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by pcwalton 3524 days ago
> We may someday get an XNU rewrite, but probably not until software engineering produces a new approach to building complex systems reliably that works at the scale (here: number of developers and shipping schedule) Apple needs.

It's conceivable to perform a gradual transition away, though. They could demote Mach to a fast IPC system that just augments BSD, similar to the way the kdbus/bus1 proposal for Linux does. That would be difficult and a long-term project, but it would fix the underlying issue in a way that mostly retains userspace compatibility. Driver compatibility would be more difficult, of course…
1 comments
tptacek 3524 days ago
That's true, but if you undertake a difficult and long-term project, you want the outcome to be decisive. Mach is ugly and a nest of bugs, but kernels implemented in C/C++ are bug magnets with several orders of magnitude more force.

My prediction is that we don't ever see an XNU refactor/ redesign/ rewrite so long as C/C++ is the kernel implementation language.

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pcwalton 3524 days ago
No argument there. :)
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