Re: [PATCH v2 2/2] board: sophgo: Add support for Milk-V Duo S

[Yao Zi <me@ziyao.cc>]

On Sun, Oct 25, 2026 at 11:30:24AM -0300, João Paulo Gonçalves wrote:
> Add support for the Milk-V Duo S, a development board based on the
> Sophgo SG2000 SoC with 512 MiB of RAM.
> 
> The SG2000 differs from the CV1800B used on the Milk-V Duo 64M and the
> SG2002 used on the Milk-V Duo 256M, but these SoCs share most of their
> IP blocks, including the CPU core, so the existing CV1800B support can
> be reused.
> 
> Add a separate board directory, target and defconfig for the Duo S,
> based on the Milk-V Duo 256M ones. Like the Duo 256M, it reuses the
> common Milk-V Duo board code. The defconfig uses the upstream devicetree
> via OF_UPSTREAM.
> 
> Link: https://milkv.io/docs/duo/getting-started/duos
> Acked-by: Andrei Lalaev <andrey.lalaev@gmail.com>
> Acked-by: Hiago De Franco <hfranco@baylibre.com>
> Signed-off-by: João Paulo Gonçalves <jpaulo.silvagoncalves@gmail.com>
> ---
>  arch/riscv/Kconfig                       |   4 +
>  board/sophgo/milkv_duo_s/Kconfig         |  30 +++++++
>  board/sophgo/milkv_duo_s/MAINTAINERS     |   8 ++
>  board/sophgo/milkv_duo_s/Makefile        |   6 ++
>  board/sophgo/milkv_duo_s/milkv_duo_s.env |   8 ++
>  configs/milkv_duo_s_defconfig            |  43 ++++++++++
>  doc/board/sophgo/index.rst               |   1 +
>  doc/board/sophgo/milkv_duo_s.rst         | 131 +++++++++++++++++++++++++++++++

Please separate documentation changes into another commit.

>  include/configs/milkv_duo_s.h            |  12 +++
>  9 files changed, 243 insertions(+)

...

> diff --git a/configs/milkv_duo_s_defconfig b/configs/milkv_duo_s_defconfig
> new file mode 100644
> index 000000000000..41a31c4ad46c
> --- /dev/null
> +++ b/configs/milkv_duo_s_defconfig
> @@ -0,0 +1,43 @@
> +CONFIG_RISCV=y
> +CONFIG_SYS_MALLOC_LEN=0x820000
> +CONFIG_SYS_MALLOC_F_LEN=0x8000
> +CONFIG_NR_DRAM_BANKS=1
> +CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y
> +CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0x82300000
> +CONFIG_DEFAULT_DEVICE_TREE="sophgo/sg2000-milkv-duo-s"
> +CONFIG_SYS_LOAD_ADDR=0x80080000
> +CONFIG_IDENT_STRING=" milkv_duo_s"
> +CONFIG_TARGET_MILKV_DUO_S=y
> +CONFIG_ARCH_RV64I=y
> +CONFIG_RISCV_SMODE=y
> +CONFIG_FIT=y
> +CONFIG_BOOTSTD_FULL=y
> +# CONFIG_BOOTMETH_EFI_BOOTMGR is not set
> +CONFIG_SD_BOOT=y
> +CONFIG_SYS_CBSIZE=512
> +CONFIG_SYS_PBSIZE=544
> +CONFIG_SYS_PROMPT="milkv_duo_s# "
> +# CONFIG_CMD_BOOTDEV is not set
> +CONFIG_CMD_MBR=y
> +CONFIG_CMD_MMC=y
> +CONFIG_CMD_POWEROFF=y
> +# CONFIG_CMD_MII is not set
> +CONFIG_CMD_EXT4_WRITE=y
> +# CONFIG_ISO_PARTITION is not set
> +# CONFIG_EFI_PARTITION is not set

Personally speaking, I prefer to turn on EFI related stuff
(BOOTMETH_EFI_BOOTMGR and EFI_PARTITION). Here EFI is more practical
since Duo-S carries 512MiB RAM, and I do have a device booted through
EFI.

But anyway, it's a embedded device and takes forever to boot a generic
distribution, so what you've done here is fine, too.

...

> diff --git a/doc/board/sophgo/index.rst b/doc/board/sophgo/index.rst
> index 19c9a19b1d4b..61aceafceea3 100644
> --- a/doc/board/sophgo/index.rst
> +++ b/doc/board/sophgo/index.rst
> @@ -7,4 +7,5 @@ Sophgo
>  
>     milkv_duo
>     milkv_duo_256m
> +   milkv_duo_s
>     licheerv_nano
> diff --git a/doc/board/sophgo/milkv_duo_s.rst b/doc/board/sophgo/milkv_duo_s.rst
> new file mode 100644
> index 000000000000..9f6bf04d1842
> --- /dev/null
> +++ b/doc/board/sophgo/milkv_duo_s.rst

...

> +Boot flow
> +~~~~~~~~~
> +The board boots from a FIP image, fip.bin, which contains the following
> +binaries:
> +
> +- FSBL (First Stage Boot Loader): the vendor bootloader [1]. It serves the
> +  same purpose as U-Boot SPL, but U-Boot does not support SPL for this SoC
> +  yet, so the vendor FSBL is required.
> +- Coprocessor firmware: the vendor firmware (cvirtos.bin) or custom firmware
> +  for the C906L coprocessor. It is not needed to boot U-Boot, but it is
> +  required by fiptool.

Please confirm whether this is correct. I remembered the coprocessor
firmware is optional, too.

> +- OpenSBI (fw_dynamic.bin), built with the board devicetree.
> +- U-Boot (u-boot.bin).

...

> +5. Set the board's boot core selection switch to RISC-V.

It'll be nice to describe the exact position of the switch.

...

Regards,
Yao Zi