[Xen-devel] mgag200 driver does not work properly with Xen

[Fernando Luiz Chaves Xavier Matos <fernando@xxxxxxxxxxxxxx>]

When using Xen Hypervisor, the video goes very slow after module load in console.
Xorg does not run.

My boot process (in kernel 3.7.1 from elrepo, my default kernel.):
1. Hypervisor is loaded (from here, the screen resolution is 640x480 - text scrolling fast)
2. Kernel is loaded
3. mgag200 module is loaded
4. Screens enter native resolution (from here, the screen resolution is 1280x768 - text scrolling is slow..).
5. Starting Xorg gives me: "failed to activate core devices".

Without Xen, the video works great, Xorg starts, everything works fast and good.

Hardware:
Motherboard: S1200BTLR
Onboard video: ServerEngines LLC Pilot III (as written in manual)
CPU: Intel Xeon E3-1270v2

Software:
OS: Centos 6.3 64-bit
Xen: 4.2.1

Kernels tested (all with Xen Hypervisor Loaded - except 2.6.32):

Kernel 2.6.32-279 (shipped with CentOS - does not support XEN_DOM0):
- Screen is fast, but with 640x480 resolution.
- Xorg starts with mga driver

Kernel 3.0.57-1.el6.elrepo.x86_64 (from elrepo.org - with XEN_DOM0 support)
- "CONFIG_DRM_MGAG200" does not exist.
- Xorg starts with mga driver

Kernel 3.7.1-3.el6xen.x86_64 (from here: https://www.crc.id.au/xen-on-rhel6-scientific-linux-6-centos-6-howto/ [^] )

- Since "CONFIG_DRM_MGAG200 is not set", screen is fast, but with 640x480 resolution.
- Xorg does not start. "Failed to activate core devices".

Kernel 3.7.1-1.el6.elrepo.x86_64 (My favorite kernel - from elrepo.org)
- "CONFIG_DRM_MGAG200=m"
- Native resolution
- Screen refresh is slow
- Xorg does not start: "Failed to activate core devices."


UPDATE: 
Tested Xen 4.2.1 with Ubuntu 12.10 32-bit kernel 3.7.1 and I got the following results:

- Xorg with Unity works with poor performance with Xen hypervisor loaded.
- Xorg with Unity is very nice without Xen hypervisor loaded.

- Text-based console performance is bad (as in Centos). Screen refresh is very slow, text scrolling also slow.
- Text-based console performance is normal without Xen.

Exactly the same issues as in CentOS.	

Content from "lspci -vv" of video card

04:00.0 VGA compatible controller: Matrox Electronics Systems Ltd. MGA 
G200e [Pilot] ServerEngines (SEP1) (rev 07) (prog-if 00 [VGA 
controller])
        Subsystem: Intel Corporation Device 0102
        Flags: bus master, fast devsel, latency 0, IRQ 23
        Memory at c0000000 (32-bit, non-prefetchable) [size=16M]
        Memory at c1810000 (32-bit, non-prefetchable) [size=16K]
        Memory at c1000000 (32-bit, non-prefetchable) [size=8M]
        Expansion ROM at c1800000 [disabled] [size=64K]
        Capabilities: [dc] Power Management version 2
        Capabilities: [e4] Express Legacy Endpoint, MSI 00
        Capabilities: [54] MSI: Enable- Count=1/1 Maskable- 64bit-
        Kernel driver in use: mgag200
        Kernel modules: mgag200


Thanks and sorry for the [very] bad english.	
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