--- hw/xfree86/os-support/bus/linuxPci.c
+++ hw/xfree86/os-support/bus/linuxPci.c
@@ -547,10 +547,10 @@ xf86GetPciDomain(PCITAG Tag)
     pPCI = xf86GetPciHostConfigFromTag(Tag);
 
     if (pPCI && (result = PCI_DOM_FROM_BUS(pPCI->busnum)))
-	return result + 1;
+	return result;
 
     if (!pPCI || pPCI->fakeDevice)
-	return 1;		/* Domain 0 is reserved */
+	return 0;
 
     if ((fd = linuxPciOpenFile(pPCI ? pPCI->tag : 0,FALSE)) < 0)
 	return 0;
@@ -558,7 +558,7 @@ xf86GetPciDomain(PCITAG Tag)
     if ((result = ioctl(fd, PCIIOC_CONTROLLER, 0)) < 0)
 	return 0;
 
-    return result + 1;		/* Domain 0 is reserved */
+    return result;
 }
 
 static pointer
@@ -629,7 +629,7 @@ linuxMapPci(int ScreenNum, int Flags, PC
     return NULL;
 }
 
-#define MAX_DOMAINS 257
+#define MAX_DOMAINS 256
 static pointer DomainMmappedIO[MAX_DOMAINS];
 
 static int
@@ -650,11 +650,10 @@ linuxOpenLegacy(PCITAG Tag, char *name)
 	domain = xf86GetPciDomain(Tag);
 	bus = PCI_BUS_NO_DOMAIN(PCI_BUS_FROM_TAG(Tag));
 
-	/* Domain 0 is reserved -- see xf86GetPciDomain() */
-	if ((domain <= 0) || (domain >= MAX_DOMAINS))
+	if ((domain < 0) || (domain >= MAX_DOMAINS))
 	    FatalError("linuxOpenLegacy():  domain out of range\n");
 
-	sprintf(path, PREFIX, domain - 1, bus, name);
+	sprintf(path, PREFIX, domain, bus, name);
 	fd = open(path, O_RDWR);
 	if (fd >= 0) {
 	    xfree(path);
@@ -686,7 +685,6 @@ _X_EXPORT pointer
 xf86MapDomainMemory(int ScreenNum, int Flags, PCITAG Tag,
 		    ADDRESS Base, unsigned long Size)
 {
-    int domain = xf86GetPciDomain(Tag);
     int fd = -1;
     pointer addr;
 
@@ -734,7 +732,7 @@ xf86MapDomainIO(int ScreenNum, int Flags
     int domain = xf86GetPciDomain(Tag);
     int fd;
 
-    if ((domain <= 0) || (domain >= MAX_DOMAINS))
+    if ((domain < 0) || (domain >= MAX_DOMAINS))
 	FatalError("xf86MapDomainIO():  domain out of range\n");
 
     if (DomainMmappedIO[domain])