[mdaniel]

Surely if Windows kernel can be taught to respond to those syscalls, XNU can be taught it even easier. But, AIUI the Windows kernel already had a concept of "personalities" from back when they were trying to integrate OS/2 so that zero-to-one for XNU could be a huge lift, not the syscalls part specifically

[shawnz]

WSL1 didn't use the existing support for personalities in NT

[heavyset_go]

XNU similarly has a concept of "flavors" and uses FreeBSD code to provide the BSD flavor. Theoretically, either Linux code or a compatibility layer could be implemented in the kernel in a similar way. The former won't happen due to licensing.

[kergonath]

> the Windows kernel already had a concept of "personalities" from back when they were trying to integrate OS/2 so that zero-to-one for XNU could be a huge lift, not the syscalls part specifically

XNU is modular, with its BSD servers on top of Mach. I don’t see this as being a strong advantage of NT.

[literalAardvark]

Exactly. So it wouldn't necessarily be easier. NT is almost a microkernel.

[9dev]

Yep. People consistently underestimate the great piece of technology NT is, it really was ahead of its time. And a shame what Microsoft is doing with it now.

[okanat]

Was it ahead? I am not sure. There was lots of research on microkernels at the time and NT was a good compromise between a mono and a microkernel. It was an engineering product of its age. A considerably good one. It is still the best popular kernel today. Not because it is the best possible with today's resouces but because nobody else cares about core OS design anymore.

I think it is the Unix side that decided to burry their heads into sand. We got Linux. It is free (of charge or licensing). It supported files, basic drivers and sockets. It got commercial support for servers. It was all Silicon Valley needed for startups. Anything else is a cost. So nobody cared. Most of the open source microkernel research slowly died after Linux. There is still some with L4 family.

Now we are overengineering our stacks to get closer to microkernel capabilities that Linux lacks using containers. I don't want to say it is ripe for disruption becuse it is hard and again nobody cares (except some network and security equipment but that's a tiny fraction).

[9dev]

> Was it ahead? I am not sure.

You say this, but then proceed to state that it had a very good design back then informed by research, and still is today. Doesn't that qualify? :-)

NT brought a HAL, proper multi-user ACLs, subsystems in user mode (that alone is amazing, even though they sadly never really gained momentum), preemptive multitasking. And then there's NTFS, with journaling, alternate streams, and shadow copies, and heaps more. A lot of it was very much ahead of UNIX at the time.

> nobody else cares about core OS design anymore.

Agree with you on that one.

[okanat]

> You say this, but then proceed to state that it had a very good design back then informed by research, and still is today. Doesn't that qualify? :-)

I meant that NT was a product that matched the state of the art OS design of its time (90s). It was the Unix world that decided to be behind in 80s forever.

NT was ahead not because it is breaking ground and bringing in new design aspects of 2020s to wider audiences but Unix world constantly decides to be hardcore conservative and backwards in OS design. They just accept that a PDP11 simulator is all you need.

It is similar to how NASA got stuck with 70s/80s design of Shuttle. There was research for newer launch systems but nobody made good engineering applications of them.

[anthk]

Unix 'died' with plan9/9front, which is far more advanced than Unix v7 for a PDP or a DEC, can't remember.

9front is to Unix was NT it's for VMS.