Help with GDB on Powerpc Targets

Tue Nov 22 18:32:31 UTC 2016

Hi Chris,

Thanks for the update on this. I'm interested what level of effort it would
take to incorporate PowerPC support.
Would that derive from Till's work? I may be able to offer support in terms
of development effort by myself or others.
Getting this working is critically important to us in the next year or so.

-Matt

On Mon, Nov 21, 2016 at 3:21 PM, Chris Johns <chrisj at rtems.org> wrote:

> Hi Matt,
>
> Please excuse the delay in responding, I am currently traveling.
>
> On 20/11/16 2:19 pm, Matt Rippa wrote:
> > I found this on Till's
> > page. http://www.slac.stanford.edu/~strauman/rtems/gdb/index.html
> >
> > Looks like all my bsp's are mentioned.
> >
>
> Yes the PowerPC is supported in Till's packages. These packages will not
> be merged into RTEMS and I do not know the status of them with the
> current code base.
>
> I have a new debug server [1] which has x86 and ARM (CortexA9) support.
> The server side of things is stable and the target support is starting
> to look good. This will be merged into the main repository once I have
> changed the name of the package from dbserver [2].
>
> I would welcome PowerPC support but I currently have no budget to
> complete that task.
>
> The new rtemsdbug server implements the latest GDB remote protocol and
> gives the user access to all threads except some special excluded
> threads needed to support the server. You attach to a running board
> giving you access to your application. With some simple techniques in
> your application you can debug initialisation. You can list the threads,
> switch to a thread and perform a back trace. A crash will put you at the
> instruction of the crash. Being a standard remote protocol it should
> integrate with a range of GUI front ends, I have been using Emacs and it
> is nice to use.
>
> At a technical level the server currently supports the "stop all" model
> and does not support the "non-stop" mode. No-stop mode could be added
> but it was not considered important for the initial release. There is no
> thread specific break-point support. It may be possible but I am not
> sure GDB's remote protocol is able to do this. I personally do not think
> this is a major issue. The server supports range stepping where
> supported which is a real performance boost when stepping. The server
> code supports libbsd and I have not tested it with the legacy stack but
> it should work.
>
> Known issues. First this is invasive debugging with software running on
> the target so there is a limit to what you can debug. Interrupts are an
> example of something you cannot debug when using TCP as the remote
> protocol. A bug which writes to any memory may corrupt the debug
> server's data or the networking stack. In general the support is really
> good for applications and even drivers which use tasks for interrupt
> processing, something that is important on SMP systems. I would like to
> refactor the transport to allow serial support. I have not tested the
> server on SMP systems.
>
> Current implementation limitations. The server needs support added to
> define XML based register sets as defined by GDB. This allows support
> for various specialised register sets such as a NEON on ARM, MMX on x86,
> or special registers found in embedded variants of devices. A current
> bug is breaking on a break point set in the path an excluded thread
> uses. This can happen when dealing with tasks that are doing things in
> the OS or networking stack.
>
> I hope this helps.
>
> Chris
>
> [1] https://ftp.rtems.org/pub/rtems/people/chrisj/dbserver/
> [2] Sebastian pointed out dbserver is a bad name due to a Goggle
>     search. I am not a database person. I will change the name
>     to rtemsdbug then merge.
>
> > -Matt
> >
> > On Fri, Nov 18, 2016 at 7:15 AM, Matt Rippa <mrippa at gemini.edu
> > <mailto:mrippa at gemini.edu>> wrote:
> >
> >     Looking for guidance running gdb on ppc targets. Remote debugging
> >     would be ideal, but any method of setting a break point or seeing a
> >     stack trace would help.
> >
> >     Is there a resource I can start reading to set this up? My three
> >     bsp's are below.
> >
> >     Thank you,
> >     -Matt
> >
> >     ../rtems-4.10.2/configure --target=powerpc-rtems4.10
> >     --prefix=/gem_sw/targetOS/RTEMS/rtems-4.10 --enable-cxx
> >     --enable-rdbg --disable-tests --enable-networking --enable-posix
> >     --enable-readline --enable-rtemsbsp="beatnik mvme2307 mvme3100"
> >
> >
> >
> >
> > _______________________________________________
> > users mailing list
> > users at rtems.org
> > http://lists.rtems.org/mailman/listinfo/users
> >
>
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