Re: [Buildroot] [PATCH 1/2] board/kontron/pitx-imx8m: use extlinux instead of U-Boot boot script

From: Heiko Thiery <heiko.thiery@gmail.com>
To: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: "Yann E. MORIN" <yann.morin.1998@free.fr>, buildroot@buildroot.org
Subject: Re: [Buildroot] [PATCH 1/2] board/kontron/pitx-imx8m: use extlinux instead of U-Boot boot script
Date: Sat, 22 Jan 2022 16:59:52 +0100	[thread overview]
Message-ID: <CAEyMn7bo68eGCoxZPjALUO38Q7JGy_BosvsLSr6YTvFeiP_sSQ@mail.gmail.com> (raw)
In-Reply-To: <20220122151130.59ae7148@windsurf>

Hi Thomas,

Am Sa., 22. Jan. 2022 um 15:11 Uhr schrieb Thomas Petazzoni
<thomas.petazzoni@bootlin.com>:
>
> On Mon, 17 Jan 2022 09:06:16 +0100
> Heiko Thiery <heiko.thiery@gmail.com> wrote:
>
> > Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
> > ---
> >  board/kontron/pitx-imx8m/boot.cmd      | 8 --------
> >  board/kontron/pitx-imx8m/extlinux.conf | 4 ++++
> >  board/kontron/pitx-imx8m/genimage.cfg  | 5 +++--
> >  board/kontron/pitx-imx8m/post-build.sh | 7 +++++--
> >  board/kontron/pitx-imx8m/post-image.sh | 2 +-
> >  configs/kontron_pitx_imx8m_defconfig   | 3 +--
> >  6 files changed, 14 insertions(+), 15 deletions(-)
> >  delete mode 100644 board/kontron/pitx-imx8m/boot.cmd
> >  create mode 100644 board/kontron/pitx-imx8m/extlinux.conf
>
> I have applied, but I am a bit worried about things are going on with
> this switch to extlinux.conf.

I was not aware of the different approaches.

> Indeed, we have:
>
>  * Platforms where the UUID is hardcoded into genimage.cfg and
>    extlinux.conf, such as board/beaglev/
>
>  * We have platforms where a "uuid" variable in filled in U-Boot before
>    triggering the extlinux.conf logic, and therefore extlinux.conf uses
>    root=PARTUUID=${uuid}. For example
>    board/freescale/imx7dsdb/rootfs_overlay/boot/extlinux/extlinux.conf,
>    board/orangepi/orangepi-zero/boot.cmd,
>    board/solidrun/mx6cubox/rootfs_overlay/boot/extlinux/extlinux.conf,
>    board/technexion/imx6ulpico/rootfs_overlay/boot/extlinux/extlinux.conf,
>    and a few others.

For the technexion board there is some logic in u-boot to setp and
discover the uuid of the root partition.

https://source.denx.de/u-boot/u-boot/-/blob/master/include/configs/pico-imx6ul.h#L90

>  * We now have platforms (kontron/smarc-sal28 and kontron/pitx-imx8m)
>    where a random UUID is generated in the post-build script, and used
>    in genimage and extlinux.conf.

With this approach it is independent if the image is installed on the
SD card or the eMMC or what else. But here one pitfall is when the
image is installed on more devices.

> I'm not sure where we want to go, and how much we want to enforce "best
> practices" that are common on all platforms, or just let each platform
> do its little business.
_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot