Different pyOCD executable used when CMSIS Solution extension is configured for Zephyr applications

[RobertRostohar]

Type: Bug Report

Describe the bug

• OS and Version: Win 11
• VS Code Version: 1.109.2
• Extension Version: 1.64.2

Different pyOCD executables are being used when CMSIS Solution extension is configured for Zephyr applications.

pyOCD is typically used for:

• Debugging by launching the debugger via launch,json: pyOCD executable shipped with the Arm CMSIS Debugger extension is used by default
• Programming through tasks via the tasks.json: pyOCD from the system PATH is used by default
• CLI from the terminal: pyOCD from the system PATH is used

Unfortunately, Zephyr includes its own version of pyOCD executable in the same folder as the west executable which is typically registered in the system PATH.

Work with Zephyr applications documentation states that the Environment Variable PATH in the CMSIS Solution settings should be set and point to the Zephyr folder with binaries. This variable is prepended to the system PATH. Once the Environment Variable PATH is configured to point to Zephyr binaries, pyOCD from Zephyr will be used in tasks and terminal, regardless of if the project itself is for Zephyr or not.

Expected behavior
Expected is that the pyOCD version shipped with the Arm CMSIS Debugger extension is used consistently. This implies that pyOCD executable from the Arm CMSIS Debugger extension is first in the PATH in order for tasks and terminal to use that pyOCD version (in addition to the debug launch).

[JonatanAntoni]

The problem results from multiple extensions contributing independently to the PATH without a distinct order. In this case, the safest way may be not relying on PATH but use a full path to pyOCD executable in launch configurations and tasks. As this probably can't be hard coded, we might need to expose the path to the pyOCD executable embedded into the debugger extension via a command and update all debugger templates to use this command.

[RobertRostohar]

How about using pyOCD from the terminal which is also a valid use case?

[JonatanAntoni]

How about using pyOCD from the terminal which is also a valid use case?

Unfortunately, the terminal might end up with the wrong order in PATH and be affected from the same issue. Unfortunately, we can't enforce any order. The user needs to drop pyOCD from the local pyenv.

As an alternative, we could rename the pyocd executable shipped with the extension to have a distinct name which can then coexist with "normal" pyOCD installations.

[jreineckearm]

Another, uglier solution could be to get the pyOCD path from CMSIS Debugger: either command, or "cmsis">"pyocd" entry in CMSIS Debugger package.json (the tool is downloaded into a fixed base folder). Then prepend both the PATH setting from CMSIS Solution and the pyOCD path from the CMSIS Solution extension. Caveat: duplicate entries of pyOCD on PATH as we should keep the path in CMSIS Debugger, too.

There is also a REPLACE operation for env vars to correct the order. But that only works so far and requires more logic.

The renamed pyOCD might be the cleanest solution but requires changes across all extensions to remain consistent.

[jreineckearm]

Spent a bit more thought on this:
I think for the coming release we should go with the simplest approach that isolates changes in a single place. That would be to prepend the pyOCD path to the PATH setting of the CMSIS Solution extension. The pyOCD path would be the concatenation of the CMSIS Debugger extension path and the known location tools/pyocd. I don't expect this to change anytime soon.
It apparently doesn't help if other extensions manipulate PATH after that (depending on activation order). But it at least eliminates the problem for PATH manipulations we have under control. Just need to make sure to use the correct OS specific separators.
@JonatanAntoni , unless there are strong concerns, can your team pick this up? We can further refine in a coming release if needed.

[JonatanAntoni]

I'll give it a try