On Mon, 2021-10-04 at 23:23 +0100, Jonathan Wakely via Gcc-help wrote: > On Mon, 4 Oct 2021 at 22:03, Bill Cunningham via Gcc-help > <gcc-help@xxxxxxxxxxx> wrote: > > > > I have bee looking at the LFS project. www.linuxfromscratch.org and > > I > > find their instructions a bit difficult. But at one point there is a > > gcc > > compiler compiled and installed with the --disable-libstdcxx option. > > Later, you are supposed to go back to your build directory and > > install > > libstdc++. I am not asking anyone to go to linuxfromscratch and > > investigate it so I will explain as much as possible as I believe I > > need > > too. > > > > This is compiling a "fake"cross compiler. Since everything is > > compiled from scratch, C++ libraries do not exist at the time of the > > first compilation. After glibc is built and installed, you go back > > to > > gcc and compile the libstdcxx libraries of gcc. Exactly how is that > > done? > > Exactly as it says at > https://www.linuxfromscratch.org/lfs/view/development/chapter05/gcc-libstdc++-pass1.html There is actually two ways for this. One is our way in LFS, another is not to pass --disable-libstdcxx, but use "make all-gcc" and "make install-gcc" to install the compiler (without libstdc++) first. Then, build and install libc. Finally, go back to the gcc build directory, and run "make all" to build the parts depending on libc, which were not built with "make all-gcc". AFAIK the second approach is often used by embedded developers (building for e.g. avr-gcc). We use the first approach in LFS because we don't want to say something like "please keep the GCC building directory here, don't remove it like building other packages" in the book. -- Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx> School of Aerospace Science and Technology, Xidian University
