[Info-vax] Ignorance promenade: On the nature of patching VMS

[abrsvc]

I suppose that in the traditional sense, a "patch" would be a modification of an existing image rather than an image replacement.  While the patch utility still exists, it is not used to modify images anymore.  That went away with the VAX.  The different structure of images along with the change in the way modules are linked makes traditional patching difficult if not impossible.  Also, instruction streams are intertwined now where on the VAX, sequential execution was the norm.

As far as what can be changed, that would be everything.  Any image can be replaced and thus any portion of OpenVMS can be "patched" in this manner.  IIRC, the new builds were done and tested with the modified images and the new ones shipped in an update.  As with any large system of code, only the modified images were shipped.  If the patch required other images to be modified, then those too were linked and shipped.

Dan