cpython/Objects/mimalloc/prim/readme.md

## Portability Primitives

This is the portability layer where all primitives needed from the OS are defined.

- `include/mimalloc/prim.h`: primitive portability API definition.
- `prim.c`: Selects one of `unix/prim.c`, `wasi/prim.c`, or `windows/prim.c` depending on the host platform
            (and on macOS, `osx/prim.c` defers to `unix/prim.c`).

Note: still work in progress, there may still be places in the sources that still depend on OS ifdef's.