Saturday, September 24, 2016

On Clusters and Infotainment

Romain Saha
Strategic Alliances Manager

I think I have IAD or internet addiction disorder. I don’t argue with people anymore. I just google until I get the answer. I can’t remember anything. Why should I? It’s all out there on the internet. I barely watch TV anymore. I’d rather just learn something using the internet. 

OK – this probably isn’t textbook IAD. Maybe it’s just the new reality. Pretty much everything anyone could possibly want to know is out there somewhere on the internet. Sometimes it’s easy to find. Sometimes it’s hard. But it almost always is out there if you look hard enough. 

You would think that in this brave new world that there’s no opportunity for confusion anymore. I thought so until I started trying to figure out how one could build a safety certified digital instrument cluster and a full-blown infotainment system using a single high powered embedded processor. I see a lot of silicon road maps in my role and those indicate that a lot of horsepower is coming online. So much horsepower that it’s starting to look like using separate processors to run disparate systems in a car doesn’t make sense anymore.

You’d think that combining a cluster and infotainment system on one SoC would be a no-brainer. Dual (or more) display support is getting pretty common and even today’s SoCs have the compute cycles, so why isn’t everybody already doing this?  It seems pretty easy until you consider that the cluster is a safety critical system. It’s not even the whole cluster, mind you. It’s just what they call telltales. Telltales are those icons that light up in your car to tell you you’re in drive and not reverse, that your traction control is offline, or that your engine is about to blow up. Small things maybe, but very useful information indeed. So, that means you have to address safety concerns for the cluster.

Why not just apply safety criteria to the whole system including the head unit then and be done with it? That is one approach certainly, but the problem is that an infotainment system is pretty much impossible to safety certify. Maybe impossible is too strong. You could probably do it, but why would you? It would probably cost way more than any savings resulting from collapsing two systems onto a single chip.  Plus it would take forever.

If that’s not the answer, then what is? Finding a way to isolate cluster safety criteria from the infotainment system can do job, as long as you can ensure complete isolation. This isn’t a new concept but still pretty rare in embedded.   This is called a hypervisor, and if it is done right, it does the trick. Well, almost. Not every hypervisor can do it right. In order to ensure isolation for this use case you need a type-1 hypervisor. Type-2 hypervisors don’t cut it.  

This is where the internet starts to fail me.  I see hypervisors described as type-1 but then see things about proprietary drivers. I see people say virtualization, but when you dig a bit deeper it’s hard to say whether it’s virtualization or para-virtualization. Type-1, type-2, para, hybrid… I’m at the point where I don’t really know what I see. 

It would be so much easier if people answered simple questions with simple answers.

  • Can you share graphics and still achieve true safety isolation? 
  •  Is the hypervisor built in a way that you can reasonably safety certify your system.
  •  Is it real-time? 
  • How much overhead does it add to the overall system? 
  • What happens if a guest OS goes rogue? 
Maybe you could ask your hypervisor supplier how they address this kind of stuff. If you get an answer that makes sense, do the world a favor and spread the word.

The second thing you need is a foundation on which to build a safety certified system. QNX, as an example, has certified both its OS and tool chain to ISO 26262 ASIL D. You can find this certification on the internet. It’s  here . If you take the time to read it, it says we did the tools and the OS. The production OS used in millions of systems shipping worldwide.
Here’s where the internet fails me again. I have looked and looked and looked for another embedded OS company with anywhere near the same level of certification. It has to be out there. I see all kinds of anecdotal “marketing" evidence but I can’t find a certificate. The closest I have come so far is a certificate for an OS, without the tools, that was issued in 2007 for Common Criteria EAL 6+ on an old single-core PowerPC processor. I must be missing something.  Can you buy a PowerPC processor anymore? I guess you should ask to see certificates to be sure you know what you’re getting.

I’m having a hard time coming to grips with the internet letting me down. I’m certain I just don’t know where to look, so if anyone has the answers I’m looking for, I’d love to hear about it. Better yet, post it somewhere on the internet that’s easy to find.

The next thing I’m going to try to find is someone with a safety certified hypervisor because you’ll need one of those too…

No comments:

Post a Comment