Simulics – A New Commercial Reverse Debugger

simulics_logo_just_logoA new entry just showed up in the world of reverse debuggingSimulics, from German company Simulics. It does seem like the company and the tool are called the same. Simulics is a rather rare breed, the full-system-simulation-based reverse debugger. We have actually only seen a few these in history, with Simics being the primary example. Most reverse debuggers apply to user-level code and use various forms of OS call intercepts to create a reproducible run. Since the Simulics company clearly comes from the deeply embedded systems field, it makes sense to take the full-system approach since that makes it possible to debug code such as interrupt handlers.

I have also updated my history of commercial reverse debuggers to include Simulics.

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UndoDB Recording during Automatic Testing

undo-logoUndoDB is an old player in the reverse debugging market, and have kept at it for ten years.  Last year, they released the Live Recorder record-replay function.  Most recently, they have showed an integration between the  recorder function and Jenkins, where the idea is that you record failing runs in your CI system and replay them on the developer’s machine.  Demo video is found on Youtube, see

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A Replay Debugger from 1995!

2016-06-05_21-29-16A comment on my old blog post about the history of reverse execution gave me a pointer to a fairly early example of replay debugging. The comment pointed at a 2002 blog post which in turn pointed at a 1999 text which almost in passing describes a seemingly working record-replay debugger from 1995. The author was a Michael Elizabeth Chastain, of whom I have not managed to find any later traces.

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Intel Blog: Finding a Linux Kernel bug by running Simics on Simics

intel sw smallI love bug and debug stories in general. Bugs are a fun and interesting part of software engineering, programming, and systems development. Stories that involve running Simics on Simics to find bugs are a particular category that is fascinating, as it shows how to apply serious software technology to solve problems related to said serious software technology.  On the Intel Software and Services blog, I just posted a story about just that: debugging a Linux kernel bug provoked by Simics, by running Simics on a small network of machines inside of Simics. See for the full story.

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UndoDB Live Recorder: Record/Replay for Live Systems

I undo-logohave a long-standing interested in debugging in general and reverse debugging in particular and the related idea of record-replay debug (see a series of blog posts I did a few years ago on the topic: history 1, history 2, history 3, S4D report, updates, Simics reverse execution, and then Lab Cloud record/replay). Recently, I found out that Undo Software, one of the pioneers in the field, had released a product called “Live Recorder“. So I went to check it out by reading their materials and comparing it to what we have seen before.

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Wind River Blog: Collaborating with Recording Checkpoints

There is a new post at my Wind River blog, about how some new features in Simics 4.8 improve the collaboration power of Simics checkpoints. For the first time, Simics checkpoint can now carry a piece of history (slice of time), which also makes reverse execution and reverse debug work with checkpoints in a logical way.

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Reverse History Part Three – Products

In this final part of my series on the history of reverse debugging I will look at the products that launched around the mid-2000s and that finally made reverse debugging available in a commercially packaged product and not just research prototypes. Part one of this series provided a background on the technology and part two discussed various research papers on the topic going back to the early 1970s. The first commercial product featuring reverse debugging was launched in 2003, and then there have been a steady trickle of new products up until today.

Originally published in January 2012. Post updated 2012-09-28 with a revised timeline for Lauterbach CTS. Post updated 2016-04-05 to include Mozilla RR. Post updated 2016-12-26 to add Simulics.

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