[Info-vax] VMS porting/rewrite, was: Re: [OT] Wirth style languages, was: Re: Obscure Ada compiler vendors?

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In article <kk11j5$etr$1 at dont-email.me>, Simon Clubley <clubley at remove_me.eisner.decus.org-Earth.UFP> writes:
>On 2013-04-08, Keith Parris <keithparris_deletethis at yahoo.com> wrote:
>> On 4/4/2013 11:01 AM, Stephen Hoffman wrote:
>>> Rewriting all of OpenVMS?  That'd lead me to this state:
>>> <http://www.youtube.com/watch?v=3L6i5AwVAbs>. Even if you were to be
>>> successful with a rewrite, once you're done with that very substantial
>>> and years-long effort and investment, you would have something
>>> approximating current-day VMS. Not the features and functions that
>>> folks would would want and would expect after all those years.
>> ...
>
>This is talking about a rewrite of the code from the ground up, maintaining
>user level API compatibility, but with different and more modern internals.
>
>>> The rest of the
>>> market is not standing still here, and you're talking about a project
>>> that took three or five years last time (Alpha to Itanium) for a fairly
>>> straight port with very few changes, and with an engineering team that
>>> was very familiar with VMS assigned to the effort full-time.   ~Thirty
>>> million lines of Bliss and C and Macro32 is a huge project to
>>> reconstitute.
>
>This is talking about a port of the existing code base to a new
>architecture.
>
>These are two separate issues and people are mixing them up.
>
>Which one are you thinking of Keith ? (This confusion showed up on the
>mailing list as well, so I think it's important to know exactly what
>you are thinking about here.)
>
>>
>> By this logic, the GNU project and Linux could never have caught up 
>> with, much less surpassed or exceeded, UNIX capabilities.
>
>The GNU project started out as building a compiler and replacing vendor
>specific versions of Unix commands/utilities with their own. (Unix makes
>it easy to replace things a bit at a time; VMS does not.)

You don't like a particular command or utility, write your own.  You can
replace these things just as easily.  Saying that it is not easy to do on
VMS means you shouldn't be a part of the project trying to do so. ;)



>However, the GNU project's own OS project, Hurd, stalled during development.
>
>Linux is far cleaner internally than VMS is (when it comes to porting),
>with a clean separation of architecture specific and non-specific
>components, and was written from the beginning in a portable language.
>
>As I mentioned on the mailing list recently, a group of university
>students could probably port Linux to a new architecture in a reasonable
>amount of time. That is simply not going to happen with the existing
>VMS code base.
>
>Furthermore, plugging new components into Linux or another Unix OS is
>easy, especially at user (ie: non-privileged) level because the Unix
>API is designed around the concept of lots of separate programs doing
>their own thing, but linked together by well defined and _public_
>interfaces.
>
>For example, writing a new shell for Linux is relatively easy. How does
>that compare to replacing DCL on VMS ?

Simple.  Write your own and use it.  There is nothing sacred or special 
about a CLI on VMS.  Of course, if you're still expecting to use any DCL
constructs, then you'll have to provide that in your CLI.  Sheesh, talk
about mythconceptions.  Hint: Shareable image; entry point at 0!  'Nuff
said.



>Since porting the existing code base does not appear to be viable, that
>leaves a new implementation which maintains the user level VMS API,
>but with very different internals.
>
>There was a experiment carried out in the 1990s with porting VAX/VMS to
>a microkernel architecture using Mach. This was not a port of VMS to
>another hardware architecture (the Mach microkernel ran on a VAX in
>this case) and the result was not even remotely production ready,
>but it did cover some of the issues which would be encountered.
>
>I read the paper which came out of that research again this weekend and
>it's worthwhile for anyone interested in this subject to actually read.
>I only have the original PS version, but Paul has a PDF version on his
>website at http://www.sture.ch/vms/Usenix_VMS-on-Mach.pdf

Much of what *IS* VMS *IS* its kernel.  Elide it and you don't have VMS!
-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

Well I speak to machines with the voice of humanity.