Debugging MCUboot

Question

Hi, 
 
 I want to debug [i.e. attach to and single step] mcuboot [running as second stage bootloader] using Ozone and JLink. 
 
 I can connect to the board via the debugger and can debug for a while, but I never get to main(). 
 
 I am probably doing it wrong, however my current approach fails with the verification of some required EXT_API functions fails, in particular the crypto libraries. I suppose I want to use these external APIs for crypto in mcuboot. 
 
 Well, my error is more of a hint than anything else. What I really want to know is: 
 
 What is the Nordic-recommended way to debug MCUBOOT with J-Link? 
 
 Cheers, 
 Odd Rune 
 Vitalthings AS [Trondheim]

vitalgobo · Answer

Well, to tie things up, I have solved it. The basic gist of it is: * Flash the merged.hex from the west build. * Make sure to run b0 (wichever you use) before attempting to debug mcuboot. Essentially, the steps are: 
 In the Ozone jdebug script: 1. We do this by inspecting the b0 elf, finding the entry point and adding a step to _SetupTaget(), in our case Target.SetReg("PC", 0x10E0") Target.SetReg("SP", 0x20003208). 2. Load the mcuboot ELF in Ozone using: File.open() in OnProjectLoad() to get access to the debug symbols. 3. In TargetDownload(): Target.LoadMemory("/home/user/blah/build/merged.hex") 
 In effect, this flashes and runs b0 (entry point at 0x10E0), and hands things over to mcuboot; so that the external APIs are registered by b0 and accessible by mcuboot [used as the second stage bl]. So that works. A second case I had was getting Segger RTT to work in mcuboot, but I've abandoned this for now as I can actually get step-debugging to work.