Why use LabVIEW on Linux?

[MrQuestion]

rolfk,

Thank you for that very descriptive answer.

I just gave you a kudo for that!

What you describe makes a lot of sense.

With the NI embedded world warming up to Linux, I do hope to see some expansion into the desktop domain.

There are several Linux builds out there that are mature and very stable.

I think Linux still has a long way to go with changing its image. I think most people get the impression that Linux is an operating system for socially impaired geeks, and people paranoid about security.  People have the impression that Linux is complex to use, and you can’t do anything without the command line.

All this is wrong, and until this image is changed I don’t see the business world taking Linux seriously. At least outside of the back end service world of IT.

Thank you,

[rolfk]

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@thoult wrote:

There's one obvious reason why NI are switching to Linux RT: cost.

Every time NI sells an embedded system running VxWorks, they have to pay a license for each one, plus seats for a development system. No such issues with LinuxRT.

Another benefit I can see is portability, for the reasons MrQuestion outlines - a greater number of development tools, ability to run a wider range of code on the target.

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I have no idea how expensive a VxWorks source code license is, but it won't be cheap. So cost certainly plays a role but I doubt that NI only looks at investement costs. Also source code licenses might come with royality free distriburtion rights, since tracking those licenses is quite a burdon for the manufacturer and basically not controllable by the VxWorks manufacturer.

Getting a Linux kernel adapted to your own hardware isn't exactly a cheap endavour either as it costs quite some very specialized human forces. Gettting it hardened and tested as a reliable RT OS is probably an even more taunting task. I'm not saying that Linux RT is a bad OS, but a single not so stupid error in one of the hardware adaptions made inside the source can already have very far reaching consequences. And even Linux still has bugs in its source code. 

Linux RT was probably more a decision because it is currently the most actively developed OS on the globe, and has the broadest support of platforms and hardware drivers of all available RT systems. It's far from a lightweight distribution so on resource constrained embedded hardware it is still not always the best choice but if you can spare some amount of RAM (which nowadays costs very little) then there isn't much of a reason NOT to use it.

The reason that NI even has used VxWorks is exactly because they switched CPU platforms. The x86 based embedded capable CPUs were either to power hungry or to underpowered performance wise at that time, so the switch to PowerPC was decided but Pharlap ETS was only availalbe for x86 architecture and porting that OS to a new CPU architecture would probably have been a very expensive exercise and most likely also run into several license issues with Pharlap/Ardence/Interval Zero. So they had to choose for an RT OS that supported PPC already. An argument could be made that they would have been better of if they went with Linux already back then, but that's already about 10 years ago, and a lot has changed in those 10 years. Linux nowadays is in many ways much different, with a clear multi-hardware architecture and much more stable than it used to be back then, and the licensing issues about using a GPL based kernel in commercial hardware has been tackled by many ADSL modem and other network router manufacturers and more in the meantime.

For the foreseeable future it seems likely that NI will stay with Linux RT for all new embedded hardware platforms. It has many advantages to various other RT OSes and the disadvantages like bigger memory footprint are nowadays not much of a concern if you don't have to squezze the last cent out of a hardware design. Cost wise the man power needed to support an embedded hardware OS of your own is likely a lot higher than any license fees you have to pay to the likes of IntervalZero or VxWorks, so I doubt that that is the major breaking point for Linux RT. Sure  $100000 or more per year may seem like a lot but for that sum you can probably only hire two programmers for that, and I'm quite sure there work more people on the support of every of the RT OSes NI currently uses.

[thoult]

I believe the license for a single developer seat for VxWorks to be in the $10k - $15k range, but have nothing to back that up with. I also believe there's a fairly substantial run-time license cost which gets passed on to the customer, i.e. me - this I understand from my field engineer. This is a scaled cost per run time license purchased, so it probably doesn't cost that much in the long run if they're selling plenty of cRIOs.

I'm trying to rack my brain for the other reasons that were given when I asked about it. I'm pretty sure there was also something about the future direction of Xilinx FPGAs.

[MrQuestion]

Interesting that you bring up Xilinx FPGA.  My co-workers are often confused why we can't develop on linux with LabVIEW FPGA. They use Linux to develop and simulated FPGA code. We also have some fairly large compile farms running on top of Linux. 

I often use Mentor Graphics ModelSim for simulating my LabVIEW FPGA code, but I'm only limited to windows. The folks running ModelSim on Linux runs circles around me with their simulations. 

If I could use LabVIEW FPGA in Linux my boss would have no issue switching over to a Linux base development platform.