It also works a lot better when you remember to git-add the patch

0001-int10-Fix-mapping-the-interrupt-vector.patch

@@ -0,0 +1,29 @@
+From 2f3267bc017a420854dc98aac1526fb8f11b1874 Mon Sep 17 00:00:00 2001
+From: Adam Jackson <ajax@redhat.com>
+Date: Wed, 4 Mar 2015 12:44:39 -0500
+Subject: [PATCH] int10: Fix mapping the interrupt vector
+
+pci_device_map_legacy returns 0 on success, and an errno value on
+failure.  It works a lot better if we don't treat 0 as failure.
+
+Signed-off-by: Adam Jackson <ajax@redhat.com>
+---
+ hw/xfree86/int10/generic.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/hw/xfree86/int10/generic.c b/hw/xfree86/int10/generic.c
+index 012d194..8d5c4da 100644
+--- a/hw/xfree86/int10/generic.c
++++ b/hw/xfree86/int10/generic.c
+@@ -104,7 +104,7 @@ readIntVec(struct pci_device *dev, unsigned char *buf, int len)
+ {
+     void *map;
+ 
+-    if (!pci_device_map_legacy(dev, 0, len, 0, &map))
++    if (pci_device_map_legacy(dev, 0, len, 0, &map))
+         return FALSE;
+ 
+     memcpy(buf, map, len);
+-- 
+1.9.3
+