libdebugger documentation

[Chris Johns]

On 03/02/2017 08:10, Joel Sherrill wrote:
>
>
> On Thu, Feb 2, 2017 at 1:51 PM, Gedare Bloom <gedare at rtems.org
> <mailto:gedare at rtems.org>> wrote:
>
>     Is there documentation on how to use / extend the new gdb server /
>     libdebugger?

There is no documentation. Adding documentation to use the debugger 
agent is easy, adding documentation to extend or add new archs is a 
large task.

>
> Is there a wish list/TODO for it? Since it is new, it might be a source
> of projects.
>

There is no TODO list and adding it as a source of projects is a good 
idea. The list would be something like:

1. ARM
    a. Add support for more ARM variants.
    b. Add hardware watch and break point support.

2. Add a SPARC backend

3. Add a PowerPC backend

4... Add XXX backend

5. Add XML support for extended register sets.

6. Add support for a serial transport

7. Add a USB OTG slave device supporting a UART class device to all use 
on boards with with USB OTG support.

All these tasks require good low level hardware knowledge and debugging 
skills. You need to be able to dig deep into the processor manuals and 
data sheets and you need to be able debug in tricky situations, for 
example debugging exceptions without any debugging support. Using qemu 
helps however on the ARM the support for the debug hardware in the 
simulator was limited which is fair enough as qemu provides the 
debugging support. Also with the ARM support you cannot use JTAG because 
the ARM's debug hardware is owned by the code you are debugging.

Chris