Post by Simon ClubleyGiven that the VMS mindset is supposed to be one of robustness and
reliability, perhaps the proper approach is to enforce a default refuse
to boot on unsupposed configuration, but allow an override with a boot
flag or SYSGEN parameter.
A fondness for arcana, inappropriate defaults, and documented and
ill-documented knobs—many of these defaults and these knobs tracing
back to the fallout arising from compatibility—seemingly became
commonly-accepted practice decades ago.
Put differently, documenting the potential for or incidents of a limit
or a crash or appropriately-trained and experienced staff has long been
viewed as meeting minimal requirements, either via the SPD or via some
other detail or document elsewhere. One of the bootcamp sessions
covering known issues with a supported feature was just surreal, for
instance. There have been other examples. Expectations and assumptions
can all change, too. I know mine have. But that's all fodder for
another time.
Post by Simon ClubleyThat way, people don't accidentally use an unsupported configuration in
production use, but you also don't stop people from using an
unsupported configuration if they choose to do so.
I fixed a whole pile of support calls with diagnostics shown for
unsupported configurations, and fixed even more support calls by
automatically detecting and fixing the most common of the errors.
It's quite correct that unsupported-hardware configurations are
incredibly difficult or ~impossible to detect, but overt
mistakes—configuration detection analogous to that Python script—should
be built in to the OpenVMS console or incorporated into the early
bootstrap. Same for similar detection built into (or shared with) the
installer.
Following another longstanding OpenVMS practice of far too chatty
bootstraps (q.v. inappropriate defaults), adding diagnostics and adding
a hardware configuration display and showing an unsupported
configuration diagnostic as needed there would parallel longstanding
console practices.
I'd probably add the unsupported display into the x86-64 error analysis
tooling or into SHOW CPU or some other diagnostic tooling visible at
run-time, and shown in SDA for crashes. This not to imply error-related
tooling is ever going to be remotely easy to create and maintain on
x86-64.
Architecturally, adding a hardware section into the system or
site-local device configuration database would make sense for this
detection. If somebody wants to mask the unsupported-configuration
error, they can edit their change into the site-local hardware
configuration data. (q.v. arcana)
Post by Simon ClubleyHowever, if you implement this, an impossible to miss message should be
output on every boot so that the flag is not set and then forgotten about.
Identifying everything unsupported is ~impossible given the constraints
OpenVMS operates under. But I wouldn't be concerned about adding some
diagnostics to an already-chatty bootstrap either, given normal OpenVMS
bootstraps and startups are purpose-designed to make that easy to hide
info and easy to ignore. Hardware, too. Default Itanium startups are
just stupidly chatty.
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