Linux Archive - Backward Compatibility of RHEL Advanced Server and GCC

Generally speaking, from my porting experienience, glibc and other
libraries create compatibility problems, although this varies from
application to application. I would definitely expect some problems, but
there are ways to manage them:

1)Do an ldd of the binary(ies) of your application on the RHEL 3 system
and map out the library dependencies:

[root@cn1 myapp]# ldd myapp
libdl.so.2 => /lib64/libdl.so.2 (0x000000351f200000)
libnsl.so.1 => /lib64/libnsl.so.1 (0x0000003522e00000)
libz.so.1 => /usr/lib64/libz.so.1 (0x000000351fa00000)
libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x000000352e400000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x000000351f600000)
libm.so.6 => /lib64/libm.so.6 (0x000000351ee00000)
libc.so.6 => /lib64/libc.so.6 (0x000000351ea00000)
/lib64/ld-linux-x86-64.so.2 (0x000000351e600000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x000000352cc00000)

This step will help you locate the exact library dependencies your
binary has.

2)Examine the version of the respective libaries in RHEL 5.

3)Attempt to compile the binary and see what happens. Most new libraries
are designed to be backwards compatible to the older version of the
libraries, but certain lib version checks on the configure and make
scripts might stop the compilation process. You might have to tweak them
and see whether it compiles properly.

4)If all else fails, you can always install the RHEL xen kernel and host
a guest RHEL 3 OS there? Have you examined that possibility? You could
then run the hypervisor (and other apps) on the latest RHEL version and
maintain full compatibility with the binary requirements.

If I were you, I would do either 4, or ask the software vendor to supply
a new version for RHEL 4/5, if possible.

GM

--
--
George Magklaras

Senior Computer Systems Engineer/UNIX Systems Administrator
EMBnet Technical Management Board
The Biotechnology Centre of Oslo,
University of Oslo
http://folk.uio.no/georgios

S. Suhasini wrote:

Hello,

We have an older setup of our software with the following details:

- OS release - RHEL AS release 3

- Gcc - 2.96

- Kernel - 2.4.21-4.EL

- Glibc - 2.3.2-95.3

- Binutils - 2.14.90.0.4

- Selinux - not present

And we would like to replace the existing setup with new version of our
software which was developed on the following environment

- OS release - RHEL server release 5

- Gcc - 4.1.1

- Kernel - 2.6.18-8.el5

- Glibc - 2.5-12

- Binutils - 2.17.50.0.6-2.el5

- Selinux - disabled

- Using Log4cxx version 0.10.0

We would like to know whether the new version of the software (compiled with
the new GCC) can be deployed and run on the older setup with RHEL AS 3 and
GCC 2.96. We need not compile again on the older setup. Will there be any
run-time libraries dependency? Would be very grateful if we get a response
for this query.

Thanks,

Suhasini.

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