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Re: [cdt-dev] Hooking into GDB/MI

Hi Jesper,


We had been in a similar situation as yourself, so I’ll share what we have done:


For many years, we’ve been maintaining our own debugger, and the API for communicating with it was gdb/mi (although it wasn’t genuine GDB).

In fact, we even implemented the initial DSF in order to drive our debugger (though it was not GDB J) in a way that supported multicore well.


But over the years, we found that implementing new features for our debugger was too hard since any changes had to be done on many levels:

The debug agent on the target, the target-side protocol, the debug engine, then gdb/mi, and finally the UI talking gdb/mi.

This made us very inefficient implementing innovations. Also, the DSF, while designed to simplify Eclipse Platform/Debug APIs,

turned out to be quite complex in itself and hard to understand and maintain. Finally, although our debugger had been

designed around gdb/mi from the get-go, we always suffered from “not being 100% GDB compatible”. We’ve found subtle

differences of behavior that cost us a lot of time to investigate and fix over the years.


So what we did in the end was, we completely moved to TCF [1] as the debugger infrastructure. There’s two key design principles

In TCF, (a) API-first design with 100% reliable, extensible public APIs, and (b) avoid adding too many layers between target and UI.

It’s been a long journey until we’ve reached full production quality, but as of today I can say that having TCF made us

extremely fast implementing new features across a wide range of target operating environments.


Actually a very well-known and renowned debugger vendor, who used to offer a GDB API for their hardware debuggers,

has implemented a TCF API just recently and they were extremely happy about the design of TCF protocol and its APIs.

See page 7 on their 2016 newsletter if you are interested.



I’m not sure which benefits you expect from changing a “direct DSF” debug adapter to using gdb/mi

as an additional layer in-between. I’m sure you’ll make the right design decisions for whatever problems

you’re trying to solve. I just wanted to make you aware of the experiences we’ve made and what others have done.









Martin Oberhuber, SMTS / Product Owner – Development Tools, Wind River

direct +43.662.457915.85  fax +43.662.457915.6


From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Jesper Eskilson
Sent: Thursday, March 17, 2016 9:28 PM
To: cdt-dev@xxxxxxxxxxx
Subject: [cdt-dev] Hooking into GDB/MI




As some of you know, we have a debugger (C-SPY) for which we have a DSF-implementation which does not use GDB. We have implemented our own set of DSF services, and this has worked fairly well over the last few years.


Inspired by the CDT hackathon, I wanted to take a stab at an idea I've had for a while, namely to "disguise" our debugger as GDB. The purpose would be to avoid having our own implementation of some rather hairy DSF service logic and also to be able to be in a better position to contribute code to DSF/GDB as well as leverage from new features being implemented in DSF/GDB.


After doing some research on GDB/MI I realized that it would be nice if we could avoid having to reimplement the GDB/MI wire protocol. Since the MI commands are nicely queued by the GdbControl service, I thought that one might be able to intercept them in e.g. queueCommand(). Each MI command would then need to be "interpreted" to interact with our debugger.


Before really digging any deeper into the intricacies of the DSF/GDB/MI internals, I thought I'd post an open question here about this. Does this seem like a reasonable idea? Or should we stay with our own DSF implementation?






Jesper Eskilson Developer

IAR Systems AB


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