Hello,
we are trying to add external interfaces on the worker to connect with the DUTs, for example a 4-port USB-to-RS232 converter. Our DUTs have multiple RS232 ports which shall be tested using this remote interface.
We have already figured out how to integrate this hardware into the LAVA environment, so that it can be used within the LAVA LXC (using static_info in the device dictionary, resulting in the four /dev/ttyUSB* devices being visible there).
First question: We need multiple of these converters attached to the worker. How do we integrate these into LAVA? They all have the same board_id, vendor_id and product_id. If I specify the board_id in the device dictionary multiple times, the device is still added only once.
There must be a way to distinguish devices at a udev level or there is no way to identify which devices to add to the LXC. If the converters are not unique, then you can only have one per DUT. You will need to purchase new hardware from a vendor who has spent the extra few cents to register unique IDs.
Think about how this would work without LXC - how would your scripts tell these devices apart? How does the kernel tell them apart? Do not rely on USB enumeration, that is known to be unreliable. What is ttyUSB7 today can be ttyUSB9 tomorrow (or more likely at some random time after N resets due to some unexpected change elsewhere or just because it could).
Without solving this, all other questions are moot.
Second question: We need a way to specify to which of the /dev/ttyUSB* ports a certain RS232 port of the DUT is connected. The place where I would assume to put such information is the device dictionary. But how can we access this information within a LAVA test shell?
Solve the first issue first - without unique identifiers, there will only be one /dev/ttyUSB* device added to the LXC in the first place.
The documentation specifies some similar mechanism for energy probes:
https://validation.linaro.org/static/docs/v2/admin-lxc-deploy.html?highlight=device_info.#other-related-devices
It says "Devices which are not directly attached to the worker can also be supported, for example energy probes which communicate over the network".
These are alternative energy probes which have dedicated values.
As far as I can tell from the code, though, this seems to be a hard-coded feature without any possibility of adding other custom hardware. Is that correct?
If yes, why isn't there a generic mechanism to supply static_info from the device dictionary in the LAVA test shell? Or is there?
How can we implement our scenario described above using LAVA?
Mit freundlichen Grüßen / Best regards
Tim Jaacks
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