can RPMSG payload be transparent for every binary BYTE?

[wenfu]

Hello every one. hope you are doing well.

I'm using i.max8m with M4 core to make an application where A53 share data with M4 by RPMSG. I use the imx_rpmsg_tty.c driver as I want to access the data from/to M4 with the common API, the tty, just like a UART attached. 

As the protocol noted, the default payload size is 496 bytes(buffer size 512byte-16byte header size), so in every single transmission transaction the max available data size is 496 bytes. In one side I filled the payload with random byte, from 0x00 to 0xFF, but in the reveive side some data got lossed. But when I send const data, just like 0x55, 0xaa... then no data got lossed. So I suspect that some byte take the same role with the protocol head. Is this possible? If so, how can I avoid this?

[igorpadykov]

Hi Wen

what bsp used in the case. One can try Demo Image  i.MX 8QuadMax MEK

with i.MX8QM MEK board. Use sect.2.8.5 Running i.MX RPMsg Test Programs

i.MX Linux Reference Manual

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[wenfu]

Hi igorpadykov,

Thanks for your reply.

The bsp I'm using is Linux4.9.28, anyway, it doesn't affect the way we use RPMSG. I have read the document you mentioned. I have go through the process on how to run the test program. As I know PRMSG protocol give a binary interface between 2 CPU cores, whcih means one can send every thing transparently. The issue I'm now facing is some user payload stoped the transmit process. It seems that there are some bug in your code, or It's my misunderstand about the protocol. Please forward this thread to your engineers. I'm know NXP team are very efficient and fast in handling problems. 

Wen

B.R.

[igorpadykov]

Hi Wen

unfortunately Linux 4.9.28 is not officially supported by nxp.

Please try suggested software and documentation.

Best regards
igor