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

Fabio Estevam
2022-04-26T01:57:40Z

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.