+#if defined(PCI_OS_LINUX)
+#include "i386-io-linux.h"
+#elif defined(PCI_OS_GNU)
+#include "i386-io-hurd.h"
+#elif defined(PCI_OS_SUNOS)
+#include "i386-io-sunos.h"
+#elif defined(PCI_OS_WINDOWS)
+#include "i386-io-windows.h"
+#elif defined(PCI_OS_CYGWIN)
+#include "i386-io-cygwin.h"
+#else
+#error Do not know how to access I/O ports on this OS.