VGA passthrough with Drivers does not work

["\"涂堂訓(Tang-Hsun Tu)\"" <iwantplay@gmail.com>]

Hi,

           In recent days, I try to passthrough VGA to a HVM windows XP 
domain on my notebook.
There are two VGAs on the notebook, one is intel IGD (primary) and the 
other is nvidia (secondary).

At first, the screen will be blank/black when I start a HVM with a 
passed VGA (primary one).
After I connect a external monitor and disable GDM,
the screen (external monitor) will start to display the WinXP logo
(it seems that the passthrouh is successful),
and it is only 16-bit color in display when enters into WinXP
(it means it does not have any VGA driver).
The original screen (on notebook) still is black.

However,
when I reboot the machine after installing the VGA driver,
the screen has become black.
I also try to install driver without passthrough before,
then change the setting to the passthrought,
but it still goes to black screen.
How can I solve this problem?

By the way, I aslo have some questions.
1. Why a external monitor can display but the original (notebook screen) 
does not?
2. In WinXP, I can see the bochs BIOS message when I start the HVM.
     However, in Windows7, I only see a disordered screen until enters 
into Winows7.
3. If the dom0 use printk (dmesg), the screen will not be align.
     It just like print a message then the screen moves up.

Thanks!

Best Regards,
Tang-Hsun Tu

Enivronment:
Host OS: Ubuntu 10.04 LTS
Dom0: 2.6.31.13
Xen: xen-4.0-testing.hg, xen-4.0.1-rc4
HVM: windows XP and windows 7
CPU: Intel(R) Core(TM) i5 CPU M 540
VGA: Intel Corporation Core Processor Integrated Graphics Controller
           nVidia Corporation Device 0a29


lspci:
00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller 
(rev 02)
00:01.0 PCI bridge: Intel Corporation Core Processor PCI Express x16 
Root Port (rev 02)
00:02.0 VGA compatible controller: Intel Corporation Core Processor 
Integrated Graphics Controller (rev 02)
00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series 
Chipset HECI Controller (rev 06)
00:1a.0 USB Controller: Intel Corporation 5 Series/3400 Series Chipset 
USB2 Enhanced Host Controller (rev 05)
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset 
High Definition Audio (rev 05)
00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI 
Express Root Port 1 (rev 05)
00:1c.1 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI 
Express Root Port 2 (rev 05)
00:1d.0 USB Controller: Intel Corporation 5 Series/3400 Series Chipset 
USB2 Enhanced Host Controller (rev 05)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev a5)
00:1f.0 ISA bridge: Intel Corporation Mobile 5 Series Chipset LPC 
Interface Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series Chipset 
4 port SATA AHCI Controller (rev 05)
00:1f.3 SMBus: Intel Corporation 5 Series/3400 Series Chipset SMBus 
Controller (rev 05)
00:1f.6 Signal processing controller: Intel Corporation 5 Series/3400 
Series Chipset Thermal Subsystem (rev 05)
01:00.0 VGA compatible controller: nVidia Corporation Device 0a29 (rev a2)
02:00.0 Ethernet controller: Atheros Communications AR8131 Gigabit 
Ethernet (rev c0)
03:00.0 Network controller: Broadcom Corporation Device 4357 (rev 01)
ff:00.0 Host bridge: Intel Corporation Core Processor QuickPath 
Architecture Generic Non-core Registers (rev 02)
ff:00.1 Host bridge: Intel Corporation Core Processor QuickPath 
Architecture System Address Decoder (rev 02)
ff:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 02)
ff:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 
(rev 02)
ff:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
ff:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 02)