Help with GDB on Powerpc Targets

Matt Rippa mrippa at
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.


On Mon, Nov 21, 2016 at 3:21 PM, Chris Johns <chrisj at> 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.
> >
> > 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]
> [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
> > <mailto:mrippa at>> 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"
> >
> >
> >
> >
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> > users mailing list
> > users at
> >
> >
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