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

[Mattijs Korpershoek <mkorpershoek@kernel.org>]

Hey Heiko,

On Thu, Jan 29, 2026 at 15:09, Mattijs Korpershoek <mkorpershoek@kernel.org> wrote:

> On Thu, Jan 29, 2026 at 11:41, Heiko Schocher <hs@nabladev.com> wrote:
>
>> Hello Mattijs,
>>
>> On 29.01.26 11:09, Mattijs Korpershoek wrote:
>>> On Mon, Jan 26, 2026 at 16:46, Heiko Schocher <hs@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@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.
>>
>> I am sorry, did not find time yet... sorry.
>>
>>> Do the same boards (as in U-Boot board definition) have multiple SoC
>>> variants (B0 and C0) ?
>>
>> Yes there is the capricorn board in U-Boot and it have different
>> variants (not all mainlined yet) with B0 and C0 variants...
>> number of boardvariants grown over the years, started even with A0 SoCs
>> (IIRC)...
>>
>>> In that case I understand it's a pain to add more script complexity.
>>
>> It is. and U-Boot could easily detect the SoC revision... and it is
>> fix ... so no need for having this configurable and making mistakes...
>
> I agree.
>
>>
>>>> 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".
>>
>> Hmm... understandable...
>>
>>> 
>>> 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.
>>
>> No idea if this is possible for all boards?
>>
>> May user want to write "some data" to an offset... which is not
>> SoC/board dependent...
>>
>> "flash bootloader" is well defined -> flash the bootloader, so I argue
>> that this should simply burn the bootloader to the correct offset...
>>
>> "raw" interface -> do what you think you need write to wherever you want...
>>
>>> I will try to use this series on VIM3 to see how it behaves. It will
>>> take some time though.
>>
>> VIM3 ? Is this a imx8qxp based hardware?
>
> No VIM3 is a board made by Khadas that has an Amlogic SoC. But they use
> the raw partition description for bootloader offset:
>
> include/configs/khadas-vim3_android.h
> 52:     "fastboot_raw_partition_bootloader=0x1 0xfff mmcpart 1\0"     \
> 53:     "fastboot_raw_partition_bootenv=0x0 0xfff mmcpart 2\0"        \
>
> So i'm wondering if this series can be useful to the VIM3 (so that we
> could drop the fastboot_raw_partition_* from khadas-vim3_android.h)

With some hacking around, I could drop both above fastboot_raw_* from
the vim3 environment and use fb_mmc_get_boot_offset() instead.

The issue I have is that fb_mmc_get_boot_offset() will return the same
offset for both BOOT1 and BOOT2. I'd like to pass a struct blk_desc* to
fb_mmc_get_boot_offset() so that I can specify the offset based on
desc->hwpart.

Do you think that's reasonable?

I won't ask you to do this in this series. This will be work I'll do
after this is merged.

>
>
>>
>> Thanks for your time!
>>
>> bye,
>> Heiko
>>> 
>>> Thanks
>>> Mattijs
>>> 
>>>>
>>>> bye,
>>>> Heiko
>>>> -- 
>>>> Nabla Software Engineering
>>>> HRB 40522 Augsburg
>>>> Phone: +49 821 45592596
>>>> E-Mail: office@nabladev.com
>>>> Geschäftsführer : Stefano Babic
>>
>> -- 
>> Nabla Software Engineering
>> HRB 40522 Augsburg
>> Phone: +49 821 45592596
>> E-Mail: office@nabladev.com
>> Geschäftsführer : Stefano Babic