RE: ACL Buffer Overflow Results in SVC Exception Triggered by BT RX Task

csheaupdesigns — Thu, 15 Feb 2024 16:13:32 GMT

Hello, it has been a long time since I visited on this issue but I wanted to return to it so I can close things out. We have been running with increased MTU buffers and resolved the MTU size negotiations in our build and things are working fine. However, I would like to understand the root cause of the issue a little better in case something similar happens in the future. I have added responses to the questions I can answer but need a little guidance with one of them. Please see below:

[quote userid="15146" url="~/f/nordic-q-a/106609/acl-buffer-overflow-results-in-svc-exception-triggered-by-bt-rx-task/461177"]

the BT RX thread issues an SVC instruction and the application ends up running the exception handler.

Do you have any log output that prints the exception info?

[/quote]

Is there a logging configuration that I can use to enable printing of this information? Is there a specific piece of information you are looking for? I believe when I get into the handler, all that is known is that an SVC instruction was issued. But if you have something I can add to try to get more information, I'm all ears.

[quote userid="15146" url="~/f/nordic-q-a/106609/acl-buffer-overflow-results-in-svc-exception-triggered-by-bt-rx-task/461177"]What version of nRF Connect SDK are you using?[/quote]

Zephyr: v3.3.99-ncs1-rc2

nrfxlib: v2.4.0

nrf: v2.4.0

[quote userid="15146" url="~/f/nordic-q-a/106609/acl-buffer-overflow-results-in-svc-exception-triggered-by-bt-rx-task/461177"]

When using the BLE sniffer

Do you have a sniffer log for when this issue occurs? Could you share the sniffer log?

[/quote]

Sniffer capture is attached. You can see the last command is responded to at line no. 168943. A command is sent down starting at 168944 and ending at 169038. This command is not supposed to have a response. But the command sent down on 169046 should and does not. Retries are attempted every two seconds thereafter for 100 seconds. At that point, the app that is managing the firmware update seems to get into a bad state and the retries start to come at a higher frequency. But, the exception occurs in the 5-10 seconds after the target stops responding.

devzone.nordicsemi.com/.../FirmwareUpdate553b013to554-_2800_S9_2900_.pcapng

RE: ACL Buffer Overflow Results in SVC Exception Triggered by BT RX Task

Sigurd — Wed, 20 Dec 2023 00:27:24 GMT

Hi!

[quote user=""]the BT RX thread issues an SVC instruction and the application ends up running the exception handler.[/quote]

Do you have any log output that prints the exception info?

What version of nRF Connect SDK are you using?

[quote user=""]When using the BLE sniffer[/quote]

Do you have a sniffer log for when this issue occurs? Could you share the sniffer log?