PCICAP_ID
if (pci_read_config(child, ptr + PCICAP_ID, 1) == capability) {
val = REG(ptr + PCICAP_ID, 1);
cap = read_config(fd, &p->pc_sel, ptr + PCICAP_ID, 1);
cap = read_config(fd, &p->pc_sel, ptr + PCICAP_ID, 1);