how to jump Application start address without bootloader.

[AmyKIM]

Hi.
I was wondering how to access Application start address without bootloader.
This is because in KDS, application can be executed without a bootloader.
I saw the following article in the NXP community and I was able to do it in action. But I wonder if this is the best way to do it.

my question
1. Isn't it possible to jump to the offset address in MCUXpresso due to debug probe?
2. Is the same method as the source best? Or if there is a way to jump like KDS, please let me know.

Source: https://community.nxp.com/t5/MCUXpresso-IDE/Debug-Fails-When-Application-is-Offset-in-Flash/m-p/8775...

Thank you.

[nxf56274]

Hi,

mcuxpresso do not support this function at now. You may use other IDE. 

Have a great day,
TIC

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[ErichStyger]

Hi @AmyKIM ,

not sure what you mean with 'access application start address without bootloader'?

The application start (or entry) address is defined as an attribute in the ELF/Dwarf, but this is indicative only. What counts is what you have in the hardware. At reset it fetches the PC and SP from the vector table, so from an application stand point you can read from that memory. Then it goes through that code (startup code) and jumps to main().

As for the debugger: it follows what the startup code does, but you can script it (with the usual gdb scripts if you like) to modify the registers and do special stuff). How such a scripting looks like: https://mcuoneclipse.com/2015/03/25/command-line-programming-and-debugging-with-gdb/

But this won't have an effect if you run it without the debugger.

I hope this helps,

Erich