I'm running Debian Lenny on a system with an AMD Athlon II 240 CPU. I'm installing KVM on my Debian system (fully updated) following this walkthrough. After installing the Xen kernel and rebooting, I attempt to install kvm and get the following error: Code: slinky:/home/user# aptitude install kvm Reading package lists... Done Building dependency tree Reading state information... Done Reading extended state information Initializing package states... Done Reading task descriptions... Done The following NEW packages will be installed: kvm 0 packages upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 1111kB of archives. After unpacking 3121kB will be used. Writing extended state information... Done Get:1 http://ftp.us.debian.org lenny/main kvm 72+dfsg-5~lenny5 [1111kB] Fetched 1111kB in 1s (726kB/s) Selecting previously deselected package kvm. (Reading database ... 29584 files and directories currently installed.) Unpacking kvm (from .../kvm_72+dfsg-5~lenny5_amd64.deb) ... Processing triggers for man-db ... Setting up kvm (72+dfsg-5~lenny5) ... Your system does not have the CPU extensions required to use KVM. Not doing anything. failed! Reading package lists... Done Building dependency tree Reading state information... Done Reading extended state information Initializing package states... Done Writing extended state information... Done Reading task descriptions... Done slinky:/home/user# egrep '(vmx|svm)' --color=always /proc/cpuinfo But when I run Code: egrep '(vmx|svm)' --color=always /proc/cpuinfo the above code in the normal kernel (the one that installed with the OS), I get the proper CPU extensions. Everything I can find says my CPU supports KVM and obviously Debian does as well, but once I boot into a Xen kernel, I can't install KVM. Anybody know what the deal is?