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80 lines
2.8 KiB
Markdown
80 lines
2.8 KiB
Markdown
# Using GDB
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To debug embedded Rust applications with GDB we currently recommend using tooling like OpenOCD,
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JLinkGDBServer or pyOCD
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Although `cargo-embed` v0.10 (and v0.10 of `probe-rs`, the library that powers `cargo-embed`)
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support spawning a GDB server it has some limitations
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- stepping through the code (e.g. GDB's `step` and `next` commands) is imprecise or doesn't work in
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some cases
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- it's not possible to have a GDB server and RTT channels running at the same time (this limitation
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is likely to be removed in v0.11)
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The rest of this section covers how to debug an embedded application within VS code using OpenOCD as
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the GDB server.
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## Dependencies
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1. You'll need to install OpenOCD. Installation instructions vary depending on your OS.
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2. Install the cortex-debug extension in VS code. Head to the extensions marketplace and search for
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"cortex-debug". Latest version at the time of writing is 0.3.7 and the author of the extension is
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"marus25"
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## Preparation
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For the best debugging experience, the `dev` (development) compilation profile should be set to its
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default settings. Modify `beginner/apps/Cargo.toml` to revert the `dev` profile to its default.
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``` diff
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panic-log = { path = "../../common/panic-log" }
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# optimize code in both profiles
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-[profile.dev]
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-codegen-units = 1
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-debug = 1
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-debug-assertions = true # !
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-incremental = false
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-lto = "fat"
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-opt-level = 'z' # !
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-overflow-checks = false
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[profile.release]
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```
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## How to
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1. In VS code, from the top menu pick "File" > "Open folder". Then open the `beginner/apps` folder.
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2. Within this folder, open the `src/bin/hello.rs` file.
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3. From the top menu, pick "Run" > "Start Debugging".
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You are now in a GDB session. Switch to the "Run" view (4th icon from the top on the left sidebar)
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and you'll see debug information like the call stack, local variables, breakpoints and CPU registers
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on the left side. On the bottom panel, you can switch to the "Debug console" to issue commands to
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the GDB server. Near the top of the GUI you'll find a row of buttons to navigate through the program
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(step, continue, etc.). Breakpoints can be added by clicking to the left of line numbers in the file
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view.
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## Debugging a different program
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To debug a different program within the `beginner/apps` folder you'll need to modify the
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`beginner/apps/.vscode/launch.json` file as follows:
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``` diff
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{
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"version": "0.2.0",
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"configurations": [
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{
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"cwd": "${workspaceRoot}",
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- // TODO to debug a different program the app name ("hello") needs to be changed
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- "executable": "./target/thumbv7em-none-eabihf/debug/hello",
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+ "executable": "./target/thumbv7em-none-eabihf/debug/blinky",
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"name": "Debug Microcontroller (launch)",
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```
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Change the name of the program from `hello` to whichever program you wish to debug.
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