Continue on experimenting with xen i though about to share my latest experiences. Right now i'm on kernel 3.8 which brings clearly some improvements over last versions. Especially shutting down windows 7 seems to be faster then before. I'm also using the official +Gentoo xen-4.2.1 ebuilds now.
Finally i could solve my udev problem.
However it wasn't really a problem with udev nor with xen. Basically the problem was that i didn't load the tap module before starting the vm. Xen aborted the start because it couldn't create a tap device (for the network). It seems that in earlier version of udev some configurations files caused the load of the module.
However, adding the tap module to /etc/conf.d/modules did solve the problem:
Since my last posts i also got some feedback from other users.
Sandy McArthur showed me a typo in the boot parameters at my first post, which made the "pci=resource_alignmet" useless. I was surprised that xen/passthru still worked, because i though those parameters where important.
However, after fixing it, the kernel couldn't boot anymore and hang at "already setup the gsi". A quick search at google didn't show up any useful information so i just removed it. You'll see my actual boot parameters below.
Fixed mac address:
Another bug which seems to be fixed recently was a problem where xen breaks badly if you don't set xsave=1 at the boot parameters. I still don't know what exactly "xsave" does, but it's not needed anymore.
My actual boot parameters are:
title Gentoo Linux XEN root (hd0,0) kernel /boot/xen.gz dom0_mem=8192M,max:8192M iommu=1 dom0_max_vcpus=4 dom0_vcpus_pin module /boot/gentoo-3.8.0 root=/dev/md3 radeon.pcie_gen2=1 softlevel=xen xen-pciback.permissive xen-pciback.hide=(01:00.0)(01:00.1)(00:12.0)(00:12.2)
There is also an ongoing work to make it possible using xen with an no-multilib profile. At my initial xen post i said xen with hvm enabled needs a multilib profile. However, +Gentoo Dev's are working to remove this dependency. You can follow the progress at bug #351648.
Right now my systems are up-to-date. (~amd64)
For the moment i don't even use any git ebuilds. It's much easier to go with the usual update flow. Windows still works flawless and very snappy, using it on a nearly daily base. Actually i'm quite addicted to Borderlands 2 and L4D2 (still the windows version). Maybe someone wants to join me in a game, my steam id is: mmike.
Below you see another screenshot of my system, running Far Cry 3 in Xen and Defcon (from +Steam) on the host over all 3 screens. With the picture in picture feature of my screen you see both games running in parallel. I should also mention that Defcon runs on VT8 while kde still runs at VT7 (whitout effects) so i can easily switch between gaming and kde - video is following the next days ;)