[Info-vax] Kernel Transplantation (was: Re: New CEO of VMS Software)

[Lawrence D'Oliveiro]

On Fri, 5 Jan 2024 19:59:12 -0500, Stephen Hoffman wrote:

> [lots of interesting stuff omitted]
> 
> From another time and place, a DEC Usenix paper from way back in 1992
> discussing a kernel-swap project:
> http://fossies.org/linux/freevms/doc/Usenix_VMS-on-Mach.PS
> 
> From a reference to that work: "In 1992, a development team from Digital
> Equipment described a proof-of-concept implementation of VMS on Mach
> 3.0. ... Their work provided independent confirmation that multiple OS
> personalities could be supported on the Mach microkernel. At the same
> time, it exposed certain limitations. For example, it proved impossible
> to accurately emulate VMS scheduling policies using Mach.

That can be blamed on the limitations of Mach. People still seem to think 
microkernels are somehow a good idea, but they really don’t help much, do 
they?

> As another example, it was not possible to emulate VMS’ strong isolation
> of kernel resource usage by different users.

Would the Linux cgroups functionality (as commonly used in the various 
container schemes) help with this?

> Preliminary measurements also
> suggested that layering VMS on Mach resulted in unacceptable performance
> overhead.

No big surprise -- microkernel trouble yet again.