Cross-Compiled Linux From Scratch - Version 2.1.0-PowerPC64-Pure64

Chapter 5. Constructing Cross-Compile Tools

5.17. EGLIBC-2.18

The EGLIBC package contains the main C library. This library provides the basic routines for allocating memory, searching directories, opening and closing files, reading and writing files, string handling, pattern matching, arithmetic, and so on.

5.17.1. Installation of EGLIBC

It should be noted that compiling EGLIBC in any way other than the method suggested in this book puts the stability of the system at risk.

The EGLIBC documentation recommends building EGLIBC outside of the source directory in a dedicated build directory: 

mkdir -v ../eglibc-build
cd ../eglibc-build

Add the following to config.cache to disable ssp when building EGLIBC: 

echo "libc_cv_ssp=no" > config.cache

Prepare EGLIBC for compilation: 

BUILD_CC="gcc" CC="${CLFS_TARGET}-gcc ${BUILD64}" \
      AR="${CLFS_TARGET}-ar" RANLIB="${CLFS_TARGET}-ranlib" \
      ../eglibc-2.18/configure --prefix=/tools \
      --host=${CLFS_TARGET} --build=${CLFS_HOST} \
      --disable-profile --with-tls --enable-kernel=2.6.32 --with-__thread \
      --with-binutils=/cross-tools/bin --with-headers=/tools/include \
      --enable-obsolete-rpc --cache-file=config.cache

The meaning of the new configure options:

BUILD_CC="gcc"

This sets EGLIBC to use the current compiler on our system. This is used to create the tools EGLIBC uses during its build.

CC="${CLFS_TARGET}-gcc ${BUILD64}"

Forces EGLIBC to build using our target architecture GCC utilizing the 64 Bit flags.

AR="${CLFS_TARGET}-ar"

This forces EGLIBC to use the ar utility we made for our target architecture.

RANLIB="${CLFS_TARGET}-ranlib"

This forces EGLIBC to use the ranlib utility we made for our target architecture.

--disable-profile

This builds the libraries without profiling information. Omit this option if profiling on the temporary tools is necessary.

--with-tls

This tells EGLIBC to use Thread Local Storage.

--enable-kernel=2.6.32

This tells EGLIBC to compile the library with support for 2.6.32 and later Linux kernels.

--with-__thread

This tells EGLIBC to use use the __thread for libc and libpthread builds.

--with-binutils=/cross-tools/bin

This tells EGLIBC to use the Binutils that are specific to our target architecture.

--with-headers=/tools/include

This tells EGLIBC to compile itself against the headers recently installed to the /tools directory, so that it knows exactly what features the kernel has and can optimize itself accordingly.

--cache-file=config.cache

This tells EGLIBC to utilize a premade cache file.

During this stage the following warning might appear: 

configure: WARNING:
*** These auxiliary programs are missing or
*** incompatible versions: msgfmt
*** some features will be disabled.
*** Check the INSTALL file for required versions.

The missing or incompatible msgfmt program is generally harmless. This msgfmt program is part of the Gettext package which the host distribution should provide.

Compile the package: 

make

Install the package: 

make install

The stubs.h header installed by eglibc looks for stubs-32.h and stubs-64.h. This configuration of eglibc only generates stubs-64.h. Fix this with the following: 

mv -v /tools/include/gnu/stubs{-64,}.h

Details on this package are located in Section 10.7.5, “Contents of EGLIBC.”