[Info-vax] 64-bit (was Re: New CEO of VMS Software)

[Simon Clubley]

On 2024-01-11, Mark Berryman <mark at theberrymans.com> wrote:
>
> Um, if I have a 64-bit app, that would mean I have complete access to 
> P0, P1, P2 space.  Now, I choose to put some data structures in P0 
> space, does that mean that the app is suddenly no longer "totally 64-bit"?
>

No, not if it is your choice instead of some API restriction.

> I've written 64-bit apps.  I've certainly never had to copy data from P2 
> space to P0 space because of some limitation.  I've used both 32-bit and 
> 64-bit item lists and descriptors, including dynamic descriptors.  None 
> of the system services or RTL routines I used had any problem accepting 
> my parameters.  Where in all of this, in your definition, has my app 
> stopped becoming a 64-bit app?
>

The moment you are forced to keep something at a location that can be
reached by a 32-bit address because of an API restriction that does not
have a 64-bit alternative, such as those seen in the RMS APIs.

That includes if the language RTL is doing the 32-bit API access for you
without it ever being explicit in your code.

> For me, it is ok for the documentation to say that a certain item needs 
> to be in P0 space.  I have no problem putting there and I still have a 
> 64-bit app with full access to 64-bit address space.  Nothing the system 
> requires to be in P0 space is dynamic.  It is set it up and forget it 
> (at least as far as anything I can remember using).
>

Yes, but that's doesn't meet David's claim of being able to create a pure
64-bit application. I was replying to that and nothing else.

Simon.

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