[Info-vax] Greater than approx 16GB disk leads to UNXSIGNAL crash

[Stephen Hoffman]

On 2021-06-01 17:45:33 +0000, Simon Clubley said:

> On 2021-06-01, Stephen Hoffman <seaohveh at hoffmanlabs.invalid> wrote:
>> 
>> OpenVMS Development never prioritized the addition of partitioning 
>> support. That, and this case involves a very old and under-patched and 
>> buggy OpenVMS VAX version. Retro-computing almost inherently involves 
>> revisiting old bugs.
> 
> It would be nice to have proper partition support on VMS, with multiple 
> bootable partitions as well.

Yes, it would. That was discussed before, and it'll undoubtedly be 
discussed again.

The work here mostly touches the storage device drivers, SET BOOTBLOCK, 
BACKUP, and a few other tools.

The common OpenVMS tools and ~all customer apps won't notice 
partitioning, though.

>> More recent OpenVMS has a hideously ugly partitioning hack commonly 
>> found on OpenVMS I64 and specifically for Itanium EFI support, and that 
>> hack is solely intended to present what OpenVMS expects (one big 
>> volume) and what EFI expects (GPT partitioning) and without allowing 
>> partition-aware tools to easily corrupt the OpenVMS one-big-volume view 
>> of the storage.  Silent console-triggered corruptions were once 
>> possible here with older EFI firmware too, when the expectations of the 
>> firmware and of OpenVMS diverged.
> 
> I wonder if we are heading towards a modern version of the various 
> WRITEBOOT issues and "fun" that sometimes happened in the old days... 
> :-)

There are always issues in this area. VSI is using a "creative" scheme 
in support of booting and crashing on x86-64, too.

There's a separate and unchanging OpenVMS installation being kept 
around particularly for assistance when crashing on x86-64.

Coincidentally, the same developer that created the ugly partitioning 
hack for OpenVMS I64 re-wrote WRITEBOOT for V8.0, too.

SET BOOTBLOCK / sys$setboot as a foreign command or when RUN / and the 
sys$setbootshr API.

SET BOOTBLOCK was intended to be necessary only for Itanium, but works 
correctly with Alpha and VAX boot devices.

The tool can also correctly "sniff" and detect a bootable VAX, Alpha, 
or Itanium storage device, among other features.

BACKUP calls into sys$setbootshr for various processing.

SET BOOTBLOCK necessarily knows all about the ugly hack for OpenVMS I64 
and EFI, too.


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