Should ITM write functions check if a debugger is connected like CMSIS ITM_SendChar ?

[jothan]

I am currently unable to run my application standalone when a debugger is not present. I am suspecting that it is because the TPIU and the ITM port are not enabled by my code. Removing traces fixes my issue.

Would it be a good idea to check if tracing is enabled like ITM_SendChar ?

https://github.com/ARM-software/CMSIS/blob/6891719834ac6ca2a79e8ded00620faffae10ae8/CMSIS/Include/core_cm3.h#L1698

If so, I would like to submit a pull request to short circuit write_all if tracing is not enabled.

[japaric]

Would it be a good idea to check if tracing is enabled like ITM_SendChar ?

I would prefer not to slow down the ITM logging functionality as I use it log data at high data rates so low overhead is a must.

I am suspecting that it is because the TPIU and the ITM port are not enabled by my code

There's ITM initialization code in #82 but it requires unsafe code. That issue is about making the initialization code safe; I would push for that instead of this issue.

[nickray]

Just ran into this issue too, agree that the write functions should not do a non-zero cost check. But the documentation might want to mention that they never return if the ITM is not enabled as in #82.

[jonas-hagen]

I experienced this issue as well, took me a while to find out whats going wrong. Because it only happens if the debugger is not connected, it is a bit hard to debug.

What about having the check done in the iwrite macros just to keep beginners (like me) away from this issue?

[bcantrill]

Just came across this issue; assuming this issue is being seen on ARMv8-M parts (vs. ARMv7-M), it seems quite likely that it is in fact a duplicate of #219.