This patch disables interrupt handling after DRI has been disabled, preventing
lockups.  See https://bugzilla.ubuntu.com/show_bug.cgi?id=2411.

--- xc/programs/Xserver/hw/xfree86/drivers/ati/r128_dri.c.orig	2004-11-15 13:26:09.725996808 +0100
+++ xc/programs/Xserver/hw/xfree86/drivers/ati/r128_dri.c	2004-11-15 13:26:21.997131312 +0100
@@ -1297,6 +1297,7 @@
     if (info->irq) {
 	drmCtlUninstHandler(info->drmFD);
 	info->irq = 0;
+	info->gen_int_cntl = 0;
     }
 
 				/* De-allocate vertex buffers */