[Info-vax] Modular VMS, was: Re: Prism/Pillar, was: Re: inertia or fundamentals about langages?

[Dave Froble]

On 5/29/2019 2:11 PM, Simon Clubley wrote:
> On 2019-05-29, Stephen Hoffman <seaohveh at hoffmanlabs.invalid> wrote:
>> On 2019-05-29 12:21:11 +0000, Simon Clubley said:
>>
>>> On 2019-05-28, Stephen Hoffman <seaohveh at hoffmanlabs.invalid> wrote:
>>>
>>>> The production ports of OpenVMS for Alpha and Itanium were interesting
>>>> and technically complex and challenging in various ways, but haven't
>>>> particularly diverged from the design and organization of the
>>>> progenitor VAX modular kernel.
>>>
>>> Should that be monolithic, instead of modular ?
>>>
>>> I wouldn't exactly call the VMS kernel modular, especially by today's
>>> standards.
>>
>> Donno.  I've always called it "modular", though "modular monolithic"
>> might be closer to current terminology.

Does terminology change what something is?  I doubt that.

>> While the OpenVMS kernel uses a monolithic address space, the
>> organization of the kernel itself is not monolithic and the various
>> pieces of the kernel are dynamically linked together during and
>> variously after bootstrap.
>>
>
> While the VMS kernel may be organised in that way, it is still a
> monolithic mass of code as far as anyone actually using it is concerned.

Depends ....

> There's no way to reload device drivers for example.

That has nothing to do with monolithic/modular/micro kernels.  That is 
just a lack of a capability.  That capability could be implemented in 
any type of kernel.

> The XQP cannot be extended by the end user so they can't plug in
> new filesystems, either in the kernel or within a process.

Depends ....

> You know the following, but for those who don't, take a look at the
> examples of what you can do in Unix-land:

Not interested.

> https://en.wikipedia.org/wiki/Filesystem_in_Userspace
>
> The process level option (ie: the ACPs) come across as being horrible to
> create and integrate into the rest of VMS and the process is undocumented.

Yep.

> The terminal driver code is so yucky and unchangable that you can't even
> edit lines that wrap a line boundary. In 2019/2009/1999, that's crazy.

Really hacked up, yeah.  But not all of us get so upset about command 
line editing.

> You can't swap out the system supplied shell (DCL) with another shell
> supplied by the user due to the heavy integration of DCL into the VMS
> way of doing things and due to the total lack of documentation about
> how to write a replacement login-level shell.

Well, you could, but there is that lack of documentation.  The original 
design was to allow for multiple CLIs.  The second one just never happened.

However, you can run some of the *ix shells.  Just don't use DCL 
commands if you do not wish to do so.


> When you only know VMS, then I suppose everything looks ok and you don't
> see a problem. When you know other operating systems however, that's when
> you _really_ see what VMS is missing.

And what VMS has.  It goes both ways.

> Even today, VMS still has leading features, such as VMS clustering.
> They can easily be hidden however by all the things you trip over or
> otherwise miss having available when you are using VMS.
>
> BTW, one final thought. Sooner or later, VSI is going to have to tackle
> the problem of trying to sell VMS to new sites in order to continue growing.
>
> When you look at VMS as it stands today and in the future, what do you
> tell those potential new sites to persuade them to have a go at
> evaluating VMS ?
>
> What do you tell them when they ask why they should look at VMS instead
> of other operating systems they are more familiar with and which have
> features they are familiar with ?

I don't know that it matters.  Some people are so ties into the *ix ways 
that they could not accept anything else.

What do you tell WEENDOZE users to get them to look at anything else?


-- 
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef at tsoft-inc.com
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