Device Tree Blob for Beaglebone Black?

[Christian Mauderer]

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