How to Implement a Custom Allocator in Rust Core for Embedded Systems?
I'm experimenting with I'm trying to configure I'm working on a project and hit a roadblock... I'm working on a Rust project for an embedded system that utilizes `core` without the standard library. I need to implement a custom allocator, but I'm running into issues with allocation failures. My target is an ARM Cortex-M microcontroller, and I'm using Rust 1.64 for this project. I attempted to use the `alloc` crate alongside my custom allocator implementation. Here's a simplified version of my allocator code: ```rust #![no_std] #![feature(global_asm)] use core::alloc::{GlobalAlloc, Layout}; struct MyAllocator; unsafe impl GlobalAlloc for MyAllocator { unsafe fn alloc(&self, layout: Layout) -> *mut u8 { // Simulating allocation by just returning a pointer // In real use, this should manage memory properly let ptr = some_memory_management_function(layout.size()) .expect("Allocation failed"); ptr } unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) { // Deallocating memory some_memory_management_function_dealloc(ptr); } } #[global_allocator] static ALLOCATOR: MyAllocator = MyAllocator; ``` When I run my application, I frequently encounter the following behavior message related to memory allocation: ``` thread 'main' panicked at 'Allocation failed', src/lib.rs:15:9 ``` I tried adjusting the memory layout and ensuring that there is enough heap memory available, but the scenario continues. I suspect there might be a question with how I'm managing the memory space or not correctly implementing the allocation and deallocation logic. Additionally, I noticed that if I commented out certain allocations, the program runs fine, which indicates that the question is specifically related to memory management. My embedded environment also has limited debugging capabilities, so tracking down the source of the allocation failure is quite challenging. Has anyone successfully implemented a custom allocator in a no_std environment? What common pitfalls should I be aware of or best practices for managing memory in Rust embedded applications? Has anyone else encountered this? This is for a CLI tool running on Windows 11. Any examples would be super helpful. For reference, this is a production mobile app. Could this be a known issue? This is for a CLI tool running on Windows 10. I'd be grateful for any help.