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.