[Info-vax] x86S Specification

[Arne Vajhøj]

On 10/18/2024 1:53 AM, Single Stage to Orbit wrote:
> On Thu, 2024-10-17 at 19:27 -0400, Arne Vajhøj wrote:
>>> One of the things proposed for removal is the Ring 1 and Ring 2
>>> privilege
>>> modes.
>>>
>>> Does OpenVMS on AMD64 make use of these modes?
>>
>> My understanding of the proposed changes are:
>>
>> 64 bit OS 64 bit app - works
>> 64 bit OS 32 bit apps - works
>> 32 bit OS 32 bit apps - gone
>> 32 bit OS 16 bit apps - gone
>> 16 bit OS 16 bit apps - gone
>>
>> VMS x86-64 is 64 bit OS 64 bit apps (the fact that pointers are
>> often stored with only low 32 bit bit in RAM is irrelevant).
> 
> His question was about the ring priviledge modes, not what apps and
> what OS will run on the proposed architecture.

I read the question. And I tried to answer.

No changes for 64 bit OS 64 bit apps - and that includes VMS.

(excluding boot process, which need to do some stuff before
it actually becomes a running 64 bit OS)

The details about why has been mentioned a few times
previously.

x86-64 in long mode only support 2 modes in PTE's, so
VMS x86-64 is a hardware 2 mode OS 4 mode OS - U in ring 3,
S, E and K in ring 0.

Arne