As I’m using UART0 for a GPS receiver on visionfive2 I wanted to be able to change u-boot related settings from linux without using the serial.
This led me down a rabbit hole to get fw_printenv from the u-boot tools to work.
Before realizing that @strlcat already created a pull request i created my own patch for the jh7110.dtsi
--- arch/riscv/boot/dts/starfive/jh7110_orig.dtsi 2023-04-25 12:18:33.840079960 +0000
+++ arch/riscv/boot/dts/starfive/jh7110.dtsi 2023-04-25 12:21:37.123148082 +0000
@@ -372,13 +372,16 @@
#size-cells = <1>;
spl@0 {
- reg = <0x0 0x40000>;
+ reg = <0x0 0x80000>;
+ };
+ uboot-env@f0000 {
+ reg = <0xf0000 0x10000>;
};
uboot@100000 {
- reg = <0x100000 0x300000>;
+ reg = <0x100000 0x400000>;
};
data@f00000 {
- reg = <0xf00000 0x100000>;
+ reg = <0x600000 0x1000000>;
};
};
};
slightly different namings and without the use of the full flash, but essentially the same just inserting siyes and offsets from Boot Address Allocation
Together with the correct /etc/fw_env.config:
# MTD device name Device offset Env. size Flash sector size Number of sectors
/dev/mtd1 0x0 0x10000
The uboot tools fw_printenv and fw_setenv just work (apt install libubootenv-tool) 
Maybe i’m now brave enough to try moving the u-boot serial to uart3…