zephyr message queue buffer alignment

RE: zephyr message queue buffer alignment

Einarh — Fri, 05 May 2023 09:32:56 GMT

I believe that is a correct interpretation yes.

RE: zephyr message queue buffer alignment

Mathi — Wed, 03 May 2023 13:57:06 GMT

Hi Einar,

What do you mean by 'full bytes'? (Sorry, if iam being slow here)

Does that mean, the constaint here is that - the 'buffer' has to be aligned to an address that is a multiple of 2, but the value of msg_size need not be a power of 2?

For example, is the following valid:

msg_size = 5;
max_msgs = 5:
alignas(myroundtonexthighpowerof2(msg_size)) char buffer[max_msgs * msg_size);

Is this a correct interpretation?

Thanks,
Mathi.

RE: zephyr message queue buffer alignment

Einarh — Wed, 03 May 2023 10:01:27 GMT

Hello

q_msg_size only refers to the size of a message in the queue, not the size of the buffer:

https://docs.zephyrproject.org/apidoc/latest/group__msgq__apis.html#ga95ef93002766901511d09c8cd8f8293b

So the way I understand it the only real restraint is that the buffer should contain a number of full bytes, which sounds reasonable for a ring buffer.

Best regards,

Einar