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Designed a kernel with only one system call, but the one system call is basically ioctl so it doesn’t really count.

I have now mostly implemented a userspace version of this kernel in C.

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I didn't do it in Rust because C is faster for the prototyping of stupid and low-level ideas no one will actually use.

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The basic idea has two parts:

1. Microkernel where communication with the kernel is also via message-passing, even for task and memory management.
2. Tight binding between IPC and CPU scheduling; each "port" has an associated function which runs when the port receives a packet. This is the only way of getting CPU time in userspace. A port can be set to get empty "idle" packets from the kernel.

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There seems to be some interest in this. I’ll MIT the code and stick it on my GitLab (I’ll self-host Gitea or something at some point, but still on GL for now) once I have a working demo.

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You don’t want to use this thing. free(buf) turns into

struct unmapspace_frm del = {
.frm = {
.dst = SPACEMGR,
.typid = UNMAPSPACE,
.frmsz = sizeof(unmapspace_frm),
.pktsz = sizeof(unmapspace_pkt)
},
.pkt = {
.here = buf
}
}
del.frm.data = &del.pkt;

send(&del);

I mean it could be improved with macros and wrapper functions but still.

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It is very difficult to program when memory allocation is asynchronous.

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It took me almost 40 lines across two functions to implement a single realloc.

Please never use this thing. I’ll post the code still, but please never use it for anything serious.

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@wmww I think you should see this whole thread. It makes a good example of what happens when I let myself pursue my crazy spur-of-the-moment ideas.

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@alexbuzzbee

Please come up with another word than, "port," otherwise that will be superconfusing forever. Cool project.

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