Re: Compile GCC using only tools isolated from host environment

[Xi Ruoyao <xry111@mengyan1223.wang>]

On Mon, 2022-03-14 at 18:43 -0400, Benjamin Lovy wrote:

/* snip */

> Now, I would like to build a fresh GCC using the previously build GCC,
> this
> glib, and the GMP/MPC/MPFR libraries I just built:
> 
> /build/gcc-11.2.0/configure \
> CFLAGS="-Wl,-dynamic-linker=/lib/ld-linux-x86-64.so.2 -Wl,-rpath,/lib
> -I/lib/gcc/x86_64-pc-linux-gnu/11.2.0/include -I/usr/include
> -I/usr/include/linux -I/lib/gcc/x86_64-pc-linux-gnu/11.2.0/include-
> fixed
> -B/bin" \

I think these FLAGS are mistaken.  --sysroot won't expand -I/usr/include
to search $SYSROOT/usr/include for example.

And, Without "-O2" your GCC will be built without optimization, which
will make a stupidly slow compiler.

>   --prefix=/bootstrap/gcc \
> --host=x86_64-pc-linux-gnu \
> --with-sysroot=/bootstrap \

You need --with-build-sysroot instead of --with-sysroot.  Read
https://gcc.gnu.org/install/configure.html for their difference.

Please note --sysroot is mostly for cross-compilation.  If you are not
building a GCC which is meant to run in a new OS tree (chroot or
container, or even reboot into a new OS tree), it's likely you shouldn't
use sysroot at all.
-- 
Xi Ruoyao <xry111@mengyan1223.wang>
School of Aerospace Science and Technology, Xidian University