first, I apologize for my bad English ... 
 
I tried to follow the instructions at:
http://de.xen-forum.net/wiki/index.php/NetBSD_3_/_Xen_2.0.7_-_Basisinstallation_und_Konfiguration_(DE)
 And 
http://www.netbsd.org/ports/xen/howto.html#netbsd-dom0  To install NetBSD 4.0, Xen 3 and get NetBSD DOM0.  
 My installation process: 
 
        Create / grub / menu.lst  
 # # # 
 Default = 0 
 Timeout = 10 
 Serial - unit = 0 - speed = 115200 - word = 8 - parity = no - stop = 1 
 Terminal - timeout = 10 vga console 
 Xen 3.1 title / NetBSD 4 (hda0, vga) 
  Root (hd0, 0) 
  Kernel () 2097152 
  Module (hd0, a) / netbsd-XEN0 root = (hd0, 0, a) ro console = tty0 
 Xen 3.1 title / NetBSD 4 (hda0, serial) 
  Root (hd0, 0) 
  Kernel () 2097152 com1 = 115200.8 n1 
  Module (hd0, a) / netbsd-XEN0 root = (hd0, 0, a) ro console = ttyS0 
 Xen 3.1 title / NetBSD 4 (hda0, backup, VGA) 
  Root (hd0, 0) 
  Kernel () 2097152 
  Module (hd0, a) / netbsd-XEN0.backup root = (hd0, 0, a) ro console = tty0 
 Xen 3.1 title / NetBSD 4 (hda0, backup, serial) 
  Root (hd0, 0) 
  Kernel () 2097152 com1 = 115200.8 n1 
  Module (hd0, a) / netbsd-XEN0.backup root = (hd0, 0, a) ro console = ttyS0 
 Title NetBSD 4.0 
  Root (hd0, 0, a) 
  Kernel - type = netbsd / netbsd-GENERIC 
 Title NetBSD Chain 
   Root (hd0, 0) 
   Chainloader +1 
 # # # 
  The system starts:
 During boot the system gives this: 
 Searching for RAID components ... 
 Boot Device: <unknown> 
 Root Device: 
 Dump device: 
 File System: 
 Init path:  
 OK, here until everything is OK. The problem I have with my 
Xfce4. 
 Thunar crash: Bad system call (core dumped) and the rights mouse click is not working. But everything else seems to work. I do not know where the error .  
 I thought maybe too little Ram, I have also set 
2097152 and after the reboot I get "hypervisor mmu update failed" 
 
 Can anyone help me and tell what is wrong. I thank you in advance. 
 Greetings, 
 Damian Sobczak