[PATCH v4] doc/raspberrypi: Added instructions for raspberrypi

Alan Cudmore alan.cudmore at gmail.com
Thu Feb 13 17:10:35 UTC 2020


Hi Niteesh,
I have followed your instructions for getting RTEMS running on the Pi
1 and 2. SMP currently is not working on the 2 for me, but that is not
a problem with these instructions.
I started to try running on QEMU following your instructions but have
not been able to get time to complete my tests.

But this is a vast improvement over "TODO", so I recommend accepting
this change.

Thanks for creating this,
Alan

On Thu, Feb 13, 2020 at 1:49 AM G. S. Niteesh <gsnb.gn at gmail.com> wrote:
>
> Can someone take a look at this, It has been unnoticed for quite a while.
>
> Thank you,
> Niteesh
>
> On Sat, Jan 25, 2020 at 10:49 PM G S Niteesh <gsnb.gn at gmail.com> wrote:
>>
>> Added instructions to run examples on raspberrypi.
>> ---
>>  user/bsps/arm/raspberrypi.rst | 111 +++++++++++++++++++++++++++++++++-
>>  1 file changed, 110 insertions(+), 1 deletion(-)
>>
>> diff --git a/user/bsps/arm/raspberrypi.rst b/user/bsps/arm/raspberrypi.rst
>> index 4ef75bd..72889a5 100644
>> --- a/user/bsps/arm/raspberrypi.rst
>> +++ b/user/bsps/arm/raspberrypi.rst
>> @@ -5,4 +5,113 @@
>>  raspberrypi
>>  ===========
>>
>> -TODO.
>> +This BSP supports `Raspberry Pi 1` and `Raspberry Pi 2` currently.
>> +The support for `Raspberry Pi 3` is work under progress.
>> +The default bootloader on the Raspberry Pi which is used to boot Raspbian
>> +or other OS can be also used to boot RTEMS. U-boot can also be used.
>> +
>> +Setup SD card
>> +----------------
>> +
>> +The Raspberry Pis have an unconventional booting mechanism. The GPU
>> +boots first, initializes itself, runs the bootloader and starts the CPU.
>> +The bootloader looks for a kernel image, by default the kernel images must
>> +have a name of the form ``kernel*.img`` but this can be changed by adding
>> +`kernel=<img_name>` to ``config.txt``.
>> +
>> +You must provide the required files for the GPU to proceed. These files
>> +can be downloaded from
>> +`the Raspberry Pi Firmware Repository <https://github.com/raspberrypi/firmware/tree/master/boot>`_.
>> +You can remove the ``kernel*.img`` files if you want too, but don't touch
>> +the other files.
>> +
>> +Copy these files in to a SD card with FAT filesystem.
>> +
>> +Kernel image
>> +------------
>> +
>> +The following steps show how to run ``hello.exe`` on a Raspberry Pi 2.
>> +The same instructions can be applied to Raspberry Pi 1 also.
>> +Other executables can be processed in a similar way.
>> +
>> +To create the kernel image:
>> +
>> +.. code-block:: none
>> +
>> +     $ arm-rtems5-objcopy -Obinary hello.exe kernel.img
>> +
>> +Copy the kernel image to the SD card.
>> +
>> +Make sure you have these lines below, in your ``config.txt``.
>> +
>> +.. code-block:: none
>> +
>> +     enable-uart=1
>> +     kernel_address=0x200000
>> +     kernel=kernel.img
>> +
>> +Testing using QEMU
>> +------------------
>> +
>> +QEMU can be built using RSB. Navigate to ``<SOURCE_BUILDER_DIR>/rtems``
>> +and run this command.
>> +
>> +.. code-block:: none
>> +
>> +     $ ../source-builder/sb-set-builder --prefix=<TOOLCHAIN_DIR> devel/qemu4.bset
>> +
>> +**Note**: Replace ``<SOURCE_BUILDER_DIR>`` and ``<TOOLCHAIN_DIR>`` with the
>> +correct path of the directories. For example, if you used quick-start section
>> +as your reference, these two will be ``$HOME/quick-start/src/rsb`` and
>> +``$HOME/quick-start/rtems/5`` respectively,
>> +
>> +QEMU along with GDB can be used for debugging, but it only supports
>> +Raspberry Pi 2 and the emulation is also incomplete. So some of the
>> +features might not work as expected.
>> +
>> +Make sure your version of QEMU is newer than v2.6, because older ones don't
>> +support Raspberry Pis.
>> +
>> +.. code-block:: none
>> +
>> +     $ qemu-system-arm -M raspi2 -m 1G -kernel hello.exe -serial mon:stdio -nographic -S -s
>> +
>> +This starts QEMU and creates a socket at port ``localhost:1234`` for GDB to
>> +connect.
>> +
>> +The Device Tree Blob (DTB) is needed to load the device tree while starting up
>> +the kernel. The BSP uses information from this file to initialize the drivers.
>> +
>> +Make sure you pass in the correct DTB file. There are currently two version of
>> +DTB for the Raspberry Pi 2 ``bcm2709-rpi-2-b.dtb`` and ``bcm2710-rpi-2-b.dtb``.
>> +The ``bcm2709-rpi-2-b.dtb`` is for Raspberry Pi 2 Model B and
>> +``bcm2710-rpi-2-b.dtb`` is for Raspberry Pi 2 Model B v1.2
>> +
>> +We need to pass in the DTB file to GDB before running the example.
>> +
>> +In a new terminal, run GDB using
>> +
>> +.. code-block:: none
>> +
>> +     $ arm-rtems5-gdb hello.exe
>> +
>> +This will open GDB and will load the symbol table from hello.exe. Issue the
>> +following commands in the GDB prompt.
>> +
>> +.. code-block:: none
>> +
>> +     (gdb) tar remote:1234
>> +     (gdb) load
>> +     (gdb) restore bcm2709-rpi-2-b.dtb binary 0x2ef00000
>> +     (gdb) set $r2 = 0x2ef00000
>> +
>> +This will connect GDB to QEMU and will load the DTB file and the application.
>> +
>> +.. code-block:: none
>> +
>> +     (gdb) continue
>> +
>> +The ``continue`` command will run the executable.
>> +
>> +**Note**: Add ``set scheduler-locking on`` in GDB if you have any issues
>> +running the examples.
>> --
>> 2.17.1
>>
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