How to resolve MISRA C:2012 Rule:8.4?

Question

I have a C code which I am trying to make it MISRA Compliance.I am getting following error in two different case:

Case 1]note 9075: external symbol 'buf' defined without a prior declaration [MISRA 2012 Rule 8.4, required] uint32_t buf[BUF_SIZE](in main.c);

How can I define it an another way so it will follow MISRA rule ?

Case 2] note 9075: external symbol 'buf' defined without a prior declaration [MISRA 2012 Rule 8.4, required] uint32_t buf[64U];

case1:
header.h
#define BUF_SIZE 64U
test.c
#include "header.h"
uint32_t buf[BUF_SIZE];

case2:
test.c
uint32_t buf[64U];

Answer 1

How can I define it an another way so it will follow MISRA rule ?

If the array is meant to be accessed by code from multiple different files , then put a declaration of it into header.h :

extern uint32_t buf[BUF_SIZE];

Do not omit the extern . Do not omit the array size, although standard C permits doing so. Keep the definition already present in the .c file, unmodified.

If the array is meant for use only in the file in which it is declared , then make it static:

static uint32_t buf[BUF_SIZE];

Do not declare it in any header in this case.