[Info-vax] VAX VMS going forward

[Stephen Hoffman]

On 2020-07-30 17:08:13 +0000, Arne Vajhj said:

> On 7/30/2020 12:56 PM, Stephen Hoffman wrote:
>> On 2020-07-30 14:49:14 +0000, Arne Vajhj said:
>> 
>>> I still don't think you are clear about what you mean by "32 bit app".
>>> 
>>> Is your "32 bit app" an app:
>>> - with only 32 bit data pointers
>>> - at least one 32 bit data pointer
>>> - data in P0 space
>>> - code in P0 space
>>> - combination of above
>>> - something else
>>> ?
>> 
>> When you understand the concept of software memory segmentation in the 
>> APIs, you'll probably better understand the references.
>> 
>> Try to create a 64-bit everything-in-P2-space app. Not a post-V7.0 P0 
>> app with P2 data, but everything related to the app in P2 space. 
>> It's... illuminating.
> 
> So are you defining:
> 
> 64 bit app = app with all of code and data in P2
> 32 bit app = app with some code or data in P0
> 
> ?
> 
> Arne

When you understand the concept of software memory segmentation in the 
APIs—the three segments here are P0, P1, and P2 space—you'll better 
understand the references.

Again, go create a 64-bit everything-in-P2-space app. From that, you'll 
develop a better understanding of how much needs to be in P0 or P1 
space, and how much needs alternate 64-bit API calls for P2 space, and 
which API calls permit P0/P1, or P2 references.

I'd prefer not to deal with P0 / P1 space entirely, and just have P2 
space as a big hunk of memory where I can have code and data and can 
ignore everything below 0x80000000, and with APIs I don't need to look 
at to figure out if they're P0/P1, or P2 space.

In some distant future OpenVMS release, maybe P0/P1 gets reclaimed for 
application use. This when the whole environment has migrated to 64-bit 
native and not this 32-/64-bit hybrid model from OpenVMS Alpha V7.0.




-- 
Pure Personal Opinion | HoffmanLabs LLC