Device Tree Blob for Beaglebone Black?

Mon Feb 24 14:46:08 UTC 2020

Hi Vijay,
My uEnv.txt was very similar, but I did not have the "fdt addr
0x88000000" command. But that did not seem to help. I still get a
fatal exception when trying to run the usb01 and ping01 programs.

Do you think the u-boot version matters?
I am using the following:
- MLO and u-boot.img from a buildroot linux build. ( u-boot 2018.1)
- RTEMS kernel master from about a week ago ( samples like unlimited
and ticker work )
- rtems-libbsd 5-freebsd-12 branch
- The am335x-boneblack.dtb compiled from the suggested commit from the
FreeBSD github repository.

I don't have a debugger, so I looked up the PC address from the register dump.
For the ping01 sample the PC indicates that it is in the fdt_ro_probe_ function.
For the usb01, it seems to crash in an termios program.

## Transferring control to RTEMS (at address 80000000) ...

RTEMS Beagleboard: am335x-based
        ARM Debug: 0x4b141000
*** LIBBSD PING 1 TEST ***

*** FATAL ***
fatal source: 9 (RTEMS_FATAL_SOURCE_EXCEPTION)

R0   = 0x00000000 R8  = 0x00000000
R1   = 0x0000feed R9  = 0x00000000
R2   = 0x00000007 R10 = 0x00000064
R3   = 0x006e6573 R11 = 0x802520a0
R4   = 0x00000007 R12 = 0x01010101
R5   = 0xfffffff7 SP  = 0x8027589c
R6   = 0x80150dac LR  = 0x8011b1d0
R7   = 0x00000000 PC  = 0x8011a11c
CPSR = 0x00000113 VEC = 0x00000004
RTEMS version: 5.0.0.588646279951ff696f3893a4c2e79aa1ba67fccf
RTEMS tools: 7.5.0 20191114 (RTEMS 5, RSB 5 (57011908b007), Newlib d14714c69)
executing thread ID: 0x08a010001
executing thread name: UI1

One more question:
I am converting the images using the following commands:
arm-rtems5-objcopy $1.exe -O binary $1.bin
gzip -9 $1.bin
mkimage -A arm -O rtems -T kernel -a 0x80000000 -e 0x80000000 -n RTEMS
-d $1.bin.gz $1-app.img

Are the 0x8000.0000 addresses correct in the mkimage command? It seems
that the RTEMS executable considers the start of RAM to be 0x8000.0000

It might be good to have an image I can try.

Thanks for the help!
Alan

On Mon, Feb 24, 2020 at 12:57 AM Vijay Kumar Banerjee
<vijaykumar9597 at gmail.com> wrote:
>
>
>
> On Sun, Feb 23, 2020 at 11:46 PM Alan Cudmore <alan.cudmore at gmail.com> wrote:
>>
>> 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
>>
> 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
>>
>> 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
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