Registering Images that Have System Version
Dependencies
Applications
that run on the OpenVMS operating system sometimes depend on the
internal interfaces of a previous version of the operating system.
For example, an application might call system routines, reference system
data cells, or system data structures. New versions of the operating
system might include changes that can break applications depending
on those interfaces.
Registering an image records information about the image in
a file called the image registry. The image activator,
INSTALL, and SYSGEN do not check the versions of images that are
recorded in the image registry. Image registry allows you to continue
to run application images (including main images, shared libraries,
and device drivers) that depend on the internal interfaces of a
previous version of the operating system.
The Image Registry facility allows you to register different
versions of an image independently. It also allows you to deregister,
analyze, and show images in the image registry.
Understanding System Version Dependency and
the Image Registry Applications
that depend on internal interfaces are bound to a particular version
of the operating system when the application is linked. Version-dependent
images reference both of the following version numbers:
The major version number of the operating
system
A set of component version numbers (version numbers
of loadable executive images) Images can be linked against SYS.STB in one of two ways:
Images linked against SYS.STB with
the Linker utility qualifier /SELECTIVE_SEARCH include component
version numbers only for those symbols that were referenced at link
time. (This is the recommended method.)
Images linked against SYS.STB without the /SELECTIVE_SEARCH
qualifier include references to all component versions.
When you attempt to run an image, the system checks to determine
if the image requires a certain version of the operating system
or of system components. If the version of the running system does
not match the version requirements of the image, the image fails.
The system
also checks version numbers when you attempt to install an image
using the Install utility (INSTALL) or connect a device driver using
the System Generation utility (SYSGEN).
When
you upgrade your system to a new version of the operating system,
an image might fail because the new version no longer matches the
image's version requirements. However, an image might continue to
be compatible with the new operating system version, even if it
fails the version check.
In OpenVMS VAX Version 6.0, the major version number
was not changed; only the version numbers for the following components
were increased to reflect changes in these areas:
FILES_VOLUMES
MEMORY_MANAGEMENT
SECURITY
As a result, many version-dependent images built in VMS VAX
Version 5.x systems (that is, images that do not reference FILES_VOLUMES,
MEMORY_MANAGEMENT, or SECURITY) will run on OpenVMS Version 6.0
without registering the images. However, version-dependent images
that do reference these components must be registered with the image
registry, as explained in this section.
In OpenVMS VAX Version 6.1, no version numbers were changed.
However, images built on VMS VAX Version 5.x systems needed to be registered if they referenced
FILES_VOLUMES, MEMORY_MANAGEMENT, or SECURITY.
To continue running a compatible image, you can register the
image using the Image Registry facility. You do not need to register
images that are linked as part of the installation because they
match the current operating system version. However, linking an
image during installation does not ensure that system version dependencies
do not exist. For information about changes in the current operating
system version that might require you to recompile an image or change
source code, see the release notes.
You must inspect and test an image carefully to avoid
system crashes and data corruption. Registering an image does not
necessarily make it work; registering only bypasses the version checks.
Using the Image Registry Facility To register an image in the image registry, run the command
procedure SYS$UPDATE:REGISTER_PRIVILEGED_IMAGE.COM. Enter a command
in the following format: $ @SYS$UPDATE:REGISTER_PRIVILEGED_IMAGE keywordfilename
HP OpenVMS System Manager's Manual, Volume 1:... 
Customizing the Operating System
