You can use CentOS on Hyper-V with 4 vCPU.

!!! PS: EXPERIMENTAL – Just Use This Kernel Source for Test Purposes !!!

1) Install a clean CentOS 5.5 x64 without logical volume

2) Use commands below to update your virtual machine:

1
2
3
4
5
6
7

cd /usr/src/redhat/RPMS/x86_64/
wget http://www.yusufozturk.info/kernel-2.6.37-hyperv.centos.x86_64.rpm
rpm -ivh kernel-2.6.37-hyperv.centos.x86_64.rpm
mkdir /boot/temp
cd /boot/temp
zcat ../initrd-2.6.37-hyperv.img | cpio -i
nano init

Check the content below. Remove the bold duplicate lines and save it.

Continue with commands below.

1
2
3
4

find . | cpio -c -o > ../initrd
cd ..
gzip -2 < initrd > initrd-2.6.37-hyperv.img
halt

After turned off your virtual machine, go to settings and remove Legacy Network Ethernet.
Power on virtual machine. Continue with commands below.

1
2
3
4
5

cd /etc/sysconfig/network-scripts/
rm -f ifcfg-eth0.bak
cd /etc/sysconfig/networking/devices/
rm -f ifcfg-eth0.bak
halt

Now add Synthetic Network Ethernet and 4 CPU. Power on virtual machine.
(Somehow I got kernel panic on a Centos VM – Please use this kernel as test purposes)