Description of problem:
When I want to use the "VGA passthrough" function Xen by having the "gfx_passthru=1" in my HVM configuration, the corresponding domain won't start.
After some work, this is due to the fact that the Xen Python try to start "qemu-dm" with the "--gfx_passthru 1" option whereas it just should be "--gfx_passthru".


Version-Release number of selected component (if applicable): 4.0.1


How reproducible:
Configure a VM with GFX passthru

Steps to Reproduce:
1. Add gfx_passthru=1 to a VM configuration file
2. Try to start the VM
3.
  
Actual results:
The VM won't start

Expected results:
The VM to start with VGA passthrough function enabled

Additional info:
This is the patch I propose to correct the problem (for the 64-bit package, should be the same for the 32-bit one after chaning the file path):
--- usr/lib64/python2.7/site-packages/xen/xend/image.py	2011-03-23 10:29:53.946082001 +0100
+++ usr/lib64/python2.7/site-packages/xen/xend/image.py	2011-03-23 10:30:18.192082001 +0100
@@ -865,7 +865,7 @@
             if a == 'keymap': a = 'k'
 
             # Handle booleans gracefully
-            if a in ['localtime', 'std-vga', 'isa', 'usb', 'acpi']:
+            if a in ['localtime', 'std-vga', 'isa', 'usb', 'acpi', 'gfx_passthru']:
                 try:
                     if v != None: v = int(v)
                     if v: ret.append("-%s" % a)