The extern declaration causes the following warning:
```
CC sys-utils/hwclock-hwclock-cmos.o
sys-utils/hwclock-cmos.c: In function 'i386_iopl':
sys-utils/hwclock-cmos.c:356:20: warning: nested extern declaration of 'ioperm' [-Wnested-externs]
356 | extern int ioperm(unsigned long from, unsigned long num, int turn_on);
| ^~~~~~
sys-utils/hwclock-cmos.c:356:20: warning: redundant redeclaration of 'ioperm' [-Wredundant-decls]
In file included from sys-utils/hwclock-cmos.c:68:
/usr/include/i386-gnu/sys/io.h:29:12: note: previous declaration of 'ioperm' with type 'int(long unsigned int, long unsigned int, int)'
29 | extern int ioperm (unsigned long int __from, unsigned long int __num,
| ^~~~~~
CCLD hwclock
```
# else
static int i386_iopl(const int level __attribute__ ((__unused__)))
{
- extern int ioperm(unsigned long from, unsigned long num, int turn_on);
return ioperm(clock_ctl_addr, 2, 1);
}
# endif