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Comment by zarvox | Hacker News Reader

My impression is that bus1 appears to have taken the (copious) feedback from the kdbus debacle and actually applied it and looked at other platforms' IPC to build a novel IPC system for Linux worth using. There's a talk [1] about the design of bus1, and comparison against IPC on other platforms where IPC is saner, and how the capability model is the right design for IPC - composable, understandable, and secure-by-default. It strikes me that the bus1 devs arrived at their design after doing the things you suggested! :)

Is there something I'm missing? What might an ideal IPC API look like to you?

[1] - https://www.youtube.com/watch?v=6zN0b6BfgLY

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> What might an ideal IPC API look like to you?

Erlang's internal IPC is doing it pretty well since before there was a Linux kernel. I don't know if that approach can be ported into the kernel and how complex they are behind the scenes, but spawn / send / receive are apparently simple concepts.

In Erlang: http://erlang.org/doc/getting_started/conc_prog.html#id68696

In Elixir: http://elixir-lang.org/getting-started/processes.html

Authentication, authorization, and resource quotas for agents are not really addressed in the Erlang model, but would be expected for IPC on a Unix-like system.

Do we really want to put all of that into the kernel and not implementing it in userland? I get the feeling that it's too much application dependent, not enough general principles.

Maybe I just don't understand the problem they are out to solve.

The reason for a bus-style IPC implemented in the kernel is the same that sendfile(2) exists. I doubt anyone thinks it's the pinnacle of great design, but reduced copies and context switching for real application workload: sometimes the more 'proper' design is sacrificed for practicality.

What might an ideal IPC API look like to you?

I can't answer that because I don't have a PhD related to IPC, and I haven't done the necessary research to fully understand the field. I have looked at how some other systems are doing it, but I know that is not a strong enough knowledge-base to build a good IPC system.

I do have enough understanding to know that when I look at a good IPC api, I will look at it and say, "wow, that's really nice."

Which IPC apis do you consider really nice? And which not?

What do you think of zeromq?

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