Details on this package are located in Section 6.25.2, “Contents of GCC.”
The GCC package contains the GNU compiler collection, which includes the C and C++ compilers.
Our first build of GCC has installed a couple of internal system
headers. Normally one of them, limits.h
, will in turn include the corresponding
system limits.h
header, in this case,
/tools/include/limits.h
. However, at
the time of the first build of gcc /tools/include/limits.h
did not exist, so the
internal header that GCC installed is a partial, self-contained
file and does not include the extended features of the system
header. This was adequate for building the temporary libc, but this
build of GCC now requires the full internal header. Create a full
version of the internal header using a command that is identical to
what the GCC build system does in normal circumstances:
cat gcc/limitx.h gcc/glimits.h gcc/limity.h > \ `dirname $($LFS_TGT-gcc -print-libgcc-file-name)`/include-fixed/limits.h
Once again, change the location of GCC's default dynamic linker to
use the one installed in /tools
.
for file in gcc/config/{linux,i386/linux{,64}}.h do cp -uv $file{,.orig} sed -e 's@/lib\(64\)\?\(32\)\?/ld@/tools&@g' \ -e 's@/usr@/tools@g' $file.orig > $file echo ' #undef STANDARD_STARTFILE_PREFIX_1 #undef STANDARD_STARTFILE_PREFIX_2 #define STANDARD_STARTFILE_PREFIX_1 "/tools/lib/" #define STANDARD_STARTFILE_PREFIX_2 ""' >> $file touch $file.orig done
If building on x86_64, change the default directory name for 64-bit libraries to “lib”:
case $(uname -m) in x86_64) sed -e '/m64=/s/lib64/lib/' \ -i.orig gcc/config/i386/t-linux64 ;; esac
As in the first build of GCC it requires the GMP, MPFR and MPC packages. Unpack the tarballs and move them into the required directory names:
tar -xf ../mpfr-4.0.2.tar.xz mv -v mpfr-4.0.2 mpfr tar -xf ../gmp-6.2.0.tar.xz mv -v gmp-6.2.0 gmp tar -xf ../mpc-1.1.0.tar.gz mv -v mpc-1.1.0 mpc
Now fix a problem introduced by Glibc-2.31:
sed -e '1161 s|^|//|' \ -i libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
Create a separate build directory again:
mkdir -v build cd build
Before starting to build GCC, remember to unset any environment variables that override the default optimization flags.
Now prepare GCC for compilation:
CC=$LFS_TGT-gcc \ CXX=$LFS_TGT-g++ \ AR=$LFS_TGT-ar \ RANLIB=$LFS_TGT-ranlib \ ../configure \ --prefix=/tools \ --with-local-prefix=/tools \ --with-native-system-header-dir=/tools/include \ --enable-languages=c,c++ \ --disable-libstdcxx-pch \ --disable-multilib \ --disable-bootstrap \ --disable-libgomp
The meaning of the new configure options:
--enable-languages=c,c++
This option ensures that both the C and C++ compilers are built.
--disable-libstdcxx-pch
Do not build the pre-compiled header (PCH) for libstdc++
. It takes up a lot of space, and
we have no use for it.
--disable-bootstrap
For native builds of GCC, the default is to do a "bootstrap" build. This does not just compile GCC, but compiles it several times. It uses the programs compiled in a first round to compile itself a second time, and then again a third time. The second and third iterations are compared to make sure it can reproduce itself flawlessly. This also implies that it was compiled correctly. However, the LFS build method should provide a solid compiler without the need to bootstrap each time.
Compile the package:
make
Install the package:
make install
As a finishing touch, create a symlink. Many programs and scripts run cc instead of gcc, which is used to keep programs generic and therefore usable on all kinds of UNIX systems where the GNU C compiler is not always installed. Running cc leaves the system administrator free to decide which C compiler to install:
ln -sv gcc /tools/bin/cc
At this point, it is imperative to stop and ensure that the basic functions (compiling and linking) of the new toolchain are working as expected. To perform a sanity check, run the following commands:
echo 'int main(){}' > dummy.c cc dummy.c readelf -l a.out | grep ': /tools'
If everything is working correctly, there should be no errors, and the output of the last command will be of the form:
[Requesting program interpreter: /tools/lib64/ld-linux-x86-64.so.2]
Note that the dynamic linker will be /tools/lib/ld-linux.so.2 for 32-bit machines.
If the output is not shown as above or there was no output at
all, then something is wrong. Investigate and retrace the steps
to find out where the problem is and correct it. This issue must
be resolved before continuing on. First, perform the sanity check
again, using gcc
instead of cc. If
this works, then the /tools/bin/cc
symlink is missing. Install the symlink as per above. Next,
ensure that the PATH
is correct. This
can be checked by running echo
$PATH and verifying that /tools/bin
is at the head of the list. If the
PATH
is wrong it could mean that you
are not logged in as user lfs
or
that something went wrong back in Section 4.4,
“Setting Up the Environment.”
Once all is well, clean up the test files:
rm -v dummy.c a.out
Details on this package are located in Section 6.25.2, “Contents of GCC.”