User guide

Backwards Compatibility Packages

Object file changes, such as the ones listed above, may interfere with the portable use of prelink.

4.1.4. Backwards Compatibility Packages

Several packages are provided to serve as an aid for those moving source code or executables from

older versions of Red Hat Enterprise Linux to the current release. These packages are intended to

be used as a temporary aid in transitioning sources to newer compilers with changed behavior, or

as a convenient way to otherwise isolate differences in the system environment from the compile

environment.

Note

Please be advised that Red Hat may remove these packages in future Red Hat Enterprise Linux

releases.

The following packages provide compatibility tools for compiling Fortran or C++ source code on the

current release of Red Hat Enterprise Linux 6 as if one was using the older compilers on Red Hat

Enterprise Linux 4:

• compat-gcc-34

• compat-gcc-34-c++

• compat-gcc-34-g77

The following package provides a compatibility runtime library for Fortran exectuables compiled on

Red Hat Enterprise Linux 5 to run without recompilation on the current release of Red Hat Enterprise

Linux 6:

• compat-libgfortran-41

Please note that backwards compatibility library packages are not provided for all supported system

libraries, just the system libraries pertaining to the compiler and the C/C++ standard libraries.

For more information about backwards compatibility library packages, refer to the Application

Compatibility section of the Red Hat Enterprise Linux 6 Migration Guide.

4.1.5. Previewing RHEL6 compiler features on RHEL5

On Red Hat Enterprise Linux 5, we have included the package gcc44 as an update. This is a backport

of the RHEL6 compiler to allow users running RHEL5 to compile their code with the RHEL6 compiler

and experiment with new features and optimizations before upgrading their systems to the next major

release. The resulting binary will be forward compatible with RHEL6, so one can compile on RHEL5

with gcc44 and run on RHEL5, RHEL6, and above.

The RHEL5 gcc44 compiler will be kept reasonably in step with the GCC 4.4.x that we ship with

RHEL6 to ease transition. Though, to get the latest features, it is recommended RHEL6 is used for

development. The gcc44 is only provided as an aid in the conversion process.

4.1.6. Running GCC

To compile using GCC tools, first install binutils and gcc; doing so will also install several

dependencies.