lfs-book/chapter05/gcc-exp.xml

<sect2>
<title>Command explanations</title>

<para><userinput>patch -Np1 -i ../gcc-&gcc-patch-version;.patch:</userinput>
This patch deals with the incorrect handling of weak symbols, the 
over-optimization of calls to those weak symbols, an atexit issue, and
the  __dso_handle symbol required for atexit's proper function.</para>

<para><userinput>make BOOT_LDFLAGS=-static:</userinput>
This is the equivalent to make LDFLAGS=-static as we use with other
packages to compile them statically.</para>

<para><userinput>--prefix=/usr:</userinput> This is NOT a typo.  GCC hard
codes some paths while compiling and so we need to pass /usr as the
prefix during ./configure.  We pass the real install prefix during the
make install command later.</para>

<para><userinput>--enable-languages=c,c++:</userinput> This only builds the C
and C++ compilers and not the other available compilers as they are, on
the average, not often used. If those other compilers are needed,
the --enable-languages parameter can be omitted.</para>

<para><userinput>--enable-threads=posix:</userinput> This enables C++ 
exception handling for multithreaded code.</para>

<para><userinput>ln -sf ../usr/bin/cpp:</userinput> This
creates the $LFS/lib/cpp symlink. Some packages explicitly try to find
cpp in /lib.</para>

<para><userinput>ln -sf ../bin/cpp:</userinput> This
creates the $LFS/usr/lib/cpp symlink as there are packages that expect
cpp to be in /usr/lib.</para>

<para><userinput>rmdir $LFS/usr/*-gnu/include</userinput> and
<userinput>rmdir $LFS/usr/*-gnu</userinput>: These directories are created
as empty directories by GCC and serve absolutely no purpose whatsoever.
It's related to cross-compilers but that doesn't apply to us and it's
considered a bug in GCC that you can't turn that off, especially since they
end up being empty directories. So we remove them manually.</para>
</sect2>