unmodified_drivers: enable unplug per default

Since xen-3.3 an official unplug protocol for emulated hardware is
available in the toolstack. The pvops kernel does the unplug per
default, so it is safe to do it also in the drivers for forward ported
xenlinux.
Currently its required to load xen-platform-pci with the module
parameter dev_unplug=all, which is cumbersome.
Also recognize the dev_unplug=never parameter, which provides the
default before this patch.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
master commit: df17e9c889
master date: 2013-09-20 11:41:08 +0200

unmodified_drivers/linux-2.6/platform-pci/platform-pci.c

@@ -66,7 +66,7 @@ MODULE_LICENSE("GPL");
 static char *dev_unplug;
 module_param(dev_unplug, charp, 0644);
 MODULE_PARM_DESC(dev_unplug, "Emulated devices to unplug: "
-		 "[all,][ide-disks,][aux-ide-disks,][nics]\n");
+		 "[all,][ide-disks,][aux-ide-disks,][nics,][never] (default is 'all')\n");
 
 struct pci_dev *xen_platform_pdev;
 
@@ -290,6 +290,10 @@ static int check_platform_magic(struct device *dev, long ioaddr, long iolen)
 	short magic, unplug = 0;
 	char protocol, *p, *q, *err;
 
+	/* Unconditionally unplug everything */
+	if (!dev_unplug)
+		unplug = UNPLUG_ALL;
+
 	for (p = dev_unplug; p; p = q) {
 		q = strchr(dev_unplug, ',');
 		if (q)
@@ -302,6 +306,8 @@ static int check_platform_magic(struct device *dev, long ioaddr, long iolen)
 			unplug |= UNPLUG_AUX_IDE_DISKS;
 		else if (!strcmp(p, "nics"))
 			unplug |= UNPLUG_ALL_NICS;
+		else if (!strcmp(p, "never"))
+			unplug = 0;
 		else
 			dev_warn(dev, "unrecognised option '%s' "
 				 "in module parameter 'dev_unplug'\n", p);