How to do raw debugging with USB TAP

[PhilMathews]

How do I debug u-boot now that I have re-downloaded it into flash. When I cycle power, it does not come up. When I attach the USB TAP and start CodeWarrior, all of the debug button are greyed out. How do I run CW without setting up a "project"?

[DistiCasMgr]

Phil,

1) The fact that you say u-boot does not come up after a board reset concerns me as it should. If this a FSL ref platform (you do not say) and a FSL BSP from the public web then the images built as standard compile and run. There is also a document in the BSP that details how to flash and wher the image should locate.

2) To debug an externaly built project (such as u-boot) you must forst have compiled it with debug info turned on. Once you have done that you can do a File | Open on the u-boot elf image within CW.

This will cause CW to create a project for that elf file asking you questons about debug connection and asking you for pointers to source files if it cannot resolve path names etc.

Once the project is created you must at the very least set the target CPU type in the EPPC Debuger Settings panel and a register init file (if y ou want to debug from the very beginning of code)

Rgds

[PhilMathews]

What should the register init file contain? Can you point me to an example for the MPC8272ADS board?

[DistiCasMgr]

Phil,

In your CW install directory there is a folder called \PowerPC_EABI_Support\Initialization_Files\PQ2

In this folder are all of the register init files for PQ2 CPUs.

The 8272ADS board is known in fact as PQ2_FADS_xxxxxxx where the xxxxx is dependant on the exact board model that you have. Take a look at the file names in there and select the board type that matches what you have.

The vast majority of the file contents are not in fact really needed for debugging a u-boot flash image as in fact u-boot will do all of the Board init. However there are a few registers that are essential to be programmed so that the debugger can find the memory mapped registers.

MSR

SYPCR

MBAR

It won't hurt to use a full register init file as u-boot when it runs will simply overwrite the registers again though. If you want help to get an exact file written, can I ask you to email support@freescale.com and provide details of the exact 8272 board that you have, as well as your linux BSP details or at the very least information about your u-boot version.