Re: [PATCH v6 09/11] doc: spacemit: flash on K1 SoC based boards

[Yao Zi <me@ziyao.cc>]

On Mon, Jul 27, 2026 at 02:59:11PM +0800, Eric Chung wrote:
> Add document on how to flash images into eMMC of K1 SoC based boards.
> 
> Signed-off-by: Eric Chung <eric.chung@riscstar.com>
> 
> ---
> v3:
> - Add document on how to flash images into SD card.
> ---
>  board/spacemit/k1/MAINTAINERS |   2 +-
>  doc/board/spacemit/index.rst  |   1 +
>  doc/board/spacemit/k1-mmc.rst | 320 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 322 insertions(+), 1 deletion(-)

...

> diff --git a/doc/board/spacemit/k1-mmc.rst b/doc/board/spacemit/k1-mmc.rst
> new file mode 100644
> index 00000000000..b0fe78c75ce
> --- /dev/null
> +++ b/doc/board/spacemit/k1-mmc.rst
> @@ -0,0 +1,320 @@

...

> +Chapter 2: SD Card Boot
> +=======================
> +
> +
> +SpacemiT K1 Bianbu SD Card Image Flashing and U-Boot Update Guide
> +==================================================================
> +
> +This guide explains how to prepare a bootable SD card with Bianbu OS for
> +SpacemiT K1 based boards and how to replace the U-Boot binary on the SD
> +card with a custom build.
> +
> +Prerequisites
> +~~~~~~~~~~~~~
> +
> +- A SpacemiT K1 based development board
> +- A microSD card (at least 8 GB capacity recommended)
> +- A card reader for your host computer
> +- A Linux host system (for ``dd``, ``fdisk``, ``lsblk`` commands)
> +- The Bianbu SD card image from
> +   <https://spacemit.com/community/resources-download/Images%20Collects/K1/Bianbu>
> +- A custom ``u-boot.itb`` file (device tree blob or U-Boot FIT image) to be
> +  written to the U-Boot partition
> +
> +Prepare the SD Card & the image
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +**1. Download the image**
> +
> +Download the released package from the official SpacemiT website:
> +
> +<https://archive.spacemit.com/image/k1/version/bianbu/v2.3.5/Bianbu-Minimal-K1-sdcard-V2.3.5-20260601180942.img.zip>
> +
> +**2. Extract the image**
> +
> +.. code-block:: console
> +
> +   $ unzip Bianbu-Minimal-K1-sdcard-V2.3.5-20260601180942.img.zip
> +
> +**3. Identify the SD card device**
> +
> +Insert the microSD card into your card reader, then run:
> +
> +.. code-block:: console
> +
> +   $ lsblk
> +
> +Compare the output before and after inserting the card to identify
> +the new device. It will typically appear as ``/dev/sdb``, ``/dev/sdc``,
> +or ``/dev/mmcblk0``.
> +
> +**4. Write the image to the SD card**
> +
> +.. code-block:: console
> +
> +   $ sudo dd if=./Bianbu-Minimal-K1-sdcard-V2.3.5-20260601180942.img of=/dev/sdb bs=1M status=progress
> +
> +The SD card is now ready as a bootable Bianbu system disk.

This looks out of scope of describing how to create a bootable SD card
with U-Boot. In my opinion, you'd better describe the requirements of
parition layout and image position for SD-card booting, to allow readers
to create their own images/bootable medium from scratch more easily,
instead of sticking to the vendored image.

Best regards,
Yao Zi