// gcc -O -o read-cfgreg-with-ioport read-cfgreg-with-ioport.c

#include <stdio.h>
#include <sys/io.h>

typedef unsigned long u32;

int main(){
	int i;
	int dat;

	iopl(3);

	u32 bus = 4, dev = 9;
	u32 adr = (bus << 16) | (dev << 11);

	dat = 0;
	for(i=0; i < 4; i++) {
		outl(adr|0x80000000 + i * 4, 0xcf8);

		dat |= ((inl(0xcfc) >> 2 & 3) << (i * 2));
	}
	printf("%02X\n", dat);

	outl(0x00000000, 0xcf8);

	iopl(0);

	return 0;
}