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

[Inochi Amaoto]

On Wed, Sep 16, 2026 at 12:10:23PM -0500, Samuel Holland wrote:
> 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
> 

This is fair, and the fact is that the current fsbl can disable
coprocessor in its configuration. So I will not take this patch
and maybe do a cleanup for existed devicetree if I have enough
time for it.

Regards,
Inohci

> > Signed-off-by: Andrei Lalaev <andrey.lalaev at gmail.com>
> > ---
> >  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 at 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 at gmail.com>
> > 
> > 
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