DSDP/DD/DebugModel

This is the Debug Model Sub-group

Lead: Pawel Piech (Wind River)
Members: Mikhail Khodjaiants (QNX), Freescale, Nokia

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Requirements discussion

Introduction

I really don't know how it's possible to start a requirements discussion without having a specific problem or use case to be solved. What generally happens in these situations, is that a set of adjectives are listed that are so un-specific that they are impossible to take an action upton: "scalable", "flexible", "responsive", etc. On the other extreme, if everyone comes to the table and describes their specific problem that they are trying to solve, the discussion tends to drift towards completely irrelevant topics and often goes to try to solve conflicting problems that aren't even in the scope of the original architecture.

So I propose a third approach to this discussion, which I think might be a lot more fun than describing intricate details of everyone's debugger. Let's define a completely theoretical debugger problem, one that we can use to represent all of the different types of problems that we have to solve for our very different debuggers. We don't necessarily have to try to roll all of our different and sometimes divergent problems into one theoretical model, we could have many different versions of the model, and then try to apply our solution to fit these different needs. As we introduce features into this model, we could tie these into specific requirements that we already have defined for our products. Hopefully this will be a lot more fun than a traditional technical discussion.

Theoretical embedded debugger model of God

Let's suppose there is a God somewhere out there, and this God has a pretty daunting task to perform: to monitor over 6,000,000,000 souls in the world, watch their deeds, listen to their prayers, count their sins, and of course issue judgment when the souls leave their bodies and are either sent to heaven, hell, or the ever popular pergutory. We would like to write a debugger for God, which would allow us to glimpse into the inner workings of the heavenly bodies, watch how God and his helper angels cope with this formidable task, and monitor their progress within our Eclipse-based debugger.

Based on this simple model, we can already draw up some requirements that our debug model will have to meet in order to effectively monitor and debug God in his work:

• There should be no assumptions about the number of objects that the debugger might need to track. It's not likely that the debugger will ever need to display information about the 6,000,000,000 souls in one view, but God is aware of all of them, and our debugger should be prepared to handle. To tie this into a concrete embedded debugging use-case, we have systems which deal with very large data sets which need to be examined by the debugger, but which could easily overwhelm the amount of memory available on the host debugger.
• The debugger views need to be able to rely on the external debugger process to perform filtering and sorting of the data to be presented to the user. Once again, the host debugger doesn't have the capacity to sort all of earth's souls according to the number of their sins, but God can probably do it in a jiff. A concrete use case for this requirement is same as above.