Question: so I thought I'd give Hyper-V on Windows Server 2008 R2 Enterprise a try on my Homeserver (yes, it's legit... got it from msdnaa). First thing to throw at it was my firewall which runs IPFire. This distribution currently uses the kernel version 2.6.32.15 and comes with the Hyper-V drivers. 

So I enabled them and at first they work just fine but after a few minutes they just fail. There are no packages going in or out anymore until I reboot the VM but sometimes even that won't work so the VM just keeps "Stopping" like forever.

Emulated networking works fine but it slow and uses more CPU. That way my firewall routes slower than when running under virtualbox on an atom N270. My server has an E6750; VM is limited to 25%, but that should still outperform this atom CPU especially since it's never going anywhere near 100% CPU load, so give me a break!

A quick google search led me to people having the same problem (even with other distributions and kernel versions that include those drivers) but no solution yet...

I already found [this](http://projectdream.org/wordpress/2010/02/17/hyper-v-2008-r2-and-linux-guests/) but I can't quite follow the author on the part where he solved the issue - especially since I need two virtual nics for my firewall distro to work (obviously one internal and one external)

What am I missing here?

Answer: 
I also had a lot of issues with any mainline kernel hv starting with 2.6.33 up to recent 2.6.36.1. It seems that either you are of the lucky ones and can get working Linux VMs or what is more often seen are network losses and crashing storage modules. I hope things improve but at the moment I still have a bad feeling.

I have the certain doubt the hv modules were primarily developed and testest with Kernels from RHEL 5 (not 6) amd SLES 10. I had to switch CentOS 5 to get a stable running Linux.

See the problems that were reported here: <http://www.panterlo.com/2010/10/10/ubuntu-10-10-and-hyper-v-r2/#comment-84>
see this list and if anything is relevant then apply it, and or if this is not production then download the beta of w2k8r2 sp1, it solves lots of little issues! 

<http://technet.microsoft.com/en-us/library/ff394763(WS.10).aspx>