DDE DDT Data abort
John Rickman (71) 631 posts |
As a very new user of the DDE Ihave been trying to use DDT to trace a problem in a modified version of the MinApp application. The application is built using MKdebugInstall. No errors. Can anyone help with this problem? |
Sprow (202) 1125 posts |
When DDT starts it sets a breakpoint for “main” automatically, so when you run your debug app you should first click “Continue” which will bypass all the decompression and C library initialisation guff. At that point you’ll be paused at “main” with the source code loaded, at which point single stepping makes sense. DDT is baffling at the best of times, but that initial run-to-main is the key. The reason for the abort is that in single stepping mode DDT actually runs the instructions in an ARM emulator, but it only knows how to emulate instructions that the compiler outputs. It would seem something in the OS or application unsqueeze process now uses a fancy pants instruction, leading (possibly some time later) to an abort. |
John Rickman (71) 631 posts |
Thanks Rob – that has helped with understanding how to get DDT to do something useful. It also shows there is no problem in the C code as I can single step from main through to to end of the wimp poll loop. |
Chris Mahoney (1684) 2113 posts |
I’m watching this thread with interest as I’ve run into that one a few times and have never figured out the “proper” way to debug it. But some things that I’ve run into in the past include forgetting the Messages file, and having the icon bar icon set to a sprite that isn’t in the pool. |
Sprow (202) 1125 posts |
If you “amu debug” then that creates !RunImage-D (of type DebImage) which is tempting to double click because that will start DDT and be in the right directory for the debugger to pick up the sources. However, MinApp$Dir hasn’t been set, and that’s needed by toolbox_initialise to find the icon bar icon and other resources. So you must either
Though I’ve not checked, I don’t think the iconbar icon will appear at the point the various toolbox calls are made – you need to let the Wimp poll. |
Chris Mahoney (1684) 2113 posts |
That’s what I normally do, and haven’t had any problems – so long as I remember to run the installed one first :) However, in this case, from context it sounds like the icon isn’t appearing with either version (after all, why would you try to debug it if it’s already working?). |