Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Thu, 11 Mar 2010 17:43:50 +0100

John Dobbins wrote:

I was wondering if anyone can suggest an approach for building EPICS on
multiple linux distributions (which may have different kernel versions,
compiler versions, etc.)
Does one define new architectures linux-x86-distribution_a
linux-x86-distribution_b?
John Dobbins
Lab for Elementary Particle Physics
Cornell University

Hi John,
We build EPICS on multiple Linux versions, e.g Scientific Linux 3 and
Scientific Linux 5. I have defined new architectures as you suggested. I
used the names SL3-x86 and SL5-x86. The advantage of this approach is
that different architectures are installed into different
sub-directories. So code cannot get mixed up even if it is on a network
drive.
I have created the configure files CONFIG.Common.SL3-x86,
CONFIG.SL3-x86.Common, CONFIG.SL3-x86.SL3-x86, and
CONFIG_SITE.SL3-x86.Common which basically just include their
"linux-x86" analogon:
> cat CONFIG.Common.SL3-x86
# Include definitions common to linux targets
include $(CONFIG)/os/CONFIG.Common.linux-x86
> cat CONFIG.SL3-x86.Common
#CONFIG.$(EPICS_HOST_ARCH).Common is required by build system
#Include definitions common to linux hosts
include $(CONFIG)/os/CONFIG.linux-x86.Common
> cat CONFIG.SL3-x86.SL3-x86
# Include common linux definitions
include $(CONFIG)/os/CONFIG.linux-x86.linux-x86
> cat CONFIG_SITE.SL3-x86.Common
include $(CONFIG)/os/CONFIG_SITE.linux-x86.Common
The same for all other Linux architectures.
Don't forget to set EPICS_HOST_ARCH everywhere correctly so that EPICS
Makefiles build the correct code. We set it for each system in a script
in /etc/profile.d/.
I have very good experiences with this approach. Unfortunately, I did
not succeed to "cross compile" e.g. SL3 on a SL5 host. That means every
code has to be compiled separately on each operating system version.
Andrew mentioned that a different kernel does not require to rebuild the
application code. But often a new Linux version comes with a new
compiler version. And gcc tends to change things (especially C++)
between versions. (Even with the same major release). I can run SL3
compiled code on SL5 but running SL5 compiled code on SL3 crashes with a
floating point exception.
So it is safest to compile separately whenever gcc and/or glibc versions
change.
Best regards,
Dirk

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System