Early debugging

[hinks]

I'm trying to follow the game boot from start using USB gecko and GDN.

I did:
- start the game paused,
- set exec breakpoint on 0x800018A8

Setting the breakpoint also started the game, right? 'cause I see a lot of action on terminal output and gecko loses connection after a while. Game is also stuck on green screen.. I've tried other address with the same result.

If I just press start the games runs, and setting the breakpoint later also works - just to prove my setup is OK (I guess).

Has anyone tried something like this?

[dcx2]

Set exec breakpoint on 800018A8 will have the game run until the first execution of whatever the code handler hooks.

I think you might want to try pressing Step instead of Set Breakpoint.  Then you can follow along from the first instruction.  I'm not sure because I never tried this myself.

[megazig]

_start sets up nintendos debugger. setting up your interrupt handler there means youre only missing os setup but get all of main. _start is the first thing run that calls init_registers, init_hardware, os setup, debugger setup, and then calls main

[hinks]

[SOLVED]

I've finally figured it out!

What needs to be done is:
- start game in paused mode,
- start GDN,
- USBgecko connects,
- game waits for USBgecko command,
- press Pause game button in GDN (mandatory!),
- now the GDN has put USBgecko in paused state (also Wii screen turns green),
- in GDN set breakpoint to 0x800018A8,
- in GDN breakpoints view, click 'Set'
- GDN should quickly stop execution and disassembly will reflect address of breakpoint

At this point the game is ready to be stepped through!

;D

[FL4SHK]

Would this work with Gecko OS Mod and Gamecube games?