> Why do we even have linear physical and virtual addresses in the first place, when pretty much everything today is object-oriented?

What a weird question, conflating one thing with the other.

I’m working on a object capability system, and trying hard to see if I can make it work using a linear address space so I don’t have to waste two or three pages per “process” [1][2] I really don’t see how objects have anything to do with virtual memory and memory isolation, as they are a higher abstraction. These objects have to live somewhere, unless the author is proposing a system without the classical model of addressable RAM.

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1: the reason I prefer a linear address space is that I want to run millions of actors/capabilities on a machine, and the latency and memory usage of switching address space and registers become really onerous. Also, I am really curious to see how ridiculously fast modern CPUs are when you’re not thrashing the TLB every millisecond or so.

2: in my case I let system processes/capabilities written in C run in linear address space where security isn’t a concern, and user space in a RISC-V VM so they can’t escape. The dream is that CHERI actually goes into production and user space can run on hardware, but that’s a big if.

The memory management story is still a big question: how do you do allocations in a linear address space? If you give out pages, there’s a lot of wastage. The alternative is a global memory allocator, which I am really not keen on. Still figuring out as I go.

> What a weird question, conflating one thing with the other.

I can only imagine he means something different by “object-oriented” than the concept at the programming language level. And if he is referring to that, then I hope no-one ever lets him near anything resembling hardware design.

Have you looked at the Apple Newton memory architecture?

http://waltersmith.us/newton/HICSS-92.pdf