[Info-vax] VMS internals design, was: Re: BASIC and AST routines

[Simon Clubley]

On 2021-11-25, Dave Froble <davef at tsoft-inc.com> wrote:
> On 11/25/2021 9:01 AM, Simon Clubley wrote:
>> VMS has given us great things such as world-leading clustering,
>> but that doesn't change the ugly nature of its internal design.
>>
>> This has caused major problems going forward as people tried to
>> enhance VMS. One such example is the need for a combined 32-bit/64-bit
>> address space.
>
> Solving a "need" is a problem?
>

In the way the underlying VMS design forced it do be done, yes, big time.

In other 64-bit operating systems, you have a mixture of pure 32-bit
ABI processes and pure 64-bit ABI processes running in the same
operating system. Far more cleaner and elegant.

>> Another such example is playing out right now as we speak.
>>
>> The engineers at VSI are talented, experienced and generally skilled
>> overall. However, due to how VMS was designed, it has taken even these
>> skilled people over 7 years so far to port VMS to x86-64 and they will
>> not be finished until the middle of next year at the earliest.
>
> VMS was designed and implemented for VAX, not generic computers.
>

And that, along with the Macro-32 implementation language, is one of
the reasons why we still don't have a production-ready port for x86-64
after 7 years of porting effort, even though VMS has already been through
ports to 2 different architectures.

>> As far as porting operating systems to a new architecture goes, that's
>> pathetic (but due to no fault of the above skilled engineers I hasten to add).
>>
>> And even then, the port is not finished. After that, they need to provide
>> a filesystem that's suitable for today's hardware and today's disk sizes.
>>
>> They have already had two goes at this and abandoned them. At current
>> schedules, you can easily add another couple of years for a new filesystem.
>>
>> For comparison, I would expect a port of Linux to a new architecture to
>> take about 6-12 months to achieve first boot (if you also had to do
>> the compiler work as well) and about another 6-9 months after that
>> to deliver initial versions of the port into the hands of the customers.
>
> Don't want no stinkin Linux ...
>

The comparison is to show what the expected timescale is for porting
to a new architecture.

>> How many people would have stayed with VMS if they knew in 2014 that
>> it would take another 8 years before they had VMS on x86-64
>
> Me!  Me me me me me me ....
>

I doubt many would have joined you.

That would be like saying a port is being started here in 2021 and will
be ready in 2029 (probably). How many other people would have gone for that ?

>> and another
>> couple of years after that before they had a filesystem suitable for
>> today's hardware ?
>
> ODS2 works for me ....
>

What happens when you need to start working with multi-TB drives ?

>> I say things that people don't like to hear. They are also the same
>> things that need to be said.
>
> What need?  And what makes you think we don't already know?
>

Your own comments above suggest you might not.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.