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rust-raspberrypi-OS-tutorials/01_wait_forever
History
Andre Richter de3ba3e871 Refactor Tests and Makefile 
- Carve out common files for tests
- Add boot tests starting tutorial 3
- Overhaul the Makefile for more structure
 		3 years ago
..
.vscode rust-analyzer: Fix error with recent version 3 years ago
src Assembly: Use local label syntax for named labels 3 years ago
Cargo.lock Give the project a name 3 years ago
Cargo.toml Give the project a name 3 years ago
Makefile Refactor Tests and Makefile 3 years ago
README.CN.md Remove xbuild. Use upstream aarch64 rust-std 🎉 🦀 4 years ago
README.md Minor fixes 3 years ago
build.rs rust-analyzer: Fix error with recent version 3 years ago

README.md

Tutorial 01 - Wait Forever

tl;dr

  • The project skeleton is set up.
  • A small piece of assembly code runs that just halts all CPU cores executing the kernel code.

Building

  • Makefile targets:
    • doc: Generate documentation.
    • qemu: Run the kernel in QEMU
    • clippy
    • clean
    • readelf: Inspect the ELF output.
    • objdump: Inspect the assembly.
    • nm: Inspect the symbols.

Code to look at

  • BSP-specific link.ld linker script.
    • Load address at 0x8_0000
    • Only .text section.
  • main.rs: Important inner attributes:
    • #![no_std], #![no_main]
  • boot.s: Assembly _start() function that executes wfe (Wait For Event), halting all cores that are executing _start().
  • We (have to) define a #[panic_handler] function to make the compiler happy.
    • Make it unimplemented!() because it will be stripped out since it is not used.

Test it

In the project folder, invoke QEMU and observe the CPU core spinning on wfe:

$ make qemu
[...]
IN:
0x00080000:  d503205f  wfe
0x00080004:  17ffffff  b        #0x80000