Building gcc for C and C++ with a custom glibc

Building gcc for C and C++ with a custom glibc

[Tom Honermann]

Hi all.  I've been trying to build a custom gcc (trunk) with a custom 
glibc (trunk) with support for C and C++ on x86_64 Linux and have so far 
been unsuccessful at identifying a sequence of configure/make 
invocations that completes successfully.  I'm not trying to build a 
cross compiler.

The scenario I'm trying to satisfy is testing some changes to gcc, and 
additional changes to libstdc++ that have new autoconf and header 
dependencies on the presence of new functions in existing glibc headers.

The glibc installation I'm trying to use was built with:

    mkdir glibc-build
    cd glibc-build
    ../glibc/configure \
         CC=gcc \
         CXX=g++ \
         --prefix /.../glibc
    make && make install

For gcc, I've tried numerous variants of the following:

    mkdir gcc-build
    cd gcc-build
    ../gcc/configure \
         CC=gcc \
         CXX=g++ \
         --prefix /.../gcc \
         --disable-multilib \
         --enable-languages=c,c++ \
         --enable-checking=release \
         --disable-bootstrap \
         --disable-lto

Things I've tried include setting CFLAGS, CXXFLAGS, and LDFLAGS to 
specify additional glibc paths, to specify alternate paths (via 
-nostdinc/-nostdinc++), setting LIBRARY_PATH and CPATH, passing 
--with-sysroot, passing --with-headers and --with-libs, passing 
--with-native-system-header-dir, some of those in conjunction with 
removing --disable-bootstrap, and wrapping gcc in a script that attempts 
to substitute certain include paths.

The problem I'm having is that, in every attempt, the glibc headers and 
libraries from under /usr end up getting used instead of the custom 
glibc ones at some point leading to build failures.

Does anyone have a recipe available for doing this?

Tom.

Re: Building gcc for C and C++ with a custom glibc

[H.J. Lu]

On Sun, Jan 17, 2021 at 1:06 PM Tom Honermann via Gcc <gcc@gcc.gnu.org> wrote:
>
> Hi all.  I've been trying to build a custom gcc (trunk) with a custom
> glibc (trunk) with support for C and C++ on x86_64 Linux and have so far
> been unsuccessful at identifying a sequence of configure/make
> invocations that completes successfully.  I'm not trying to build a
> cross compiler.
>
> The scenario I'm trying to satisfy is testing some changes to gcc, and
> additional changes to libstdc++ that have new autoconf and header
> dependencies on the presence of new functions in existing glibc headers.
>
> The glibc installation I'm trying to use was built with:
>
>     mkdir glibc-build
>     cd glibc-build
>     ../glibc/configure \
>          CC=gcc \
>          CXX=g++ \
>          --prefix /.../glibc
>     make && make install
>
> For gcc, I've tried numerous variants of the following:
>
>     mkdir gcc-build
>     cd gcc-build
>     ../gcc/configure \
>          CC=gcc \
>          CXX=g++ \
>          --prefix /.../gcc \
>          --disable-multilib \
>          --enable-languages=c,c++ \
>          --enable-checking=release \
>          --disable-bootstrap \
>          --disable-lto
>
> Things I've tried include setting CFLAGS, CXXFLAGS, and LDFLAGS to
> specify additional glibc paths, to specify alternate paths (via
> -nostdinc/-nostdinc++), setting LIBRARY_PATH and CPATH, passing
> --with-sysroot, passing --with-headers and --with-libs, passing
> --with-native-system-header-dir, some of those in conjunction with
> removing --disable-bootstrap, and wrapping gcc in a script that attempts
> to substitute certain include paths.
>
> The problem I'm having is that, in every attempt, the glibc headers and
> libraries from under /usr end up getting used instead of the custom
> glibc ones at some point leading to build failures.
>
> Does anyone have a recipe available for doing this?

Try scripts/build-many-glibcs.py in glibc source.

-- 
H.J.

Re: Building gcc for C and C++ with a custom glibc

[Tom Honermann]

On 1/17/21 4:08 PM, H.J. Lu wrote:
> On Sun, Jan 17, 2021 at 1:06 PM Tom Honermann via Gcc <gcc@gcc.gnu.org> wrote:
>> Hi all.  I've been trying to build a custom gcc (trunk) with a custom
>> glibc (trunk) with support for C and C++ on x86_64 Linux and have so far
>> been unsuccessful at identifying a sequence of configure/make
>> invocations that completes successfully.  I'm not trying to build a
>> cross compiler.
>>
>> The scenario I'm trying to satisfy is testing some changes to gcc, and
>> additional changes to libstdc++ that have new autoconf and header
>> dependencies on the presence of new functions in existing glibc headers.
>>
>> The glibc installation I'm trying to use was built with:
>>
>>      mkdir glibc-build
>>      cd glibc-build
>>      ../glibc/configure \
>>           CC=gcc \
>>           CXX=g++ \
>>           --prefix /.../glibc
>>      make && make install
>>
>> For gcc, I've tried numerous variants of the following:
>>
>>      mkdir gcc-build
>>      cd gcc-build
>>      ../gcc/configure \
>>           CC=gcc \
>>           CXX=g++ \
>>           --prefix /.../gcc \
>>           --disable-multilib \
>>           --enable-languages=c,c++ \
>>           --enable-checking=release \
>>           --disable-bootstrap \
>>           --disable-lto
>>
>> Things I've tried include setting CFLAGS, CXXFLAGS, and LDFLAGS to
>> specify additional glibc paths, to specify alternate paths (via
>> -nostdinc/-nostdinc++), setting LIBRARY_PATH and CPATH, passing
>> --with-sysroot, passing --with-headers and --with-libs, passing
>> --with-native-system-header-dir, some of those in conjunction with
>> removing --disable-bootstrap, and wrapping gcc in a script that attempts
>> to substitute certain include paths.
>>
>> The problem I'm having is that, in every attempt, the glibc headers and
>> libraries from under /usr end up getting used instead of the custom
>> glibc ones at some point leading to build failures.
>>
>> Does anyone have a recipe available for doing this?
> Try scripts/build-many-glibcs.py in glibc source.
>
Thank you for the suggestion.  I studied the script and tried using it, 
but it also encountered errors during the 2nd stage gcc build.  I didn't 
delve into those errors.

This is what ended up working for me:

    mkdir -p "$BINUTILS_BUILD_DIR"
    cd "$BINUTILS_BUILD_DIR"
    "../$BINUTILS_SOURCE_DIR/configure" \
       CC=gcc \
       CXX=g++ \
       --prefix "$INSTALL_DIR" \
       --with-sysroot="$INSTALL_DIR" \
       --disable-multilib \
    ;
    make -j 4 && make install
    cd -

    cd "$LINUX_SOURCE_DIR"
    make INSTALL_HDR_PATH="$INSTALL_DIR" headers_install
    cd -

    mkdir -p "$GLIBC_BUILD_DIR"
    cd "$GLIBC_BUILD_DIR"
    "../$GLIBC_SOURCE_DIR/configure" \
       CC=gcc \
       CXX=g++ \
       --prefix "$INSTALL_DIR" \
       --disable-multilib \
       --with-headers="$INSTALL_DIR/include" \
    ;
    make -j 4 && make install
    cd -

    # Fixup paths in libc.so and libm.so.  I wasn't able to find a
    combination of
    # 'configure --prefix' and 'make prefix=... DESTIDIR=...' that did
    the right thing.
    cp "$INSTALL_DIR/lib/libc.so" "$INSTALL_DIR/lib/libc.so.orig"
    sed -e "s%$INSTALL_DIR%%g" "$INSTALL_DIR/lib/libc.so.orig" >
    "$INSTALL_DIR/lib/libc.so"
    rm -f "$INSTALL_DIR/lib/libc.so.orig"
    cp "$INSTALL_DIR/lib/libm.so" "$INSTALL_DIR/lib/libm.so.orig"
    sed -e "s%$INSTALL_DIR%%g" "$INSTALL_DIR/lib/libm.so.orig" >
    "$INSTALL_DIR/lib/libm.so"
    rm -f "$INSTALL_DIR/lib/libm.so.orig"

    mkdir -p "$GCC_BUILD_DIR"
    cd "$GCC_BUILD_DIR"
    "../$GCC_SOURCE_DIR/configure" \
       CC=gcc \
       CXX=g++ \
       --prefix "$INSTALL_DIR" \
       --with-sysroot="$INSTALL_DIR" \
       --with-native-system-header-dir="/include" \
       --enable-languages=c,c++ \
       --disable-bootstrap \
       --disable-multilib \
       --enable-checking=release \
       --disable-lto \
    ;
    make -j 4 && make install
    cd -

Tom.