Help with GDB on Powerpc Targets

[Chris Johns]

On 23/11/2016 05:32, Matt Rippa wrote:
> Thanks for the update on this. I'm interested what level of effort it
> would take to incorporate PowerPC support.

To support the PowerPC you need to implement something similar to the 
ARM back end but for the PowerPC. Please check the package for the ARM 
back end source.

> Would that derive from Till's work?

No it would not be derived from Till's work. It may reference some parts 
if suitable but I do not know if that is needed. The ARM needed new and 
highly specific exception handlers and I used a hack in the i386 
exceptions to hook a handler so I have not needed to looked into Till's 
work in detail. Note, the i386 exception handler should be change to 
directly handle the exceptions like the ARM does.

The ARM back end exports these functions:

  rtems_debugger_target_configure
  rtems_debugger_target_enable
  rtems_debugger_target_disable
  rtems_debugger_target_read_regs
  rtems_debugger_target_write_regs
  rtems_debugger_target_reg_pc
  rtems_debugger_target_frame_pc
  rtems_debugger_target_reg_sp
  rtems_debugger_target_tcb_sp
  rtems_debugger_target_thread_stepping
  rtems_debugger_target_exception_to_signal
  rtems_debugger_target_hwbreak_control
  rtems_debugger_target_cache_sync

You need to support exception handling to catch and report break points, 
un-handled exceptions and any hardware related support that may be used. 
The exception handlers need to save a complete context and be able to 
return and resume execution.

Supporting custom register sets will expand the back end interface.

> I may be able to offer support in
> terms of development effort by myself or others.

Great.

> Getting this working is critically important to us in the next year or so.

I would welcome PowerPC support.

Chris