Peter Relson wrote:
This whole thread is exactly why it is important to code your applications to programming interfaces. Intercepting, front-ending, whatever: you are only asking for trouble.
IBM provides a programming interface for intercepting SVC calls called SVC screening. This facility has been used by a great many ISVs--including Phoenix--to intercept SVC calls in a way that limits the intercept to a a subset of SVCs for a single, targeted TCB.
Whether by oversight, laziness, perceived difficulty of implementation, or whatever, IBM implemented no equivalent programming interface for PC calls. PC call intercepts, if needed, must always be done at a system level using "unintended" interfaces.
It should be obvious, but I will clarify for those that might not be privileged code programmers, that intercepting PC calls using these "unintended" interfaces is considerably more difficult to implement than SVC screening and, because the intercept must be at a system level, programming errors here are several orders of magnitude more likely to expose the system to instability than similar programming errors in SVC screening routines.
If IBM chooses to provide no equivalent function to SVC screening for PCs, then proceeds to change numerous services to use PCs instead of SVCs, and then complains because software that used to intercept SVC calls with SVC screening now uses "unintended" programing interfaces to intercept the equivalent PC calls, what can I really say about that? I just don't have much sympathy...
-- Edward E Jaffe Phoenix Software International, Inc 831 Parkview Drive North El Segundo, CA 90245 310-338-0400 x318 edja...@phoenixsoftware.com http://www.phoenixsoftware.com/ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
