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

Subject: Revision tracking on vendor supplied updates?
From: Josh Stein <stein@aps.anl.gov>
To: EPICS tech-talk <tech-talk@aps.anl.gov>
Date: Tue, 05 Jan 2010 11:20:44 -0600
Community,

With the proliferation of small highly-distributed IOCs and remote I/O we are seeing a rapid increase in the number of "intelligent" devices connected to our control systems. One outcome of this is the widespread use of vendor specified 'firmware' within these devices. Often times this firmware is not quite... as firm... as one would hope, and numerous updates are released over the lifespan of our embedded designs.

This concerns me in a number of ways.

First; without delving into the minutia of a specific manufacturer's software engineering processes (which I am usually not privy to), I am - in effect - (re)installing software in a (presumably) mature system with little knowledge of the ramification of this upgrade. Take for example a PLC based system which I've deployed in the past. The software on this PLC (ladder logic) was written 8 years ago, and a portion of that software was a "workaround" for a race condition which exhibited itself in a predictable (and documented) manner. A recent firmware update of that PLC apparently corrected this error, and hence made the workaround code unnecessary. I can envision a case in which a designer inadvertently "takes advantage" of an undocumented feature in a subsystem which is then removed or deprecated via firmware update. A routine or tangential upgrade may make that system fail altogether, or (more dangerous) act in an unexpected manner, with the culprit hard to detect.

Second (similar to #1, but subtly different); do I just trust a vendor that their firmware will not introduce problems to my current system? I have seen on more than one occasion firmware updates with little or no change logs accompanying them. An easy answer would be "don't fix it if it ain't broke," but that is not reasonable. We have systems here that require periodic updates to keep up with newer or updated commercial products - for example, the latest I/O modules for the Koyo PLCs will not function with the processors we have without a firmware update first. Another easy answer is "test test and test," but I believe that is not necessarily practical nor exhaustive.

Finally; assuming firmware updates are an accepted price to pay for COTS devices, how do we manage and track them? More often than not I'm going to receive not only a proprietary (binary) firmware image, but also a custom loader and procedure. Here at the APS, a PLC firmware update has the potential to take many hours of effort to physically walk the machine and connect a windows based laptop to each installation to perform the update. Note that this also (typically) will shut the system down as the firmware is applied so cannot be done during beam operations. What about "rolling back" to a previous version? I have seen systems which do not allow this with current loaders.

How is the community handling COTS firmware updates?

Oh - and happy holidays!

--Josh Stein






Replies:
RE: Revision tracking on vendor supplied updates? Dalesio, Leo

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