[Info-vax] CRTL and RMS vs SSIO

[Simon Clubley]

On 2021-10-12, Lawrence D?Oliveiro <lawrencedo99 at gmail.com> wrote:
> On Wednesday, October 13, 2021 at 9:54:14 AM UTC+13, Stephen Hoffman wrote:
>> The DEC OpenVMS advanced development group did do a prototype of 
>> OpenVMS on Mach a ~quarter-century ago. 
>
> Yeah, but Mach is a microkernel, with all the downsides that microkernels have.
>

Microkernels have moved on and microkernels have massive security advantages.

BTW, QNX, which is a RTOS with a massive user base, is microkernel based.

>> Possible areas where kernel modifications might necessary? Linux memory 
>> management is thoroughly two-ring, and OpenVMS expectations are 
>> four-ring. Do you drop those areas from OpenVMS, and force app source 
>> code changes? 
>
> Where is there app code that cares about this?
>

Any program that interacts with DCL for one simple example.

In the current VMS design, you can't move DCL into user mode, or allow
user-controlled code to execute in DCL's supervisor mode, without ending
up with an operating system that has all the security of MS-DOS.

Other examples have already been posted.

Simon.

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