[Info-vax] VSI licencing policy (again), was: Re: VSI has a new CEO

[Dan Cross]

In article <608dc068-5afe-4f04-850e-9dbb6e474c69n at googlegroups.com>,
Lawrence Dâ  Oliveiro  <lawrencedo99 at gmail.com> wrote:
>On Monday, August 9, 2021 at 4:27:34 PM UTC+12, John Dallman wrote:
>> [Windows NT] was initially shipped on MIPS, PowerPC and Alpha, and the dropping of 
>> those platforms was because they weren't much used, rather than because 
>> they didn't work. It then shipped on Itanium, which was dropped because 
>> the market preferred x86-64, rather than because it didn't work.
>
>All of which were supported on Linux, and continued to be supported on Linux
>long after Microsoft had abandoned them. So you see, it wasn't
>just a matter of the popularity (or not) of those architectures.

FTR, NT first booted on an in-house i860 workstation built by
microsoft.

But porting VMS to run "on top of" Linux would likely be far more
work than just running directly on bare hardware.  Linux's internal
kernel architecture is very different from that of VMS; a non-trivial
translation layer would have to be implemented.

>Alpha is an interesting case. In spite of it being a 64-bit architecture,
>Windows NT only ever ran on it in 32-bit 'TASO' mode. OpenVMS
>got as far as a hybrid 32/64-bit port, but I don't think it ever
>managed to go full 64-bit.

Running on the bare hardware, in a lot of respects, is not the
hard part.  I imagine drivers and compilers are a much bigger
issue than booting, page tables and context switching.  As others
pointed out, you need the compilers anyway to support customers.
Given the system call differences between VMS and Linux, it's
unclear how much you could really leverage Unix drivers, but
there's no reason those couldn't be ported if they can be used.

>The only two fully-64-bit OSes to run on Alpha were DEC's Tru64
>Unix ... and Linux.

I found that doubtful. NetBSD claims full 64-bit support on Alpha.
I imagine so does OpenBSD.  I don't know what the status of
FreeBSD was, but I imagine they were full 64-bit.  The plan 9
kernel on Alpha was a 64-bit kernel, though admittedly pretty
much a 32-bit API.

	- Dan C.