[Buildroot] [PATCH 1/1] board/mender: add a mender board example configuration.

[Adam Duskett]

Hey Thomas

On Tue, Aug 27, 2019 at 12:23 AM Thomas Petazzoni
<thomas.petazzoni at bootlin.com> wrote:
>
> Hello Adam,
>
> On Mon, 26 Aug 2019 13:36:19 -0700
> aduskett at gmail.com wrote:
>
> > From: Adam Duskett <Aduskett at gmail.com>
> >
> > Buildroot currently has all of the needed packages to use Mender as the primary
> > update system. However; there isn't any documentation or examples now that
> > provide a starting point for users. This lack of documentation makes setting up
> > a Mender based update system difficult and time-consuming.
> >
> > Provided in this patch series is a mender_x86_64_efi_defconfig -that sets up an
> > x86_64 EFI based build that is ready to flash to a USB pen drive or use in a
> > QEMU environment. The system partition exchema comprises of two equally sized
> > root partitions and a 64M data partition that is mounted to /var/lib/mender as
> > a persistent data store partition.
> >
> > There is a board/mender/readme.txt provided which gives users documentation on
> > how to flash the built image or boot the image using QEMU as well.
> >
> > Signed-off-by: Adam Duskett <Aduskett at gmail.com>
>
> Thanks for proposing this. I am wondering if adding more and more
> defconfigs is the right way of "documenting" things like that. It
> definitely makes sense to have some documented examples/demos to show
> how to use a particular feature, but I don't know if defconfigs are the
> right way. Or if they are, perhaps we should have a way to clearly
> distinguish the regular defconfigs (i.e minimal ones just to get
> started with a HW platform) from the demo/example ones.
>
Usually, I would agree with documenting the process; however; in this case, the
best course of action is a series of examples. The reasoning behind the separate
defconfig standard is that using Mender as the update system with Buildroot,
several system settings need to be set up; in the case of x86, this includes
the following partition layout:
  - Root A
  - Root B
  - Data

Note:
  A separate boot partition is also supported; however; Buildroot doesn't
support building multiple file systems in one command. Because of this
limitation, I wasn't able to include building an initrd file system in a
single example (Perhaps Dracut could do this if we add the package someday).

For ARM, using Mender also requires patching UBoot, so having examples which
include the official mender patches and specific UBoot version would be an
enormous help for anybody wanting to use Mender on ARM boards.

As for your comment about distinguishing the regular defconfigs, perhaps having
_demo or _example in the defconfig names would help?

> > diff --git a/board/mender/post-image-efi-gpt.sh b/board/mender/post-image-efi-gpt.sh
> > new file mode 100755
> > index 0000000000..76ddfa5d47
> > --- /dev/null
> > +++ b/board/mender/post-image-efi-gpt.sh
>
> Please use the genimage capability to generate GPT partition tables. It
> wasn't supported in genimage back when the pc_x86_64_efi_defconfig was
> introduced, but there is a patch pending in patchwork to convert
> pc_x86_64_efi_defconfig to use this genimage capability.
>
> Thanks,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

Thanks!

Adam