[Info-vax] What would be involved in moving RMS into kernel mode ?

[Arne Vajhøj]

On 5/10/2023 8:38 AM, Simon Clubley wrote:
> On 2023-05-09, Arne Vajhøj <arne at vajhoej.dk> wrote:
>> They key metric should be robustness. And based on
>> what has been posted here and in VSI forum, then VMS 9.2
>> is pretty solid. There are some reports about problems
>> in DECWindows and development tools, but the core
>> OS seems to be rock solid. I don't think I have seen anyone
>> post about system crashes.
> 
> Unoptimised code can make invalid assumptions that are only revealed
> when the code is run through an optimiser. Any such problems in VMS
> should be discovered rather quickly however once compiled in optimised
> mode. It's still a requirement for VMS to go through this process before
> it can be considered to be production-ready however.

Increasing optimization can cause in-correct code to start
producing bad results.

So building with increased optimization requires test.

But that is not a one time issue.

Every time the LLVM team add new optimizations (or change
existing optimizations) and VSI grab the new LLVM, then
it could in theory cause a problem. And it does require
new test.

That will be the situation as long as VMS exist.

Sure going from unoptimized cross compilers to
optimized (probably not with all optimization enabled
in the first round) is going to be a bigger
change than updating LLVM with new optimizations.
But it is just "bigger" not a different concept.

So I don't think "risk of later optimization triggering
latent bugs" is a good reason for not going to production.

Arne