You can run the application directly on an FVP that the Arm Development Studio includes:
FVP_MPS2_Cortex-M3.exe -a target/thumbv7m-none-eabi/debug/examples/armds
To disable FVP visualization, which can reduce the start time, add the following command option:
-C fvp_mps2.mps2_visualisation.disable-visualisation=1
This option has no other effect on the behavior of the FVP.
The application runs to completion on the FVP, and you will see output similar to:
Total sum to 1 is 1
Calculated sum is 1
Total sum to 2 is 3
Calculated sum is 3
...
Though Rust applications are not officially supported by the debugger, the DWARF5 debug format has been the default since the 6.0 (Arm Development Studio 2023.1) release.
This means that in general, you can debug Rust applications.
By default, Arm Development Studio is not aware of Rust (.rs) source files.
Navigate the menu to Window > Preferences, and then General > Editors > File Associations.
Click Add, and enter .rs file type.
Highlight the .rs file type from the list, and add C/C++ Editor as the Associated editor. Click Apply and Close.
Launch the Arm Debugger, and create a New > Model Connection from the File menu.
When prompted, provide a meaningful debug connection name.
Select the MPS2_Cortex_M3 FVP from the list of Arm FVP (Installed with Arm DS), and click Finish.
When the Edit Configuration pane appears, navigate to Files, and locate the above armds executable as the Application on host to download.
In the Debugger tab, select either Debug from entry point or Debug from symbol (main), as preferred. The entry point is the low-level library code, it is unlikely you have access to this source, but if you do, you should be prompted to Set Path Substitution to refer to where this code is stored.
To set a breakpoint (at main) either use the Functions view, or the Commands view:
break main
and click the Run icon (or enter continue on command line). Execution will stop at main, and the armds.rs source file will open.
The debugger shows that execution has stopped at main. It is possible to set breakpoints directly in this source code by double-clicking on the left-hand margin.
Set a breakpoint at the sum += n; line within the for loop. Run to this point.
The Functions view lists all function symbols. Many of the library functions have their names mangled. However you will be able to locate main in there.
The Disassembly view shows the low-level code, along with mangled symbol names where possible.
You can see the text output of the hprintln calls in this view.
The variables view displays the values of the variables as they change.
The sum and n variables are displayed as expected.
The start and end of the implicit for loop counter iter are shown.
Run to the line:
hprintln!("Calculated sum is {}\n", calc).unwrap();
As a non-mutable variable, calc only exists while it is in use. Observe that it appears in the variables view.
Run the application, and observe the variable values change as the code progresses.