Device Tree Blob for Beaglebone Black?

[Christian Mauderer]

On 24/02/2020 06:57, Vijay Kumar Banerjee wrote:
> 
> 
> On Sun, Feb 23, 2020 at 11:46 PM Alan Cudmore <alan.cudmore at gmail.com
> <mailto:alan.cudmore at gmail.com>> wrote:
> 
>     Hi Christian,
>     Thanks for the quick response. I followed the instructions in the
>     docs.rtems.org <http://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
> 
> Hi Alan,
> 
> I checked with the usb01 and ping01 tests running on libbsd master
> and the dtb from the commit mentioned by Christian. I can't reproduce
> the error and it seems to run as expected. I'm not sure where the
> error might be coming from. Below I'm pasting the contents of my uEnv.txt
> If the error isn't in the uEnv, I can send you my sd card image(offlist)
> so that you
> can try that on your board and that might give some hint on what was going
> wrong.
> 
> ```
> setenv bootdelay 5
> uenvcmd=run boot
> boot=fatload mmc 0 0x80800000 rtems-app.img ; fatload mmc 0 0x88000000
> am335x-boneblack.dtb ; fdt addr 0x88000000; bootm 0x80800000 - 0x88000000
> ```
> 
> Best regards,
> Vijay

Hello Alan,

another point: You know that your exception is in fdt_ro_probe_. So I
assume you have a debugger connected? Can you post a full backtrace so
that we can see from which driver the exception comes from?

Best regards

Christian

> 
>     On Sun, Feb 23, 2020 at 11:32 AM Christian Mauderer
>     <list at c-mauderer.de <mailto: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
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