RPMsg modify buffer size not working

[OBaselga]

Hi everyone,

I'm working with OpenAMP on CM4 and I would like to increase the buffer size of RPMsg messages. When sending with VIRT_UART_Transmit() from CM4 to CA7, gives me an error when the message exceeds 496 bytes due to the RPMSG_BUFFER_SIZE value in rpmsg_virtio.h, which is set to 512 bytes.

Aiming to reach 1024 bytes in size, when I set that value, RPMsg keeps giving the same error. Why?

This is my simple code:

void t0Task(void *argument)
{
 
  int i;
 
  int count = 0x0, simulated_channels = 64;
 
  const int SIZE_DATA = 7;
 
  unsigned char msg[SIZE_DATA * simulated_channels], msg2[SIZE_DATA];
 
  while (1)
  {
	  strcpy(msg,"");
	  for (i = 0; i < simulated_channels; i++) {
		  sprintf(msg2, "%06X ", count);
		  strcat(msg, msg2);
		  count = (count + 1) % 0xFFFFFF;
	  }
 
	  if(VIRT_UART_Transmit(&virtUART0, (uint8_t*)msg, strlen(msg)) == VIRT_UART_ERROR) {
		  VIRT_UART_Transmit(&virtUART0, "Error size\n", 20);
	  }
	  osDelay(1);
  }
}

Note that messages of less than 496 bytes are sent successfully.

Regards.

[Olivier GALLIEN]

Hi @Óscar Baselga​ ,

Is this point still open your side ?

Else maybe this previous post can provide you few hints :

https://community.st.com/s/question/0D53W00000qwjyiSAA/increased-1024-rpmsg-buffer-size-will-fail-on-mailbox-vdev-declaration

First, you have to pay attention when you increase RPMSG_BUFFER_SIZE to not exceed the reserved memory budget, either by reducing buffer number or extend the reserved memory.

Let me know where you stand.

Olivier