Re: [PATCH] riscv: dts: sophgo: sg2000-milkv-duo-s: reserve memory for RTOS

[Samuel Holland]

Hi Andrei,

On 2026-09-16 11:06 AM, Andrei Lalaev wrote:
> The FSBL loads the coprocessor firmware into the last 2 MB of RAM.
> Reserve this region to prevent Linux from using it.

If the FSBL wants to reserve some RAM, it should modify the devicetree at
runtime to add that reservation. Adding the reservation here creates an
unnecessary ABI surface between the FSBL and all consumers of the devicetree.

Regards,
Samuel

> Signed-off-by: Andrei Lalaev <andrey.lalaev@xxxxxxxxx>
> ---
>  arch/riscv/boot/dts/sophgo/sg2000-milkv-duo-s.dts | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/riscv/boot/dts/sophgo/sg2000-milkv-duo-s.dts b/arch/riscv/boot/dts/sophgo/sg2000-milkv-duo-s.dts
> index 78a257839f6f..693c9fd7b771 100644
> --- a/arch/riscv/boot/dts/sophgo/sg2000-milkv-duo-s.dts
> +++ b/arch/riscv/boot/dts/sophgo/sg2000-milkv-duo-s.dts
> @@ -22,6 +22,17 @@ chosen {
>  		stdout-path = "serial0:115200n8";
>  	};
>  
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		coprocessor_rtos: region@9fe00000 {
> +			reg = <0x9fe00000 0x200000>;
> +			no-map;
> +		};
> +	};
> +
>  	wifi_pwrseq: wifi-pwrseq {
>  		compatible = "mmc-pwrseq-simple";
>  		reset-gpios = <&porta 15 GPIO_ACTIVE_LOW>;
> 
> ---
> base-commit: 9b87fdc9af2fbfcdb5c24a64139685ef80f6573f
> change-id: 20260916-milkv-duo-s-rtos-memory-7a94933e35bd
> 
> Best regards,
> --  
> Andrei Lalaev <andrey.lalaev@xxxxxxxxx>
> 
> 
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