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From: Linus Walleij <linus.walleij@linaro.org>
To: Stephan Gerhold <stephan@gerhold.net>
Cc: U-Boot Mailing List <u-boot@lists.denx.de>
Subject: Re: [PATCH 2/2] board: stemmy: Copy atags for booting downstream/vendor kernel
Date: Thu, 8 Jul 2021 01:54:58 +0200	[thread overview]
Message-ID: <CACRpkdbT4UmFYnG4=d2fmq_s8wGhyhvbANnK0O_XnZBZNeGu5Q@mail.gmail.com> (raw)
In-Reply-To: <20210707105855.89260-2-stephan@gerhold.net>

On Wed, Jul 7, 2021 at 12:59 PM Stephan Gerhold <stephan@gerhold.net> wrote:

> The U-Boot "stemmy" board is mainly intended to simplify booting
> mainline Linux on various smartphones from Samsung based on ST-Ericsson
> Ux500. While the mainline kernel is working great, there are still some
> features missing there. In particular, it is currently not possible to
> charge the battery when using the mainline kernel.
>
> This means that it is still necessary to boot the downstream/vendor
> kernel from Samsung sometimes to charge the device. That kernel is
> ancient, still uses board files + ATAGS instead of device trees and
> relies on a strange very long kernel command line hardcoded in the
> Samsung bootloader.
>
> Actually, since mainline is booted with device trees there is a very
> simple way to make the old downstream kernel work as well: We can
> simply take most of the ATAGS passed to U-Boot from the Samsung
> bootloader and copy them as-is when booting a kernel without device
> tree. That way the long command line and other needed ATAGS are copied
> as-is without having to bother with them.
>
> The only exception is the ATAG_INITRD - since the initrd is loaded
> by U-Boot, the atag for that should be generated in U-Boot so it points
> to the correct address. All other ATAGS are copied as-is and not
> generated in U-Boot.
>
> Also use the chance and provide a serial# for U-Boot by parsing the
> ATAG_SERIAL that is also passed by the Samsung bootloader.
>
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

  reply	other threads:[~2021-07-07 23:55 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-07 10:58 [PATCH 1/2] board: stemmy: Parse atags to get available memory Stephan Gerhold
2021-07-07 10:58 ` [PATCH 2/2] board: stemmy: Copy atags for booting downstream/vendor kernel Stephan Gerhold
2021-07-07 23:54   ` Linus Walleij [this message]
2021-07-14 20:53   ` Tom Rini
2021-07-07 23:53 ` [PATCH 1/2] board: stemmy: Parse atags to get available memory Linus Walleij
2021-07-14 20:53 ` Tom Rini

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