Feature Request: Add Ellisys-compatible trace exporter (offline, no RF required)

[LingaoM]

Motivation

Currently, Bumble provides a powerful software-based Bluetooth stack with support for virtual controllers, link simulation, and rich debugging logs (including LL PDUs and HCI events).

However, there is no built-in way to export traces in a format that can be opened by external Bluetooth protocol analyzers such as Ellisys Bluetooth Analyzer.

In contrast, simulation frameworks such as BabbleSim (bbsim) are able to export traces compatible with Ellisys tools, which is extremely useful for:

• Offline protocol analysis
• Debugging complex LL procedures
• Sharing traces with QA / certification teams
• Comparing simulated behavior with real hardware captures

Proposal

Add a trace exporter module to Bumble that can output captured link-layer and HCI activity into an Ellisys-compatible trace format (or an intermediate format that can be converted).

The exporter should:

• Work entirely offline (no RF hardware required)
• Hook into existing Controller / Link layers
• Capture:
• Advertising PDUs
• Data PDUs
• Control PDUs
• Connection events
• Timestamps
• Optionally include:
• Channel index
• Access address
• Direction (master/slave)
• RSSI (if available or simulated)

[zxzxwu]

The major problem is that we didn't 1:1 simulate the physical and link layers. Link-layer spec of Bluetooth is quite complicated, so we made some trade-off to simplify the emulator implementation, but such changes cannot be applied to log based on the standard spec, or they cannot be properly parsed by viewers.

[zxzxwu]

However, exporting HCI packets should be possible. We already have BT snooper and PCAP snooper. Ellisys format is not on our roadmap (it's not popular on our side and not opened?), but it's welcomed to contribute them.

[barbibulle]

For LL traces, I think this would be best done at the Root Canal level, where the link layer protocol is more closely followed. Since Bumble can interface naturally with Root Canal, this would make the integration very straightforward. Root Canal is also open source, I suggest making a request with the project's maintainers.

[zxzxwu]

Well, it's a good direction, but actually Rootcanal is not more formal than Bumble 😓

https://github.com/google/rootcanal/blob/main/packets/link_layer_packets.pdl