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<== Date ==> <== Thread ==>

Subject: Re: medm with epics-base 3.14.6+
From: Ralph Lange <[email protected]>
To: Emmanuel Mayssat <[email protected]>
Cc: EPICS Tech Talk <[email protected]>
Date: Mon, 23 Jul 2007 11:20:01 +0200
Hi Emmanuel,

Emmanuel Mayssat wrote:
I am trying to update my driver to a more recent epics base.
I assume that if I do so, I need to recompile the epics extensions.
Not necessarily. Depends on your definition of "extensions":

You are right, if you mean "IOC-type" extensions that are (at least partly) running on the IOC. Drivers, Auto-Save/Restore, CA put logging - that kind of extensions. Everything running on one IOC has to be compiled against the same version of EPICS base.

For the "classical" extensions, there is always Channel Access between your IOC and the extension. CA works as a big integrator - a compatibility layer that allows a wild mix of EPICS base versions on IOCs and clients.

There is no need to run all your IOCs with the same version of base. There is no need to run all CA clients compiled against the same version of base.
This is an important feature: In large operational systems with short shutdown phases it would be impossible to upgrade hundreds of IOCs or all CA client applications at the same time.


Two obvious exceptions:
You can only avoid running into problems with bugs that have been fixed by running recent versions of base (this applies to the IOC aka CA server as well as to the client side).
If you plan to use CA features that have been added at some point (e.g. large array buffers), you have to make sure that all servers and clients using the feature have been compiled against a version of base that supports it. (Not necessarily the same version, but a recent enough version to support the feature.)


Cheers,
Ralph


Replies:
cvt_dbaddr called twice Lei Ge
References:
medm with epics-base 3.14.6+ Emmanuel Mayssat

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