TXT Capable Desktop Virtualization System

Having worked on XenClient XT for the past year I’ve experienced the pain of debugging vendors TXT implementations first hand. TXT may be a nearly 6 year old technology but it’s just now coming into use and many vendors platforms have only received internal testing. We’ve found a number of ways for platforms to fail in strange ways and we’ve had to work with the vendors to get their implementations working for a system like XT that uses tboot as part of our measured launch.

For development Citrix has provided me with a number of systems but I’ve been meaning to put one together for myself for some time now. I’ve always liked building my own so I wasn’t thrilled with the prospect of purchasing a Dell / HP system. Home builds are always a bit cooler, a bit cheaper, and more fun in general. That said I was a bit worried about being able to find a motherboard / CPU combo with full AND WORKING VT-x, VT-d and TXT. It wasn’t as bad as I expected. So the following is a breakdown of the home build system I put together specifically to run XT.

Case

I always start building systems with the case. This will dictate size which in turn limits your choices for motherboards. I’ve had a string of successes building systems in Lian Li cases so again they were my first choice. I wanted this system to be as small as possible. Lian Li happens to make probably the best mini-ITX case on the market: the PC-Q02A. This case is tiny and it comes bundled with a 300W power supply. No room in the back of the case for PCI cards either so if you buy this don’t expect to throw a graphics card in it. Whatever you need has to be on the motherboard!

CPU

Since I intend to run XT on this system the CPU has to support the full Intel vPro suite including TXT. This limited me to high-end intel i5 and i7 processors. Since this system will be in a small, low power case I wanted a 65W CPU and went with the Intel i7-2600S. CPUs aren’t really where you want to save money on your build so I didn’t skimp here.

Motherboard

The motherboard is really where vPro and TXT are either made or broken. The BIOS is where CPU features are either enabled or disabled and many motherboard vendors don’t list anything in their docs about TXT compatibility. This is mostly because home users typically don’t really care. In this case we do so some research is required. I played it safe and went with an Intel DQ67EP. TXT and the TPM worked flawlessly. One thing that was a deviation from the platforms from Dell and HP I’ve played with was the TPM came without an EK populated. It’s a simple case of running tpm_createek on the system but because all of the vendor platforms come with an EK pre-populated the XT code doesn’t account for this situation. Easy to work around.

RAM

From here it’s just a matter of getting RAM and hard drive / CD-ROM. Since this system will be running virutalized desktops the more RAM the better. XT doesn’t over commit RAM so if you want to run two desktops with 4G of RAM each you’ll need a bit more than 8G of RAM since the dom0 and service VMs will need a bit too. I picked up 16G of G.SKILL Ares RAM. Generally I run 3 desktops: one Debian Squeeze for development, one Debian Wheezy for my personal stuffs and one Windows 7 for required email and GoToMeetings each with 4G of ram. This system has no problems handling all 3 at the same time.

Disks

Hard disk is always faster and bigger is better. This is where I saved money though since I’ve already got a huge (6T!) NFS server for bulk storage. I went with a modest 120G OCZ Agility 3. I haven’t done any benchmarking but it’s big enough for my root filesystems and fast enough as well. I also put in a Sony Optiarc BC-5650H-01 6X Slim Blu-Ray Reader. I got in on the cheap from an ebay seller. It’s one of those fancy slimline drives so there’s no tray to eject. I hardly ever use optical media except to rip CDs on to my NFS storage. Not sure how much I’ll use this but it’s nice even though it doesn’t match the case 🙂

Photos

I wish there were something in this last photo to give some perspective on the size of the case. Basically it’s the size of a lunchbox 🙂

XT Configuration

Once it’s all put together with XT installed it pretty much “just works”. The USB stack on XT isn’t perfect so some USB devices won’t work unless you pass the USB controller directly through to a guest using Xen’s PCI passthrough stuff. Since XT doesn’t support USB 3.0 anyways I’ve passed the 3.0 controller on the motherboard through directly to my Windows 7 guest to get my webcam working. The Plantronics headset you see in the photo works fine over the virtualized USB stack though and together they make for a pretty sweet VoIP / Video Converencing / GoToMeeting setup. So that’s it. A home build Intel i7 system with 16G of ram, an SSD and Intel TXT / measured boot running XenClient XT. Pretty solid home system by my standards.

2 thoughts on “TXT Capable Desktop Virtualization System

  1. How good is PCI passthrough nowadays? I’m assuming you can share most any card with one guest and do some fancy networking footwork through the host?

    I’ve long dreamt of building a gaming/video rig where I could run an IDS/firewall on dom0 (networking to the guest via a virtual adapter) and have good graphics speeds to boot. But then I’m paranoid, maybe?

    Reid

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    1. In the later 4.X Xen releases it’s actually quite good. Passing through stuff like a NIC “just works”. GPUs can get tricky but it’s usually the fault of the desktop. Dell has a tendency to treat their “primary” PCIe slot special and the BIOS reconfigures a bunch of stuff automagically when there’s a graphics card in it (disable intel graphics hardware etc). This will break PCI passthrough on Xen last time I checked.

      A good work around on the Dell is to use the 4xPCIe slot instead of the 16x. With this config on a Dell 990 I was able to pass through an ATI card to a guest with no problems. This left the Intel graphics in dom0. Nvidia cards have a tendency to be more difficult but I’ve heard of people having success passing through large SLI cards to guests for CUDA processing.

      I haven’t tried any of this on the Intel board from this post though. If you get adventurous and start playing around let me know what you come up with.

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