Device Tree Blob for Beaglebone Black?

[Alan Cudmore]

Hi Christian,
Thanks for the quick response. I followed the instructions in the
docs.rtems.org manual and generated the dtb from the FreeBSD commit
that Vijay suggested. It still resulted in an exception in the same
function.

Do you know if a specific commit of rtems-libbsd is required to work
with that dtb?
I tried master, and then the "5-freebsd-12" branch.

Thanks,
Alan

On Sun, Feb 23, 2020 at 11:32 AM Christian Mauderer <list at c-mauderer.de> wrote:
>
> On 23/02/2020 17:07, Alan Cudmore wrote:
> > I have been trying to bring up RTEMS with rtems-libbsd on the
> > beaglebone black (latest master).
> >
> > I can run the regular RTEMS samples on the board, and a couple of the
> > rtems-libbsd testsuite examples run as well.
> >
> > The samples such as ping01 and usb01 get a fatal exception in the
> > function fdt_ro_probe_ , leading me to believe that maybe I am not
> > using the correct device tree blob.
> >
> > I'm using the instructions here:
> > https://git.rtems.org/rtems-docs/tree/user/bsps/arm/beagle.rst
> >
> > And I have am loading am335x-boneblack.dtb that I copied from a linux
> > u-boot build. The instructions talk about getting the one from the
> > FreeBSD repository, but there are many other files included in that
> > dts source.
> >
> > What dtb is normally used for the Beaglebone black RTEMS libbsd testing?
> >
> > Is the dtb needed for the non-libbsd BSP?
> >
> > Also, is the ethernet supported on the RTEMS beagle BSP, or do I need
> > libbsd to get ethernet?
> >
> > Thanks,
> > Alan
>
> Hello Alan,
>
> I recommend to use the FreeBSD device trees. libbsd is FreeBSD based and
> therefore works best with them. Normally I would suggest to use the
> version matching the FreeBSD commit used in libbsd. But unfortunately in
> the last commit that doesn't seem to work. Vijay had some problems with
> it and noted that the version from FreeBSD commit
> 19a6ceb89dbacf74697d493e48c388767126d418 works fine.
>
> Regarding Ethernet support: As far as I know there is no support for the
> legacy stack. But the one in libbsd worked fine the last time I tested
> it (which was when I ported it). If you really want to use the legacy
> stack please note that it is still an IPv4 only one and therefore it is
> quite limited nowadays.
>
> Best regards
>
> Christian