SEARCH_DIR("/usr/i686-pc-linux-gnu/lib")
SEARCH_DIR("/usr/local/lib")
SEARCH_DIR("/lib")
SEARCH_DIR("/usr/lib");
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 /lib/libc.so.6 succeeded
Lastly, 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 /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. The most
likely reason is that something went wrong with the specs file
adjustment. Any issues will need to be resolved before continuing
with the process.
Once everything is working correctly, clean up the test files:
rm -v dummy.c a.out dummy.log
Finally, move a misplaced file:
mkdir -pv /usr/share/gdb/auto-load/usr/lib
mv -v /usr/lib/*gdb.py /usr/share/gdb/auto-load/usr/lib