haiku VS Lemon-OS

Haiku uses the System V ABI (mostly.) So, we're doing the same things Linux and the BSDs are here, simply by using GCC or Clang without any special tuning here.

> I reckon that before trying to claim you've innovated here it might be a good sense check to compare baseline.

The baseline is "what are other operating systems' kernel- and userland-level condition variables APIs?" And none of the ones I looked at had anything like what Haiku has here, they all have something which is the more classical "lock-switched condvars" just like POSIX has.

The API itself does not depend on what memory ordering semantics are any more than a "mutex_lock()" API does. The implementation will be somewhat contingent on it, of course, but those are two separate matters.

> What exactly are the Haiku atomic operations, in terms of the C++ 11 Memory Model?

The atomic_() functions are (on most architectures, x86 included) implemented using GCC/Clang's __atomic_* functions, with various __ATOMIC_* orderings chosen as appropriate. You can see them defined in the system header here: https://github.com/haiku/haiku/blob/master/headers/os/suppor...

> because you're innovating before 2011, you're inventing the model

No, not really? GCC has had atomic builtins since at least 4.1.0 in 2006. The documentation (https://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins...) says: "In most cases, these builtins are considered a full barrier. That is, no memory operand will be moved across the operation, either forward or backward." -- which is basically equivalent to today's __ATOMIC_SEQ_CST.

> so Haiku is off in the jungle on its own and everybody else has a map now, figure out where you are on that map first.

We already did that years ago. The atomic_() functions linked above in SupportDefs.h have been implemented using the C++11-standard GCC builtins since 2014, and the older __sync_ builtins for years before that.

Anyway, the algorithm described in this article, even if Haiku's atomic functions were not 1:1 with C++11-standard definitions (which they are, as noted above), is clearly portable to other OS kernels. So I am not sure what basis your comment has, regardless.

I'm currently trying to build Haiku from source (following https://github.com/haiku/haiku/blob/master/ReadMe.Compiling.md), but I'm getting errors while building with "jam -q -j12 @nightly-anyboot".

Something like this? https://github.com/haiku/haiku/tree/master/src/add-ons/accelerants/radeon

There is a topic named "What Your OS Looks Like" in OSDEV forum, I got inspiration from it, especially nifanfa and LemonOS. And also a book named "30日でできる! OS自作入門".

Lemon OS Github: https://github.com/fido2020/Lemon-OS