Packing Rhai into 128KB under no-std on STM32

[liunianzmj]

error:

[schungx]

That is strange as the exact same command line passed CI... The once_cell crate didn't need to specify alloc before...

I'll look into it. Perhaps a new version of once_cell.

In the meantime you can specially include once_cell/alloc in your dependencies.

[liunianzmj]

Thank you very much, this problem has been solved, but now there is a new problem, I want to run on the 128kb memory stm32 microcontroller can be implemented? So far the following error has occurred

[schungx]

The standard Rhai with all libraries is too large to fit inside 128KB.

You'd want to use a minimal build. Check this out: https://rhai.rs/book/start/builds/minimal.html

[liunianzmj]

It still doesn't work

[schungx]

Well, did you use Engine::new_raw?

Otherwise you'd be pulling in the entire standard library which will be very large.

[schungx]

I would also say that, if you want to keep arrays and maps, it would probably be difficult to fit it inside 128KB, possibly together with your own code as well...

[liunianzmj]

I used Engine::new_raw, the feature is also used, but it still does not work, what is the minimum memory required?

[liunianzmj]

How do I get rhai to use this memory?

[schungx]

Hhhmmm... No idea. I'm not an embedded programmer myself...

Maybe you can search on the net... Probably you'll need a custom allocator that can allocate from specific locations.

BTW l think I'd also need to turn off memory-heavy stuff like strings interning and function resolution caching... Maybe I'll add that into Rhai.

[liunianzmj]

Thank you very much. I have solved this problem, but I found that about 160KB of FLASH was added to the packaged program after adding rhai. How can I solve this problem?

[schungx]

about 160KB of FLASH was added to the packaged program

As I mentioned, it is quite difficult to fit inside 64K if you don't take out language features. I remember some user successfully packed it under 64K, but he had to disable arrays and objects support (no_index and no_object). However, that was quite a long time ago for a very old version, and much more code has been added since then.

If you want to pack under 128K, then I think it is possible...

Are you sure you're making a release build with optimization for size?

Also have you strip your binary? Unix symbol tables can be quite huge.

[liunianzmj]

Yes, I'm making an optimized size version now. How to reduce the size? Currently I have disabled no_index, no_object, but it still needs 143KB.

[schungx]

Have you stripped the binary?

[liunianzmj]

It's stripped off but it's only 1KB too small