[PATCH v1 0/2] fastboot: mmc: fix bootloader offset

[Mattijs Korpershoek]

On Mon, Jan 26, 2026 at 16:46, Heiko Schocher <hs at nabladev.com> wrote:

> Hello Mattijs,
>
> On 26.01.26 10:48, Mattijs Korpershoek wrote:
>> Hi Heiko,
>> 
>> Thank you for the patch.
>
> You are welcome!
>
>> 
>> On Sat, Jan 24, 2026 at 06:47, Heiko Schocher <hs at nabladev.com> wrote:
>> 
>>> Not for all SoCs the bootloader start at offset 0x0,
>>> in a hardware partition of an emmc. So we need the possibility to
>>> set the correct offset, where bootloader starts.
>>>
>>> Example:
>>>
>>> imx8qxp revision C0 emmc Partition layout
>>>
>>> | eMMC block / partition | Offset     | Size  | Purpose                        |
>>> | ---------------------- | ---------- | ----- | ------------------------------ |
>>> | /dev/mmcblk0boot0      | 0x0        | 2MB   | imx-boot-container A           |
>>> |                        | 0x00220000 | 128kB | secure boot signature rootfs A |
>>> | /dev/mmcblk0boot1      | 0x0        | 2MB   | imx-boot-container B           |
>>> |                        | 0x00200000 | 8kB   | U-Boot env 0                   |
>>> |                        | 0x00202000 | 8kB   | U-Boot env 1                   |
>>> |                        | 0x00220000 | 128kB | secure boot signature rootfs B |
>>>
>>> imx8qxp rev B0 emmc Partition layout
>>>
>>> | eMMC block / partition | Offset     | Size  | Purpose                        |
>>> | ---------------------- | ---------- | ----- | ------------------------------ |
>>> | /dev/mmcblk0boot0      | 0x00008000 | 2MB   | imx-boot-container A           |
>>> |                        | 0x00220000 | 128kB | secure boot signature rootfs A |
>>> | /dev/mmcblk0boot1      | 0x0        | 8kB   | U-Boot env 0                   |
>>> |                        | 0x00002000 | 8kB   | U-Boot env 1                   |
>>> |                        | 0x00008000 | 2MB   | imx-boot-container B           |
>>>
>> 
>> Why can't we use raw partition descriptors for this?
>> 
>> See:
>> https://docs.u-boot.org/en/latest/android/fastboot.html#raw-partition-descriptors
>
> Thanks for this hint!
>
> Possible yes ( I must try)... but this will lead in adding
> complexity to scripts people use all over there and needs
> to adapt CI setups, as siemens has B0 and C0 variants.

If you try, please let me know.

Do the same boards (as in U-Boot board definition) have multiple SoC
variants (B0 and C0) ?

In that case I understand it's a pain to add more script complexity.

>
> If we introduce this series, user has nothing to know about
> offsets for different CPU modules as no change in API for
> them...

I understand, and I do like this approach as well. I just don't like
having 2 code paths/approaches for the "same thing".

I am not saying that this is a NAK, but i'd like to iterate a bit to see
if we can either deprecated raw partition descriptors (and migrate
existing boards) or use that everywhere.

I will try to use this series on VIM3 to see how it behaves. It will
take some time though.

Thanks
Mattijs

>
> bye,
> Heiko
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