Configuration Management for FPGA Designs - c

Question

Which configuration management tool is the best for FPGA designs, specifically Xilinx FPGA's programmed with VHDL and C for the embedded (microblaze) software?

Answer 1

There isn't a "best", but configuration control solutions that work for software will be OK for FPGAs - the flow is very similar. I use Subversion at work and git at home, and wrote a little on 'why' at my blog.
In other answers, binary files keep getting mentioned - the only binary files I deal with are compilation products (equivalent to software object and executables), so I don't keep them in the version control repository, I keep a zipfile for each release/tag that I create with all the important (and irritatingly slow to reproduce) ones in.

Answer 2

I don't think it much matters what revision control tool you use -- anything that you would consider good in general will probably be OK here. I personally use Git for a sizable Verilog + software project, and I'm quite happy with it.
What will bite you in the ass -- no matter what version control you use -- is this: The Xilinx tools don't generally respect a clean division between "input" and "output" or between (human edited) "source" and (opaque) "binary." Many of the tools like to store some state information, like a last-run time or a hash value, in their "input" files meaning that you'll get lots of false changes. Coregen does this to its .xco files, and project navigator (the main GUI) does this to its .xise files. Also, both tools have a habit of inserting or removing lines for default-valued parameters, seemingly at random.
The biggest issue I've encountered is the work-flow with Coregen: In many cases, at least one of the following is true:
You have to manually edit the HDL files produced by Coregen.
The parameters that went into Coregen are stored somewhere other than the .xco file (usually in what looks like an output file).
You have to copy-and-paste the output from Coregen into your top-level design.
This means that there is no single logical source/master location for your input to the core-generating process. So even if you have the .xco file under version control, there's no expectation that the design you're running corresponds to it. If you re-generate "the same" core from its nominal inputs, you probably won't get the right outputs. And don't even think about merging.

Answer 3

I suggest CM tools that support version labeling and binary files. Most Software CM applications are fine with ASCII text files. They may just store a "difference" file rather than the entire file for updates.
My recommendations: PVCS, ClearCase and Subversion. DO NOT USE Microsoft SourceSafe. I don't like it because it only supports one label per revision.

Answer 4

I've seen Perforce and Subversion used in a couple of FPGA-intensive companies.

Answer 5

We use Perforce, and its great. You can have your code that lives in Linux-land checked in side-by-side with your Specs and Docs that live in Windows-land. And you get branching, labels, etc.
I've seen everything from Clearcase to RCS used, and it is really all okay for this kind of thing. The important thing is to get a good set of check-in policies established for your group, and make sure they stick to it.
And have automated nightly regressions. That way, when someone breaks the rules, they can be identified and publicly shamed.

Answer 6

I have personally used Perforce, Subverion, git and ClearCase for FPGA projects. Since VHDL and C are just text files, any works fine. However be sure to capture the other project and contraint files and any libraries you use.
Also think about what to do with the outputs, e.g. log file and bitstreams. Both tend to be big and the bitstreams are binaries.

Answer 7

Previously I used Subversion but have switched to git two years ago. Git handles FPGA design files just as well as it handles every other text and binary file. Git is all you need for version controlling your files and artifacts.
For building the designs, I recommend just using a single ISE project called "ise" (living in a subdirectory called "ise/"). You can take a look at my (very modest) FPGA open-source project on github for the file layout. I don't bother storing the ISE files at all since they are easy to regenerate. The only things I save are the Verilog files and some ISIM waveform config files. In other projects that use coregen I save the coregen.cgp project file and all of the *.xco scripts for regenerating cores. Then I use a Makefile for actually running coregen on the *.xco files. There are a few other Xilinx-specific files you should version control too: *.ucf, *.coe, *.xcf, etc.
I experimented with using Makefiles and the Xilinx command-line tools but found that ISE did a much better job tracking dependencies and calling the tools with the right arguments. Just don't make the mistake of trying to version control your ise/ project files or you will go mad. Xilinx has something like 300 different file types which change every release. If you want to save a file, you can try the ISE project file itself with a .xise extension. Anything that is hard to recreate, like the golden bitfile that you know works and took 6 hours to build, you might want to copy that and configuration manage it explicitly.