Ubuntu under Hyper-V – How to overcome screen resolution issue

Recently, I got a new SSD (Sandisk 256 GB in case you’re wondering) and as part of setting it up, I decided to clean install Windows 8 instead of moving my existing Windows 7 setup over. One of the things I wanted to try out was the integrated Hyper-V support in Windows 8 to host my Ubuntu VM instead of using VMWare Player. Windows 8 Pro has native Hyper-V but you’ll need to turn it on from Control Panel/Programs/Turn Windows features on or off. Please note that if you turn on Hyper-V you cannot install VMWare Player on the machine. You will need to turn off Hyper-V if you need to install VMWare Player – the two cannot co-exist as of now.

One of the first tasks I needed to accomplish was to migrate the existing VMWare Ubuntu VM hard-disk to Hyper-V. You can do this using 2Tware convert VHD (available here). Using this freeware, you can convert the VMWare disk into VHD format. Now all I needed to do was setup a new VM in Hyper-V and attach the VHD to this VM. Everything worked remarkably well – Microsoft has released Linux drivers for running Linux VMs under Hyper-V and Ubuntu LTS 12.04 has these drivers as part of the image. So my old VM worked flawlessly on Hyper-V (networking was fine, mouse and keyboard were mostly fine).

There was one hitch however – the maximum resolution of X in my VM was set to 1152×864. Turns out the current video support for Linux in Hyper-V only allows a maximum resolution of 1152×864 (basically you’re using the VESA framebuffer video driver as there’s no synthetic video driver for Hyper-V yet). The good news is that Microsoft has already added the synthetic video driver with resolution support for upto 1900×1200 to the Linux kernel. However, it is going to be a while before this shows up in a LTS Ubuntu distribution. In the meantime, a much better solution exists for working with your Linux VM from your Windows machine – note that this tip actually applies to both VMWare and Hyper-V and for the most part, I prefer this setup over running the VM full-screen.

The trick consists of the following steps:

1. Run PuTTY to establish an SSH session with your VM. Enable tunneling of X over SSH in the PuTTY options
2. Run an X server on your windows machine – xming is what I use. It works with no configuration hassle.
3. Now you can launch any X program from your PuTTY session and it will show as a native window in your Windows machine.

With this setup, I interact with the VM much better (this is very similar to, but IMO better than VMWare’s Unity mode). Of course, if you really want a Linux Window Manager and a richer environment like KDE or Gnome or Unity you’ll need to configure xming so you run it in one window mode. For me, since I mostly work in the Linux terminal, gvim and xemacs, the multi-window mode is much more useful.

Update 8/16/2014

Finally updated one of my VMs to Ubuntu 14.04 – the resolution was still stuck at 1152×864. A quick check of loaded modules with lsmod showed that the hyper-v synthetic frame buffer driver hyperv_fb was loaded. A brief search helped me figure out that I needed to pass in a kernel option at boot. So to get the higher resolution, add this to /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=hyperv_fb:1920x1080"

Then run sudo update-grub and reboot your VM and now you should be able to get your VM at 1920×1080 resolution.