remote/client: support OpenOCD bootstrap without environment

[ozan956]

The bootstrap fallback path was too narrow for OpenOCD-based setups without a
local environment.

Previously, labgrid-client bootstrap only auto-created OpenOCDDriver for
NetworkAlteraUSBBlaster. If a place exposed only NetworkUSBDebugger, the
client still failed with target has no compatible resource available even
though OpenOCDDriver can bind to that resource type.

The existing bootstrap_args path was also too limited. It only handled raw
key=value strings, which was not sufficient for OpenOCDDriver arguments
such as load_commands, search, or config, where structured values like
lists are often required.

This change:

• extends the bootstrap fallback to NetworkUSBDebugger
• parses bootstrap driver arguments as YAML values
• allows structured OpenOCD driver arguments to be passed directly from the CLI

This makes CLI-only OpenOCD bootstrap flows usable in more cases without
requiring a local environment file.

I verified the change with focused regression tests:

pytest -q tests/test_client.py -k 'bootstrap_network_usb_debugger or bootstrap_openocd_args'

Checklist

• Tests for the feature
• PR has been tested

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46.2%. Comparing base (06fd06c) to head (8026458).
✅ All tests successful. No failed tests found.

Additional details and impacted files

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+ Coverage    46.0%   46.2%   +0.2%     
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  Files         180     180             
  Lines       14462   14475     +13     
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+ Hits         6654    6695     +41     
+ Misses       7808    7780     -28     

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3.11	46.2% <100.0%> (+0.2%)	⬆️
3.12	46.2% <100.0%> (+0.2%)	⬆️
3.13	46.2% <100.0%> (+0.2%)	⬆️
3.14	46.2% <100.0%> (+0.2%)	⬆️

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[Emantor]

Do we need a complete yaml definition and loader for the bootstrap arguments? Can't we instead supply an openocd native target configuration instead or limit this to a list of key-value items?

[ozan956]

Do we need a complete yaml definition and loader for the bootstrap arguments? Can't we instead supply an openocd native target configuration instead or limit this to a list of key-value items?

Thanks @Emantor,

As you see I am trying to solve two problems. First, extending the bootstrap fallback path so labgrid-client bootstrap can also instantiate OpenOCDDriver for NetworkUSBDebugger when no local environment is available. Second, making it possible to pass the structured OpenOCD driver arguments needed by that CLI-only path.

Regarding your suggestion, I can say that this can work for some cases, but I do not think its the best option to have a config wrapper like that. The main reason is that the arguments here are not only static target configuration. They also describe the bootstrap workflow itself, for example custom source ..., init, autoboot_elf, and shutdown sequences. Those are valid OpenOCD commands, so they can certainly be moved into a script file, but requiring a separate OpenOCD file for every target or case-specific variation would add maintenance overhead ( since there can be multiple config/command combinations for multiple boards) and keep the CLI-only path less practical.

I do agree that the generic YAML parsing may be overkill. The important part for me is the ability to pass the OpenOCD-specific structured arguments needed by this bootstrap flow, not to introduce a fully generic typed argument mechanism for bootstrap in general. So, I think we can maybe restrict this path to a small whitelist of OpenOCD-specific keys such as config, search, load_commands, interface_config, etc.