vJunsos-Router on Eve Bare Metal - a solution!

[aalston]

Hi All,

So I have an Asus R500A-E12-RS4U which has an AMD Genoa 64 Core CPU in it. I enabled SVM in the bios - and try as I might I couldn't get vJunos-Router to boot - because it claimed that Nested KVM was not enabled (and I tried multiple options, including the start parameters that tell it to use IvyBridge and vmx=on etc.

Eventually I found a solution and figured I'd share it here for anyone else that is struggling.

Basically - the problem is found in the fact that vRouter has a start script that looks for vmx capabilities on the cpu - and AMD uses SVM. So - to fix this, first I needed to look at the image and get it to a point where I could edit the actual JunOS image:

modprobe nbd max_part=8
qemu-nbd --connect=/dev/nbd0 /opt/unetlab/addons/qemu/vjunosrouter-25.2R1.9/virtioa.qcow2
mount /dev/nbd0p2 /mnt

This will mount the main image on /mnt

Then cd /mnt/home/pfe/junos

In this folder you will find a file called start-junos-sh

There is a line in the script that looks as follows:

CPU_FLAG=$(cat /proc/cpuinfo | grep -ci vmx)

if you change this line to replace vmx with svm so that the line looks like:

CPU_FLAG=$(cat /proc/cpuinfo | grep -ci svm)

(Alternatively you could probably modified this to read CPU_FLAG=$(cat /proc/cpuinfo |grep -ciE "svm|vmx") though I haven't tested this)

Then, save the file, unmount /mnt (and if you wish to rmmod nbd), and add new routers to the lab using the now modified image. This time though, change the cpu flag sent to qemu to read -cpu host

And bingo - everything starts up fine and just works!

Hope this is helpful to someone.