On 2020-04-05 16:34, G. S. Niteesh wrote:
Hii,
It has been quite a few days since the last mail.
Chris, can you please take a look at this when you are free?
I am sorry for not tracking this thread. I would like to work on this
but currently it is not high on my list as I work on getting a release
done. I am pleased to see the tool getting attention and I think it is
an important tool for RTEMS to have so please do not take my lack of
attention as an indication I do not think it is important.
Thanks
Chris
Thanks,
Niteesh
On Mon, Mar 23, 2020 at 1:23 AM Christian Mauderer <l...@c-mauderer.de
<mailto:l...@c-mauderer.de>> wrote:
Hello Niteesh,
thanks for the (private) remainder. This thread really stopped quite
some time ago. A lot of us are quite busy right now but that shouldn't
happen. If you don't get a response for some question: Please give it
about a week of time and then just ping the thread.
On 05/03/2020 11:06, G. S. Niteesh wrote:
> On Wed, Feb 26, 2020 at 8:39 AM Chris Johns <chr...@rtems.org
<mailto:chr...@rtems.org>
> <mailto:chr...@rtems.org <mailto:chr...@rtems.org>>> wrote:
>
> On 22/2/20 1:45 am, G. S. Niteesh wrote:
> > Hi,
> >
> > This is regarding adding RPi support to the boot image
generation
> tool.
> >
> > The boot process for Raspberry Pi is very unconventional.
The GPU
> starts
> > first, initializes RAM, other hardware, loads the
bootloaders and
> then starts
> > the ARM CPU.
> >
> > The minimum files that are required to boot an RPi are
> > bootcode.bin, startx.elf, fixup.dat, kernel.img, config.txt
> > There are also other variants of startx.elf and fixup.dat.
> > Please have a look
> >
> at
https://www.raspberrypi.org/documentation/configuration/config-txt/boot.md
> > for information on the variants.
> >
> > From what I have tried on my Rpi3 model b v1.2 the minimum
files
> that are
> > required are start_x.elf, fixup_x.dat, bootcode.bin,
kernel.img,
> config.txt
> > But for this to work, we must add start_x=1 to config.txt
because
> by default
> > start.elf is loaded.
>
> Hello Chris,
>
>
> I would have look at how the tool maps to RPi to know if it needs
> more work :)
>
>
> Did you take a look at it?
Chris is most likely too busy with the release right now.
>
> In my opinion, there are two ways to do it.
> The first would be to modify the U-Boot bootloader object to have a
> files field
> to make sure the user provides all the necessary files(fixup.dat,
> startx.elf, config.txt).
> So after this change the rtems-boot.ini for RPI should look something
> like this
> [u-boot-raspberrypi]
> uses = u-boot-arm-raspberrypi
> ..
> ..
> first_stage = %{ubootdir}/bootcode.bin
> boot_device = mmc 0
> second_stage = uboot or startx
> files = [config.txt, fixup.dat etc]
> But also please keep in mind that if we want to support RPi4 then the
> first_stage
> will start4x.elf since bootcode.bin is now replaced by code in the
> EEPROM in RPi4 SOC.
As far as I understand that approach it more or less tells: To start a
raspberry you need U-Boot. U-Boot needs the fixup.dat, startx.elf and
config.txt to boot. But that sounds a bit wrong. On Raspberry U-Boot is
purely optional, isn't it? So from a high-level view it would be more a
- Raspberry needs fixup.dat, startx.elf and config.txt
- That can start either:
- an application or
- an U-Boot which can then start an application (or do other things)
>
> Another approach will be to create the default Raspberry Pi
bootloader
> object. But having
> support for U-Boot is important since it will allow for automatic
testing.
That approach sounds more correct. But I don't really know the
rtems-boot-image tool. That makes it a lot harder for me to tell whether
that approach works well. From that ignorant position I would say that
it would be nice to have a boot-image command that can be called with or
without a option (like --with-u-boot). Alternatively maybe two targets
would be possible. One raspiboot-u-boot-pi1 and one raspiboot-raw-pi1.
But your best bet might is to wait for Chris to get free again and
answer that question. He knows the boot image tool and can tell you a
lot better which concept works best.
Best regards
Christian
>
> Which one do you think is a better approach?
>
> Thank you.
>
>
> >
> > So, what should be the values for the first and second
stages in
> rtems-boot.ini
> > for Rpi?
>
> Would this be bootcode.bin?
>
> > And also wouldn't it be nice if we could add a files field,
which
> will copy the
> > specified files to the image? This would save a lot of
typing in
> case of RPi
>
> Do you have an example?
>
> Chris
>
>
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