Consider the following C program:

```C
int a = 3;
void *p = &a;

int main(void) {
    return 0;
}
```

Compile it:

```
gcc -Wall -g a.c
```

Then run it with stap:

```
$ stap -e 'probe process.function("main") { p = @var("p"); println(usymname(p)); exit() }' -c ./a.out
0x601020
```

It fails to return the string "a", which is the global C variable name in the target program.

GDB does support resolving global C variables by default. For this example:

```
(gdb) p p
$3 = (void *) 0x601020 <a>
```

We've got the variable symbol name `a` in the `p` command output here.