Re: [PATCH v3 2/2] imx8mn/8mp: Allow booting via USB

Michael Nazzareno Trimarchi
2022-04-26T05:41:15Z

Hi Fabio

On Tue, Apr 26, 2022 at 3:57 AM Fabio Estevam <festevam@gmail.com> wrote:
>
> Hi Tim,
>
> On Mon, Apr 25, 2022 at 8:15 PM Tim Harvey <tharvey@gateworks.com> wrote:
>
> > Tested-By: Tim Harvey <tharvey@gateworks.com>
>
> Thanks.
>
> > agreed it would be a separate issue... just curious if you knew where
> > that was coming from. It certainly isn't a common behavior to boot via
> > USB then expect 'saveenv' to save to a specific eMMC device.
> >
> > >
> > > I see that you replied to Peng's patch:
> > > "imx: dynamic setting mmcdev and mmcroot" and this is likely the cause
> > > for your env numbering problem.
> >
> > That has nothing to do with the mmc device used for U-Boot env. Commit
> > f342c9e381c0 ("imx: dynamic setting mmcdev and mmcroot") adds setting
> > 'mmcroot=' if mmcautodetect=yes which seems to me like a completely
> > inappropriate hack that assumes U-Boot's mmc device numbering matches
>
> Agreed.
>
> > the kernels device numbering (which has changed over time and is not a
> > stable ABI). I believe you have been involved in discussions about
> > that in the past as well regarding how to best tell the kernel what
> > the root device is. Every discussion I have seen (and there have been
> > many over the years) end up with the recommendation of using UUID.
>
> Yes, using UUID is good solution for that.
>
> mmc alias also works in kernels > 5.10 too.

What changes if we drop? Does the board boot anyway?

Michael

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Michael Nazzareno Trimarchi
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michael@amarulasolutions.com
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