Xorg problem with xen

["edu gargiulo" <egargiulo+lists@gmail.com>]

After install xen-linux-system on a running system, I can't start X.
The X log says

xf86MapVidMem: Could not mmap framebuffer (0xfbfd0000,0x4000) (Invalid argument)

I'm running unstable on amd64 and using nv video card driver. How can
I fix this? I need to run X for domUs. Is there someone on this list
thas had succesfully compiled xen-3.3 on debian-amd64?

regards,

--
edu