Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 9 Jan 2017 12:06:57 -0600

Hi Hugo,

On 01/09/2017 11:36 AM, Hugo Slepicka wrote:
> How is the community handling cases similar to rhel7-x86_64 versus
> rhel6-x86_64 given that"EPICS_HOST_ARCH" returns "linux-x86_64" for both?
> 
> One possible solutions would be to use something like:
>        <shared_path>/<os_version>/base/.../<EPICS_HOST_ARCH>/...
>        - where os_version would be: rhel5, rhel6, deb7, deb8, etc.

That effectively involves having different installations of Base for
each OS version. Possible, but can be confusing.

The approach that we use here at APS for extensions such as MEDM (which
we install on a shared drive) is to always build these tools on the
oldest OS version that we currently support, and ensure that any newer
OSs always install the necessary backwards-compatibility packages that
provide older .so versions of the system libraries so those older OS
binaries will run properly on the newer OS. This works for us on RHEL,
but I don't know if Debian provides those kinds of packages. This may
not work if you have a mix of RHEL and DEB distro's, but you might be
able to combine this with the approach below.

> Another solution would be to apply a local patch to the EPICS building
> system to return a specific value for EPICS_HOST_ARCH including the
> <os_version>, e.g. rhel6-x86_64, resulting in something like this:
>        <shared_path>/base/.../<NEW_EPICS_HOST_ARCH>/...

You can set the EPICS_HOST_ARCH environment variable in some system
configuration file(s) such as /etc/profile.d/epics.sh to avoid having to
patch the base/startup/EpicsHostArch* files since they aren't used if
that variable is already set. Then you can adopt the solution Mark
Rivers described of using host-arch aliases and creating
base/configure/os/CONFIG.* files for your different OS versions.

- Andrew

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System