I'm putting this patch out for comments rather than merging, since I'm
aware that it won't apply to Linus' tree any more.

 - Add segment to pci_bus.
 - Change the sysfs name of each device to include a 16-bit segment ID.

diff -urpNX dontdiff linux-2.5.66/drivers/pci/probe.c linux-2.5.66-laptop/drivers/pci/probe.c
--- linux-2.5.66/drivers/pci/probe.c	2003-04-04 08:43:01.000000000 -0600
+++ linux-2.5.66-laptop/drivers/pci/probe.c	2003-04-04 14:36:37.000000000 -0600
@@ -510,7 +510,7 @@ pci_scan_device(struct pci_bus *bus, int
 	pci_name_device(dev);
 
 	/* now put in global tree */
-	strcpy(dev->dev.bus_id,dev->slot_name);
+	sprintf(dev->dev.bus_id, "%04x:%s", bus->segment, dev->slot_name);
 	dev->dev.dma_mask = &dev->dma_mask;
 
 	return dev;
diff -urpNX dontdiff linux-2.5.66/drivers/pcmcia/cardbus.c linux-2.5.66-laptop/drivers/pcmcia/cardbus.c
--- linux-2.5.66/drivers/pcmcia/cardbus.c	2003-04-04 08:43:59.000000000 -0600
+++ linux-2.5.66-laptop/drivers/pcmcia/cardbus.c	2003-04-04 14:36:36.000000000 -0600
@@ -282,7 +282,8 @@ int cb_alloc(socket_info_t * s)
 
 		pci_setup_device(dev);
 
-		strcpy(dev->dev.bus_id, dev->slot_name);
+		sprintf(dev->dev.bus_id, "%04x:%s", bus->segment,
+				dev->slot_name);
 
 		/* We need to assign resources for expansion ROM. */
 		for (r = 0; r < 7; r++) {
diff -urpNX dontdiff linux-2.5.66/include/linux/pci.h linux-2.5.66-laptop/include/linux/pci.h
--- linux-2.5.66/include/linux/pci.h	2003-04-04 08:43:21.000000000 -0600
+++ linux-2.5.66-laptop/include/linux/pci.h	2003-04-04 14:07:34.000000000 -0600
@@ -451,6 +451,7 @@ struct pci_bus {
 	void		*sysdata;	/* hook for sys-specific extension */
 	struct proc_dir_entry *procdir;	/* directory entry in /proc/bus/pci */
 
+	unsigned short	segment;	/* domain/segment number */
 	unsigned char	number;		/* bus number */
 	unsigned char	primary;	/* number of primary bridge */
 	unsigned char	secondary;	/* number of secondary bridge */

.